diff options
Diffstat (limited to 'arch/x86/kvm/mmu/mmu.c')
| -rw-r--r-- | arch/x86/kvm/mmu/mmu.c | 6442 |
1 files changed, 4202 insertions, 2240 deletions
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 845d114ae075..02c450686b4a 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -14,6 +14,7 @@ * Yaniv Kamay <yaniv@qumranet.com> * Avi Kivity <avi@qumranet.com> */ +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include "irq.h" #include "ioapic.h" @@ -22,7 +23,9 @@ #include "tdp_mmu.h" #include "x86.h" #include "kvm_cache_regs.h" +#include "smm.h" #include "kvm_emulate.h" +#include "page_track.h" #include "cpuid.h" #include "spte.h" @@ -42,20 +45,24 @@ #include <linux/uaccess.h> #include <linux/hash.h> #include <linux/kern_levels.h> +#include <linux/kstrtox.h> #include <linux/kthread.h> +#include <linux/wordpart.h> #include <asm/page.h> #include <asm/memtype.h> #include <asm/cmpxchg.h> #include <asm/io.h> #include <asm/set_memory.h> +#include <asm/spec-ctrl.h> #include <asm/vmx.h> -#include <asm/kvm_page_track.h> + #include "trace.h" -extern bool itlb_multihit_kvm_mitigation; +static bool nx_hugepage_mitigation_hard_disabled; int __read_mostly nx_huge_pages = -1; +static uint __read_mostly nx_huge_pages_recovery_period_ms; #ifdef CONFIG_PREEMPT_RT /* Recovery can cause latency spikes, disable it for PREEMPT_RT. */ static uint __read_mostly nx_huge_pages_recovery_ratio = 0; @@ -63,24 +70,28 @@ static uint __read_mostly nx_huge_pages_recovery_ratio = 0; static uint __read_mostly nx_huge_pages_recovery_ratio = 60; #endif +static int get_nx_huge_pages(char *buffer, const struct kernel_param *kp); static int set_nx_huge_pages(const char *val, const struct kernel_param *kp); -static int set_nx_huge_pages_recovery_ratio(const char *val, const struct kernel_param *kp); +static int set_nx_huge_pages_recovery_param(const char *val, const struct kernel_param *kp); static const struct kernel_param_ops nx_huge_pages_ops = { .set = set_nx_huge_pages, - .get = param_get_bool, + .get = get_nx_huge_pages, }; -static const struct kernel_param_ops nx_huge_pages_recovery_ratio_ops = { - .set = set_nx_huge_pages_recovery_ratio, +static const struct kernel_param_ops nx_huge_pages_recovery_param_ops = { + .set = set_nx_huge_pages_recovery_param, .get = param_get_uint, }; module_param_cb(nx_huge_pages, &nx_huge_pages_ops, &nx_huge_pages, 0644); __MODULE_PARM_TYPE(nx_huge_pages, "bool"); -module_param_cb(nx_huge_pages_recovery_ratio, &nx_huge_pages_recovery_ratio_ops, +module_param_cb(nx_huge_pages_recovery_ratio, &nx_huge_pages_recovery_param_ops, &nx_huge_pages_recovery_ratio, 0644); __MODULE_PARM_TYPE(nx_huge_pages_recovery_ratio, "uint"); +module_param_cb(nx_huge_pages_recovery_period_ms, &nx_huge_pages_recovery_param_ops, + &nx_huge_pages_recovery_period_ms, 0644); +__MODULE_PARM_TYPE(nx_huge_pages_recovery_period_ms, "uint"); static bool __read_mostly force_flush_and_sync_on_reuse; module_param_named(flush_on_reuse, force_flush_and_sync_on_reuse, bool, 0644); @@ -94,53 +105,52 @@ module_param_named(flush_on_reuse, force_flush_and_sync_on_reuse, bool, 0644); */ bool tdp_enabled = false; -static int max_huge_page_level __read_mostly; -static int max_tdp_level __read_mostly; - -enum { - AUDIT_PRE_PAGE_FAULT, - AUDIT_POST_PAGE_FAULT, - AUDIT_PRE_PTE_WRITE, - AUDIT_POST_PTE_WRITE, - AUDIT_PRE_SYNC, - AUDIT_POST_SYNC -}; +static bool __ro_after_init tdp_mmu_allowed; -#ifdef MMU_DEBUG -bool dbg = 0; -module_param(dbg, bool, 0644); +#ifdef CONFIG_X86_64 +bool __read_mostly tdp_mmu_enabled = true; +module_param_named(tdp_mmu, tdp_mmu_enabled, bool, 0444); +EXPORT_SYMBOL_FOR_KVM_INTERNAL(tdp_mmu_enabled); #endif -#define PTE_PREFETCH_NUM 8 - -#define PT32_LEVEL_BITS 10 - -#define PT32_LEVEL_SHIFT(level) \ - (PAGE_SHIFT + (level - 1) * PT32_LEVEL_BITS) - -#define PT32_LVL_OFFSET_MASK(level) \ - (PT32_BASE_ADDR_MASK & ((1ULL << (PAGE_SHIFT + (((level) - 1) \ - * PT32_LEVEL_BITS))) - 1)) - -#define PT32_INDEX(address, level)\ - (((address) >> PT32_LEVEL_SHIFT(level)) & ((1 << PT32_LEVEL_BITS) - 1)) - +static int max_huge_page_level __read_mostly; +static int tdp_root_level __read_mostly; +static int max_tdp_level __read_mostly; -#define PT32_BASE_ADDR_MASK PAGE_MASK -#define PT32_DIR_BASE_ADDR_MASK \ - (PAGE_MASK & ~((1ULL << (PAGE_SHIFT + PT32_LEVEL_BITS)) - 1)) -#define PT32_LVL_ADDR_MASK(level) \ - (PAGE_MASK & ~((1ULL << (PAGE_SHIFT + (((level) - 1) \ - * PT32_LEVEL_BITS))) - 1)) +#define PTE_PREFETCH_NUM 8 #include <trace/events/kvm.h> -/* make pte_list_desc fit well in cache line */ -#define PTE_LIST_EXT 3 +/* make pte_list_desc fit well in cache lines */ +#define PTE_LIST_EXT 14 +/* + * struct pte_list_desc is the core data structure used to implement a custom + * list for tracking a set of related SPTEs, e.g. all the SPTEs that map a + * given GFN when used in the context of rmaps. Using a custom list allows KVM + * to optimize for the common case where many GFNs will have at most a handful + * of SPTEs pointing at them, i.e. allows packing multiple SPTEs into a small + * memory footprint, which in turn improves runtime performance by exploiting + * cache locality. + * + * A list is comprised of one or more pte_list_desc objects (descriptors). + * Each individual descriptor stores up to PTE_LIST_EXT SPTEs. If a descriptor + * is full and a new SPTEs needs to be added, a new descriptor is allocated and + * becomes the head of the list. This means that by definitions, all tail + * descriptors are full. + * + * Note, the meta data fields are deliberately placed at the start of the + * structure to optimize the cacheline layout; accessing the descriptor will + * touch only a single cacheline so long as @spte_count<=6 (or if only the + * descriptors metadata is accessed). + */ struct pte_list_desc { - u64 *sptes[PTE_LIST_EXT]; struct pte_list_desc *more; + /* The number of PTEs stored in _this_ descriptor. */ + u32 spte_count; + /* The number of PTEs stored in all tails of this descriptor. */ + u32 tail_count; + u64 *sptes[PTE_LIST_EXT]; }; struct kvm_shadow_walk_iterator { @@ -170,11 +180,8 @@ struct kvm_shadow_walk_iterator { static struct kmem_cache *pte_list_desc_cache; struct kmem_cache *mmu_page_header_cache; -static struct percpu_counter kvm_total_used_mmu_pages; static void mmu_spte_set(u64 *sptep, u64 spte); -static union kvm_mmu_page_role -kvm_mmu_calc_root_page_role(struct kvm_vcpu *vcpu); struct kvm_mmu_role_regs { const unsigned long cr0; @@ -187,11 +194,12 @@ struct kvm_mmu_role_regs { /* * Yes, lot's of underscores. They're a hint that you probably shouldn't be - * reading from the role_regs. Once the mmu_role is constructed, it becomes + * reading from the role_regs. Once the root_role is constructed, it becomes * the single source of truth for the MMU's state. */ #define BUILD_MMU_ROLE_REGS_ACCESSOR(reg, name, flag) \ -static inline bool ____is_##reg##_##name(struct kvm_mmu_role_regs *regs)\ +static inline bool __maybe_unused \ +____is_##reg##_##name(const struct kvm_mmu_role_regs *regs) \ { \ return !!(regs->reg & flag); \ } @@ -213,19 +221,28 @@ BUILD_MMU_ROLE_REGS_ACCESSOR(efer, lma, EFER_LMA); * and the vCPU may be incorrect/irrelevant. */ #define BUILD_MMU_ROLE_ACCESSOR(base_or_ext, reg, name) \ -static inline bool is_##reg##_##name(struct kvm_mmu *mmu) \ +static inline bool __maybe_unused is_##reg##_##name(struct kvm_mmu *mmu) \ { \ - return !!(mmu->mmu_role. base_or_ext . reg##_##name); \ + return !!(mmu->cpu_role. base_or_ext . reg##_##name); \ } -BUILD_MMU_ROLE_ACCESSOR(ext, cr0, pg); BUILD_MMU_ROLE_ACCESSOR(base, cr0, wp); BUILD_MMU_ROLE_ACCESSOR(ext, cr4, pse); -BUILD_MMU_ROLE_ACCESSOR(ext, cr4, pae); BUILD_MMU_ROLE_ACCESSOR(ext, cr4, smep); BUILD_MMU_ROLE_ACCESSOR(ext, cr4, smap); BUILD_MMU_ROLE_ACCESSOR(ext, cr4, pke); BUILD_MMU_ROLE_ACCESSOR(ext, cr4, la57); BUILD_MMU_ROLE_ACCESSOR(base, efer, nx); +BUILD_MMU_ROLE_ACCESSOR(ext, efer, lma); + +static inline bool is_cr0_pg(struct kvm_mmu *mmu) +{ + return mmu->cpu_role.base.level > 0; +} + +static inline bool is_cr4_pae(struct kvm_mmu *mmu) +{ + return !mmu->cpu_role.base.has_4_byte_gpte; +} static struct kvm_mmu_role_regs vcpu_to_role_regs(struct kvm_vcpu *vcpu) { @@ -238,45 +255,38 @@ static struct kvm_mmu_role_regs vcpu_to_role_regs(struct kvm_vcpu *vcpu) return regs; } -static int role_regs_to_root_level(struct kvm_mmu_role_regs *regs) +static unsigned long get_guest_cr3(struct kvm_vcpu *vcpu) { - if (!____is_cr0_pg(regs)) - return 0; - else if (____is_efer_lma(regs)) - return ____is_cr4_la57(regs) ? PT64_ROOT_5LEVEL : - PT64_ROOT_4LEVEL; - else if (____is_cr4_pae(regs)) - return PT32E_ROOT_LEVEL; - else - return PT32_ROOT_LEVEL; + return kvm_read_cr3(vcpu); } -static inline bool kvm_available_flush_tlb_with_range(void) +static inline unsigned long kvm_mmu_get_guest_pgd(struct kvm_vcpu *vcpu, + struct kvm_mmu *mmu) { - return kvm_x86_ops.tlb_remote_flush_with_range; + if (IS_ENABLED(CONFIG_MITIGATION_RETPOLINE) && mmu->get_guest_pgd == get_guest_cr3) + return kvm_read_cr3(vcpu); + + return mmu->get_guest_pgd(vcpu); } -static void kvm_flush_remote_tlbs_with_range(struct kvm *kvm, - struct kvm_tlb_range *range) +static inline bool kvm_available_flush_remote_tlbs_range(void) { - int ret = -ENOTSUPP; - - if (range && kvm_x86_ops.tlb_remote_flush_with_range) - ret = static_call(kvm_x86_tlb_remote_flush_with_range)(kvm, range); - - if (ret) - kvm_flush_remote_tlbs(kvm); +#if IS_ENABLED(CONFIG_HYPERV) + return kvm_x86_ops.flush_remote_tlbs_range; +#else + return false; +#endif } -void kvm_flush_remote_tlbs_with_address(struct kvm *kvm, - u64 start_gfn, u64 pages) -{ - struct kvm_tlb_range range; +static gfn_t kvm_mmu_page_get_gfn(struct kvm_mmu_page *sp, int index); - range.start_gfn = start_gfn; - range.pages = pages; +/* Flush the range of guest memory mapped by the given SPTE. */ +static void kvm_flush_remote_tlbs_sptep(struct kvm *kvm, u64 *sptep) +{ + struct kvm_mmu_page *sp = sptep_to_sp(sptep); + gfn_t gfn = kvm_mmu_page_get_gfn(sp, spte_index(sptep)); - kvm_flush_remote_tlbs_with_range(kvm, &range); + kvm_flush_remote_tlbs_gfn(kvm, gfn, sp->role.level); } static void mark_mmio_spte(struct kvm_vcpu *vcpu, u64 *sptep, u64 gfn, @@ -318,43 +328,27 @@ static bool check_mmio_spte(struct kvm_vcpu *vcpu, u64 spte) return likely(kvm_gen == spte_gen); } -static gpa_t translate_gpa(struct kvm_vcpu *vcpu, gpa_t gpa, u32 access, - struct x86_exception *exception) -{ - /* Check if guest physical address doesn't exceed guest maximum */ - if (kvm_vcpu_is_illegal_gpa(vcpu, gpa)) { - exception->error_code |= PFERR_RSVD_MASK; - return UNMAPPED_GVA; - } - - return gpa; -} - static int is_cpuid_PSE36(void) { return 1; } -static gfn_t pse36_gfn_delta(u32 gpte) -{ - int shift = 32 - PT32_DIR_PSE36_SHIFT - PAGE_SHIFT; - - return (gpte & PT32_DIR_PSE36_MASK) << shift; -} - #ifdef CONFIG_X86_64 static void __set_spte(u64 *sptep, u64 spte) { + KVM_MMU_WARN_ON(is_ept_ve_possible(spte)); WRITE_ONCE(*sptep, spte); } static void __update_clear_spte_fast(u64 *sptep, u64 spte) { + KVM_MMU_WARN_ON(is_ept_ve_possible(spte)); WRITE_ONCE(*sptep, spte); } static u64 __update_clear_spte_slow(u64 *sptep, u64 spte) { + KVM_MMU_WARN_ON(is_ept_ve_possible(spte)); return xchg(sptep, spte); } @@ -441,8 +435,8 @@ static u64 __update_clear_spte_slow(u64 *sptep, u64 spte) * The idea using the light way get the spte on x86_32 guest is from * gup_get_pte (mm/gup.c). * - * An spte tlb flush may be pending, because kvm_set_pte_rmapp - * coalesces them and we are running out of the MMU lock. Therefore + * An spte tlb flush may be pending, because they are coalesced and + * we are running out of the MMU lock. Therefore * we need to protect against in-progress updates of the spte. * * Reading the spte while an update is in progress may get the old value @@ -479,30 +473,6 @@ retry: } #endif -static bool spte_has_volatile_bits(u64 spte) -{ - if (!is_shadow_present_pte(spte)) - return false; - - /* - * Always atomically update spte if it can be updated - * out of mmu-lock, it can ensure dirty bit is not lost, - * also, it can help us to get a stable is_writable_pte() - * to ensure tlb flush is not missed. - */ - if (spte_can_locklessly_be_made_writable(spte) || - is_access_track_spte(spte)) - return true; - - if (spte_ad_enabled(spte)) { - if ((spte & shadow_accessed_mask) == 0 || - (is_writable_pte(spte) && (spte & shadow_dirty_mask) == 0)) - return true; - } - - return false; -} - /* Rules for using mmu_spte_set: * Set the sptep from nonpresent to present. * Note: the sptep being assigned *must* be either not present @@ -511,116 +481,60 @@ static bool spte_has_volatile_bits(u64 spte) */ static void mmu_spte_set(u64 *sptep, u64 new_spte) { - WARN_ON(is_shadow_present_pte(*sptep)); + WARN_ON_ONCE(is_shadow_present_pte(*sptep)); __set_spte(sptep, new_spte); } -/* - * Update the SPTE (excluding the PFN), but do not track changes in its - * accessed/dirty status. +/* Rules for using mmu_spte_update: + * Update the state bits, it means the mapped pfn is not changed. + * + * Returns true if the TLB needs to be flushed */ -static u64 mmu_spte_update_no_track(u64 *sptep, u64 new_spte) +static bool mmu_spte_update(u64 *sptep, u64 new_spte) { u64 old_spte = *sptep; - WARN_ON(!is_shadow_present_pte(new_spte)); + WARN_ON_ONCE(!is_shadow_present_pte(new_spte)); + check_spte_writable_invariants(new_spte); if (!is_shadow_present_pte(old_spte)) { mmu_spte_set(sptep, new_spte); - return old_spte; + return false; } - if (!spte_has_volatile_bits(old_spte)) + if (!spte_needs_atomic_update(old_spte)) __update_clear_spte_fast(sptep, new_spte); else old_spte = __update_clear_spte_slow(sptep, new_spte); - WARN_ON(spte_to_pfn(old_spte) != spte_to_pfn(new_spte)); + WARN_ON_ONCE(!is_shadow_present_pte(old_spte) || + spte_to_pfn(old_spte) != spte_to_pfn(new_spte)); - return old_spte; -} - -/* Rules for using mmu_spte_update: - * Update the state bits, it means the mapped pfn is not changed. - * - * Whenever we overwrite a writable spte with a read-only one we - * should flush remote TLBs. Otherwise rmap_write_protect - * will find a read-only spte, even though the writable spte - * might be cached on a CPU's TLB, the return value indicates this - * case. - * - * Returns true if the TLB needs to be flushed - */ -static bool mmu_spte_update(u64 *sptep, u64 new_spte) -{ - bool flush = false; - u64 old_spte = mmu_spte_update_no_track(sptep, new_spte); - - if (!is_shadow_present_pte(old_spte)) - return false; - - /* - * For the spte updated out of mmu-lock is safe, since - * we always atomically update it, see the comments in - * spte_has_volatile_bits(). - */ - if (spte_can_locklessly_be_made_writable(old_spte) && - !is_writable_pte(new_spte)) - flush = true; - - /* - * Flush TLB when accessed/dirty states are changed in the page tables, - * to guarantee consistency between TLB and page tables. - */ - - if (is_accessed_spte(old_spte) && !is_accessed_spte(new_spte)) { - flush = true; - kvm_set_pfn_accessed(spte_to_pfn(old_spte)); - } - - if (is_dirty_spte(old_spte) && !is_dirty_spte(new_spte)) { - flush = true; - kvm_set_pfn_dirty(spte_to_pfn(old_spte)); - } - - return flush; + return leaf_spte_change_needs_tlb_flush(old_spte, new_spte); } /* * Rules for using mmu_spte_clear_track_bits: * It sets the sptep from present to nonpresent, and track the * state bits, it is used to clear the last level sptep. - * Returns non-zero if the PTE was previously valid. + * Returns the old PTE. */ -static int mmu_spte_clear_track_bits(u64 *sptep) +static u64 mmu_spte_clear_track_bits(struct kvm *kvm, u64 *sptep) { - kvm_pfn_t pfn; u64 old_spte = *sptep; + int level = sptep_to_sp(sptep)->role.level; - if (!spte_has_volatile_bits(old_spte)) - __update_clear_spte_fast(sptep, 0ull); + if (!is_shadow_present_pte(old_spte) || + !spte_needs_atomic_update(old_spte)) + __update_clear_spte_fast(sptep, SHADOW_NONPRESENT_VALUE); else - old_spte = __update_clear_spte_slow(sptep, 0ull); + old_spte = __update_clear_spte_slow(sptep, SHADOW_NONPRESENT_VALUE); if (!is_shadow_present_pte(old_spte)) - return 0; - - pfn = spte_to_pfn(old_spte); - - /* - * KVM does not hold the refcount of the page used by - * kvm mmu, before reclaiming the page, we should - * unmap it from mmu first. - */ - WARN_ON(!kvm_is_reserved_pfn(pfn) && !page_count(pfn_to_page(pfn))); - - if (is_accessed_spte(old_spte)) - kvm_set_pfn_accessed(pfn); - - if (is_dirty_spte(old_spte)) - kvm_set_pfn_dirty(pfn); + return old_spte; - return 1; + kvm_update_page_stats(kvm, level, -1); + return old_spte; } /* @@ -630,7 +544,7 @@ static int mmu_spte_clear_track_bits(u64 *sptep) */ static void mmu_spte_clear_no_track(u64 *sptep) { - __update_clear_spte_fast(sptep, 0ull); + __update_clear_spte_fast(sptep, SHADOW_NONPRESENT_VALUE); } static u64 mmu_spte_get_lockless(u64 *sptep) @@ -638,74 +552,43 @@ static u64 mmu_spte_get_lockless(u64 *sptep) return __get_spte_lockless(sptep); } -/* Restore an acc-track PTE back to a regular PTE */ -static u64 restore_acc_track_spte(u64 spte) +static inline bool is_tdp_mmu_active(struct kvm_vcpu *vcpu) { - u64 new_spte = spte; - u64 saved_bits = (spte >> SHADOW_ACC_TRACK_SAVED_BITS_SHIFT) - & SHADOW_ACC_TRACK_SAVED_BITS_MASK; - - WARN_ON_ONCE(spte_ad_enabled(spte)); - WARN_ON_ONCE(!is_access_track_spte(spte)); - - new_spte &= ~shadow_acc_track_mask; - new_spte &= ~(SHADOW_ACC_TRACK_SAVED_BITS_MASK << - SHADOW_ACC_TRACK_SAVED_BITS_SHIFT); - new_spte |= saved_bits; - - return new_spte; + return tdp_mmu_enabled && vcpu->arch.mmu->root_role.direct; } -/* Returns the Accessed status of the PTE and resets it at the same time. */ -static bool mmu_spte_age(u64 *sptep) +static void walk_shadow_page_lockless_begin(struct kvm_vcpu *vcpu) { - u64 spte = mmu_spte_get_lockless(sptep); - - if (!is_accessed_spte(spte)) - return false; - - if (spte_ad_enabled(spte)) { - clear_bit((ffs(shadow_accessed_mask) - 1), - (unsigned long *)sptep); + if (is_tdp_mmu_active(vcpu)) { + kvm_tdp_mmu_walk_lockless_begin(); } else { /* - * Capture the dirty status of the page, so that it doesn't get - * lost when the SPTE is marked for access tracking. + * Prevent page table teardown by making any free-er wait during + * kvm_flush_remote_tlbs() IPI to all active vcpus. */ - if (is_writable_pte(spte)) - kvm_set_pfn_dirty(spte_to_pfn(spte)); + local_irq_disable(); - spte = mark_spte_for_access_track(spte); - mmu_spte_update_no_track(sptep, spte); + /* + * Make sure a following spte read is not reordered ahead of the write + * to vcpu->mode. + */ + smp_store_mb(vcpu->mode, READING_SHADOW_PAGE_TABLES); } - - return true; -} - -static void walk_shadow_page_lockless_begin(struct kvm_vcpu *vcpu) -{ - /* - * Prevent page table teardown by making any free-er wait during - * kvm_flush_remote_tlbs() IPI to all active vcpus. - */ - local_irq_disable(); - - /* - * Make sure a following spte read is not reordered ahead of the write - * to vcpu->mode. - */ - smp_store_mb(vcpu->mode, READING_SHADOW_PAGE_TABLES); } static void walk_shadow_page_lockless_end(struct kvm_vcpu *vcpu) { - /* - * Make sure the write to vcpu->mode is not reordered in front of - * reads to sptes. If it does, kvm_mmu_commit_zap_page() can see us - * OUTSIDE_GUEST_MODE and proceed to free the shadow page table. - */ - smp_store_release(&vcpu->mode, OUTSIDE_GUEST_MODE); - local_irq_enable(); + if (is_tdp_mmu_active(vcpu)) { + kvm_tdp_mmu_walk_lockless_end(); + } else { + /* + * Make sure the write to vcpu->mode is not reordered in front of + * reads to sptes. If it does, kvm_mmu_commit_zap_page() can see us + * OUTSIDE_GUEST_MODE and proceed to free the shadow page table. + */ + smp_store_release(&vcpu->mode, OUTSIDE_GUEST_MODE); + local_irq_enable(); + } } static int mmu_topup_memory_caches(struct kvm_vcpu *vcpu, bool maybe_indirect) @@ -717,12 +600,18 @@ static int mmu_topup_memory_caches(struct kvm_vcpu *vcpu, bool maybe_indirect) 1 + PT64_ROOT_MAX_LEVEL + PTE_PREFETCH_NUM); if (r) return r; + if (kvm_has_mirrored_tdp(vcpu->kvm)) { + r = kvm_mmu_topup_memory_cache(&vcpu->arch.mmu_external_spt_cache, + PT64_ROOT_MAX_LEVEL); + if (r) + return r; + } r = kvm_mmu_topup_memory_cache(&vcpu->arch.mmu_shadow_page_cache, PT64_ROOT_MAX_LEVEL); if (r) return r; if (maybe_indirect) { - r = kvm_mmu_topup_memory_cache(&vcpu->arch.mmu_gfn_array_cache, + r = kvm_mmu_topup_memory_cache(&vcpu->arch.mmu_shadowed_info_cache, PT64_ROOT_MAX_LEVEL); if (r) return r; @@ -735,40 +624,80 @@ static void mmu_free_memory_caches(struct kvm_vcpu *vcpu) { kvm_mmu_free_memory_cache(&vcpu->arch.mmu_pte_list_desc_cache); kvm_mmu_free_memory_cache(&vcpu->arch.mmu_shadow_page_cache); - kvm_mmu_free_memory_cache(&vcpu->arch.mmu_gfn_array_cache); + kvm_mmu_free_memory_cache(&vcpu->arch.mmu_shadowed_info_cache); + kvm_mmu_free_memory_cache(&vcpu->arch.mmu_external_spt_cache); kvm_mmu_free_memory_cache(&vcpu->arch.mmu_page_header_cache); } -static struct pte_list_desc *mmu_alloc_pte_list_desc(struct kvm_vcpu *vcpu) -{ - return kvm_mmu_memory_cache_alloc(&vcpu->arch.mmu_pte_list_desc_cache); -} - static void mmu_free_pte_list_desc(struct pte_list_desc *pte_list_desc) { kmem_cache_free(pte_list_desc_cache, pte_list_desc); } +static bool sp_has_gptes(struct kvm_mmu_page *sp); + static gfn_t kvm_mmu_page_get_gfn(struct kvm_mmu_page *sp, int index) { - if (!sp->role.direct) - return sp->gfns[index]; + if (sp->role.passthrough) + return sp->gfn; + + if (sp->shadowed_translation) + return sp->shadowed_translation[index] >> PAGE_SHIFT; - return sp->gfn + (index << ((sp->role.level - 1) * PT64_LEVEL_BITS)); + return sp->gfn + (index << ((sp->role.level - 1) * SPTE_LEVEL_BITS)); } -static void kvm_mmu_page_set_gfn(struct kvm_mmu_page *sp, int index, gfn_t gfn) +/* + * For leaf SPTEs, fetch the *guest* access permissions being shadowed. Note + * that the SPTE itself may have a more constrained access permissions that + * what the guest enforces. For example, a guest may create an executable + * huge PTE but KVM may disallow execution to mitigate iTLB multihit. + */ +static u32 kvm_mmu_page_get_access(struct kvm_mmu_page *sp, int index) +{ + if (sp->shadowed_translation) + return sp->shadowed_translation[index] & ACC_ALL; + + /* + * For direct MMUs (e.g. TDP or non-paging guests) or passthrough SPs, + * KVM is not shadowing any guest page tables, so the "guest access + * permissions" are just ACC_ALL. + * + * For direct SPs in indirect MMUs (shadow paging), i.e. when KVM + * is shadowing a guest huge page with small pages, the guest access + * permissions being shadowed are the access permissions of the huge + * page. + * + * In both cases, sp->role.access contains the correct access bits. + */ + return sp->role.access; +} + +static void kvm_mmu_page_set_translation(struct kvm_mmu_page *sp, int index, + gfn_t gfn, unsigned int access) { - if (!sp->role.direct) { - sp->gfns[index] = gfn; + if (sp->shadowed_translation) { + sp->shadowed_translation[index] = (gfn << PAGE_SHIFT) | access; return; } - if (WARN_ON(gfn != kvm_mmu_page_get_gfn(sp, index))) - pr_err_ratelimited("gfn mismatch under direct page %llx " - "(expected %llx, got %llx)\n", - sp->gfn, - kvm_mmu_page_get_gfn(sp, index), gfn); + WARN_ONCE(access != kvm_mmu_page_get_access(sp, index), + "access mismatch under %s page %llx (expected %u, got %u)\n", + sp->role.passthrough ? "passthrough" : "direct", + sp->gfn, kvm_mmu_page_get_access(sp, index), access); + + WARN_ONCE(gfn != kvm_mmu_page_get_gfn(sp, index), + "gfn mismatch under %s page %llx (expected %llx, got %llx)\n", + sp->role.passthrough ? "passthrough" : "direct", + sp->gfn, kvm_mmu_page_get_gfn(sp, index), gfn); +} + +static void kvm_mmu_page_set_access(struct kvm_mmu_page *sp, int index, + unsigned int access) +{ + gfn_t gfn = kvm_mmu_page_get_gfn(sp, index); + + kvm_mmu_page_set_translation(sp, index, gfn, access); } /* @@ -784,25 +713,35 @@ static struct kvm_lpage_info *lpage_info_slot(gfn_t gfn, return &slot->arch.lpage_info[level - 2][idx]; } -static void update_gfn_disallow_lpage_count(struct kvm_memory_slot *slot, +/* + * The most significant bit in disallow_lpage tracks whether or not memory + * attributes are mixed, i.e. not identical for all gfns at the current level. + * The lower order bits are used to refcount other cases where a hugepage is + * disallowed, e.g. if KVM has shadow a page table at the gfn. + */ +#define KVM_LPAGE_MIXED_FLAG BIT(31) + +static void update_gfn_disallow_lpage_count(const struct kvm_memory_slot *slot, gfn_t gfn, int count) { struct kvm_lpage_info *linfo; - int i; + int old, i; for (i = PG_LEVEL_2M; i <= KVM_MAX_HUGEPAGE_LEVEL; ++i) { linfo = lpage_info_slot(gfn, slot, i); + + old = linfo->disallow_lpage; linfo->disallow_lpage += count; - WARN_ON(linfo->disallow_lpage < 0); + WARN_ON_ONCE((old ^ linfo->disallow_lpage) & KVM_LPAGE_MIXED_FLAG); } } -void kvm_mmu_gfn_disallow_lpage(struct kvm_memory_slot *slot, gfn_t gfn) +void kvm_mmu_gfn_disallow_lpage(const struct kvm_memory_slot *slot, gfn_t gfn) { update_gfn_disallow_lpage_count(slot, gfn, 1); } -void kvm_mmu_gfn_allow_lpage(struct kvm_memory_slot *slot, gfn_t gfn) +void kvm_mmu_gfn_allow_lpage(const struct kvm_memory_slot *slot, gfn_t gfn) { update_gfn_disallow_lpage_count(slot, gfn, -1); } @@ -814,27 +753,56 @@ static void account_shadowed(struct kvm *kvm, struct kvm_mmu_page *sp) gfn_t gfn; kvm->arch.indirect_shadow_pages++; + /* + * Ensure indirect_shadow_pages is elevated prior to re-reading guest + * child PTEs in FNAME(gpte_changed), i.e. guarantee either in-flight + * emulated writes are visible before re-reading guest PTEs, or that + * an emulated write will see the elevated count and acquire mmu_lock + * to update SPTEs. Pairs with the smp_mb() in kvm_mmu_track_write(). + */ + smp_mb(); + gfn = sp->gfn; slots = kvm_memslots_for_spte_role(kvm, sp->role); slot = __gfn_to_memslot(slots, gfn); /* the non-leaf shadow pages are keeping readonly. */ if (sp->role.level > PG_LEVEL_4K) - return kvm_slot_page_track_add_page(kvm, slot, gfn, - KVM_PAGE_TRACK_WRITE); + return __kvm_write_track_add_gfn(kvm, slot, gfn); kvm_mmu_gfn_disallow_lpage(slot, gfn); + + if (kvm_mmu_slot_gfn_write_protect(kvm, slot, gfn, PG_LEVEL_4K)) + kvm_flush_remote_tlbs_gfn(kvm, gfn, PG_LEVEL_4K); } -void account_huge_nx_page(struct kvm *kvm, struct kvm_mmu_page *sp) +void track_possible_nx_huge_page(struct kvm *kvm, struct kvm_mmu_page *sp, + enum kvm_mmu_type mmu_type) { - if (sp->lpage_disallowed) + /* + * If it's possible to replace the shadow page with an NX huge page, + * i.e. if the shadow page is the only thing currently preventing KVM + * from using a huge page, add the shadow page to the list of "to be + * zapped for NX recovery" pages. Note, the shadow page can already be + * on the list if KVM is reusing an existing shadow page, i.e. if KVM + * links a shadow page at multiple points. + */ + if (!list_empty(&sp->possible_nx_huge_page_link)) return; ++kvm->stat.nx_lpage_splits; - list_add_tail(&sp->lpage_disallowed_link, - &kvm->arch.lpage_disallowed_mmu_pages); - sp->lpage_disallowed = true; + ++kvm->arch.possible_nx_huge_pages[mmu_type].nr_pages; + list_add_tail(&sp->possible_nx_huge_page_link, + &kvm->arch.possible_nx_huge_pages[mmu_type].pages); +} + +static void account_nx_huge_page(struct kvm *kvm, struct kvm_mmu_page *sp, + bool nx_huge_page_possible) +{ + sp->nx_huge_page_disallowed = true; + + if (nx_huge_page_possible) + track_possible_nx_huge_page(kvm, sp, KVM_SHADOW_MMU); } static void unaccount_shadowed(struct kvm *kvm, struct kvm_mmu_page *sp) @@ -848,22 +816,32 @@ static void unaccount_shadowed(struct kvm *kvm, struct kvm_mmu_page *sp) slots = kvm_memslots_for_spte_role(kvm, sp->role); slot = __gfn_to_memslot(slots, gfn); if (sp->role.level > PG_LEVEL_4K) - return kvm_slot_page_track_remove_page(kvm, slot, gfn, - KVM_PAGE_TRACK_WRITE); + return __kvm_write_track_remove_gfn(kvm, slot, gfn); kvm_mmu_gfn_allow_lpage(slot, gfn); } -void unaccount_huge_nx_page(struct kvm *kvm, struct kvm_mmu_page *sp) +void untrack_possible_nx_huge_page(struct kvm *kvm, struct kvm_mmu_page *sp, + enum kvm_mmu_type mmu_type) { + if (list_empty(&sp->possible_nx_huge_page_link)) + return; + --kvm->stat.nx_lpage_splits; - sp->lpage_disallowed = false; - list_del(&sp->lpage_disallowed_link); + --kvm->arch.possible_nx_huge_pages[mmu_type].nr_pages; + list_del_init(&sp->possible_nx_huge_page_link); } -static struct kvm_memory_slot * -gfn_to_memslot_dirty_bitmap(struct kvm_vcpu *vcpu, gfn_t gfn, - bool no_dirty_log) +static void unaccount_nx_huge_page(struct kvm *kvm, struct kvm_mmu_page *sp) +{ + sp->nx_huge_page_disallowed = false; + + untrack_possible_nx_huge_page(kvm, sp, KVM_SHADOW_MMU); +} + +static struct kvm_memory_slot *gfn_to_memslot_dirty_bitmap(struct kvm_vcpu *vcpu, + gfn_t gfn, + bool no_dirty_log) { struct kvm_memory_slot *slot; @@ -880,163 +858,351 @@ gfn_to_memslot_dirty_bitmap(struct kvm_vcpu *vcpu, gfn_t gfn, * About rmap_head encoding: * * If the bit zero of rmap_head->val is clear, then it points to the only spte - * in this rmap chain. Otherwise, (rmap_head->val & ~1) points to a struct + * in this rmap chain. Otherwise, (rmap_head->val & ~3) points to a struct * pte_list_desc containing more mappings. */ +#define KVM_RMAP_MANY BIT(0) + +/* + * rmaps and PTE lists are mostly protected by mmu_lock (the shadow MMU always + * operates with mmu_lock held for write), but rmaps can be walked without + * holding mmu_lock so long as the caller can tolerate SPTEs in the rmap chain + * being zapped/dropped _while the rmap is locked_. + * + * Other than the KVM_RMAP_LOCKED flag, modifications to rmap entries must be + * done while holding mmu_lock for write. This allows a task walking rmaps + * without holding mmu_lock to concurrently walk the same entries as a task + * that is holding mmu_lock but _not_ the rmap lock. Neither task will modify + * the rmaps, thus the walks are stable. + * + * As alluded to above, SPTEs in rmaps are _not_ protected by KVM_RMAP_LOCKED, + * only the rmap chains themselves are protected. E.g. holding an rmap's lock + * ensures all "struct pte_list_desc" fields are stable. + */ +#define KVM_RMAP_LOCKED BIT(1) + +static unsigned long __kvm_rmap_lock(struct kvm_rmap_head *rmap_head) +{ + unsigned long old_val, new_val; + + lockdep_assert_preemption_disabled(); + + /* + * Elide the lock if the rmap is empty, as lockless walkers (read-only + * mode) don't need to (and can't) walk an empty rmap, nor can they add + * entries to the rmap. I.e. the only paths that process empty rmaps + * do so while holding mmu_lock for write, and are mutually exclusive. + */ + old_val = atomic_long_read(&rmap_head->val); + if (!old_val) + return 0; + + do { + /* + * If the rmap is locked, wait for it to be unlocked before + * trying acquire the lock, e.g. to avoid bouncing the cache + * line. + */ + while (old_val & KVM_RMAP_LOCKED) { + cpu_relax(); + old_val = atomic_long_read(&rmap_head->val); + } + + /* + * Recheck for an empty rmap, it may have been purged by the + * task that held the lock. + */ + if (!old_val) + return 0; + + new_val = old_val | KVM_RMAP_LOCKED; + /* + * Use try_cmpxchg_acquire() to prevent reads and writes to the rmap + * from being reordered outside of the critical section created by + * __kvm_rmap_lock(). + * + * Pairs with the atomic_long_set_release() in kvm_rmap_unlock(). + * + * For the !old_val case, no ordering is needed, as there is no rmap + * to walk. + */ + } while (!atomic_long_try_cmpxchg_acquire(&rmap_head->val, &old_val, new_val)); + + /* + * Return the old value, i.e. _without_ the LOCKED bit set. It's + * impossible for the return value to be 0 (see above), i.e. the read- + * only unlock flow can't get a false positive and fail to unlock. + */ + return old_val; +} + +static unsigned long kvm_rmap_lock(struct kvm *kvm, + struct kvm_rmap_head *rmap_head) +{ + lockdep_assert_held_write(&kvm->mmu_lock); + + return __kvm_rmap_lock(rmap_head); +} + +static void __kvm_rmap_unlock(struct kvm_rmap_head *rmap_head, + unsigned long val) +{ + KVM_MMU_WARN_ON(val & KVM_RMAP_LOCKED); + /* + * Ensure that all accesses to the rmap have completed before unlocking + * the rmap. + * + * Pairs with the atomic_long_try_cmpxchg_acquire() in __kvm_rmap_lock(). + */ + atomic_long_set_release(&rmap_head->val, val); +} + +static void kvm_rmap_unlock(struct kvm *kvm, + struct kvm_rmap_head *rmap_head, + unsigned long new_val) +{ + lockdep_assert_held_write(&kvm->mmu_lock); + + __kvm_rmap_unlock(rmap_head, new_val); +} + +static unsigned long kvm_rmap_get(struct kvm_rmap_head *rmap_head) +{ + return atomic_long_read(&rmap_head->val) & ~KVM_RMAP_LOCKED; +} + +/* + * If mmu_lock isn't held, rmaps can only be locked in read-only mode. The + * actual locking is the same, but the caller is disallowed from modifying the + * rmap, and so the unlock flow is a nop if the rmap is/was empty. + */ +static unsigned long kvm_rmap_lock_readonly(struct kvm_rmap_head *rmap_head) +{ + unsigned long rmap_val; + + preempt_disable(); + rmap_val = __kvm_rmap_lock(rmap_head); + + if (!rmap_val) + preempt_enable(); + + return rmap_val; +} + +static void kvm_rmap_unlock_readonly(struct kvm_rmap_head *rmap_head, + unsigned long old_val) +{ + if (!old_val) + return; + + KVM_MMU_WARN_ON(old_val != kvm_rmap_get(rmap_head)); + + __kvm_rmap_unlock(rmap_head, old_val); + preempt_enable(); +} /* * Returns the number of pointers in the rmap chain, not counting the new one. */ -static int pte_list_add(struct kvm_vcpu *vcpu, u64 *spte, - struct kvm_rmap_head *rmap_head) +static int pte_list_add(struct kvm *kvm, struct kvm_mmu_memory_cache *cache, + u64 *spte, struct kvm_rmap_head *rmap_head) { + unsigned long old_val, new_val; struct pte_list_desc *desc; - int i, count = 0; - - if (!rmap_head->val) { - rmap_printk("%p %llx 0->1\n", spte, *spte); - rmap_head->val = (unsigned long)spte; - } else if (!(rmap_head->val & 1)) { - rmap_printk("%p %llx 1->many\n", spte, *spte); - desc = mmu_alloc_pte_list_desc(vcpu); - desc->sptes[0] = (u64 *)rmap_head->val; + int count = 0; + + old_val = kvm_rmap_lock(kvm, rmap_head); + + if (!old_val) { + new_val = (unsigned long)spte; + } else if (!(old_val & KVM_RMAP_MANY)) { + desc = kvm_mmu_memory_cache_alloc(cache); + desc->sptes[0] = (u64 *)old_val; desc->sptes[1] = spte; - rmap_head->val = (unsigned long)desc | 1; + desc->spte_count = 2; + desc->tail_count = 0; + new_val = (unsigned long)desc | KVM_RMAP_MANY; ++count; } else { - rmap_printk("%p %llx many->many\n", spte, *spte); - desc = (struct pte_list_desc *)(rmap_head->val & ~1ul); - while (desc->sptes[PTE_LIST_EXT-1]) { - count += PTE_LIST_EXT; - - if (!desc->more) { - desc->more = mmu_alloc_pte_list_desc(vcpu); - desc = desc->more; - break; - } - desc = desc->more; + desc = (struct pte_list_desc *)(old_val & ~KVM_RMAP_MANY); + count = desc->tail_count + desc->spte_count; + + /* + * If the previous head is full, allocate a new head descriptor + * as tail descriptors are always kept full. + */ + if (desc->spte_count == PTE_LIST_EXT) { + desc = kvm_mmu_memory_cache_alloc(cache); + desc->more = (struct pte_list_desc *)(old_val & ~KVM_RMAP_MANY); + desc->spte_count = 0; + desc->tail_count = count; + new_val = (unsigned long)desc | KVM_RMAP_MANY; + } else { + new_val = old_val; } - for (i = 0; desc->sptes[i]; ++i) - ++count; - desc->sptes[i] = spte; + desc->sptes[desc->spte_count++] = spte; } + + kvm_rmap_unlock(kvm, rmap_head, new_val); + return count; } -static void -pte_list_desc_remove_entry(struct kvm_rmap_head *rmap_head, - struct pte_list_desc *desc, int i, - struct pte_list_desc *prev_desc) +static void pte_list_desc_remove_entry(struct kvm *kvm, unsigned long *rmap_val, + struct pte_list_desc *desc, int i) { - int j; + struct pte_list_desc *head_desc = (struct pte_list_desc *)(*rmap_val & ~KVM_RMAP_MANY); + int j = head_desc->spte_count - 1; + + /* + * The head descriptor should never be empty. A new head is added only + * when adding an entry and the previous head is full, and heads are + * removed (this flow) when they become empty. + */ + KVM_BUG_ON_DATA_CORRUPTION(j < 0, kvm); - for (j = PTE_LIST_EXT - 1; !desc->sptes[j] && j > i; --j) - ; - desc->sptes[i] = desc->sptes[j]; - desc->sptes[j] = NULL; - if (j != 0) + /* + * Replace the to-be-freed SPTE with the last valid entry from the head + * descriptor to ensure that tail descriptors are full at all times. + * Note, this also means that tail_count is stable for each descriptor. + */ + desc->sptes[i] = head_desc->sptes[j]; + head_desc->sptes[j] = NULL; + head_desc->spte_count--; + if (head_desc->spte_count) return; - if (!prev_desc && !desc->more) - rmap_head->val = 0; + + /* + * The head descriptor is empty. If there are no tail descriptors, + * nullify the rmap head to mark the list as empty, else point the rmap + * head at the next descriptor, i.e. the new head. + */ + if (!head_desc->more) + *rmap_val = 0; else - if (prev_desc) - prev_desc->more = desc->more; - else - rmap_head->val = (unsigned long)desc->more | 1; - mmu_free_pte_list_desc(desc); + *rmap_val = (unsigned long)head_desc->more | KVM_RMAP_MANY; + mmu_free_pte_list_desc(head_desc); } -static void __pte_list_remove(u64 *spte, struct kvm_rmap_head *rmap_head) +static void pte_list_remove(struct kvm *kvm, u64 *spte, + struct kvm_rmap_head *rmap_head) { struct pte_list_desc *desc; - struct pte_list_desc *prev_desc; + unsigned long rmap_val; int i; - if (!rmap_head->val) { - pr_err("%s: %p 0->BUG\n", __func__, spte); - BUG(); - } else if (!(rmap_head->val & 1)) { - rmap_printk("%p 1->0\n", spte); - if ((u64 *)rmap_head->val != spte) { - pr_err("%s: %p 1->BUG\n", __func__, spte); - BUG(); - } - rmap_head->val = 0; + rmap_val = kvm_rmap_lock(kvm, rmap_head); + if (KVM_BUG_ON_DATA_CORRUPTION(!rmap_val, kvm)) + goto out; + + if (!(rmap_val & KVM_RMAP_MANY)) { + if (KVM_BUG_ON_DATA_CORRUPTION((u64 *)rmap_val != spte, kvm)) + goto out; + + rmap_val = 0; } else { - rmap_printk("%p many->many\n", spte); - desc = (struct pte_list_desc *)(rmap_head->val & ~1ul); - prev_desc = NULL; + desc = (struct pte_list_desc *)(rmap_val & ~KVM_RMAP_MANY); while (desc) { - for (i = 0; i < PTE_LIST_EXT && desc->sptes[i]; ++i) { + for (i = 0; i < desc->spte_count; ++i) { if (desc->sptes[i] == spte) { - pte_list_desc_remove_entry(rmap_head, - desc, i, prev_desc); - return; + pte_list_desc_remove_entry(kvm, &rmap_val, + desc, i); + goto out; } } - prev_desc = desc; desc = desc->more; } - pr_err("%s: %p many->many\n", __func__, spte); - BUG(); + + KVM_BUG_ON_DATA_CORRUPTION(true, kvm); } + +out: + kvm_rmap_unlock(kvm, rmap_head, rmap_val); } -static void pte_list_remove(struct kvm_rmap_head *rmap_head, u64 *sptep) +static void kvm_zap_one_rmap_spte(struct kvm *kvm, + struct kvm_rmap_head *rmap_head, u64 *sptep) { - mmu_spte_clear_track_bits(sptep); - __pte_list_remove(sptep, rmap_head); + mmu_spte_clear_track_bits(kvm, sptep); + pte_list_remove(kvm, sptep, rmap_head); } -static struct kvm_rmap_head *__gfn_to_rmap(gfn_t gfn, int level, - struct kvm_memory_slot *slot) +/* Return true if at least one SPTE was zapped, false otherwise */ +static bool kvm_zap_all_rmap_sptes(struct kvm *kvm, + struct kvm_rmap_head *rmap_head) { - unsigned long idx; + struct pte_list_desc *desc, *next; + unsigned long rmap_val; + int i; - idx = gfn_to_index(gfn, slot->base_gfn, level); - return &slot->arch.rmap[level - PG_LEVEL_4K][idx]; -} + rmap_val = kvm_rmap_lock(kvm, rmap_head); + if (!rmap_val) + return false; -static struct kvm_rmap_head *gfn_to_rmap(struct kvm *kvm, gfn_t gfn, - struct kvm_mmu_page *sp) -{ - struct kvm_memslots *slots; - struct kvm_memory_slot *slot; + if (!(rmap_val & KVM_RMAP_MANY)) { + mmu_spte_clear_track_bits(kvm, (u64 *)rmap_val); + goto out; + } - slots = kvm_memslots_for_spte_role(kvm, sp->role); - slot = __gfn_to_memslot(slots, gfn); - return __gfn_to_rmap(gfn, sp->role.level, slot); + desc = (struct pte_list_desc *)(rmap_val & ~KVM_RMAP_MANY); + + for (; desc; desc = next) { + for (i = 0; i < desc->spte_count; i++) + mmu_spte_clear_track_bits(kvm, desc->sptes[i]); + next = desc->more; + mmu_free_pte_list_desc(desc); + } +out: + /* rmap_head is meaningless now, remember to reset it */ + kvm_rmap_unlock(kvm, rmap_head, 0); + return true; } -static bool rmap_can_add(struct kvm_vcpu *vcpu) +unsigned int pte_list_count(struct kvm_rmap_head *rmap_head) { - struct kvm_mmu_memory_cache *mc; + unsigned long rmap_val = kvm_rmap_get(rmap_head); + struct pte_list_desc *desc; - mc = &vcpu->arch.mmu_pte_list_desc_cache; - return kvm_mmu_memory_cache_nr_free_objects(mc); + if (!rmap_val) + return 0; + else if (!(rmap_val & KVM_RMAP_MANY)) + return 1; + + desc = (struct pte_list_desc *)(rmap_val & ~KVM_RMAP_MANY); + return desc->tail_count + desc->spte_count; } -static int rmap_add(struct kvm_vcpu *vcpu, u64 *spte, gfn_t gfn) +static struct kvm_rmap_head *gfn_to_rmap(gfn_t gfn, int level, + const struct kvm_memory_slot *slot) { - struct kvm_mmu_page *sp; - struct kvm_rmap_head *rmap_head; + unsigned long idx; - sp = sptep_to_sp(spte); - kvm_mmu_page_set_gfn(sp, spte - sp->spt, gfn); - rmap_head = gfn_to_rmap(vcpu->kvm, gfn, sp); - return pte_list_add(vcpu, spte, rmap_head); + idx = gfn_to_index(gfn, slot->base_gfn, level); + return &slot->arch.rmap[level - PG_LEVEL_4K][idx]; } static void rmap_remove(struct kvm *kvm, u64 *spte) { + struct kvm_memslots *slots; + struct kvm_memory_slot *slot; struct kvm_mmu_page *sp; gfn_t gfn; struct kvm_rmap_head *rmap_head; sp = sptep_to_sp(spte); - gfn = kvm_mmu_page_get_gfn(sp, spte - sp->spt); - rmap_head = gfn_to_rmap(kvm, gfn, sp); - __pte_list_remove(spte, rmap_head); + gfn = kvm_mmu_page_get_gfn(sp, spte_index(spte)); + + /* + * Unlike rmap_add, rmap_remove does not run in the context of a vCPU + * so we have to determine which memslots to use based on context + * information in sp->role. + */ + slots = kvm_memslots_for_spte_role(kvm, sp->role); + + slot = __gfn_to_memslot(slots, gfn); + rmap_head = gfn_to_rmap(gfn, sp->role.level, slot); + + pte_list_remove(kvm, spte, rmap_head); } /* @@ -1045,6 +1211,7 @@ static void rmap_remove(struct kvm *kvm, u64 *spte) */ struct rmap_iterator { /* private fields */ + struct rmap_head *head; struct pte_list_desc *desc; /* holds the sptep if not NULL */ int pos; /* index of the sptep */ }; @@ -1059,23 +1226,19 @@ struct rmap_iterator { static u64 *rmap_get_first(struct kvm_rmap_head *rmap_head, struct rmap_iterator *iter) { - u64 *sptep; + unsigned long rmap_val = kvm_rmap_get(rmap_head); - if (!rmap_head->val) + if (!rmap_val) return NULL; - if (!(rmap_head->val & 1)) { + if (!(rmap_val & KVM_RMAP_MANY)) { iter->desc = NULL; - sptep = (u64 *)rmap_head->val; - goto out; + return (u64 *)rmap_val; } - iter->desc = (struct pte_list_desc *)(rmap_head->val & ~1ul); + iter->desc = (struct pte_list_desc *)(rmap_val & ~KVM_RMAP_MANY); iter->pos = 0; - sptep = iter->desc->sptes[iter->pos]; -out: - BUG_ON(!is_shadow_present_pte(*sptep)); - return sptep; + return iter->desc->sptes[iter->pos]; } /* @@ -1085,14 +1248,11 @@ out: */ static u64 *rmap_get_next(struct rmap_iterator *iter) { - u64 *sptep; - if (iter->desc) { if (iter->pos < PTE_LIST_EXT - 1) { ++iter->pos; - sptep = iter->desc->sptes[iter->pos]; - if (sptep) - goto out; + if (iter->desc->sptes[iter->pos]) + return iter->desc->sptes[iter->pos]; } iter->desc = iter->desc->more; @@ -1100,48 +1260,44 @@ static u64 *rmap_get_next(struct rmap_iterator *iter) if (iter->desc) { iter->pos = 0; /* desc->sptes[0] cannot be NULL */ - sptep = iter->desc->sptes[iter->pos]; - goto out; + return iter->desc->sptes[iter->pos]; } } return NULL; -out: - BUG_ON(!is_shadow_present_pte(*sptep)); - return sptep; } -#define for_each_rmap_spte(_rmap_head_, _iter_, _spte_) \ - for (_spte_ = rmap_get_first(_rmap_head_, _iter_); \ - _spte_; _spte_ = rmap_get_next(_iter_)) +#define __for_each_rmap_spte(_rmap_head_, _iter_, _sptep_) \ + for (_sptep_ = rmap_get_first(_rmap_head_, _iter_); \ + _sptep_; _sptep_ = rmap_get_next(_iter_)) + +#define for_each_rmap_spte(_rmap_head_, _iter_, _sptep_) \ + __for_each_rmap_spte(_rmap_head_, _iter_, _sptep_) \ + if (!WARN_ON_ONCE(!is_shadow_present_pte(*(_sptep_)))) \ + +#define for_each_rmap_spte_lockless(_rmap_head_, _iter_, _sptep_, _spte_) \ + __for_each_rmap_spte(_rmap_head_, _iter_, _sptep_) \ + if (is_shadow_present_pte(_spte_ = mmu_spte_get_lockless(sptep))) static void drop_spte(struct kvm *kvm, u64 *sptep) { - if (mmu_spte_clear_track_bits(sptep)) + u64 old_spte = mmu_spte_clear_track_bits(kvm, sptep); + + if (is_shadow_present_pte(old_spte)) rmap_remove(kvm, sptep); } - -static bool __drop_large_spte(struct kvm *kvm, u64 *sptep) +static void drop_large_spte(struct kvm *kvm, u64 *sptep, bool flush) { - if (is_large_pte(*sptep)) { - WARN_ON(sptep_to_sp(sptep)->role.level == PG_LEVEL_4K); - drop_spte(kvm, sptep); - --kvm->stat.lpages; - return true; - } + struct kvm_mmu_page *sp; - return false; -} + sp = sptep_to_sp(sptep); + WARN_ON_ONCE(sp->role.level == PG_LEVEL_4K); -static void drop_large_spte(struct kvm_vcpu *vcpu, u64 *sptep) -{ - if (__drop_large_spte(vcpu->kvm, sptep)) { - struct kvm_mmu_page *sp = sptep_to_sp(sptep); + drop_spte(kvm, sptep); - kvm_flush_remote_tlbs_with_address(vcpu->kvm, sp->gfn, - KVM_PAGES_PER_HPAGE(sp->role.level)); - } + if (flush) + kvm_flush_remote_tlbs_sptep(kvm, sptep); } /* @@ -1162,11 +1318,9 @@ static bool spte_write_protect(u64 *sptep, bool pt_protect) u64 spte = *sptep; if (!is_writable_pte(spte) && - !(pt_protect && spte_can_locklessly_be_made_writable(spte))) + !(pt_protect && is_mmu_writable_spte(spte))) return false; - rmap_printk("spte %p %llx\n", sptep, *sptep); - if (pt_protect) spte &= ~shadow_mmu_writable_mask; spte = spte & ~PT_WRITABLE_MASK; @@ -1174,9 +1328,8 @@ static bool spte_write_protect(u64 *sptep, bool pt_protect) return mmu_spte_update(sptep, spte); } -static bool __rmap_write_protect(struct kvm *kvm, - struct kvm_rmap_head *rmap_head, - bool pt_protect) +static bool rmap_write_protect(struct kvm_rmap_head *rmap_head, + bool pt_protect) { u64 *sptep; struct rmap_iterator iter; @@ -1192,23 +1345,11 @@ static bool spte_clear_dirty(u64 *sptep) { u64 spte = *sptep; - rmap_printk("spte %p %llx\n", sptep, *sptep); - - MMU_WARN_ON(!spte_ad_enabled(spte)); + KVM_MMU_WARN_ON(!spte_ad_enabled(spte)); spte &= ~shadow_dirty_mask; return mmu_spte_update(sptep, spte); } -static bool spte_wrprot_for_clear_dirty(u64 *sptep) -{ - bool was_writable = test_and_clear_bit(PT_WRITABLE_SHIFT, - (unsigned long *)sptep); - if (was_writable && !spte_ad_enabled(*sptep)) - kvm_set_pfn_dirty(spte_to_pfn(*sptep)); - - return was_writable; -} - /* * Gets the GFN ready for another round of dirty logging by clearing the * - D bit on ad-enabled SPTEs, and @@ -1216,37 +1357,30 @@ static bool spte_wrprot_for_clear_dirty(u64 *sptep) * Returns true iff any D or W bits were cleared. */ static bool __rmap_clear_dirty(struct kvm *kvm, struct kvm_rmap_head *rmap_head, - struct kvm_memory_slot *slot) + const struct kvm_memory_slot *slot) { u64 *sptep; struct rmap_iterator iter; bool flush = false; - for_each_rmap_spte(rmap_head, &iter, sptep) + for_each_rmap_spte(rmap_head, &iter, sptep) { if (spte_ad_need_write_protect(*sptep)) - flush |= spte_wrprot_for_clear_dirty(sptep); + flush |= test_and_clear_bit(PT_WRITABLE_SHIFT, + (unsigned long *)sptep); else flush |= spte_clear_dirty(sptep); + } return flush; } -/** - * kvm_mmu_write_protect_pt_masked - write protect selected PT level pages - * @kvm: kvm instance - * @slot: slot to protect - * @gfn_offset: start of the BITS_PER_LONG pages we care about - * @mask: indicates which pages we should protect - * - * Used when we do not need to care about huge page mappings. - */ static void kvm_mmu_write_protect_pt_masked(struct kvm *kvm, struct kvm_memory_slot *slot, gfn_t gfn_offset, unsigned long mask) { struct kvm_rmap_head *rmap_head; - if (is_tdp_mmu_enabled(kvm)) + if (tdp_mmu_enabled) kvm_tdp_mmu_clear_dirty_pt_masked(kvm, slot, slot->base_gfn + gfn_offset, mask, true); @@ -1254,32 +1388,22 @@ static void kvm_mmu_write_protect_pt_masked(struct kvm *kvm, return; while (mask) { - rmap_head = __gfn_to_rmap(slot->base_gfn + gfn_offset + __ffs(mask), - PG_LEVEL_4K, slot); - __rmap_write_protect(kvm, rmap_head, false); + rmap_head = gfn_to_rmap(slot->base_gfn + gfn_offset + __ffs(mask), + PG_LEVEL_4K, slot); + rmap_write_protect(rmap_head, false); /* clear the first set bit */ mask &= mask - 1; } } -/** - * kvm_mmu_clear_dirty_pt_masked - clear MMU D-bit for PT level pages, or write - * protect the page if the D-bit isn't supported. - * @kvm: kvm instance - * @slot: slot to clear D-bit - * @gfn_offset: start of the BITS_PER_LONG pages we care about - * @mask: indicates which pages we should clear D-bit - * - * Used for PML to re-log the dirty GPAs after userspace querying dirty_bitmap. - */ static void kvm_mmu_clear_dirty_pt_masked(struct kvm *kvm, struct kvm_memory_slot *slot, gfn_t gfn_offset, unsigned long mask) { struct kvm_rmap_head *rmap_head; - if (is_tdp_mmu_enabled(kvm)) + if (tdp_mmu_enabled) kvm_tdp_mmu_clear_dirty_pt_masked(kvm, slot, slot->base_gfn + gfn_offset, mask, false); @@ -1287,8 +1411,8 @@ static void kvm_mmu_clear_dirty_pt_masked(struct kvm *kvm, return; while (mask) { - rmap_head = __gfn_to_rmap(slot->base_gfn + gfn_offset + __ffs(mask), - PG_LEVEL_4K, slot); + rmap_head = gfn_to_rmap(slot->base_gfn + gfn_offset + __ffs(mask), + PG_LEVEL_4K, slot); __rmap_clear_dirty(kvm, rmap_head, slot); /* clear the first set bit */ @@ -1296,24 +1420,16 @@ static void kvm_mmu_clear_dirty_pt_masked(struct kvm *kvm, } } -/** - * kvm_arch_mmu_enable_log_dirty_pt_masked - enable dirty logging for selected - * PT level pages. - * - * It calls kvm_mmu_write_protect_pt_masked to write protect selected pages to - * enable dirty logging for them. - * - * We need to care about huge page mappings: e.g. during dirty logging we may - * have such mappings. - */ void kvm_arch_mmu_enable_log_dirty_pt_masked(struct kvm *kvm, struct kvm_memory_slot *slot, gfn_t gfn_offset, unsigned long mask) { /* - * Huge pages are NOT write protected when we start dirty logging in - * initially-all-set mode; must write protect them here so that they - * are split to 4K on the first write. + * If the slot was assumed to be "initially all dirty", write-protect + * huge pages to ensure they are split to 4KiB on the first write (KVM + * dirty logs at 4KiB granularity). If eager page splitting is enabled, + * immediately try to split huge pages, e.g. so that vCPUs don't get + * saddled with the cost of splitting. * * The gfn_offset is guaranteed to be aligned to 64, but the base_gfn * of memslot has no such restriction, so the range can cross two large @@ -1323,6 +1439,9 @@ void kvm_arch_mmu_enable_log_dirty_pt_masked(struct kvm *kvm, gfn_t start = slot->base_gfn + gfn_offset + __ffs(mask); gfn_t end = slot->base_gfn + gfn_offset + __fls(mask); + if (READ_ONCE(eager_page_split)) + kvm_mmu_try_split_huge_pages(kvm, slot, start, end + 1, PG_LEVEL_4K); + kvm_mmu_slot_gfn_write_protect(kvm, slot, start, PG_LEVEL_2M); /* Cross two large pages? */ @@ -1332,16 +1451,25 @@ void kvm_arch_mmu_enable_log_dirty_pt_masked(struct kvm *kvm, PG_LEVEL_2M); } - /* Now handle 4K PTEs. */ - if (kvm_x86_ops.cpu_dirty_log_size) + /* + * (Re)Enable dirty logging for all 4KiB SPTEs that map the GFNs in + * mask. If PML is enabled and the GFN doesn't need to be write- + * protected for other reasons, e.g. shadow paging, clear the Dirty bit. + * Otherwise clear the Writable bit. + * + * Note that kvm_mmu_clear_dirty_pt_masked() is called whenever PML is + * enabled but it chooses between clearing the Dirty bit and Writeable + * bit based on the context. + */ + if (kvm->arch.cpu_dirty_log_size) kvm_mmu_clear_dirty_pt_masked(kvm, slot, gfn_offset, mask); else kvm_mmu_write_protect_pt_masked(kvm, slot, gfn_offset, mask); } -int kvm_cpu_dirty_log_size(void) +int kvm_cpu_dirty_log_size(struct kvm *kvm) { - return kvm_x86_ops.cpu_dirty_log_size; + return kvm->arch.cpu_dirty_log_size; } bool kvm_mmu_slot_gfn_write_protect(struct kvm *kvm, @@ -1354,19 +1482,19 @@ bool kvm_mmu_slot_gfn_write_protect(struct kvm *kvm, if (kvm_memslots_have_rmaps(kvm)) { for (i = min_level; i <= KVM_MAX_HUGEPAGE_LEVEL; ++i) { - rmap_head = __gfn_to_rmap(gfn, i, slot); - write_protected |= __rmap_write_protect(kvm, rmap_head, true); + rmap_head = gfn_to_rmap(gfn, i, slot); + write_protected |= rmap_write_protect(rmap_head, true); } } - if (is_tdp_mmu_enabled(kvm)) + if (tdp_mmu_enabled) write_protected |= kvm_tdp_mmu_write_protect_gfn(kvm, slot, gfn, min_level); return write_protected; } -static bool rmap_write_protect(struct kvm_vcpu *vcpu, u64 gfn) +static bool kvm_vcpu_write_protect_gfn(struct kvm_vcpu *vcpu, u64 gfn) { struct kvm_memory_slot *slot; @@ -1374,73 +1502,15 @@ static bool rmap_write_protect(struct kvm_vcpu *vcpu, u64 gfn) return kvm_mmu_slot_gfn_write_protect(vcpu->kvm, slot, gfn, PG_LEVEL_4K); } -static bool kvm_zap_rmapp(struct kvm *kvm, struct kvm_rmap_head *rmap_head, - struct kvm_memory_slot *slot) +static bool kvm_zap_rmap(struct kvm *kvm, struct kvm_rmap_head *rmap_head, + const struct kvm_memory_slot *slot) { - u64 *sptep; - struct rmap_iterator iter; - bool flush = false; - - while ((sptep = rmap_get_first(rmap_head, &iter))) { - rmap_printk("spte %p %llx.\n", sptep, *sptep); - - pte_list_remove(rmap_head, sptep); - flush = true; - } - - return flush; -} - -static bool kvm_unmap_rmapp(struct kvm *kvm, struct kvm_rmap_head *rmap_head, - struct kvm_memory_slot *slot, gfn_t gfn, int level, - pte_t unused) -{ - return kvm_zap_rmapp(kvm, rmap_head, slot); -} - -static bool kvm_set_pte_rmapp(struct kvm *kvm, struct kvm_rmap_head *rmap_head, - struct kvm_memory_slot *slot, gfn_t gfn, int level, - pte_t pte) -{ - u64 *sptep; - struct rmap_iterator iter; - int need_flush = 0; - u64 new_spte; - kvm_pfn_t new_pfn; - - WARN_ON(pte_huge(pte)); - new_pfn = pte_pfn(pte); - -restart: - for_each_rmap_spte(rmap_head, &iter, sptep) { - rmap_printk("spte %p %llx gfn %llx (%d)\n", - sptep, *sptep, gfn, level); - - need_flush = 1; - - if (pte_write(pte)) { - pte_list_remove(rmap_head, sptep); - goto restart; - } else { - new_spte = kvm_mmu_changed_pte_notifier_make_spte( - *sptep, new_pfn); - - mmu_spte_clear_track_bits(sptep); - mmu_spte_set(sptep, new_spte); - } - } - - if (need_flush && kvm_available_flush_tlb_with_range()) { - kvm_flush_remote_tlbs_with_address(kvm, gfn, 1); - return 0; - } - - return need_flush; + return kvm_zap_all_rmap_sptes(kvm, rmap_head); } struct slot_rmap_walk_iterator { /* input fields. */ - struct kvm_memory_slot *slot; + const struct kvm_memory_slot *slot; gfn_t start_gfn; gfn_t end_gfn; int start_level; @@ -1455,20 +1525,19 @@ struct slot_rmap_walk_iterator { struct kvm_rmap_head *end_rmap; }; -static void -rmap_walk_init_level(struct slot_rmap_walk_iterator *iterator, int level) +static void rmap_walk_init_level(struct slot_rmap_walk_iterator *iterator, + int level) { iterator->level = level; iterator->gfn = iterator->start_gfn; - iterator->rmap = __gfn_to_rmap(iterator->gfn, level, iterator->slot); - iterator->end_rmap = __gfn_to_rmap(iterator->end_gfn, level, - iterator->slot); + iterator->rmap = gfn_to_rmap(iterator->gfn, level, iterator->slot); + iterator->end_rmap = gfn_to_rmap(iterator->end_gfn, level, iterator->slot); } -static void -slot_rmap_walk_init(struct slot_rmap_walk_iterator *iterator, - struct kvm_memory_slot *slot, int start_level, - int end_level, gfn_t start_gfn, gfn_t end_gfn) +static void slot_rmap_walk_init(struct slot_rmap_walk_iterator *iterator, + const struct kvm_memory_slot *slot, + int start_level, int end_level, + gfn_t start_gfn, gfn_t end_gfn) { iterator->slot = slot; iterator->start_level = start_level; @@ -1486,9 +1555,11 @@ static bool slot_rmap_walk_okay(struct slot_rmap_walk_iterator *iterator) static void slot_rmap_walk_next(struct slot_rmap_walk_iterator *iterator) { - if (++iterator->rmap <= iterator->end_rmap) { - iterator->gfn += (1UL << KVM_HPAGE_GFN_SHIFT(iterator->level)); - return; + while (++iterator->rmap <= iterator->end_rmap) { + iterator->gfn += KVM_PAGES_PER_HPAGE(iterator->level); + + if (atomic_long_read(&iterator->rmap->val)) + return; } if (++iterator->level > iterator->end_level) { @@ -1506,103 +1577,199 @@ static void slot_rmap_walk_next(struct slot_rmap_walk_iterator *iterator) slot_rmap_walk_okay(_iter_); \ slot_rmap_walk_next(_iter_)) -typedef bool (*rmap_handler_t)(struct kvm *kvm, struct kvm_rmap_head *rmap_head, - struct kvm_memory_slot *slot, gfn_t gfn, - int level, pte_t pte); +/* The return value indicates if tlb flush on all vcpus is needed. */ +typedef bool (*slot_rmaps_handler) (struct kvm *kvm, + struct kvm_rmap_head *rmap_head, + const struct kvm_memory_slot *slot); -static __always_inline bool kvm_handle_gfn_range(struct kvm *kvm, - struct kvm_gfn_range *range, - rmap_handler_t handler) +static __always_inline bool __walk_slot_rmaps(struct kvm *kvm, + const struct kvm_memory_slot *slot, + slot_rmaps_handler fn, + int start_level, int end_level, + gfn_t start_gfn, gfn_t end_gfn, + bool can_yield, bool flush_on_yield, + bool flush) { struct slot_rmap_walk_iterator iterator; - bool ret = false; - for_each_slot_rmap_range(range->slot, PG_LEVEL_4K, KVM_MAX_HUGEPAGE_LEVEL, - range->start, range->end - 1, &iterator) - ret |= handler(kvm, iterator.rmap, range->slot, iterator.gfn, - iterator.level, range->pte); + lockdep_assert_held_write(&kvm->mmu_lock); - return ret; + for_each_slot_rmap_range(slot, start_level, end_level, start_gfn, + end_gfn, &iterator) { + if (iterator.rmap) + flush |= fn(kvm, iterator.rmap, slot); + + if (!can_yield) + continue; + + if (need_resched() || rwlock_needbreak(&kvm->mmu_lock)) { + if (flush && flush_on_yield) { + kvm_flush_remote_tlbs_range(kvm, start_gfn, + iterator.gfn - start_gfn + 1); + flush = false; + } + cond_resched_rwlock_write(&kvm->mmu_lock); + } + } + + return flush; } -bool kvm_unmap_gfn_range(struct kvm *kvm, struct kvm_gfn_range *range) +static __always_inline bool walk_slot_rmaps(struct kvm *kvm, + const struct kvm_memory_slot *slot, + slot_rmaps_handler fn, + int start_level, int end_level, + bool flush_on_yield) { - bool flush = false; - - if (kvm_memslots_have_rmaps(kvm)) - flush = kvm_handle_gfn_range(kvm, range, kvm_unmap_rmapp); + return __walk_slot_rmaps(kvm, slot, fn, start_level, end_level, + slot->base_gfn, slot->base_gfn + slot->npages - 1, + true, flush_on_yield, false); +} - if (is_tdp_mmu_enabled(kvm)) - flush |= kvm_tdp_mmu_unmap_gfn_range(kvm, range, flush); +static __always_inline bool walk_slot_rmaps_4k(struct kvm *kvm, + const struct kvm_memory_slot *slot, + slot_rmaps_handler fn, + bool flush_on_yield) +{ + return walk_slot_rmaps(kvm, slot, fn, PG_LEVEL_4K, PG_LEVEL_4K, flush_on_yield); +} - return flush; +static bool __kvm_rmap_zap_gfn_range(struct kvm *kvm, + const struct kvm_memory_slot *slot, + gfn_t start, gfn_t end, bool can_yield, + bool flush) +{ + return __walk_slot_rmaps(kvm, slot, kvm_zap_rmap, + PG_LEVEL_4K, KVM_MAX_HUGEPAGE_LEVEL, + start, end - 1, can_yield, true, flush); } -bool kvm_set_spte_gfn(struct kvm *kvm, struct kvm_gfn_range *range) +bool kvm_unmap_gfn_range(struct kvm *kvm, struct kvm_gfn_range *range) { bool flush = false; + /* + * To prevent races with vCPUs faulting in a gfn using stale data, + * zapping a gfn range must be protected by mmu_invalidate_in_progress + * (and mmu_invalidate_seq). The only exception is memslot deletion; + * in that case, SRCU synchronization ensures that SPTEs are zapped + * after all vCPUs have unlocked SRCU, guaranteeing that vCPUs see the + * invalid slot. + */ + lockdep_assert_once(kvm->mmu_invalidate_in_progress || + lockdep_is_held(&kvm->slots_lock)); + if (kvm_memslots_have_rmaps(kvm)) - flush = kvm_handle_gfn_range(kvm, range, kvm_set_pte_rmapp); + flush = __kvm_rmap_zap_gfn_range(kvm, range->slot, + range->start, range->end, + range->may_block, flush); - if (is_tdp_mmu_enabled(kvm)) - flush |= kvm_tdp_mmu_set_spte_gfn(kvm, range); + if (tdp_mmu_enabled) + flush = kvm_tdp_mmu_unmap_gfn_range(kvm, range, flush); + + if (kvm_x86_ops.set_apic_access_page_addr && + range->slot->id == APIC_ACCESS_PAGE_PRIVATE_MEMSLOT) + kvm_make_all_cpus_request(kvm, KVM_REQ_APIC_PAGE_RELOAD); return flush; } -static bool kvm_age_rmapp(struct kvm *kvm, struct kvm_rmap_head *rmap_head, - struct kvm_memory_slot *slot, gfn_t gfn, int level, - pte_t unused) +#define RMAP_RECYCLE_THRESHOLD 1000 + +static void __rmap_add(struct kvm *kvm, + struct kvm_mmu_memory_cache *cache, + const struct kvm_memory_slot *slot, + u64 *spte, gfn_t gfn, unsigned int access) { - u64 *sptep; - struct rmap_iterator iter; - int young = 0; + struct kvm_mmu_page *sp; + struct kvm_rmap_head *rmap_head; + int rmap_count; - for_each_rmap_spte(rmap_head, &iter, sptep) - young |= mmu_spte_age(sptep); + sp = sptep_to_sp(spte); + kvm_mmu_page_set_translation(sp, spte_index(spte), gfn, access); + kvm_update_page_stats(kvm, sp->role.level, 1); - return young; + rmap_head = gfn_to_rmap(gfn, sp->role.level, slot); + rmap_count = pte_list_add(kvm, cache, spte, rmap_head); + + if (rmap_count > kvm->stat.max_mmu_rmap_size) + kvm->stat.max_mmu_rmap_size = rmap_count; + if (rmap_count > RMAP_RECYCLE_THRESHOLD) { + kvm_zap_all_rmap_sptes(kvm, rmap_head); + kvm_flush_remote_tlbs_gfn(kvm, gfn, sp->role.level); + } } -static bool kvm_test_age_rmapp(struct kvm *kvm, struct kvm_rmap_head *rmap_head, - struct kvm_memory_slot *slot, gfn_t gfn, - int level, pte_t unused) +static void rmap_add(struct kvm_vcpu *vcpu, const struct kvm_memory_slot *slot, + u64 *spte, gfn_t gfn, unsigned int access) { - u64 *sptep; - struct rmap_iterator iter; + struct kvm_mmu_memory_cache *cache = &vcpu->arch.mmu_pte_list_desc_cache; - for_each_rmap_spte(rmap_head, &iter, sptep) - if (is_accessed_spte(*sptep)) - return 1; - return 0; + __rmap_add(vcpu->kvm, cache, slot, spte, gfn, access); } -#define RMAP_RECYCLE_THRESHOLD 1000 - -static void rmap_recycle(struct kvm_vcpu *vcpu, u64 *spte, gfn_t gfn) +static bool kvm_rmap_age_gfn_range(struct kvm *kvm, + struct kvm_gfn_range *range, + bool test_only) { struct kvm_rmap_head *rmap_head; - struct kvm_mmu_page *sp; + struct rmap_iterator iter; + unsigned long rmap_val; + bool young = false; + u64 *sptep; + gfn_t gfn; + int level; + u64 spte; - sp = sptep_to_sp(spte); + for (level = PG_LEVEL_4K; level <= KVM_MAX_HUGEPAGE_LEVEL; level++) { + for (gfn = range->start; gfn < range->end; + gfn += KVM_PAGES_PER_HPAGE(level)) { + rmap_head = gfn_to_rmap(gfn, level, range->slot); + rmap_val = kvm_rmap_lock_readonly(rmap_head); + + for_each_rmap_spte_lockless(rmap_head, &iter, sptep, spte) { + if (!is_accessed_spte(spte)) + continue; + + if (test_only) { + kvm_rmap_unlock_readonly(rmap_head, rmap_val); + return true; + } - rmap_head = gfn_to_rmap(vcpu->kvm, gfn, sp); + if (spte_ad_enabled(spte)) + clear_bit((ffs(shadow_accessed_mask) - 1), + (unsigned long *)sptep); + else + /* + * If the following cmpxchg fails, the + * spte is being concurrently modified + * and should most likely stay young. + */ + cmpxchg64(sptep, spte, + mark_spte_for_access_track(spte)); + young = true; + } - kvm_unmap_rmapp(vcpu->kvm, rmap_head, NULL, gfn, sp->role.level, __pte(0)); - kvm_flush_remote_tlbs_with_address(vcpu->kvm, sp->gfn, - KVM_PAGES_PER_HPAGE(sp->role.level)); + kvm_rmap_unlock_readonly(rmap_head, rmap_val); + } + } + return young; +} + +static bool kvm_may_have_shadow_mmu_sptes(struct kvm *kvm) +{ + return !tdp_mmu_enabled || READ_ONCE(kvm->arch.indirect_shadow_pages); } bool kvm_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range) { bool young = false; - if (kvm_memslots_have_rmaps(kvm)) - young = kvm_handle_gfn_range(kvm, range, kvm_age_rmapp); + if (tdp_mmu_enabled) + young = kvm_tdp_mmu_age_gfn_range(kvm, range); - if (is_tdp_mmu_enabled(kvm)) - young |= kvm_tdp_mmu_age_gfn_range(kvm, range); + if (kvm_may_have_shadow_mmu_sptes(kvm)) + young |= kvm_rmap_age_gfn_range(kvm, range, false); return young; } @@ -1611,51 +1778,52 @@ bool kvm_test_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range) { bool young = false; - if (kvm_memslots_have_rmaps(kvm)) - young = kvm_handle_gfn_range(kvm, range, kvm_test_age_rmapp); + if (tdp_mmu_enabled) + young = kvm_tdp_mmu_test_age_gfn(kvm, range); - if (is_tdp_mmu_enabled(kvm)) - young |= kvm_tdp_mmu_test_age_gfn(kvm, range); + if (young) + return young; + + if (kvm_may_have_shadow_mmu_sptes(kvm)) + young |= kvm_rmap_age_gfn_range(kvm, range, true); return young; } -#ifdef MMU_DEBUG -static int is_empty_shadow_page(u64 *spt) +static void kvm_mmu_check_sptes_at_free(struct kvm_mmu_page *sp) { - u64 *pos; - u64 *end; +#ifdef CONFIG_KVM_PROVE_MMU + int i; - for (pos = spt, end = pos + PAGE_SIZE / sizeof(u64); pos != end; pos++) - if (is_shadow_present_pte(*pos)) { - printk(KERN_ERR "%s: %p %llx\n", __func__, - pos, *pos); - return 0; - } - return 1; -} + for (i = 0; i < SPTE_ENT_PER_PAGE; i++) { + if (KVM_MMU_WARN_ON(is_shadow_present_pte(sp->spt[i]))) + pr_err_ratelimited("SPTE %llx (@ %p) for gfn %llx shadow-present at free", + sp->spt[i], &sp->spt[i], + kvm_mmu_page_get_gfn(sp, i)); + } #endif +} -/* - * This value is the sum of all of the kvm instances's - * kvm->arch.n_used_mmu_pages values. We need a global, - * aggregate version in order to make the slab shrinker - * faster - */ -static inline void kvm_mod_used_mmu_pages(struct kvm *kvm, unsigned long nr) +static void kvm_account_mmu_page(struct kvm *kvm, struct kvm_mmu_page *sp) +{ + kvm->arch.n_used_mmu_pages++; + kvm_account_pgtable_pages((void *)sp->spt, +1); +} + +static void kvm_unaccount_mmu_page(struct kvm *kvm, struct kvm_mmu_page *sp) { - kvm->arch.n_used_mmu_pages += nr; - percpu_counter_add(&kvm_total_used_mmu_pages, nr); + kvm->arch.n_used_mmu_pages--; + kvm_account_pgtable_pages((void *)sp->spt, -1); } -static void kvm_mmu_free_page(struct kvm_mmu_page *sp) +static void kvm_mmu_free_shadow_page(struct kvm_mmu_page *sp) { - MMU_WARN_ON(!is_empty_shadow_page(sp->spt)); + kvm_mmu_check_sptes_at_free(sp); + hlist_del(&sp->hash_link); list_del(&sp->link); free_page((unsigned long)sp->spt); - if (!sp->role.direct) - free_page((unsigned long)sp->gfns); + free_page((unsigned long)sp->shadowed_translation); kmem_cache_free(mmu_page_header_cache, sp); } @@ -1664,49 +1832,29 @@ static unsigned kvm_page_table_hashfn(gfn_t gfn) return hash_64(gfn, KVM_MMU_HASH_SHIFT); } -static void mmu_page_add_parent_pte(struct kvm_vcpu *vcpu, +static void mmu_page_add_parent_pte(struct kvm *kvm, + struct kvm_mmu_memory_cache *cache, struct kvm_mmu_page *sp, u64 *parent_pte) { if (!parent_pte) return; - pte_list_add(vcpu, parent_pte, &sp->parent_ptes); + pte_list_add(kvm, cache, parent_pte, &sp->parent_ptes); } -static void mmu_page_remove_parent_pte(struct kvm_mmu_page *sp, +static void mmu_page_remove_parent_pte(struct kvm *kvm, struct kvm_mmu_page *sp, u64 *parent_pte) { - __pte_list_remove(parent_pte, &sp->parent_ptes); + pte_list_remove(kvm, parent_pte, &sp->parent_ptes); } -static void drop_parent_pte(struct kvm_mmu_page *sp, +static void drop_parent_pte(struct kvm *kvm, struct kvm_mmu_page *sp, u64 *parent_pte) { - mmu_page_remove_parent_pte(sp, parent_pte); + mmu_page_remove_parent_pte(kvm, sp, parent_pte); mmu_spte_clear_no_track(parent_pte); } -static struct kvm_mmu_page *kvm_mmu_alloc_page(struct kvm_vcpu *vcpu, int direct) -{ - struct kvm_mmu_page *sp; - - sp = kvm_mmu_memory_cache_alloc(&vcpu->arch.mmu_page_header_cache); - sp->spt = kvm_mmu_memory_cache_alloc(&vcpu->arch.mmu_shadow_page_cache); - if (!direct) - sp->gfns = kvm_mmu_memory_cache_alloc(&vcpu->arch.mmu_gfn_array_cache); - set_page_private(virt_to_page(sp->spt), (unsigned long)sp); - - /* - * active_mmu_pages must be a FIFO list, as kvm_zap_obsolete_pages() - * depends on valid pages being added to the head of the list. See - * comments in kvm_zap_obsolete_pages(). - */ - sp->mmu_valid_gen = vcpu->kvm->arch.mmu_valid_gen; - list_add(&sp->link, &vcpu->kvm->arch.active_mmu_pages); - kvm_mod_used_mmu_pages(vcpu->kvm, +1); - return sp; -} - static void mark_unsync(u64 *spte); static void kvm_mmu_mark_parents_unsync(struct kvm_mmu_page *sp) { @@ -1721,23 +1869,15 @@ static void kvm_mmu_mark_parents_unsync(struct kvm_mmu_page *sp) static void mark_unsync(u64 *spte) { struct kvm_mmu_page *sp; - unsigned int index; sp = sptep_to_sp(spte); - index = spte - sp->spt; - if (__test_and_set_bit(index, sp->unsync_child_bitmap)) + if (__test_and_set_bit(spte_index(spte), sp->unsync_child_bitmap)) return; if (sp->unsync_children++) return; kvm_mmu_mark_parents_unsync(sp); } -static int nonpaging_sync_page(struct kvm_vcpu *vcpu, - struct kvm_mmu_page *sp) -{ - return 0; -} - #define KVM_PAGE_ARRAY_NR 16 struct kvm_mmu_pages { @@ -1767,7 +1907,7 @@ static int mmu_pages_add(struct kvm_mmu_pages *pvec, struct kvm_mmu_page *sp, static inline void clear_unsync_child_bit(struct kvm_mmu_page *sp, int idx) { --sp->unsync_children; - WARN_ON((int)sp->unsync_children < 0); + WARN_ON_ONCE((int)sp->unsync_children < 0); __clear_bit(idx, sp->unsync_child_bitmap); } @@ -1785,7 +1925,7 @@ static int __mmu_unsync_walk(struct kvm_mmu_page *sp, continue; } - child = to_shadow_page(ent & PT64_BASE_ADDR_MASK); + child = spte_to_child_sp(ent); if (child->unsync_children) { if (mmu_pages_add(pvec, child, i)) @@ -1825,7 +1965,7 @@ static int mmu_unsync_walk(struct kvm_mmu_page *sp, static void kvm_unlink_unsync_page(struct kvm *kvm, struct kvm_mmu_page *sp) { - WARN_ON(!sp->unsync); + WARN_ON_ONCE(!sp->unsync); trace_kvm_mmu_sync_page(sp); sp->unsync = 0; --kvm->stat.mmu_unsync; @@ -1836,27 +1976,128 @@ static bool kvm_mmu_prepare_zap_page(struct kvm *kvm, struct kvm_mmu_page *sp, static void kvm_mmu_commit_zap_page(struct kvm *kvm, struct list_head *invalid_list); +static bool sp_has_gptes(struct kvm_mmu_page *sp) +{ + if (sp->role.direct) + return false; + + if (sp->role.passthrough) + return false; + + return true; +} + +static __ro_after_init HLIST_HEAD(empty_page_hash); + +static struct hlist_head *kvm_get_mmu_page_hash(struct kvm *kvm, gfn_t gfn) +{ + /* + * Ensure the load of the hash table pointer itself is ordered before + * loads to walk the table. The pointer is set at runtime outside of + * mmu_lock when the TDP MMU is enabled, i.e. when the hash table of + * shadow pages becomes necessary only when KVM needs to shadow L1's + * TDP for an L2 guest. Pairs with the smp_store_release() in + * kvm_mmu_alloc_page_hash(). + */ + struct hlist_head *page_hash = smp_load_acquire(&kvm->arch.mmu_page_hash); + + lockdep_assert_held(&kvm->mmu_lock); + + if (!page_hash) + return &empty_page_hash; + + return &page_hash[kvm_page_table_hashfn(gfn)]; +} + #define for_each_valid_sp(_kvm, _sp, _list) \ hlist_for_each_entry(_sp, _list, hash_link) \ if (is_obsolete_sp((_kvm), (_sp))) { \ } else -#define for_each_gfn_indirect_valid_sp(_kvm, _sp, _gfn) \ - for_each_valid_sp(_kvm, _sp, \ - &(_kvm)->arch.mmu_page_hash[kvm_page_table_hashfn(_gfn)]) \ - if ((_sp)->gfn != (_gfn) || (_sp)->role.direct) {} else +#define for_each_gfn_valid_sp_with_gptes(_kvm, _sp, _gfn) \ + for_each_valid_sp(_kvm, _sp, kvm_get_mmu_page_hash(_kvm, _gfn)) \ + if ((_sp)->gfn != (_gfn) || !sp_has_gptes(_sp)) {} else -static bool kvm_sync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp, - struct list_head *invalid_list) +static bool kvm_sync_page_check(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp) { - if (vcpu->arch.mmu->sync_page(vcpu, sp) == 0) { - kvm_mmu_prepare_zap_page(vcpu->kvm, sp, invalid_list); + union kvm_mmu_page_role root_role = vcpu->arch.mmu->root_role; + + /* + * Ignore various flags when verifying that it's safe to sync a shadow + * page using the current MMU context. + * + * - level: not part of the overall MMU role and will never match as the MMU's + * level tracks the root level + * - access: updated based on the new guest PTE + * - quadrant: not part of the overall MMU role (similar to level) + */ + const union kvm_mmu_page_role sync_role_ign = { + .level = 0xf, + .access = 0x7, + .quadrant = 0x3, + .passthrough = 0x1, + }; + + /* + * Direct pages can never be unsync, and KVM should never attempt to + * sync a shadow page for a different MMU context, e.g. if the role + * differs then the memslot lookup (SMM vs. non-SMM) will be bogus, the + * reserved bits checks will be wrong, etc... + */ + if (WARN_ON_ONCE(sp->role.direct || !vcpu->arch.mmu->sync_spte || + (sp->role.word ^ root_role.word) & ~sync_role_ign.word)) return false; - } return true; } +static int kvm_sync_spte(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp, int i) +{ + /* sp->spt[i] has initial value of shadow page table allocation */ + if (sp->spt[i] == SHADOW_NONPRESENT_VALUE) + return 0; + + return vcpu->arch.mmu->sync_spte(vcpu, sp, i); +} + +static int __kvm_sync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp) +{ + int flush = 0; + int i; + + if (!kvm_sync_page_check(vcpu, sp)) + return -1; + + for (i = 0; i < SPTE_ENT_PER_PAGE; i++) { + int ret = kvm_sync_spte(vcpu, sp, i); + + if (ret < -1) + return -1; + flush |= ret; + } + + /* + * Note, any flush is purely for KVM's correctness, e.g. when dropping + * an existing SPTE or clearing W/A/D bits to ensure an mmu_notifier + * unmap or dirty logging event doesn't fail to flush. The guest is + * responsible for flushing the TLB to ensure any changes in protection + * bits are recognized, i.e. until the guest flushes or page faults on + * a relevant address, KVM is architecturally allowed to let vCPUs use + * cached translations with the old protection bits. + */ + return flush; +} + +static int kvm_sync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp, + struct list_head *invalid_list) +{ + int ret = __kvm_sync_page(vcpu, sp); + + if (ret < 0) + kvm_mmu_prepare_zap_page(vcpu->kvm, sp, invalid_list); + return ret; +} + static bool kvm_mmu_remote_flush_or_zap(struct kvm *kvm, struct list_head *invalid_list, bool remote_flush) @@ -1871,27 +2112,13 @@ static bool kvm_mmu_remote_flush_or_zap(struct kvm *kvm, return true; } -static void kvm_mmu_flush_or_zap(struct kvm_vcpu *vcpu, - struct list_head *invalid_list, - bool remote_flush, bool local_flush) -{ - if (kvm_mmu_remote_flush_or_zap(vcpu->kvm, invalid_list, remote_flush)) - return; - - if (local_flush) - kvm_make_request(KVM_REQ_TLB_FLUSH_CURRENT, vcpu); -} - -#ifdef CONFIG_KVM_MMU_AUDIT -#include "mmu_audit.c" -#else -static void kvm_mmu_audit(struct kvm_vcpu *vcpu, int point) { } -static void mmu_audit_disable(void) { } -#endif - static bool is_obsolete_sp(struct kvm *kvm, struct kvm_mmu_page *sp) { - return sp->role.invalid || + if (sp->role.invalid) + return true; + + /* TDP MMU pages do not use the MMU generation. */ + return !is_tdp_mmu_page(sp) && unlikely(sp->mmu_valid_gen != kvm->arch.mmu_valid_gen); } @@ -1935,11 +2162,11 @@ static int mmu_pages_first(struct kvm_mmu_pages *pvec, if (pvec->nr == 0) return 0; - WARN_ON(pvec->page[0].idx != INVALID_INDEX); + WARN_ON_ONCE(pvec->page[0].idx != INVALID_INDEX); sp = pvec->page[0].sp; level = sp->role.level; - WARN_ON(level == PG_LEVEL_4K); + WARN_ON_ONCE(level == PG_LEVEL_4K); parents->parent[level-2] = sp; @@ -1961,14 +2188,14 @@ static void mmu_pages_clear_parents(struct mmu_page_path *parents) if (!sp) return; - WARN_ON(idx == INVALID_INDEX); + WARN_ON_ONCE(idx == INVALID_INDEX); clear_unsync_child_bit(sp, idx); level++; } while (!sp->unsync_children); } -static void mmu_sync_children(struct kvm_vcpu *vcpu, - struct kvm_mmu_page *parent) +static int mmu_sync_children(struct kvm_vcpu *vcpu, + struct kvm_mmu_page *parent, bool can_yield) { int i; struct kvm_mmu_page *sp; @@ -1981,26 +2208,32 @@ static void mmu_sync_children(struct kvm_vcpu *vcpu, bool protected = false; for_each_sp(pages, sp, parents, i) - protected |= rmap_write_protect(vcpu, sp->gfn); + protected |= kvm_vcpu_write_protect_gfn(vcpu, sp->gfn); if (protected) { - kvm_flush_remote_tlbs(vcpu->kvm); + kvm_mmu_remote_flush_or_zap(vcpu->kvm, &invalid_list, true); flush = false; } for_each_sp(pages, sp, parents, i) { kvm_unlink_unsync_page(vcpu->kvm, sp); - flush |= kvm_sync_page(vcpu, sp, &invalid_list); + flush |= kvm_sync_page(vcpu, sp, &invalid_list) > 0; mmu_pages_clear_parents(&parents); } if (need_resched() || rwlock_needbreak(&vcpu->kvm->mmu_lock)) { - kvm_mmu_flush_or_zap(vcpu, &invalid_list, false, flush); + kvm_mmu_remote_flush_or_zap(vcpu->kvm, &invalid_list, flush); + if (!can_yield) { + kvm_make_request(KVM_REQ_MMU_SYNC, vcpu); + return -EINTR; + } + cond_resched_rwlock_write(&vcpu->kvm->mmu_lock); flush = false; } } - kvm_mmu_flush_or_zap(vcpu, &invalid_list, false, flush); + kvm_mmu_remote_flush_or_zap(vcpu->kvm, &invalid_list, flush); + return 0; } static void __clear_sp_write_flooding_count(struct kvm_mmu_page *sp) @@ -2013,35 +2246,24 @@ static void clear_sp_write_flooding_count(u64 *spte) __clear_sp_write_flooding_count(sptep_to_sp(spte)); } -static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu, - gfn_t gfn, - gva_t gaddr, - unsigned level, - int direct, - unsigned int access) +/* + * The vCPU is required when finding indirect shadow pages; the shadow + * page may already exist and syncing it needs the vCPU pointer in + * order to read guest page tables. Direct shadow pages are never + * unsync, thus @vcpu can be NULL if @role.direct is true. + */ +static struct kvm_mmu_page *kvm_mmu_find_shadow_page(struct kvm *kvm, + struct kvm_vcpu *vcpu, + gfn_t gfn, + struct hlist_head *sp_list, + union kvm_mmu_page_role role) { - bool direct_mmu = vcpu->arch.mmu->direct_map; - union kvm_mmu_page_role role; - struct hlist_head *sp_list; - unsigned quadrant; struct kvm_mmu_page *sp; + int ret; int collisions = 0; LIST_HEAD(invalid_list); - role = vcpu->arch.mmu->mmu_role.base; - role.level = level; - role.direct = direct; - if (role.direct) - role.gpte_is_8_bytes = true; - role.access = access; - if (!direct_mmu && vcpu->arch.mmu->root_level <= PT32_ROOT_LEVEL) { - quadrant = gaddr >> (PAGE_SHIFT + (PT64_PT_BITS * level)); - quadrant &= (1 << ((PT32_PT_BITS - PT64_PT_BITS) * level)) - 1; - role.quadrant = quadrant; - } - - sp_list = &vcpu->kvm->arch.mmu_page_hash[kvm_page_table_hashfn(gfn)]; - for_each_valid_sp(vcpu->kvm, sp, sp_list) { + for_each_valid_sp(kvm, sp, sp_list) { if (sp->gfn != gfn) { collisions++; continue; @@ -2057,16 +2279,20 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu, * Unsync pages must not be left as is, because the new * upper-level page will be write-protected. */ - if (level > PG_LEVEL_4K && sp->unsync) - kvm_mmu_prepare_zap_page(vcpu->kvm, sp, + if (role.level > PG_LEVEL_4K && sp->unsync) + kvm_mmu_prepare_zap_page(kvm, sp, &invalid_list); continue; } - if (direct_mmu) - goto trace_get_page; + /* unsync and write-flooding only apply to indirect SPs. */ + if (sp->role.direct) + goto out; if (sp->unsync) { + if (KVM_BUG_ON(!vcpu, kvm)) + break; + /* * The page is good, but is stale. kvm_sync_page does * get the latest guest state, but (unlike mmu_unsync_children) @@ -2079,67 +2305,197 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu, * If the sync fails, the page is zapped. If so, break * in order to rebuild it. */ - if (!kvm_sync_page(vcpu, sp, &invalid_list)) + ret = kvm_sync_page(vcpu, sp, &invalid_list); + if (ret < 0) break; - WARN_ON(!list_empty(&invalid_list)); - kvm_make_request(KVM_REQ_TLB_FLUSH_CURRENT, vcpu); + WARN_ON_ONCE(!list_empty(&invalid_list)); + if (ret > 0) + kvm_flush_remote_tlbs(kvm); } - if (sp->unsync_children) - kvm_make_request(KVM_REQ_MMU_SYNC, vcpu); - __clear_sp_write_flooding_count(sp); -trace_get_page: - trace_kvm_mmu_get_page(sp, false); goto out; } - ++vcpu->kvm->stat.mmu_cache_miss; + sp = NULL; + ++kvm->stat.mmu_cache_miss; + +out: + kvm_mmu_commit_zap_page(kvm, &invalid_list); + + if (collisions > kvm->stat.max_mmu_page_hash_collisions) + kvm->stat.max_mmu_page_hash_collisions = collisions; + return sp; +} + +/* Caches used when allocating a new shadow page. */ +struct shadow_page_caches { + struct kvm_mmu_memory_cache *page_header_cache; + struct kvm_mmu_memory_cache *shadow_page_cache; + struct kvm_mmu_memory_cache *shadowed_info_cache; +}; + +static struct kvm_mmu_page *kvm_mmu_alloc_shadow_page(struct kvm *kvm, + struct shadow_page_caches *caches, + gfn_t gfn, + struct hlist_head *sp_list, + union kvm_mmu_page_role role) +{ + struct kvm_mmu_page *sp; + + sp = kvm_mmu_memory_cache_alloc(caches->page_header_cache); + sp->spt = kvm_mmu_memory_cache_alloc(caches->shadow_page_cache); + if (!role.direct && role.level <= KVM_MAX_HUGEPAGE_LEVEL) + sp->shadowed_translation = kvm_mmu_memory_cache_alloc(caches->shadowed_info_cache); + + set_page_private(virt_to_page(sp->spt), (unsigned long)sp); - sp = kvm_mmu_alloc_page(vcpu, direct); + INIT_LIST_HEAD(&sp->possible_nx_huge_page_link); + + /* + * active_mmu_pages must be a FIFO list, as kvm_zap_obsolete_pages() + * depends on valid pages being added to the head of the list. See + * comments in kvm_zap_obsolete_pages(). + */ + sp->mmu_valid_gen = kvm->arch.mmu_valid_gen; + list_add(&sp->link, &kvm->arch.active_mmu_pages); + kvm_account_mmu_page(kvm, sp); sp->gfn = gfn; sp->role = role; hlist_add_head(&sp->hash_link, sp_list); - if (!direct) { - account_shadowed(vcpu->kvm, sp); - if (level == PG_LEVEL_4K && rmap_write_protect(vcpu, gfn)) - kvm_flush_remote_tlbs_with_address(vcpu->kvm, gfn, 1); + if (sp_has_gptes(sp)) + account_shadowed(kvm, sp); + + return sp; +} + +/* Note, @vcpu may be NULL if @role.direct is true; see kvm_mmu_find_shadow_page. */ +static struct kvm_mmu_page *__kvm_mmu_get_shadow_page(struct kvm *kvm, + struct kvm_vcpu *vcpu, + struct shadow_page_caches *caches, + gfn_t gfn, + union kvm_mmu_page_role role) +{ + struct hlist_head *sp_list; + struct kvm_mmu_page *sp; + bool created = false; + + /* + * No need for memory barriers, unlike in kvm_get_mmu_page_hash(), as + * mmu_page_hash must be set prior to creating the first shadow root, + * i.e. reaching this point is fully serialized by slots_arch_lock. + */ + BUG_ON(!kvm->arch.mmu_page_hash); + sp_list = &kvm->arch.mmu_page_hash[kvm_page_table_hashfn(gfn)]; + + sp = kvm_mmu_find_shadow_page(kvm, vcpu, gfn, sp_list, role); + if (!sp) { + created = true; + sp = kvm_mmu_alloc_shadow_page(kvm, caches, gfn, sp_list, role); } - trace_kvm_mmu_get_page(sp, true); -out: - kvm_mmu_commit_zap_page(vcpu->kvm, &invalid_list); - if (collisions > vcpu->kvm->stat.max_mmu_page_hash_collisions) - vcpu->kvm->stat.max_mmu_page_hash_collisions = collisions; + trace_kvm_mmu_get_page(sp, created); return sp; } +static struct kvm_mmu_page *kvm_mmu_get_shadow_page(struct kvm_vcpu *vcpu, + gfn_t gfn, + union kvm_mmu_page_role role) +{ + struct shadow_page_caches caches = { + .page_header_cache = &vcpu->arch.mmu_page_header_cache, + .shadow_page_cache = &vcpu->arch.mmu_shadow_page_cache, + .shadowed_info_cache = &vcpu->arch.mmu_shadowed_info_cache, + }; + + return __kvm_mmu_get_shadow_page(vcpu->kvm, vcpu, &caches, gfn, role); +} + +static union kvm_mmu_page_role kvm_mmu_child_role(u64 *sptep, bool direct, + unsigned int access) +{ + struct kvm_mmu_page *parent_sp = sptep_to_sp(sptep); + union kvm_mmu_page_role role; + + role = parent_sp->role; + role.level--; + role.access = access; + role.direct = direct; + role.passthrough = 0; + + /* + * If the guest has 4-byte PTEs then that means it's using 32-bit, + * 2-level, non-PAE paging. KVM shadows such guests with PAE paging + * (i.e. 8-byte PTEs). The difference in PTE size means that KVM must + * shadow each guest page table with multiple shadow page tables, which + * requires extra bookkeeping in the role. + * + * Specifically, to shadow the guest's page directory (which covers a + * 4GiB address space), KVM uses 4 PAE page directories, each mapping + * 1GiB of the address space. @role.quadrant encodes which quarter of + * the address space each maps. + * + * To shadow the guest's page tables (which each map a 4MiB region), KVM + * uses 2 PAE page tables, each mapping a 2MiB region. For these, + * @role.quadrant encodes which half of the region they map. + * + * Concretely, a 4-byte PDE consumes bits 31:22, while an 8-byte PDE + * consumes bits 29:21. To consume bits 31:30, KVM's uses 4 shadow + * PDPTEs; those 4 PAE page directories are pre-allocated and their + * quadrant is assigned in mmu_alloc_root(). A 4-byte PTE consumes + * bits 21:12, while an 8-byte PTE consumes bits 20:12. To consume + * bit 21 in the PTE (the child here), KVM propagates that bit to the + * quadrant, i.e. sets quadrant to '0' or '1'. The parent 8-byte PDE + * covers bit 21 (see above), thus the quadrant is calculated from the + * _least_ significant bit of the PDE index. + */ + if (role.has_4_byte_gpte) { + WARN_ON_ONCE(role.level != PG_LEVEL_4K); + role.quadrant = spte_index(sptep) & 1; + } + + return role; +} + +static struct kvm_mmu_page *kvm_mmu_get_child_sp(struct kvm_vcpu *vcpu, + u64 *sptep, gfn_t gfn, + bool direct, unsigned int access) +{ + union kvm_mmu_page_role role; + + if (is_shadow_present_pte(*sptep) && !is_large_pte(*sptep)) + return ERR_PTR(-EEXIST); + + role = kvm_mmu_child_role(sptep, direct, access); + return kvm_mmu_get_shadow_page(vcpu, gfn, role); +} + static void shadow_walk_init_using_root(struct kvm_shadow_walk_iterator *iterator, struct kvm_vcpu *vcpu, hpa_t root, u64 addr) { iterator->addr = addr; iterator->shadow_addr = root; - iterator->level = vcpu->arch.mmu->shadow_root_level; + iterator->level = vcpu->arch.mmu->root_role.level; - if (iterator->level == PT64_ROOT_4LEVEL && - vcpu->arch.mmu->root_level < PT64_ROOT_4LEVEL && - !vcpu->arch.mmu->direct_map) - --iterator->level; + if (iterator->level >= PT64_ROOT_4LEVEL && + vcpu->arch.mmu->cpu_role.base.level < PT64_ROOT_4LEVEL && + !vcpu->arch.mmu->root_role.direct) + iterator->level = PT32E_ROOT_LEVEL; if (iterator->level == PT32E_ROOT_LEVEL) { /* * prev_root is currently only used for 64-bit hosts. So only * the active root_hpa is valid here. */ - BUG_ON(root != vcpu->arch.mmu->root_hpa); + BUG_ON(root != vcpu->arch.mmu->root.hpa); iterator->shadow_addr = vcpu->arch.mmu->pae_root[(addr >> 30) & 3]; - iterator->shadow_addr &= PT64_BASE_ADDR_MASK; + iterator->shadow_addr &= SPTE_BASE_ADDR_MASK; --iterator->level; if (!iterator->shadow_addr) iterator->level = 0; @@ -2149,7 +2505,7 @@ static void shadow_walk_init_using_root(struct kvm_shadow_walk_iterator *iterato static void shadow_walk_init(struct kvm_shadow_walk_iterator *iterator, struct kvm_vcpu *vcpu, u64 addr) { - shadow_walk_init_using_root(iterator, vcpu, vcpu->arch.mmu->root_hpa, + shadow_walk_init_using_root(iterator, vcpu, vcpu->arch.mmu->root.hpa, addr); } @@ -2158,7 +2514,7 @@ static bool shadow_walk_okay(struct kvm_shadow_walk_iterator *iterator) if (iterator->level < PG_LEVEL_4K) return false; - iterator->index = SHADOW_PT_INDEX(iterator->addr, iterator->level); + iterator->index = SPTE_INDEX(iterator->addr, iterator->level); iterator->sptep = ((u64 *)__va(iterator->shadow_addr)) + iterator->index; return true; } @@ -2166,12 +2522,12 @@ static bool shadow_walk_okay(struct kvm_shadow_walk_iterator *iterator) static void __shadow_walk_next(struct kvm_shadow_walk_iterator *iterator, u64 spte) { - if (is_last_spte(spte, iterator->level)) { + if (!is_shadow_present_pte(spte) || is_last_spte(spte, iterator->level)) { iterator->level = 0; return; } - iterator->shadow_addr = spte & PT64_BASE_ADDR_MASK; + iterator->shadow_addr = spte & SPTE_BASE_ADDR_MASK; --iterator->level; } @@ -2180,23 +2536,47 @@ static void shadow_walk_next(struct kvm_shadow_walk_iterator *iterator) __shadow_walk_next(iterator, *iterator->sptep); } -static void link_shadow_page(struct kvm_vcpu *vcpu, u64 *sptep, - struct kvm_mmu_page *sp) +static void __link_shadow_page(struct kvm *kvm, + struct kvm_mmu_memory_cache *cache, u64 *sptep, + struct kvm_mmu_page *sp, bool flush) { u64 spte; BUILD_BUG_ON(VMX_EPT_WRITABLE_MASK != PT_WRITABLE_MASK); + /* + * If an SPTE is present already, it must be a leaf and therefore + * a large one. Drop it, and flush the TLB if needed, before + * installing sp. + */ + if (is_shadow_present_pte(*sptep)) + drop_large_spte(kvm, sptep, flush); + spte = make_nonleaf_spte(sp->spt, sp_ad_disabled(sp)); mmu_spte_set(sptep, spte); - mmu_page_add_parent_pte(vcpu, sp, sptep); + mmu_page_add_parent_pte(kvm, cache, sp, sptep); - if (sp->unsync_children || sp->unsync) + /* + * The non-direct sub-pagetable must be updated before linking. For + * L1 sp, the pagetable is updated via kvm_sync_page() in + * kvm_mmu_find_shadow_page() without write-protecting the gfn, + * so sp->unsync can be true or false. For higher level non-direct + * sp, the pagetable is updated/synced via mmu_sync_children() in + * FNAME(fetch)(), so sp->unsync_children can only be false. + * WARN_ON_ONCE() if anything happens unexpectedly. + */ + if (WARN_ON_ONCE(sp->unsync_children) || sp->unsync) mark_unsync(sptep); } +static void link_shadow_page(struct kvm_vcpu *vcpu, u64 *sptep, + struct kvm_mmu_page *sp) +{ + __link_shadow_page(vcpu->kvm, &vcpu->arch.mmu_pte_list_desc_cache, sptep, sp, true); +} + static void validate_direct_spte(struct kvm_vcpu *vcpu, u64 *sptep, unsigned direct_access) { @@ -2210,12 +2590,12 @@ static void validate_direct_spte(struct kvm_vcpu *vcpu, u64 *sptep, * so we should update the spte at this point to get * a new sp with the correct access. */ - child = to_shadow_page(*sptep & PT64_BASE_ADDR_MASK); + child = spte_to_child_sp(*sptep); if (child->role.access == direct_access) return; - drop_parent_pte(child, sptep); - kvm_flush_remote_tlbs_with_address(vcpu->kvm, child->gfn, 1); + drop_parent_pte(vcpu->kvm, child, sptep); + kvm_flush_remote_tlbs_sptep(vcpu->kvm, sptep); } } @@ -2230,11 +2610,9 @@ static int mmu_page_zap_pte(struct kvm *kvm, struct kvm_mmu_page *sp, if (is_shadow_present_pte(pte)) { if (is_last_spte(pte, sp->role.level)) { drop_spte(kvm, spte); - if (is_large_pte(pte)) - --kvm->stat.lpages; } else { - child = to_shadow_page(pte & PT64_BASE_ADDR_MASK); - drop_parent_pte(child, spte); + child = spte_to_child_sp(pte); + drop_parent_pte(kvm, child, spte); /* * Recursively zap nested TDP SPs, parentless SPs are @@ -2242,11 +2620,12 @@ static int mmu_page_zap_pte(struct kvm *kvm, struct kvm_mmu_page *sp, * avoids retaining a large number of stale nested SPs. */ if (tdp_enabled && invalid_list && - child->role.guest_mode && !child->parent_ptes.val) + child->role.guest_mode && + !atomic_long_read(&child->parent_ptes.val)) return kvm_mmu_prepare_zap_page(kvm, child, invalid_list); } - } else if (is_mmio_spte(pte)) { + } else if (is_mmio_spte(kvm, pte)) { mmu_spte_clear_no_track(spte); } return 0; @@ -2259,7 +2638,7 @@ static int kvm_mmu_page_unlink_children(struct kvm *kvm, int zapped = 0; unsigned i; - for (i = 0; i < PT64_ENT_PER_PAGE; ++i) + for (i = 0; i < SPTE_ENT_PER_PAGE; ++i) zapped += mmu_page_zap_pte(kvm, sp, sp->spt + i, invalid_list); return zapped; @@ -2271,7 +2650,7 @@ static void kvm_mmu_unlink_parents(struct kvm *kvm, struct kvm_mmu_page *sp) struct rmap_iterator iter; while ((sptep = rmap_get_first(&sp->parent_ptes, &iter))) - drop_parent_pte(sp, sptep); + drop_parent_pte(kvm, sp, sptep); } static int mmu_zap_unsync_children(struct kvm *kvm, @@ -2303,8 +2682,9 @@ static bool __kvm_mmu_prepare_zap_page(struct kvm *kvm, struct list_head *invalid_list, int *nr_zapped) { - bool list_unstable; + bool list_unstable, zapped_root = false; + lockdep_assert_held_write(&kvm->mmu_lock); trace_kvm_mmu_prepare_zap_page(sp); ++kvm->stat.mmu_shadow_zapped; *nr_zapped = mmu_zap_unsync_children(kvm, sp, invalid_list); @@ -2314,7 +2694,7 @@ static bool __kvm_mmu_prepare_zap_page(struct kvm *kvm, /* Zapping children means active_mmu_pages has become unstable. */ list_unstable = *nr_zapped; - if (!sp->role.invalid && !sp->role.direct) + if (!sp->role.invalid && sp_has_gptes(sp)) unaccount_shadowed(kvm, sp); if (sp->unsync) @@ -2332,7 +2712,7 @@ static bool __kvm_mmu_prepare_zap_page(struct kvm *kvm, list_add(&sp->link, invalid_list); else list_move(&sp->link, invalid_list); - kvm_mod_used_mmu_pages(kvm, -1); + kvm_unaccount_mmu_page(kvm, sp); } else { /* * Remove the active root from the active page list, the root @@ -2345,14 +2725,20 @@ static bool __kvm_mmu_prepare_zap_page(struct kvm *kvm, * in kvm_mmu_zap_all_fast(). Note, is_obsolete_sp() also * treats invalid shadow pages as being obsolete. */ - if (!is_obsolete_sp(kvm, sp)) - kvm_reload_remote_mmus(kvm); + zapped_root = !is_obsolete_sp(kvm, sp); } - if (sp->lpage_disallowed) - unaccount_huge_nx_page(kvm, sp); + if (sp->nx_huge_page_disallowed) + unaccount_nx_huge_page(kvm, sp); sp->role.invalid = 1; + + /* + * Make the request to free obsolete roots after marking the root + * invalid, otherwise other vCPUs may not see it as invalid. + */ + if (zapped_root) + kvm_make_all_cpus_request(kvm, KVM_REQ_MMU_FREE_OBSOLETE_ROOTS); return list_unstable; } @@ -2385,8 +2771,8 @@ static void kvm_mmu_commit_zap_page(struct kvm *kvm, kvm_flush_remote_tlbs(kvm); list_for_each_entry_safe(sp, nsp, invalid_list, link) { - WARN_ON(!sp->role.invalid || sp->root_count); - kvm_mmu_free_page(sp); + WARN_ON_ONCE(!sp->role.invalid || sp->root_count); + kvm_mmu_free_shadow_page(sp); } } @@ -2479,46 +2865,56 @@ void kvm_mmu_change_mmu_pages(struct kvm *kvm, unsigned long goal_nr_mmu_pages) write_unlock(&kvm->mmu_lock); } -int kvm_mmu_unprotect_page(struct kvm *kvm, gfn_t gfn) +bool __kvm_mmu_unprotect_gfn_and_retry(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, + bool always_retry) { - struct kvm_mmu_page *sp; + struct kvm *kvm = vcpu->kvm; LIST_HEAD(invalid_list); - int r; + struct kvm_mmu_page *sp; + gpa_t gpa = cr2_or_gpa; + bool r = false; + + /* + * Bail early if there aren't any write-protected shadow pages to avoid + * unnecessarily taking mmu_lock lock, e.g. if the gfn is write-tracked + * by a third party. Reading indirect_shadow_pages without holding + * mmu_lock is safe, as this is purely an optimization, i.e. a false + * positive is benign, and a false negative will simply result in KVM + * skipping the unprotect+retry path, which is also an optimization. + */ + if (!READ_ONCE(kvm->arch.indirect_shadow_pages)) + goto out; + + if (!vcpu->arch.mmu->root_role.direct) { + gpa = kvm_mmu_gva_to_gpa_write(vcpu, cr2_or_gpa, NULL); + if (gpa == INVALID_GPA) + goto out; + } - pgprintk("%s: looking for gfn %llx\n", __func__, gfn); - r = 0; write_lock(&kvm->mmu_lock); - for_each_gfn_indirect_valid_sp(kvm, sp, gfn) { - pgprintk("%s: gfn %llx role %x\n", __func__, gfn, - sp->role.word); - r = 1; + for_each_gfn_valid_sp_with_gptes(kvm, sp, gpa_to_gfn(gpa)) kvm_mmu_prepare_zap_page(kvm, sp, &invalid_list); - } + + /* + * Snapshot the result before zapping, as zapping will remove all list + * entries, i.e. checking the list later would yield a false negative. + */ + r = !list_empty(&invalid_list); kvm_mmu_commit_zap_page(kvm, &invalid_list); write_unlock(&kvm->mmu_lock); +out: + if (r || always_retry) { + vcpu->arch.last_retry_eip = kvm_rip_read(vcpu); + vcpu->arch.last_retry_addr = cr2_or_gpa; + } return r; } -static int kvm_mmu_unprotect_page_virt(struct kvm_vcpu *vcpu, gva_t gva) -{ - gpa_t gpa; - int r; - - if (vcpu->arch.mmu->direct_map) - return 0; - - gpa = kvm_mmu_gva_to_gpa_read(vcpu, gva, NULL); - - r = kvm_mmu_unprotect_page(vcpu->kvm, gpa >> PAGE_SHIFT); - - return r; -} - -static void kvm_unsync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp) +static void kvm_unsync_page(struct kvm *kvm, struct kvm_mmu_page *sp) { trace_kvm_mmu_unsync_page(sp); - ++vcpu->kvm->stat.mmu_unsync; + ++kvm->stat.mmu_unsync; sp->unsync = 1; kvm_mmu_mark_parents_unsync(sp); @@ -2530,34 +2926,64 @@ static void kvm_unsync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp) * were marked unsync (or if there is no shadow page), -EPERM if the SPTE must * be write-protected. */ -int mmu_try_to_unsync_pages(struct kvm_vcpu *vcpu, gfn_t gfn, bool can_unsync) +int mmu_try_to_unsync_pages(struct kvm *kvm, const struct kvm_memory_slot *slot, + gfn_t gfn, bool synchronizing, bool prefetch) { struct kvm_mmu_page *sp; + bool locked = false; /* * Force write-protection if the page is being tracked. Note, the page * track machinery is used to write-protect upper-level shadow pages, * i.e. this guards the role.level == 4K assertion below! */ - if (kvm_page_track_is_active(vcpu, gfn, KVM_PAGE_TRACK_WRITE)) + if (kvm_gfn_is_write_tracked(kvm, slot, gfn)) return -EPERM; /* * The page is not write-tracked, mark existing shadow pages unsync - * unless KVM is synchronizing an unsync SP (can_unsync = false). In - * that case, KVM must complete emulation of the guest TLB flush before - * allowing shadow pages to become unsync (writable by the guest). + * unless KVM is synchronizing an unsync SP. In that case, KVM must + * complete emulation of the guest TLB flush before allowing shadow + * pages to become unsync (writable by the guest). */ - for_each_gfn_indirect_valid_sp(vcpu->kvm, sp, gfn) { - if (!can_unsync) + for_each_gfn_valid_sp_with_gptes(kvm, sp, gfn) { + if (synchronizing) return -EPERM; if (sp->unsync) continue; - WARN_ON(sp->role.level != PG_LEVEL_4K); - kvm_unsync_page(vcpu, sp); + if (prefetch) + return -EEXIST; + + /* + * TDP MMU page faults require an additional spinlock as they + * run with mmu_lock held for read, not write, and the unsync + * logic is not thread safe. Take the spinklock regardless of + * the MMU type to avoid extra conditionals/parameters, there's + * no meaningful penalty if mmu_lock is held for write. + */ + if (!locked) { + locked = true; + spin_lock(&kvm->arch.mmu_unsync_pages_lock); + + /* + * Recheck after taking the spinlock, a different vCPU + * may have since marked the page unsync. A false + * negative on the unprotected check above is not + * possible as clearing sp->unsync _must_ hold mmu_lock + * for write, i.e. unsync cannot transition from 1->0 + * while this CPU holds mmu_lock for read (or write). + */ + if (READ_ONCE(sp->unsync)) + continue; + } + + WARN_ON_ONCE(sp->role.level != PG_LEVEL_4K); + kvm_unsync_page(kvm, sp); } + if (locked) + spin_unlock(&kvm->arch.mmu_unsync_pages_lock); /* * We need to ensure that the marking of unsync pages is visible @@ -2593,58 +3019,42 @@ int mmu_try_to_unsync_pages(struct kvm_vcpu *vcpu, gfn_t gfn, bool can_unsync) * (sp->unsync = true) * * The write barrier below ensures that 1.1 happens before 1.2 and thus - * the situation in 2.4 does not arise. The implicit barrier in 2.2 - * pairs with this write barrier. + * the situation in 2.4 does not arise. It pairs with the read barrier + * in is_unsync_root(), placed between 2.1's load of SPTE.W and 2.3. */ smp_wmb(); return 0; } -static int set_spte(struct kvm_vcpu *vcpu, u64 *sptep, - unsigned int pte_access, int level, - gfn_t gfn, kvm_pfn_t pfn, bool speculative, - bool can_unsync, bool host_writable) -{ - u64 spte; - struct kvm_mmu_page *sp; - int ret; - - sp = sptep_to_sp(sptep); - - ret = make_spte(vcpu, pte_access, level, gfn, pfn, *sptep, speculative, - can_unsync, host_writable, sp_ad_disabled(sp), &spte); - - if (spte & PT_WRITABLE_MASK) - kvm_vcpu_mark_page_dirty(vcpu, gfn); - - if (*sptep == spte) - ret |= SET_SPTE_SPURIOUS; - else if (mmu_spte_update(sptep, spte)) - ret |= SET_SPTE_NEED_REMOTE_TLB_FLUSH; - return ret; -} - -static int mmu_set_spte(struct kvm_vcpu *vcpu, u64 *sptep, - unsigned int pte_access, bool write_fault, int level, - gfn_t gfn, kvm_pfn_t pfn, bool speculative, - bool host_writable) +static int mmu_set_spte(struct kvm_vcpu *vcpu, struct kvm_memory_slot *slot, + u64 *sptep, unsigned int pte_access, gfn_t gfn, + kvm_pfn_t pfn, struct kvm_page_fault *fault) { + struct kvm_mmu_page *sp = sptep_to_sp(sptep); + int level = sp->role.level; int was_rmapped = 0; - int rmap_count; - int set_spte_ret; int ret = RET_PF_FIXED; bool flush = false; + bool wrprot; + u64 spte; - pgprintk("%s: spte %llx write_fault %d gfn %llx\n", __func__, - *sptep, write_fault, gfn); + /* Prefetching always gets a writable pfn. */ + bool host_writable = !fault || fault->map_writable; + bool prefetch = !fault || fault->prefetch; + bool write_fault = fault && fault->write; if (unlikely(is_noslot_pfn(pfn))) { + vcpu->stat.pf_mmio_spte_created++; mark_mmio_spte(vcpu, sptep, gfn, pte_access); return RET_PF_EMULATE; } if (is_shadow_present_pte(*sptep)) { + if (prefetch && is_last_spte(*sptep, level) && + pfn == spte_to_pfn(*sptep)) + return RET_PF_SPURIOUS; + /* * If we overwrite a PTE page pointer with a 2MB PMD, unlink * the parent of the now unreachable PTE. @@ -2653,93 +3063,88 @@ static int mmu_set_spte(struct kvm_vcpu *vcpu, u64 *sptep, struct kvm_mmu_page *child; u64 pte = *sptep; - child = to_shadow_page(pte & PT64_BASE_ADDR_MASK); - drop_parent_pte(child, sptep); + child = spte_to_child_sp(pte); + drop_parent_pte(vcpu->kvm, child, sptep); flush = true; - } else if (pfn != spte_to_pfn(*sptep)) { - pgprintk("hfn old %llx new %llx\n", - spte_to_pfn(*sptep), pfn); + } else if (WARN_ON_ONCE(pfn != spte_to_pfn(*sptep))) { drop_spte(vcpu->kvm, sptep); flush = true; } else was_rmapped = 1; } - set_spte_ret = set_spte(vcpu, sptep, pte_access, level, gfn, pfn, - speculative, true, host_writable); - if (set_spte_ret & SET_SPTE_WRITE_PROTECTED_PT) { - if (write_fault) - ret = RET_PF_EMULATE; - kvm_make_request(KVM_REQ_TLB_FLUSH_CURRENT, vcpu); - } + wrprot = make_spte(vcpu, sp, slot, pte_access, gfn, pfn, *sptep, prefetch, + false, host_writable, &spte); - if (set_spte_ret & SET_SPTE_NEED_REMOTE_TLB_FLUSH || flush) - kvm_flush_remote_tlbs_with_address(vcpu->kvm, gfn, - KVM_PAGES_PER_HPAGE(level)); - - /* - * The fault is fully spurious if and only if the new SPTE and old SPTE - * are identical, and emulation is not required. - */ - if ((set_spte_ret & SET_SPTE_SPURIOUS) && ret == RET_PF_FIXED) { - WARN_ON_ONCE(!was_rmapped); - return RET_PF_SPURIOUS; + if (*sptep == spte) { + ret = RET_PF_SPURIOUS; + } else { + flush |= mmu_spte_update(sptep, spte); + trace_kvm_mmu_set_spte(level, gfn, sptep); } - pgprintk("%s: setting spte %llx\n", __func__, *sptep); - trace_kvm_mmu_set_spte(level, gfn, sptep); - if (!was_rmapped && is_large_pte(*sptep)) - ++vcpu->kvm->stat.lpages; + if (wrprot && write_fault) + ret = RET_PF_WRITE_PROTECTED; - if (is_shadow_present_pte(*sptep)) { - if (!was_rmapped) { - rmap_count = rmap_add(vcpu, sptep, gfn); - if (rmap_count > RMAP_RECYCLE_THRESHOLD) - rmap_recycle(vcpu, sptep, gfn); - } + if (flush) + kvm_flush_remote_tlbs_gfn(vcpu->kvm, gfn, level); + + if (!was_rmapped) { + WARN_ON_ONCE(ret == RET_PF_SPURIOUS); + rmap_add(vcpu, slot, sptep, gfn, pte_access); + } else { + /* Already rmapped but the pte_access bits may have changed. */ + kvm_mmu_page_set_access(sp, spte_index(sptep), pte_access); } return ret; } -static kvm_pfn_t pte_prefetch_gfn_to_pfn(struct kvm_vcpu *vcpu, gfn_t gfn, - bool no_dirty_log) -{ - struct kvm_memory_slot *slot; - - slot = gfn_to_memslot_dirty_bitmap(vcpu, gfn, no_dirty_log); - if (!slot) - return KVM_PFN_ERR_FAULT; - - return gfn_to_pfn_memslot_atomic(slot, gfn); -} - -static int direct_pte_prefetch_many(struct kvm_vcpu *vcpu, - struct kvm_mmu_page *sp, - u64 *start, u64 *end) +static bool kvm_mmu_prefetch_sptes(struct kvm_vcpu *vcpu, gfn_t gfn, u64 *sptep, + int nr_pages, unsigned int access) { struct page *pages[PTE_PREFETCH_NUM]; struct kvm_memory_slot *slot; - unsigned int access = sp->role.access; - int i, ret; - gfn_t gfn; + int i; + + if (WARN_ON_ONCE(nr_pages > PTE_PREFETCH_NUM)) + return false; - gfn = kvm_mmu_page_get_gfn(sp, start - sp->spt); slot = gfn_to_memslot_dirty_bitmap(vcpu, gfn, access & ACC_WRITE_MASK); if (!slot) - return -1; + return false; - ret = gfn_to_page_many_atomic(slot, gfn, pages, end - start); - if (ret <= 0) - return -1; + nr_pages = kvm_prefetch_pages(slot, gfn, pages, nr_pages); + if (nr_pages <= 0) + return false; + + for (i = 0; i < nr_pages; i++, gfn++, sptep++) { + mmu_set_spte(vcpu, slot, sptep, access, gfn, + page_to_pfn(pages[i]), NULL); - for (i = 0; i < ret; i++, gfn++, start++) { - mmu_set_spte(vcpu, start, access, false, sp->role.level, gfn, - page_to_pfn(pages[i]), true, true); - put_page(pages[i]); + /* + * KVM always prefetches writable pages from the primary MMU, + * and KVM can make its SPTE writable in the fast page handler, + * without notifying the primary MMU. Mark pages/folios dirty + * now to ensure file data is written back if it ends up being + * written by the guest. Because KVM's prefetching GUPs + * writable PTEs, the probability of unnecessary writeback is + * extremely low. + */ + kvm_release_page_dirty(pages[i]); } - return 0; + return true; +} + +static bool direct_pte_prefetch_many(struct kvm_vcpu *vcpu, + struct kvm_mmu_page *sp, + u64 *start, u64 *end) +{ + gfn_t gfn = kvm_mmu_page_get_gfn(sp, spte_index(start)); + unsigned int access = sp->role.access; + + return kvm_mmu_prefetch_sptes(vcpu, gfn, start, end - start, access); } static void __direct_pte_prefetch(struct kvm_vcpu *vcpu, @@ -2748,21 +3153,24 @@ static void __direct_pte_prefetch(struct kvm_vcpu *vcpu, u64 *spte, *start = NULL; int i; - WARN_ON(!sp->role.direct); + WARN_ON_ONCE(!sp->role.direct); - i = (sptep - sp->spt) & ~(PTE_PREFETCH_NUM - 1); + i = spte_index(sptep) & ~(PTE_PREFETCH_NUM - 1); spte = sp->spt + i; for (i = 0; i < PTE_PREFETCH_NUM; i++, spte++) { if (is_shadow_present_pte(*spte) || spte == sptep) { if (!start) continue; - if (direct_pte_prefetch_many(vcpu, sp, start, spte) < 0) - break; + if (!direct_pte_prefetch_many(vcpu, sp, start, spte)) + return; + start = NULL; } else if (!start) start = spte; } + if (start) + direct_pte_prefetch_many(vcpu, sp, start, spte); } static void direct_pte_prefetch(struct kvm_vcpu *vcpu, u64 *sptep) @@ -2786,21 +3194,47 @@ static void direct_pte_prefetch(struct kvm_vcpu *vcpu, u64 *sptep) * If addresses are being invalidated, skip prefetching to avoid * accidentally prefetching those addresses. */ - if (unlikely(vcpu->kvm->mmu_notifier_count)) + if (unlikely(vcpu->kvm->mmu_invalidate_in_progress)) return; __direct_pte_prefetch(vcpu, sp, sptep); } -static int host_pfn_mapping_level(struct kvm *kvm, gfn_t gfn, kvm_pfn_t pfn, +/* + * Lookup the mapping level for @gfn in the current mm. + * + * WARNING! Use of host_pfn_mapping_level() requires the caller and the end + * consumer to be tied into KVM's handlers for MMU notifier events! + * + * There are several ways to safely use this helper: + * + * - Check mmu_invalidate_retry_gfn() after grabbing the mapping level, before + * consuming it. In this case, mmu_lock doesn't need to be held during the + * lookup, but it does need to be held while checking the MMU notifier. + * + * - Hold mmu_lock AND ensure there is no in-progress MMU notifier invalidation + * event for the hva. This can be done by explicit checking the MMU notifier + * or by ensuring that KVM already has a valid mapping that covers the hva. + * + * - Do not use the result to install new mappings, e.g. use the host mapping + * level only to decide whether or not to zap an entry. In this case, it's + * not required to hold mmu_lock (though it's highly likely the caller will + * want to hold mmu_lock anyways, e.g. to modify SPTEs). + * + * Note! The lookup can still race with modifications to host page tables, but + * the above "rules" ensure KVM will not _consume_ the result of the walk if a + * race with the primary MMU occurs. + */ +static int host_pfn_mapping_level(struct kvm *kvm, gfn_t gfn, const struct kvm_memory_slot *slot) { + int level = PG_LEVEL_4K; unsigned long hva; - pte_t *pte; - int level; - - if (!PageCompound(pfn_to_page(pfn)) && !kvm_is_zone_device_pfn(pfn)) - return PG_LEVEL_4K; + unsigned long flags; + pgd_t pgd; + p4d_t p4d; + pud_t pud; + pmd_t pmd; /* * Note, using the already-retrieved memslot and __gfn_to_hva_memslot() @@ -2812,18 +3246,115 @@ static int host_pfn_mapping_level(struct kvm *kvm, gfn_t gfn, kvm_pfn_t pfn, */ hva = __gfn_to_hva_memslot(slot, gfn); - pte = lookup_address_in_mm(kvm->mm, hva, &level); - if (unlikely(!pte)) - return PG_LEVEL_4K; + /* + * Disable IRQs to prevent concurrent tear down of host page tables, + * e.g. if the primary MMU promotes a P*D to a huge page and then frees + * the original page table. + */ + local_irq_save(flags); + + /* + * Read each entry once. As above, a non-leaf entry can be promoted to + * a huge page _during_ this walk. Re-reading the entry could send the + * walk into the weeks, e.g. p*d_leaf() returns false (sees the old + * value) and then p*d_offset() walks into the target huge page instead + * of the old page table (sees the new value). + */ + pgd = READ_ONCE(*pgd_offset(kvm->mm, hva)); + if (pgd_none(pgd)) + goto out; + + p4d = READ_ONCE(*p4d_offset(&pgd, hva)); + if (p4d_none(p4d) || !p4d_present(p4d)) + goto out; + + pud = READ_ONCE(*pud_offset(&p4d, hva)); + if (pud_none(pud) || !pud_present(pud)) + goto out; + + if (pud_leaf(pud)) { + level = PG_LEVEL_1G; + goto out; + } + pmd = READ_ONCE(*pmd_offset(&pud, hva)); + if (pmd_none(pmd) || !pmd_present(pmd)) + goto out; + + if (pmd_leaf(pmd)) + level = PG_LEVEL_2M; + +out: + local_irq_restore(flags); return level; } -int kvm_mmu_max_mapping_level(struct kvm *kvm, - const struct kvm_memory_slot *slot, gfn_t gfn, - kvm_pfn_t pfn, int max_level) +static u8 kvm_max_level_for_order(int order) +{ + BUILD_BUG_ON(KVM_MAX_HUGEPAGE_LEVEL > PG_LEVEL_1G); + + KVM_MMU_WARN_ON(order != KVM_HPAGE_GFN_SHIFT(PG_LEVEL_1G) && + order != KVM_HPAGE_GFN_SHIFT(PG_LEVEL_2M) && + order != KVM_HPAGE_GFN_SHIFT(PG_LEVEL_4K)); + + if (order >= KVM_HPAGE_GFN_SHIFT(PG_LEVEL_1G)) + return PG_LEVEL_1G; + + if (order >= KVM_HPAGE_GFN_SHIFT(PG_LEVEL_2M)) + return PG_LEVEL_2M; + + return PG_LEVEL_4K; +} + +static u8 kvm_gmem_max_mapping_level(struct kvm *kvm, struct kvm_page_fault *fault, + const struct kvm_memory_slot *slot, gfn_t gfn, + bool is_private) +{ + u8 max_level, coco_level; + kvm_pfn_t pfn; + + /* For faults, use the gmem information that was resolved earlier. */ + if (fault) { + pfn = fault->pfn; + max_level = fault->max_level; + } else { + /* TODO: Call into guest_memfd once hugepages are supported. */ + WARN_ONCE(1, "Get pfn+order from guest_memfd"); + pfn = KVM_PFN_ERR_FAULT; + max_level = PG_LEVEL_4K; + } + + if (max_level == PG_LEVEL_4K) + return max_level; + + /* + * CoCo may influence the max mapping level, e.g. due to RMP or S-EPT + * restrictions. A return of '0' means "no additional restrictions", to + * allow for using an optional "ret0" static call. + */ + coco_level = kvm_x86_call(gmem_max_mapping_level)(kvm, pfn, is_private); + if (coco_level) + max_level = min(max_level, coco_level); + + return max_level; +} + +int kvm_mmu_max_mapping_level(struct kvm *kvm, struct kvm_page_fault *fault, + const struct kvm_memory_slot *slot, gfn_t gfn) { struct kvm_lpage_info *linfo; + int host_level, max_level; + bool is_private; + + lockdep_assert_held(&kvm->mmu_lock); + + if (fault) { + max_level = fault->max_level; + is_private = fault->is_private; + } else { + max_level = PG_LEVEL_NUM; + is_private = kvm_mem_is_private(kvm, gfn); + } max_level = min(max_level, max_huge_page_level); for ( ; max_level > PG_LEVEL_4K; max_level--) { @@ -2835,225 +3366,247 @@ int kvm_mmu_max_mapping_level(struct kvm *kvm, if (max_level == PG_LEVEL_4K) return PG_LEVEL_4K; - return host_pfn_mapping_level(kvm, gfn, pfn, slot); + if (is_private || kvm_memslot_is_gmem_only(slot)) + host_level = kvm_gmem_max_mapping_level(kvm, fault, slot, gfn, + is_private); + else + host_level = host_pfn_mapping_level(kvm, gfn, slot); + return min(host_level, max_level); } -int kvm_mmu_hugepage_adjust(struct kvm_vcpu *vcpu, gfn_t gfn, - int max_level, kvm_pfn_t *pfnp, - bool huge_page_disallowed, int *req_level) +void kvm_mmu_hugepage_adjust(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault) { - struct kvm_memory_slot *slot; - kvm_pfn_t pfn = *pfnp; + struct kvm_memory_slot *slot = fault->slot; kvm_pfn_t mask; - int level; - *req_level = PG_LEVEL_4K; - - if (unlikely(max_level == PG_LEVEL_4K)) - return PG_LEVEL_4K; + fault->huge_page_disallowed = fault->exec && fault->nx_huge_page_workaround_enabled; - if (is_error_noslot_pfn(pfn) || kvm_is_reserved_pfn(pfn)) - return PG_LEVEL_4K; - - slot = gfn_to_memslot_dirty_bitmap(vcpu, gfn, true); - if (!slot) - return PG_LEVEL_4K; + if (unlikely(fault->max_level == PG_LEVEL_4K)) + return; - level = kvm_mmu_max_mapping_level(vcpu->kvm, slot, gfn, pfn, max_level); - if (level == PG_LEVEL_4K) - return level; + if (is_error_noslot_pfn(fault->pfn)) + return; - *req_level = level = min(level, max_level); + if (kvm_slot_dirty_track_enabled(slot)) + return; /* * Enforce the iTLB multihit workaround after capturing the requested * level, which will be used to do precise, accurate accounting. */ - if (huge_page_disallowed) - return PG_LEVEL_4K; + fault->req_level = kvm_mmu_max_mapping_level(vcpu->kvm, fault, + fault->slot, fault->gfn); + if (fault->req_level == PG_LEVEL_4K || fault->huge_page_disallowed) + return; /* - * mmu_notifier_retry() was successful and mmu_lock is held, so + * mmu_invalidate_retry() was successful and mmu_lock is held, so * the pmd can't be split from under us. */ - mask = KVM_PAGES_PER_HPAGE(level) - 1; - VM_BUG_ON((gfn & mask) != (pfn & mask)); - *pfnp = pfn & ~mask; - - return level; + fault->goal_level = fault->req_level; + mask = KVM_PAGES_PER_HPAGE(fault->goal_level) - 1; + VM_BUG_ON((fault->gfn & mask) != (fault->pfn & mask)); + fault->pfn &= ~mask; } -void disallowed_hugepage_adjust(u64 spte, gfn_t gfn, int cur_level, - kvm_pfn_t *pfnp, int *goal_levelp) +void disallowed_hugepage_adjust(struct kvm_page_fault *fault, u64 spte, int cur_level) { - int level = *goal_levelp; - - if (cur_level == level && level > PG_LEVEL_4K && + if (cur_level > PG_LEVEL_4K && + cur_level == fault->goal_level && is_shadow_present_pte(spte) && - !is_large_pte(spte)) { + !is_large_pte(spte) && + spte_to_child_sp(spte)->nx_huge_page_disallowed) { /* - * A small SPTE exists for this pfn, but FNAME(fetch) - * and __direct_map would like to create a large PTE - * instead: just force them to go down another level, - * patching back for them into pfn the next 9 bits of - * the address. + * A small SPTE exists for this pfn, but FNAME(fetch), + * direct_map(), or kvm_tdp_mmu_map() would like to create a + * large PTE instead: just force them to go down another level, + * patching back for them into pfn the next 9 bits of the + * address. */ - u64 page_mask = KVM_PAGES_PER_HPAGE(level) - - KVM_PAGES_PER_HPAGE(level - 1); - *pfnp |= gfn & page_mask; - (*goal_levelp)--; + u64 page_mask = KVM_PAGES_PER_HPAGE(cur_level) - + KVM_PAGES_PER_HPAGE(cur_level - 1); + fault->pfn |= fault->gfn & page_mask; + fault->goal_level--; } } -static int __direct_map(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code, - int map_writable, int max_level, kvm_pfn_t pfn, - bool prefault, bool is_tdp) +static int direct_map(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault) { - bool nx_huge_page_workaround_enabled = is_nx_huge_page_enabled(); - bool write = error_code & PFERR_WRITE_MASK; - bool exec = error_code & PFERR_FETCH_MASK; - bool huge_page_disallowed = exec && nx_huge_page_workaround_enabled; struct kvm_shadow_walk_iterator it; struct kvm_mmu_page *sp; - int level, req_level, ret; - gfn_t gfn = gpa >> PAGE_SHIFT; - gfn_t base_gfn = gfn; + int ret; + gfn_t base_gfn = fault->gfn; - level = kvm_mmu_hugepage_adjust(vcpu, gfn, max_level, &pfn, - huge_page_disallowed, &req_level); + kvm_mmu_hugepage_adjust(vcpu, fault); - trace_kvm_mmu_spte_requested(gpa, level, pfn); - for_each_shadow_entry(vcpu, gpa, it) { + trace_kvm_mmu_spte_requested(fault); + for_each_shadow_entry(vcpu, fault->addr, it) { /* * We cannot overwrite existing page tables with an NX * large page, as the leaf could be executable. */ - if (nx_huge_page_workaround_enabled) - disallowed_hugepage_adjust(*it.sptep, gfn, it.level, - &pfn, &level); + if (fault->nx_huge_page_workaround_enabled) + disallowed_hugepage_adjust(fault, *it.sptep, it.level); - base_gfn = gfn & ~(KVM_PAGES_PER_HPAGE(it.level) - 1); - if (it.level == level) + base_gfn = gfn_round_for_level(fault->gfn, it.level); + if (it.level == fault->goal_level) break; - drop_large_spte(vcpu, it.sptep); - if (!is_shadow_present_pte(*it.sptep)) { - sp = kvm_mmu_get_page(vcpu, base_gfn, it.addr, - it.level - 1, true, ACC_ALL); + sp = kvm_mmu_get_child_sp(vcpu, it.sptep, base_gfn, true, ACC_ALL); + if (sp == ERR_PTR(-EEXIST)) + continue; - link_shadow_page(vcpu, it.sptep, sp); - if (is_tdp && huge_page_disallowed && - req_level >= it.level) - account_huge_nx_page(vcpu->kvm, sp); - } + link_shadow_page(vcpu, it.sptep, sp); + if (fault->huge_page_disallowed) + account_nx_huge_page(vcpu->kvm, sp, + fault->req_level >= it.level); } - ret = mmu_set_spte(vcpu, it.sptep, ACC_ALL, - write, level, base_gfn, pfn, prefault, - map_writable); + if (WARN_ON_ONCE(it.level != fault->goal_level)) + return -EFAULT; + + ret = mmu_set_spte(vcpu, fault->slot, it.sptep, ACC_ALL, + base_gfn, fault->pfn, fault); if (ret == RET_PF_SPURIOUS) return ret; direct_pte_prefetch(vcpu, it.sptep); - ++vcpu->stat.pf_fixed; return ret; } -static void kvm_send_hwpoison_signal(unsigned long address, struct task_struct *tsk) +static void kvm_send_hwpoison_signal(struct kvm_memory_slot *slot, gfn_t gfn) { - send_sig_mceerr(BUS_MCEERR_AR, (void __user *)address, PAGE_SHIFT, tsk); + unsigned long hva = gfn_to_hva_memslot(slot, gfn); + + send_sig_mceerr(BUS_MCEERR_AR, (void __user *)hva, PAGE_SHIFT, current); } -static int kvm_handle_bad_page(struct kvm_vcpu *vcpu, gfn_t gfn, kvm_pfn_t pfn) +static int kvm_handle_error_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault) { + if (is_sigpending_pfn(fault->pfn)) { + kvm_handle_signal_exit(vcpu); + return -EINTR; + } + /* * Do not cache the mmio info caused by writing the readonly gfn * into the spte otherwise read access on readonly gfn also can * caused mmio page fault and treat it as mmio access. */ - if (pfn == KVM_PFN_ERR_RO_FAULT) + if (fault->pfn == KVM_PFN_ERR_RO_FAULT) return RET_PF_EMULATE; - if (pfn == KVM_PFN_ERR_HWPOISON) { - kvm_send_hwpoison_signal(kvm_vcpu_gfn_to_hva(vcpu, gfn), current); + if (fault->pfn == KVM_PFN_ERR_HWPOISON) { + kvm_send_hwpoison_signal(fault->slot, fault->gfn); return RET_PF_RETRY; } return -EFAULT; } -static bool handle_abnormal_pfn(struct kvm_vcpu *vcpu, gva_t gva, gfn_t gfn, - kvm_pfn_t pfn, unsigned int access, - int *ret_val) +static int kvm_handle_noslot_fault(struct kvm_vcpu *vcpu, + struct kvm_page_fault *fault, + unsigned int access) { - /* The pfn is invalid, report the error! */ - if (unlikely(is_error_pfn(pfn))) { - *ret_val = kvm_handle_bad_page(vcpu, gfn, pfn); - return true; - } + gva_t gva = fault->is_tdp ? 0 : fault->addr; - if (unlikely(is_noslot_pfn(pfn))) { - vcpu_cache_mmio_info(vcpu, gva, gfn, - access & shadow_mmio_access_mask); - /* - * If MMIO caching is disabled, emulate immediately without - * touching the shadow page tables as attempting to install an - * MMIO SPTE will just be an expensive nop. - */ - if (unlikely(!shadow_mmio_value)) { - *ret_val = RET_PF_EMULATE; - return true; - } + if (fault->is_private) { + kvm_mmu_prepare_memory_fault_exit(vcpu, fault); + return -EFAULT; } - return false; + vcpu_cache_mmio_info(vcpu, gva, fault->gfn, + access & shadow_mmio_access_mask); + + fault->slot = NULL; + fault->pfn = KVM_PFN_NOSLOT; + fault->map_writable = false; + + /* + * If MMIO caching is disabled, emulate immediately without + * touching the shadow page tables as attempting to install an + * MMIO SPTE will just be an expensive nop. + */ + if (unlikely(!enable_mmio_caching)) + return RET_PF_EMULATE; + + /* + * Do not create an MMIO SPTE for a gfn greater than host.MAXPHYADDR, + * any guest that generates such gfns is running nested and is being + * tricked by L0 userspace (you can observe gfn > L1.MAXPHYADDR if and + * only if L1's MAXPHYADDR is inaccurate with respect to the + * hardware's). + */ + if (unlikely(fault->gfn > kvm_mmu_max_gfn())) + return RET_PF_EMULATE; + + return RET_PF_CONTINUE; } -static bool page_fault_can_be_fast(u32 error_code) +static bool page_fault_can_be_fast(struct kvm *kvm, struct kvm_page_fault *fault) { /* - * Do not fix the mmio spte with invalid generation number which - * need to be updated by slow page fault path. + * Page faults with reserved bits set, i.e. faults on MMIO SPTEs, only + * reach the common page fault handler if the SPTE has an invalid MMIO + * generation number. Refreshing the MMIO generation needs to go down + * the slow path. Note, EPT Misconfigs do NOT set the PRESENT flag! */ - if (unlikely(error_code & PFERR_RSVD_MASK)) + if (fault->rsvd) return false; - /* See if the page fault is due to an NX violation */ - if (unlikely(((error_code & (PFERR_FETCH_MASK | PFERR_PRESENT_MASK)) - == (PFERR_FETCH_MASK | PFERR_PRESENT_MASK)))) + /* + * For hardware-protected VMs, certain conditions like attempting to + * perform a write to a page which is not in the state that the guest + * expects it to be in can result in a nested/extended #PF. In this + * case, the below code might misconstrue this situation as being the + * result of a write-protected access, and treat it as a spurious case + * rather than taking any action to satisfy the real source of the #PF + * such as generating a KVM_EXIT_MEMORY_FAULT. This can lead to the + * guest spinning on a #PF indefinitely, so don't attempt the fast path + * in this case. + * + * Note that the kvm_mem_is_private() check might race with an + * attribute update, but this will either result in the guest spinning + * on RET_PF_SPURIOUS until the update completes, or an actual spurious + * case might go down the slow path. Either case will resolve itself. + */ + if (kvm->arch.has_private_mem && + fault->is_private != kvm_mem_is_private(kvm, fault->gfn)) return false; /* * #PF can be fast if: - * 1. The shadow page table entry is not present, which could mean that - * the fault is potentially caused by access tracking (if enabled). - * 2. The shadow page table entry is present and the fault - * is caused by write-protect, that means we just need change the W - * bit of the spte which can be done out of mmu-lock. * - * However, if access tracking is disabled we know that a non-present - * page must be a genuine page fault where we have to create a new SPTE. - * So, if access tracking is disabled, we return true only for write - * accesses to a present page. + * 1. The shadow page table entry is not present and A/D bits are + * disabled _by KVM_, which could mean that the fault is potentially + * caused by access tracking (if enabled). If A/D bits are enabled + * by KVM, but disabled by L1 for L2, KVM is forced to disable A/D + * bits for L2 and employ access tracking, but the fast page fault + * mechanism only supports direct MMUs. + * 2. The shadow page table entry is present, the access is a write, + * and no reserved bits are set (MMIO SPTEs cannot be "fixed"), i.e. + * the fault was caused by a write-protection violation. If the + * SPTE is MMU-writable (determined later), the fault can be fixed + * by setting the Writable bit, which can be done out of mmu_lock. */ + if (!fault->present) + return !kvm_ad_enabled; - return shadow_acc_track_mask != 0 || - ((error_code & (PFERR_WRITE_MASK | PFERR_PRESENT_MASK)) - == (PFERR_WRITE_MASK | PFERR_PRESENT_MASK)); + /* + * Note, instruction fetches and writes are mutually exclusive, ignore + * the "exec" flag. + */ + return fault->write; } /* * Returns true if the SPTE was fixed successfully. Otherwise, * someone else modified the SPTE from its original value. */ -static bool -fast_pf_fix_direct_spte(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp, - u64 *sptep, u64 old_spte, u64 new_spte) +static bool fast_pf_fix_direct_spte(struct kvm_vcpu *vcpu, + struct kvm_page_fault *fault, + u64 *sptep, u64 old_spte, u64 new_spte) { - gfn_t gfn; - - WARN_ON(!sp->role.direct); - /* * Theoretically we could also set dirty bit (and flush TLB) here in * order to eliminate unnecessary PML logging. See comments in @@ -3064,48 +3617,52 @@ fast_pf_fix_direct_spte(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp, * harm. This also avoids the TLB flush needed after setting dirty bit * so non-PML cases won't be impacted. * - * Compare with set_spte where instead shadow_dirty_mask is set. + * Compare with make_spte() where instead shadow_dirty_mask is set. */ - if (cmpxchg64(sptep, old_spte, new_spte) != old_spte) + if (!try_cmpxchg64(sptep, &old_spte, new_spte)) return false; - if (is_writable_pte(new_spte) && !is_writable_pte(old_spte)) { - /* - * The gfn of direct spte is stable since it is - * calculated by sp->gfn. - */ - gfn = kvm_mmu_page_get_gfn(sp, sptep - sp->spt); - kvm_vcpu_mark_page_dirty(vcpu, gfn); - } + if (is_writable_pte(new_spte) && !is_writable_pte(old_spte)) + mark_page_dirty_in_slot(vcpu->kvm, fault->slot, fault->gfn); return true; } -static bool is_access_allowed(u32 fault_err_code, u64 spte) +/* + * Returns the last level spte pointer of the shadow page walk for the given + * gpa, and sets *spte to the spte value. This spte may be non-preset. If no + * walk could be performed, returns NULL and *spte does not contain valid data. + * + * Contract: + * - Must be called between walk_shadow_page_lockless_{begin,end}. + * - The returned sptep must not be used after walk_shadow_page_lockless_end. + */ +static u64 *fast_pf_get_last_sptep(struct kvm_vcpu *vcpu, gpa_t gpa, u64 *spte) { - if (fault_err_code & PFERR_FETCH_MASK) - return is_executable_pte(spte); + struct kvm_shadow_walk_iterator iterator; + u64 old_spte; + u64 *sptep = NULL; - if (fault_err_code & PFERR_WRITE_MASK) - return is_writable_pte(spte); + for_each_shadow_entry_lockless(vcpu, gpa, iterator, old_spte) { + sptep = iterator.sptep; + *spte = old_spte; + } - /* Fault was on Read access */ - return spte & PT_PRESENT_MASK; + return sptep; } /* * Returns one of RET_PF_INVALID, RET_PF_FIXED or RET_PF_SPURIOUS. */ -static int fast_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, - u32 error_code) +static int fast_page_fault(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault) { - struct kvm_shadow_walk_iterator iterator; struct kvm_mmu_page *sp; int ret = RET_PF_INVALID; - u64 spte = 0ull; + u64 spte; + u64 *sptep; uint retry_count = 0; - if (!page_fault_can_be_fast(error_code)) + if (!page_fault_can_be_fast(vcpu->kvm, fault)) return ret; walk_shadow_page_lockless_begin(vcpu); @@ -3113,14 +3670,23 @@ static int fast_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, do { u64 new_spte; - for_each_shadow_entry_lockless(vcpu, cr2_or_gpa, iterator, spte) - if (!is_shadow_present_pte(spte)) - break; + if (tdp_mmu_enabled) + sptep = kvm_tdp_mmu_fast_pf_get_last_sptep(vcpu, fault->gfn, &spte); + else + sptep = fast_pf_get_last_sptep(vcpu, fault->addr, &spte); + + /* + * It's entirely possible for the mapping to have been zapped + * by a different task, but the root page should always be + * available as the vCPU holds a reference to its root(s). + */ + if (WARN_ON_ONCE(!sptep)) + spte = FROZEN_SPTE; if (!is_shadow_present_pte(spte)) break; - sp = sptep_to_sp(iterator.sptep); + sp = sptep_to_sp(sptep); if (!is_last_spte(spte, sp->role.level)) break; @@ -3134,43 +3700,55 @@ static int fast_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, * Need not check the access of upper level table entries since * they are always ACC_ALL. */ - if (is_access_allowed(error_code, spte)) { + if (is_access_allowed(fault, spte)) { ret = RET_PF_SPURIOUS; break; } new_spte = spte; - if (is_access_track_spte(spte)) - new_spte = restore_acc_track_spte(new_spte); + /* + * KVM only supports fixing page faults outside of MMU lock for + * direct MMUs, nested MMUs are always indirect, and KVM always + * uses A/D bits for non-nested MMUs. Thus, if A/D bits are + * enabled, the SPTE can't be an access-tracked SPTE. + */ + if (unlikely(!kvm_ad_enabled) && is_access_track_spte(spte)) + new_spte = restore_acc_track_spte(new_spte) | + shadow_accessed_mask; /* - * Currently, to simplify the code, write-protection can - * be removed in the fast path only if the SPTE was - * write-protected for dirty-logging or access tracking. + * To keep things simple, only SPTEs that are MMU-writable can + * be made fully writable outside of mmu_lock, e.g. only SPTEs + * that were write-protected for dirty-logging or access + * tracking are handled here. Don't bother checking if the + * SPTE is writable to prioritize running with A/D bits enabled. + * The is_access_allowed() check above handles the common case + * of the fault being spurious, and the SPTE is known to be + * shadow-present, i.e. except for access tracking restoration + * making the new SPTE writable, the check is wasteful. */ - if ((error_code & PFERR_WRITE_MASK) && - spte_can_locklessly_be_made_writable(spte)) { + if (fault->write && is_mmu_writable_spte(spte)) { new_spte |= PT_WRITABLE_MASK; /* - * Do not fix write-permission on the large spte. Since - * we only dirty the first page into the dirty-bitmap in + * Do not fix write-permission on the large spte when + * dirty logging is enabled. Since we only dirty the + * first page into the dirty-bitmap in * fast_pf_fix_direct_spte(), other pages are missed * if its slot has dirty logging enabled. * * Instead, we let the slow page fault path create a * normal spte to fix the access. - * - * See the comments in kvm_arch_commit_memory_region(). */ - if (sp->role.level > PG_LEVEL_4K) + if (sp->role.level > PG_LEVEL_4K && + kvm_slot_dirty_track_enabled(fault->slot)) break; } /* Verify that the fault can be handled in the fast path */ if (new_spte == spte || - !is_access_allowed(error_code, new_spte)) + !is_access_allowed(fault, new_spte)) break; /* @@ -3178,24 +3756,24 @@ static int fast_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, * since the gfn is not stable for indirect shadow page. See * Documentation/virt/kvm/locking.rst to get more detail. */ - if (fast_pf_fix_direct_spte(vcpu, sp, iterator.sptep, spte, - new_spte)) { + if (fast_pf_fix_direct_spte(vcpu, fault, sptep, spte, new_spte)) { ret = RET_PF_FIXED; break; } if (++retry_count > 4) { - printk_once(KERN_WARNING - "kvm: Fast #PF retrying more than 4 times.\n"); + pr_warn_once("Fast #PF retrying more than 4 times.\n"); break; } } while (true); - trace_fast_page_fault(vcpu, cr2_or_gpa, error_code, iterator.sptep, - spte, ret); + trace_fast_page_fault(vcpu, fault, sptep, spte, ret); walk_shadow_page_lockless_end(vcpu); + if (ret != RET_PF_INVALID) + vcpu->stat.pf_fast++; + return ret; } @@ -3207,29 +3785,40 @@ static void mmu_free_root_page(struct kvm *kvm, hpa_t *root_hpa, if (!VALID_PAGE(*root_hpa)) return; - sp = to_shadow_page(*root_hpa & PT64_BASE_ADDR_MASK); + sp = root_to_sp(*root_hpa); + if (WARN_ON_ONCE(!sp)) + return; - if (is_tdp_mmu_page(sp)) - kvm_tdp_mmu_put_root(kvm, sp, false); - else if (!--sp->root_count && sp->role.invalid) - kvm_mmu_prepare_zap_page(kvm, sp, invalid_list); + if (is_tdp_mmu_page(sp)) { + lockdep_assert_held_read(&kvm->mmu_lock); + kvm_tdp_mmu_put_root(kvm, sp); + } else { + lockdep_assert_held_write(&kvm->mmu_lock); + if (!--sp->root_count && sp->role.invalid) + kvm_mmu_prepare_zap_page(kvm, sp, invalid_list); + } *root_hpa = INVALID_PAGE; } /* roots_to_free must be some combination of the KVM_MMU_ROOT_* flags */ -void kvm_mmu_free_roots(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu, +void kvm_mmu_free_roots(struct kvm *kvm, struct kvm_mmu *mmu, ulong roots_to_free) { - struct kvm *kvm = vcpu->kvm; + bool is_tdp_mmu = tdp_mmu_enabled && mmu->root_role.direct; int i; LIST_HEAD(invalid_list); - bool free_active_root = roots_to_free & KVM_MMU_ROOT_CURRENT; + bool free_active_root; + + WARN_ON_ONCE(roots_to_free & ~KVM_MMU_ROOTS_ALL); BUILD_BUG_ON(KVM_MMU_NUM_PREV_ROOTS >= BITS_PER_LONG); /* Before acquiring the MMU lock, see if we need to do any real work. */ - if (!(free_active_root && VALID_PAGE(mmu->root_hpa))) { + free_active_root = (roots_to_free & KVM_MMU_ROOT_CURRENT) + && VALID_PAGE(mmu->root.hpa); + + if (!free_active_root) { for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++) if ((roots_to_free & KVM_MMU_ROOT_PREVIOUS(i)) && VALID_PAGE(mmu->prev_roots[i].hpa)) @@ -3239,7 +3828,10 @@ void kvm_mmu_free_roots(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu, return; } - write_lock(&kvm->mmu_lock); + if (is_tdp_mmu) + read_lock(&kvm->mmu_lock); + else + write_lock(&kvm->mmu_lock); for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++) if (roots_to_free & KVM_MMU_ROOT_PREVIOUS(i)) @@ -3247,9 +3839,10 @@ void kvm_mmu_free_roots(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu, &invalid_list); if (free_active_root) { - if (mmu->shadow_root_level >= PT64_ROOT_4LEVEL && - (mmu->root_level >= PT64_ROOT_4LEVEL || mmu->direct_map)) { - mmu_free_root_page(kvm, &mmu->root_hpa, &invalid_list); + if (kvm_mmu_is_dummy_root(mmu->root.hpa)) { + /* Nothing to cleanup for dummy roots. */ + } else if (root_to_sp(mmu->root.hpa)) { + mmu_free_root_page(kvm, &mmu->root.hpa, &invalid_list); } else if (mmu->pae_root) { for (i = 0; i < 4; ++i) { if (!IS_VALID_PAE_ROOT(mmu->pae_root[i])) @@ -3260,18 +3853,24 @@ void kvm_mmu_free_roots(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu, mmu->pae_root[i] = INVALID_PAE_ROOT; } } - mmu->root_hpa = INVALID_PAGE; - mmu->root_pgd = 0; + mmu->root.hpa = INVALID_PAGE; + mmu->root.pgd = 0; } - kvm_mmu_commit_zap_page(kvm, &invalid_list); - write_unlock(&kvm->mmu_lock); + if (is_tdp_mmu) { + read_unlock(&kvm->mmu_lock); + WARN_ON_ONCE(!list_empty(&invalid_list)); + } else { + kvm_mmu_commit_zap_page(kvm, &invalid_list); + write_unlock(&kvm->mmu_lock); + } } -EXPORT_SYMBOL_GPL(kvm_mmu_free_roots); +EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_mmu_free_roots); -void kvm_mmu_free_guest_mode_roots(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu) +void kvm_mmu_free_guest_mode_roots(struct kvm *kvm, struct kvm_mmu *mmu) { unsigned long roots_to_free = 0; + struct kvm_mmu_page *sp; hpa_t root_hpa; int i; @@ -3279,41 +3878,35 @@ void kvm_mmu_free_guest_mode_roots(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu) * This should not be called while L2 is active, L2 can't invalidate * _only_ its own roots, e.g. INVVPID unconditionally exits. */ - WARN_ON_ONCE(mmu->mmu_role.base.guest_mode); + WARN_ON_ONCE(mmu->root_role.guest_mode); for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++) { root_hpa = mmu->prev_roots[i].hpa; if (!VALID_PAGE(root_hpa)) continue; - if (!to_shadow_page(root_hpa) || - to_shadow_page(root_hpa)->role.guest_mode) + sp = root_to_sp(root_hpa); + if (!sp || sp->role.guest_mode) roots_to_free |= KVM_MMU_ROOT_PREVIOUS(i); } - kvm_mmu_free_roots(vcpu, mmu, roots_to_free); + kvm_mmu_free_roots(kvm, mmu, roots_to_free); } -EXPORT_SYMBOL_GPL(kvm_mmu_free_guest_mode_roots); +EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_mmu_free_guest_mode_roots); - -static int mmu_check_root(struct kvm_vcpu *vcpu, gfn_t root_gfn) +static hpa_t mmu_alloc_root(struct kvm_vcpu *vcpu, gfn_t gfn, int quadrant, + u8 level) { - int ret = 0; - - if (!kvm_vcpu_is_visible_gfn(vcpu, root_gfn)) { - kvm_make_request(KVM_REQ_TRIPLE_FAULT, vcpu); - ret = 1; - } + union kvm_mmu_page_role role = vcpu->arch.mmu->root_role; + struct kvm_mmu_page *sp; - return ret; -} + role.level = level; + role.quadrant = quadrant; -static hpa_t mmu_alloc_root(struct kvm_vcpu *vcpu, gfn_t gfn, gva_t gva, - u8 level, bool direct) -{ - struct kvm_mmu_page *sp; + WARN_ON_ONCE(quadrant && !role.has_4_byte_gpte); + WARN_ON_ONCE(role.direct && role.has_4_byte_gpte); - sp = kvm_mmu_get_page(vcpu, gfn, gva, level, direct, ACC_ALL); + sp = kvm_mmu_get_shadow_page(vcpu, gfn, role); ++sp->root_count; return __pa(sp->spt); @@ -3322,22 +3915,27 @@ static hpa_t mmu_alloc_root(struct kvm_vcpu *vcpu, gfn_t gfn, gva_t gva, static int mmu_alloc_direct_roots(struct kvm_vcpu *vcpu) { struct kvm_mmu *mmu = vcpu->arch.mmu; - u8 shadow_root_level = mmu->shadow_root_level; + u8 shadow_root_level = mmu->root_role.level; hpa_t root; unsigned i; int r; + if (tdp_mmu_enabled) { + if (kvm_has_mirrored_tdp(vcpu->kvm) && + !VALID_PAGE(mmu->mirror_root_hpa)) + kvm_tdp_mmu_alloc_root(vcpu, true); + kvm_tdp_mmu_alloc_root(vcpu, false); + return 0; + } + write_lock(&vcpu->kvm->mmu_lock); r = make_mmu_pages_available(vcpu); if (r < 0) goto out_unlock; - if (is_tdp_mmu_enabled(vcpu->kvm)) { - root = kvm_tdp_mmu_get_vcpu_root_hpa(vcpu); - mmu->root_hpa = root; - } else if (shadow_root_level >= PT64_ROOT_4LEVEL) { - root = mmu_alloc_root(vcpu, 0, 0, shadow_root_level, true); - mmu->root_hpa = root; + if (shadow_root_level >= PT64_ROOT_4LEVEL) { + root = mmu_alloc_root(vcpu, 0, 0, shadow_root_level); + mmu->root.hpa = root; } else if (shadow_root_level == PT32E_ROOT_LEVEL) { if (WARN_ON_ONCE(!mmu->pae_root)) { r = -EIO; @@ -3347,56 +3945,144 @@ static int mmu_alloc_direct_roots(struct kvm_vcpu *vcpu) for (i = 0; i < 4; ++i) { WARN_ON_ONCE(IS_VALID_PAE_ROOT(mmu->pae_root[i])); - root = mmu_alloc_root(vcpu, i << (30 - PAGE_SHIFT), - i << 30, PT32_ROOT_LEVEL, true); + root = mmu_alloc_root(vcpu, i << (30 - PAGE_SHIFT), 0, + PT32_ROOT_LEVEL); mmu->pae_root[i] = root | PT_PRESENT_MASK | - shadow_me_mask; + shadow_me_value; } - mmu->root_hpa = __pa(mmu->pae_root); + mmu->root.hpa = __pa(mmu->pae_root); } else { WARN_ONCE(1, "Bad TDP root level = %d\n", shadow_root_level); r = -EIO; goto out_unlock; } - /* root_pgd is ignored for direct MMUs. */ - mmu->root_pgd = 0; + /* root.pgd is ignored for direct MMUs. */ + mmu->root.pgd = 0; out_unlock: write_unlock(&vcpu->kvm->mmu_lock); return r; } +static int kvm_mmu_alloc_page_hash(struct kvm *kvm) +{ + struct hlist_head *h; + + if (kvm->arch.mmu_page_hash) + return 0; + + h = kvcalloc(KVM_NUM_MMU_PAGES, sizeof(*h), GFP_KERNEL_ACCOUNT); + if (!h) + return -ENOMEM; + + /* + * Ensure the hash table pointer is set only after all stores to zero + * the memory are retired. Pairs with the smp_load_acquire() in + * kvm_get_mmu_page_hash(). Note, mmu_lock must be held for write to + * add (or remove) shadow pages, and so readers are guaranteed to see + * an empty list for their current mmu_lock critical section. + */ + smp_store_release(&kvm->arch.mmu_page_hash, h); + return 0; +} + +static int mmu_first_shadow_root_alloc(struct kvm *kvm) +{ + struct kvm_memslots *slots; + struct kvm_memory_slot *slot; + int r = 0, i, bkt; + + /* + * Check if this is the first shadow root being allocated before + * taking the lock. + */ + if (kvm_shadow_root_allocated(kvm)) + return 0; + + mutex_lock(&kvm->slots_arch_lock); + + /* Recheck, under the lock, whether this is the first shadow root. */ + if (kvm_shadow_root_allocated(kvm)) + goto out_unlock; + + r = kvm_mmu_alloc_page_hash(kvm); + if (r) + goto out_unlock; + + /* + * Check if memslot metadata actually needs to be allocated, e.g. all + * metadata will be allocated upfront if TDP is disabled. + */ + if (kvm_memslots_have_rmaps(kvm) && + kvm_page_track_write_tracking_enabled(kvm)) + goto out_success; + + for (i = 0; i < kvm_arch_nr_memslot_as_ids(kvm); i++) { + slots = __kvm_memslots(kvm, i); + kvm_for_each_memslot(slot, bkt, slots) { + /* + * Both of these functions are no-ops if the target is + * already allocated, so unconditionally calling both + * is safe. Intentionally do NOT free allocations on + * failure to avoid having to track which allocations + * were made now versus when the memslot was created. + * The metadata is guaranteed to be freed when the slot + * is freed, and will be kept/used if userspace retries + * KVM_RUN instead of killing the VM. + */ + r = memslot_rmap_alloc(slot, slot->npages); + if (r) + goto out_unlock; + r = kvm_page_track_write_tracking_alloc(slot); + if (r) + goto out_unlock; + } + } + + /* + * Ensure that shadow_root_allocated becomes true strictly after + * all the related pointers are set. + */ +out_success: + smp_store_release(&kvm->arch.shadow_root_allocated, true); + +out_unlock: + mutex_unlock(&kvm->slots_arch_lock); + return r; +} + static int mmu_alloc_shadow_roots(struct kvm_vcpu *vcpu) { struct kvm_mmu *mmu = vcpu->arch.mmu; u64 pdptrs[4], pm_mask; gfn_t root_gfn, root_pgd; + int quadrant, i, r; hpa_t root; - unsigned i; - int r; - root_pgd = mmu->get_guest_pgd(vcpu); - root_gfn = root_pgd >> PAGE_SHIFT; + root_pgd = kvm_mmu_get_guest_pgd(vcpu, mmu); + root_gfn = (root_pgd & __PT_BASE_ADDR_MASK) >> PAGE_SHIFT; - if (mmu_check_root(vcpu, root_gfn)) - return 1; + if (!kvm_vcpu_is_visible_gfn(vcpu, root_gfn)) { + mmu->root.hpa = kvm_mmu_get_dummy_root(); + return 0; + } /* * On SVM, reading PDPTRs might access guest memory, which might fault * and thus might sleep. Grab the PDPTRs before acquiring mmu_lock. */ - if (mmu->root_level == PT32E_ROOT_LEVEL) { + if (mmu->cpu_role.base.level == PT32E_ROOT_LEVEL) { for (i = 0; i < 4; ++i) { pdptrs[i] = mmu->get_pdptr(vcpu, i); if (!(pdptrs[i] & PT_PRESENT_MASK)) continue; - if (mmu_check_root(vcpu, pdptrs[i] >> PAGE_SHIFT)) - return 1; + if (!kvm_vcpu_is_visible_gfn(vcpu, pdptrs[i] >> PAGE_SHIFT)) + pdptrs[i] = 0; } } - r = alloc_all_memslots_rmaps(vcpu->kvm); + r = mmu_first_shadow_root_alloc(vcpu->kvm); if (r) return r; @@ -3409,10 +4095,10 @@ static int mmu_alloc_shadow_roots(struct kvm_vcpu *vcpu) * Do we shadow a long mode page table? If so we need to * write-protect the guests page table root. */ - if (mmu->root_level >= PT64_ROOT_4LEVEL) { + if (mmu->cpu_role.base.level >= PT64_ROOT_4LEVEL) { root = mmu_alloc_root(vcpu, root_gfn, 0, - mmu->shadow_root_level, false); - mmu->root_hpa = root; + mmu->root_role.level); + mmu->root.hpa = root; goto set_root_pgd; } @@ -3426,22 +4112,29 @@ static int mmu_alloc_shadow_roots(struct kvm_vcpu *vcpu) * or a PAE 3-level page table. In either case we need to be aware that * the shadow page table may be a PAE or a long mode page table. */ - pm_mask = PT_PRESENT_MASK | shadow_me_mask; - if (mmu->shadow_root_level == PT64_ROOT_4LEVEL) { + pm_mask = PT_PRESENT_MASK | shadow_me_value; + if (mmu->root_role.level >= PT64_ROOT_4LEVEL) { pm_mask |= PT_ACCESSED_MASK | PT_WRITABLE_MASK | PT_USER_MASK; if (WARN_ON_ONCE(!mmu->pml4_root)) { r = -EIO; goto out_unlock; } - mmu->pml4_root[0] = __pa(mmu->pae_root) | pm_mask; + + if (mmu->root_role.level == PT64_ROOT_5LEVEL) { + if (WARN_ON_ONCE(!mmu->pml5_root)) { + r = -EIO; + goto out_unlock; + } + mmu->pml5_root[0] = __pa(mmu->pml4_root) | pm_mask; + } } for (i = 0; i < 4; ++i) { WARN_ON_ONCE(IS_VALID_PAE_ROOT(mmu->pae_root[i])); - if (mmu->root_level == PT32E_ROOT_LEVEL) { + if (mmu->cpu_role.base.level == PT32E_ROOT_LEVEL) { if (!(pdptrs[i] & PT_PRESENT_MASK)) { mmu->pae_root[i] = INVALID_PAE_ROOT; continue; @@ -3449,28 +4142,40 @@ static int mmu_alloc_shadow_roots(struct kvm_vcpu *vcpu) root_gfn = pdptrs[i] >> PAGE_SHIFT; } - root = mmu_alloc_root(vcpu, root_gfn, i << 30, - PT32_ROOT_LEVEL, false); + /* + * If shadowing 32-bit non-PAE page tables, each PAE page + * directory maps one quarter of the guest's non-PAE page + * directory. Othwerise each PAE page direct shadows one guest + * PAE page directory so that quadrant should be 0. + */ + quadrant = (mmu->cpu_role.base.level == PT32_ROOT_LEVEL) ? i : 0; + + root = mmu_alloc_root(vcpu, root_gfn, quadrant, PT32_ROOT_LEVEL); mmu->pae_root[i] = root | pm_mask; } - if (mmu->shadow_root_level == PT64_ROOT_4LEVEL) - mmu->root_hpa = __pa(mmu->pml4_root); + if (mmu->root_role.level == PT64_ROOT_5LEVEL) + mmu->root.hpa = __pa(mmu->pml5_root); + else if (mmu->root_role.level == PT64_ROOT_4LEVEL) + mmu->root.hpa = __pa(mmu->pml4_root); else - mmu->root_hpa = __pa(mmu->pae_root); + mmu->root.hpa = __pa(mmu->pae_root); set_root_pgd: - mmu->root_pgd = root_pgd; + mmu->root.pgd = root_pgd; out_unlock: write_unlock(&vcpu->kvm->mmu_lock); - return 0; + return r; } static int mmu_alloc_special_roots(struct kvm_vcpu *vcpu) { struct kvm_mmu *mmu = vcpu->arch.mmu; - u64 *pml4_root, *pae_root; + bool need_pml5 = mmu->root_role.level > PT64_ROOT_4LEVEL; + u64 *pml5_root = NULL; + u64 *pml4_root = NULL; + u64 *pae_root; /* * When shadowing 32-bit or PAE NPT with 64-bit NPT, the PML4 and PDP @@ -3478,25 +4183,27 @@ static int mmu_alloc_special_roots(struct kvm_vcpu *vcpu) * equivalent level in the guest's NPT to shadow. Allocate the tables * on demand, as running a 32-bit L1 VMM on 64-bit KVM is very rare. */ - if (mmu->direct_map || mmu->root_level >= PT64_ROOT_4LEVEL || - mmu->shadow_root_level < PT64_ROOT_4LEVEL) + if (mmu->root_role.direct || + mmu->cpu_role.base.level >= PT64_ROOT_4LEVEL || + mmu->root_role.level < PT64_ROOT_4LEVEL) return 0; /* - * This mess only works with 4-level paging and needs to be updated to - * work with 5-level paging. + * NPT, the only paging mode that uses this horror, uses a fixed number + * of levels for the shadow page tables, e.g. all MMUs are 4-level or + * all MMus are 5-level. Thus, this can safely require that pml5_root + * is allocated if the other roots are valid and pml5 is needed, as any + * prior MMU would also have required pml5. */ - if (WARN_ON_ONCE(mmu->shadow_root_level != PT64_ROOT_4LEVEL)) - return -EIO; - - if (mmu->pae_root && mmu->pml4_root) + if (mmu->pae_root && mmu->pml4_root && (!need_pml5 || mmu->pml5_root)) return 0; /* * The special roots should always be allocated in concert. Yell and * bail if KVM ends up in a state where only one of the roots is valid. */ - if (WARN_ON_ONCE(!tdp_enabled || mmu->pae_root || mmu->pml4_root)) + if (WARN_ON_ONCE(!tdp_enabled || mmu->pae_root || mmu->pml4_root || + (need_pml5 && mmu->pml5_root))) return -EIO; /* @@ -3507,16 +4214,66 @@ static int mmu_alloc_special_roots(struct kvm_vcpu *vcpu) if (!pae_root) return -ENOMEM; +#ifdef CONFIG_X86_64 pml4_root = (void *)get_zeroed_page(GFP_KERNEL_ACCOUNT); - if (!pml4_root) { - free_page((unsigned long)pae_root); - return -ENOMEM; + if (!pml4_root) + goto err_pml4; + + if (need_pml5) { + pml5_root = (void *)get_zeroed_page(GFP_KERNEL_ACCOUNT); + if (!pml5_root) + goto err_pml5; } +#endif mmu->pae_root = pae_root; mmu->pml4_root = pml4_root; + mmu->pml5_root = pml5_root; return 0; + +#ifdef CONFIG_X86_64 +err_pml5: + free_page((unsigned long)pml4_root); +err_pml4: + free_page((unsigned long)pae_root); + return -ENOMEM; +#endif +} + +static bool is_unsync_root(hpa_t root) +{ + struct kvm_mmu_page *sp; + + if (!VALID_PAGE(root) || kvm_mmu_is_dummy_root(root)) + return false; + + /* + * The read barrier orders the CPU's read of SPTE.W during the page table + * walk before the reads of sp->unsync/sp->unsync_children here. + * + * Even if another CPU was marking the SP as unsync-ed simultaneously, + * any guest page table changes are not guaranteed to be visible anyway + * until this VCPU issues a TLB flush strictly after those changes are + * made. We only need to ensure that the other CPU sets these flags + * before any actual changes to the page tables are made. The comments + * in mmu_try_to_unsync_pages() describe what could go wrong if this + * requirement isn't satisfied. + */ + smp_rmb(); + sp = root_to_sp(root); + + /* + * PAE roots (somewhat arbitrarily) aren't backed by shadow pages, the + * PDPTEs for a given PAE root need to be synchronized individually. + */ + if (WARN_ON_ONCE(!sp)) + return false; + + if (sp->unsync || sp->unsync_children) + return true; + + return false; } void kvm_mmu_sync_roots(struct kvm_vcpu *vcpu) @@ -3524,74 +4281,62 @@ void kvm_mmu_sync_roots(struct kvm_vcpu *vcpu) int i; struct kvm_mmu_page *sp; - if (vcpu->arch.mmu->direct_map) + if (vcpu->arch.mmu->root_role.direct) return; - if (!VALID_PAGE(vcpu->arch.mmu->root_hpa)) + if (!VALID_PAGE(vcpu->arch.mmu->root.hpa)) return; vcpu_clear_mmio_info(vcpu, MMIO_GVA_ANY); - if (vcpu->arch.mmu->root_level >= PT64_ROOT_4LEVEL) { - hpa_t root = vcpu->arch.mmu->root_hpa; - sp = to_shadow_page(root); + if (vcpu->arch.mmu->cpu_role.base.level >= PT64_ROOT_4LEVEL) { + hpa_t root = vcpu->arch.mmu->root.hpa; - /* - * Even if another CPU was marking the SP as unsync-ed - * simultaneously, any guest page table changes are not - * guaranteed to be visible anyway until this VCPU issues a TLB - * flush strictly after those changes are made. We only need to - * ensure that the other CPU sets these flags before any actual - * changes to the page tables are made. The comments in - * mmu_try_to_unsync_pages() describe what could go wrong if - * this requirement isn't satisfied. - */ - if (!smp_load_acquire(&sp->unsync) && - !smp_load_acquire(&sp->unsync_children)) + if (!is_unsync_root(root)) return; - write_lock(&vcpu->kvm->mmu_lock); - kvm_mmu_audit(vcpu, AUDIT_PRE_SYNC); - - mmu_sync_children(vcpu, sp); + sp = root_to_sp(root); - kvm_mmu_audit(vcpu, AUDIT_POST_SYNC); + write_lock(&vcpu->kvm->mmu_lock); + mmu_sync_children(vcpu, sp, true); write_unlock(&vcpu->kvm->mmu_lock); return; } write_lock(&vcpu->kvm->mmu_lock); - kvm_mmu_audit(vcpu, AUDIT_PRE_SYNC); for (i = 0; i < 4; ++i) { hpa_t root = vcpu->arch.mmu->pae_root[i]; if (IS_VALID_PAE_ROOT(root)) { - root &= PT64_BASE_ADDR_MASK; - sp = to_shadow_page(root); - mmu_sync_children(vcpu, sp); + sp = spte_to_child_sp(root); + mmu_sync_children(vcpu, sp, true); } } - kvm_mmu_audit(vcpu, AUDIT_POST_SYNC); write_unlock(&vcpu->kvm->mmu_lock); } -static gpa_t nonpaging_gva_to_gpa(struct kvm_vcpu *vcpu, gpa_t vaddr, - u32 access, struct x86_exception *exception) +void kvm_mmu_sync_prev_roots(struct kvm_vcpu *vcpu) { - if (exception) - exception->error_code = 0; - return vaddr; + unsigned long roots_to_free = 0; + int i; + + for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++) + if (is_unsync_root(vcpu->arch.mmu->prev_roots[i].hpa)) + roots_to_free |= KVM_MMU_ROOT_PREVIOUS(i); + + /* sync prev_roots by simply freeing them */ + kvm_mmu_free_roots(vcpu->kvm, vcpu->arch.mmu, roots_to_free); } -static gpa_t nonpaging_gva_to_gpa_nested(struct kvm_vcpu *vcpu, gpa_t vaddr, - u32 access, - struct x86_exception *exception) +static gpa_t nonpaging_gva_to_gpa(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu, + gpa_t vaddr, u64 access, + struct x86_exception *exception) { if (exception) exception->error_code = 0; - return vcpu->arch.nested_mmu.translate_gpa(vcpu, vaddr, access, exception); + return kvm_translate_gpa(vcpu, mmu, vaddr, access, exception); } static bool mmio_info_in_cache(struct kvm_vcpu *vcpu, u64 addr, bool direct) @@ -3612,6 +4357,8 @@ static bool mmio_info_in_cache(struct kvm_vcpu *vcpu, u64 addr, bool direct) /* * Return the level of the lowest level SPTE added to sptes. * That SPTE may be non-present. + * + * Must be called between walk_shadow_page_lockless_{begin,end}. */ static int get_walk(struct kvm_vcpu *vcpu, u64 addr, u64 *sptes, int *root_level) { @@ -3619,8 +4366,6 @@ static int get_walk(struct kvm_vcpu *vcpu, u64 addr, u64 *sptes, int *root_level int leaf = -1; u64 spte; - walk_shadow_page_lockless_begin(vcpu); - for (shadow_walk_init(&iterator, vcpu, addr), *root_level = iterator.level; shadow_walk_okay(&iterator); @@ -3629,13 +4374,24 @@ static int get_walk(struct kvm_vcpu *vcpu, u64 addr, u64 *sptes, int *root_level spte = mmu_spte_get_lockless(iterator.sptep); sptes[leaf] = spte; - - if (!is_shadow_present_pte(spte)) - break; } - walk_shadow_page_lockless_end(vcpu); + return leaf; +} + +static int get_sptes_lockless(struct kvm_vcpu *vcpu, u64 addr, u64 *sptes, + int *root_level) +{ + int leaf; + walk_shadow_page_lockless_begin(vcpu); + + if (is_tdp_mmu_active(vcpu)) + leaf = kvm_tdp_mmu_get_walk(vcpu, addr, sptes, root_level); + else + leaf = get_walk(vcpu, addr, sptes, root_level); + + walk_shadow_page_lockless_end(vcpu); return leaf; } @@ -3647,11 +4403,7 @@ static bool get_mmio_spte(struct kvm_vcpu *vcpu, u64 addr, u64 *sptep) int root, leaf, level; bool reserved = false; - if (is_tdp_mmu(vcpu->arch.mmu)) - leaf = kvm_tdp_mmu_get_walk(vcpu, addr, sptes, &root); - else - leaf = get_walk(vcpu, addr, sptes, &root); - + leaf = get_sptes_lockless(vcpu, addr, sptes, &root); if (unlikely(leaf < 0)) { *sptep = 0ull; return reserved; @@ -3694,10 +4446,10 @@ static int handle_mmio_page_fault(struct kvm_vcpu *vcpu, u64 addr, bool direct) return RET_PF_EMULATE; reserved = get_mmio_spte(vcpu, addr, &spte); - if (WARN_ON(reserved)) + if (WARN_ON_ONCE(reserved)) return -EINVAL; - if (is_mmio_spte(spte)) { + if (is_mmio_spte(vcpu->kvm, spte)) { gfn_t gfn = get_mmio_spte_gfn(spte); unsigned int access = get_mmio_spte_access(spte); @@ -3720,20 +4472,19 @@ static int handle_mmio_page_fault(struct kvm_vcpu *vcpu, u64 addr, bool direct) } static bool page_fault_handle_page_track(struct kvm_vcpu *vcpu, - u32 error_code, gfn_t gfn) + struct kvm_page_fault *fault) { - if (unlikely(error_code & PFERR_RSVD_MASK)) + if (unlikely(fault->rsvd)) return false; - if (!(error_code & PFERR_PRESENT_MASK) || - !(error_code & PFERR_WRITE_MASK)) + if (!fault->present || !fault->write) return false; /* * guest is writing the page which is write tracked which can * not be fixed by page fault handler. */ - if (kvm_page_track_is_active(vcpu, gfn, KVM_PAGE_TRACK_WRITE)) + if (kvm_gfn_is_write_tracked(vcpu->kvm, fault->slot, fault->gfn)) return true; return false; @@ -3745,144 +4496,342 @@ static void shadow_page_table_clear_flood(struct kvm_vcpu *vcpu, gva_t addr) u64 spte; walk_shadow_page_lockless_begin(vcpu); - for_each_shadow_entry_lockless(vcpu, addr, iterator, spte) { + for_each_shadow_entry_lockless(vcpu, addr, iterator, spte) clear_sp_write_flooding_count(iterator.sptep); - if (!is_shadow_present_pte(spte)) - break; - } walk_shadow_page_lockless_end(vcpu); } -static bool kvm_arch_setup_async_pf(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, - gfn_t gfn) +static u32 alloc_apf_token(struct kvm_vcpu *vcpu) +{ + /* make sure the token value is not 0 */ + u32 id = vcpu->arch.apf.id; + + if (id << 12 == 0) + vcpu->arch.apf.id = 1; + + return (vcpu->arch.apf.id++ << 12) | vcpu->vcpu_id; +} + +static bool kvm_arch_setup_async_pf(struct kvm_vcpu *vcpu, + struct kvm_page_fault *fault) { struct kvm_arch_async_pf arch; - arch.token = (vcpu->arch.apf.id++ << 12) | vcpu->vcpu_id; - arch.gfn = gfn; - arch.direct_map = vcpu->arch.mmu->direct_map; - arch.cr3 = vcpu->arch.mmu->get_guest_pgd(vcpu); + arch.token = alloc_apf_token(vcpu); + arch.gfn = fault->gfn; + arch.error_code = fault->error_code; + arch.direct_map = vcpu->arch.mmu->root_role.direct; + arch.cr3 = kvm_mmu_get_guest_pgd(vcpu, vcpu->arch.mmu); + + return kvm_setup_async_pf(vcpu, fault->addr, + kvm_vcpu_gfn_to_hva(vcpu, fault->gfn), &arch); +} + +void kvm_arch_async_page_ready(struct kvm_vcpu *vcpu, struct kvm_async_pf *work) +{ + int r; + + if (WARN_ON_ONCE(work->arch.error_code & PFERR_PRIVATE_ACCESS)) + return; + + if ((vcpu->arch.mmu->root_role.direct != work->arch.direct_map) || + work->wakeup_all) + return; + + r = kvm_mmu_reload(vcpu); + if (unlikely(r)) + return; + + if (!vcpu->arch.mmu->root_role.direct && + work->arch.cr3 != kvm_mmu_get_guest_pgd(vcpu, vcpu->arch.mmu)) + return; + + r = kvm_mmu_do_page_fault(vcpu, work->cr2_or_gpa, work->arch.error_code, + true, NULL, NULL); + + /* + * Account fixed page faults, otherwise they'll never be counted, but + * ignore stats for all other return times. Page-ready "faults" aren't + * truly spurious and never trigger emulation + */ + if (r == RET_PF_FIXED) + vcpu->stat.pf_fixed++; +} + +static void kvm_mmu_finish_page_fault(struct kvm_vcpu *vcpu, + struct kvm_page_fault *fault, int r) +{ + kvm_release_faultin_page(vcpu->kvm, fault->refcounted_page, + r == RET_PF_RETRY, fault->map_writable); +} + +static int kvm_mmu_faultin_pfn_gmem(struct kvm_vcpu *vcpu, + struct kvm_page_fault *fault) +{ + int max_order, r; + + if (!kvm_slot_has_gmem(fault->slot)) { + kvm_mmu_prepare_memory_fault_exit(vcpu, fault); + return -EFAULT; + } - return kvm_setup_async_pf(vcpu, cr2_or_gpa, - kvm_vcpu_gfn_to_hva(vcpu, gfn), &arch); + r = kvm_gmem_get_pfn(vcpu->kvm, fault->slot, fault->gfn, &fault->pfn, + &fault->refcounted_page, &max_order); + if (r) { + kvm_mmu_prepare_memory_fault_exit(vcpu, fault); + return r; + } + + fault->map_writable = !(fault->slot->flags & KVM_MEM_READONLY); + fault->max_level = kvm_max_level_for_order(max_order); + + return RET_PF_CONTINUE; } -static bool try_async_pf(struct kvm_vcpu *vcpu, bool prefault, gfn_t gfn, - gpa_t cr2_or_gpa, kvm_pfn_t *pfn, hva_t *hva, - bool write, bool *writable) +static int __kvm_mmu_faultin_pfn(struct kvm_vcpu *vcpu, + struct kvm_page_fault *fault) { - struct kvm_memory_slot *slot = kvm_vcpu_gfn_to_memslot(vcpu, gfn); - bool async; + unsigned int foll = fault->write ? FOLL_WRITE : 0; + + if (fault->is_private || kvm_memslot_is_gmem_only(fault->slot)) + return kvm_mmu_faultin_pfn_gmem(vcpu, fault); + + foll |= FOLL_NOWAIT; + fault->pfn = __kvm_faultin_pfn(fault->slot, fault->gfn, foll, + &fault->map_writable, &fault->refcounted_page); + + /* + * If resolving the page failed because I/O is needed to fault-in the + * page, then either set up an asynchronous #PF to do the I/O, or if + * doing an async #PF isn't possible, retry with I/O allowed. All + * other failures are terminal, i.e. retrying won't help. + */ + if (fault->pfn != KVM_PFN_ERR_NEEDS_IO) + return RET_PF_CONTINUE; + + if (!fault->prefetch && kvm_can_do_async_pf(vcpu)) { + trace_kvm_try_async_get_page(fault->addr, fault->gfn); + if (kvm_find_async_pf_gfn(vcpu, fault->gfn)) { + trace_kvm_async_pf_repeated_fault(fault->addr, fault->gfn); + kvm_make_request(KVM_REQ_APF_HALT, vcpu); + return RET_PF_RETRY; + } else if (kvm_arch_setup_async_pf(vcpu, fault)) { + return RET_PF_RETRY; + } + } + + /* + * Allow gup to bail on pending non-fatal signals when it's also allowed + * to wait for IO. Note, gup always bails if it is unable to quickly + * get a page and a fatal signal, i.e. SIGKILL, is pending. + */ + foll |= FOLL_INTERRUPTIBLE; + foll &= ~FOLL_NOWAIT; + fault->pfn = __kvm_faultin_pfn(fault->slot, fault->gfn, foll, + &fault->map_writable, &fault->refcounted_page); + + return RET_PF_CONTINUE; +} + +static int kvm_mmu_faultin_pfn(struct kvm_vcpu *vcpu, + struct kvm_page_fault *fault, unsigned int access) +{ + struct kvm_memory_slot *slot = fault->slot; + struct kvm *kvm = vcpu->kvm; + int ret; + + if (KVM_BUG_ON(kvm_is_gfn_alias(kvm, fault->gfn), kvm)) + return -EFAULT; + + /* + * Note that the mmu_invalidate_seq also serves to detect a concurrent + * change in attributes. is_page_fault_stale() will detect an + * invalidation relate to fault->fn and resume the guest without + * installing a mapping in the page tables. + */ + fault->mmu_seq = vcpu->kvm->mmu_invalidate_seq; + smp_rmb(); + + /* + * Now that we have a snapshot of mmu_invalidate_seq we can check for a + * private vs. shared mismatch. + */ + if (fault->is_private != kvm_mem_is_private(kvm, fault->gfn)) { + kvm_mmu_prepare_memory_fault_exit(vcpu, fault); + return -EFAULT; + } + + if (unlikely(!slot)) + return kvm_handle_noslot_fault(vcpu, fault, access); /* * Retry the page fault if the gfn hit a memslot that is being deleted * or moved. This ensures any existing SPTEs for the old memslot will - * be zapped before KVM inserts a new MMIO SPTE for the gfn. + * be zapped before KVM inserts a new MMIO SPTE for the gfn. Punt the + * error to userspace if this is a prefault, as KVM's prefaulting ABI + * doesn't provide the same forward progress guarantees as KVM_RUN. */ - if (slot && (slot->flags & KVM_MEMSLOT_INVALID)) - return true; + if (slot->flags & KVM_MEMSLOT_INVALID) { + if (fault->prefetch) + return -EAGAIN; - /* Don't expose private memslots to L2. */ - if (is_guest_mode(vcpu) && !kvm_is_visible_memslot(slot)) { - *pfn = KVM_PFN_NOSLOT; - *writable = false; - return false; + return RET_PF_RETRY; } - async = false; - *pfn = __gfn_to_pfn_memslot(slot, gfn, false, &async, - write, writable, hva); - if (!async) - return false; /* *pfn has correct page already */ + if (slot->id == APIC_ACCESS_PAGE_PRIVATE_MEMSLOT) { + /* + * Don't map L1's APIC access page into L2, KVM doesn't support + * using APICv/AVIC to accelerate L2 accesses to L1's APIC, + * i.e. the access needs to be emulated. Emulating access to + * L1's APIC is also correct if L1 is accelerating L2's own + * virtual APIC, but for some reason L1 also maps _L1's_ APIC + * into L2. Note, vcpu_is_mmio_gpa() always treats access to + * the APIC as MMIO. Allow an MMIO SPTE to be created, as KVM + * uses different roots for L1 vs. L2, i.e. there is no danger + * of breaking APICv/AVIC for L1. + */ + if (is_guest_mode(vcpu)) + return kvm_handle_noslot_fault(vcpu, fault, access); - if (!prefault && kvm_can_do_async_pf(vcpu)) { - trace_kvm_try_async_get_page(cr2_or_gpa, gfn); - if (kvm_find_async_pf_gfn(vcpu, gfn)) { - trace_kvm_async_pf_doublefault(cr2_or_gpa, gfn); - kvm_make_request(KVM_REQ_APF_HALT, vcpu); - return true; - } else if (kvm_arch_setup_async_pf(vcpu, cr2_or_gpa, gfn)) - return true; + /* + * If the APIC access page exists but is disabled, go directly + * to emulation without caching the MMIO access or creating a + * MMIO SPTE. That way the cache doesn't need to be purged + * when the AVIC is re-enabled. + */ + if (!kvm_apicv_activated(vcpu->kvm)) + return RET_PF_EMULATE; } - *pfn = __gfn_to_pfn_memslot(slot, gfn, false, NULL, - write, writable, hva); - return false; + /* + * Check for a relevant mmu_notifier invalidation event before getting + * the pfn from the primary MMU, and before acquiring mmu_lock. + * + * For mmu_lock, if there is an in-progress invalidation and the kernel + * allows preemption, the invalidation task may drop mmu_lock and yield + * in response to mmu_lock being contended, which is *very* counter- + * productive as this vCPU can't actually make forward progress until + * the invalidation completes. + * + * Retrying now can also avoid unnessary lock contention in the primary + * MMU, as the primary MMU doesn't necessarily hold a single lock for + * the duration of the invalidation, i.e. faulting in a conflicting pfn + * can cause the invalidation to take longer by holding locks that are + * needed to complete the invalidation. + * + * Do the pre-check even for non-preemtible kernels, i.e. even if KVM + * will never yield mmu_lock in response to contention, as this vCPU is + * *guaranteed* to need to retry, i.e. waiting until mmu_lock is held + * to detect retry guarantees the worst case latency for the vCPU. + */ + if (mmu_invalidate_retry_gfn_unsafe(kvm, fault->mmu_seq, fault->gfn)) + return RET_PF_RETRY; + + ret = __kvm_mmu_faultin_pfn(vcpu, fault); + if (ret != RET_PF_CONTINUE) + return ret; + + if (unlikely(is_error_pfn(fault->pfn))) + return kvm_handle_error_pfn(vcpu, fault); + + if (WARN_ON_ONCE(!fault->slot || is_noslot_pfn(fault->pfn))) + return kvm_handle_noslot_fault(vcpu, fault, access); + + /* + * Check again for a relevant mmu_notifier invalidation event purely to + * avoid contending mmu_lock. Most invalidations will be detected by + * the previous check, but checking is extremely cheap relative to the + * overall cost of failing to detect the invalidation until after + * mmu_lock is acquired. + */ + if (mmu_invalidate_retry_gfn_unsafe(kvm, fault->mmu_seq, fault->gfn)) { + kvm_mmu_finish_page_fault(vcpu, fault, RET_PF_RETRY); + return RET_PF_RETRY; + } + + return RET_PF_CONTINUE; } -static int direct_page_fault(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code, - bool prefault, int max_level, bool is_tdp) +/* + * Returns true if the page fault is stale and needs to be retried, i.e. if the + * root was invalidated by a memslot update or a relevant mmu_notifier fired. + */ +static bool is_page_fault_stale(struct kvm_vcpu *vcpu, + struct kvm_page_fault *fault) { - bool is_tdp_mmu_fault = is_tdp_mmu(vcpu->arch.mmu); - bool write = error_code & PFERR_WRITE_MASK; - bool map_writable; + struct kvm_mmu_page *sp = root_to_sp(vcpu->arch.mmu->root.hpa); - gfn_t gfn = gpa >> PAGE_SHIFT; - unsigned long mmu_seq; - kvm_pfn_t pfn; - hva_t hva; + /* Special roots, e.g. pae_root, are not backed by shadow pages. */ + if (sp && is_obsolete_sp(vcpu->kvm, sp)) + return true; + + /* + * Roots without an associated shadow page are considered invalid if + * there is a pending request to free obsolete roots. The request is + * only a hint that the current root _may_ be obsolete and needs to be + * reloaded, e.g. if the guest frees a PGD that KVM is tracking as a + * previous root, then __kvm_mmu_prepare_zap_page() signals all vCPUs + * to reload even if no vCPU is actively using the root. + */ + if (!sp && kvm_test_request(KVM_REQ_MMU_FREE_OBSOLETE_ROOTS, vcpu)) + return true; + + /* + * Check for a relevant mmu_notifier invalidation event one last time + * now that mmu_lock is held, as the "unsafe" checks performed without + * holding mmu_lock can get false negatives. + */ + return fault->slot && + mmu_invalidate_retry_gfn(vcpu->kvm, fault->mmu_seq, fault->gfn); +} + +static int direct_page_fault(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault) +{ int r; - if (page_fault_handle_page_track(vcpu, error_code, gfn)) - return RET_PF_EMULATE; + /* Dummy roots are used only for shadowing bad guest roots. */ + if (WARN_ON_ONCE(kvm_mmu_is_dummy_root(vcpu->arch.mmu->root.hpa))) + return RET_PF_RETRY; - if (!is_tdp_mmu_fault) { - r = fast_page_fault(vcpu, gpa, error_code); - if (r != RET_PF_INVALID) - return r; - } + if (page_fault_handle_page_track(vcpu, fault)) + return RET_PF_WRITE_PROTECTED; + + r = fast_page_fault(vcpu, fault); + if (r != RET_PF_INVALID) + return r; r = mmu_topup_memory_caches(vcpu, false); if (r) return r; - mmu_seq = vcpu->kvm->mmu_notifier_seq; - smp_rmb(); - - if (try_async_pf(vcpu, prefault, gfn, gpa, &pfn, &hva, - write, &map_writable)) - return RET_PF_RETRY; - - if (handle_abnormal_pfn(vcpu, is_tdp ? 0 : gpa, gfn, pfn, ACC_ALL, &r)) + r = kvm_mmu_faultin_pfn(vcpu, fault, ACC_ALL); + if (r != RET_PF_CONTINUE) return r; r = RET_PF_RETRY; + write_lock(&vcpu->kvm->mmu_lock); - if (is_tdp_mmu_fault) - read_lock(&vcpu->kvm->mmu_lock); - else - write_lock(&vcpu->kvm->mmu_lock); - - if (!is_noslot_pfn(pfn) && mmu_notifier_retry_hva(vcpu->kvm, mmu_seq, hva)) + if (is_page_fault_stale(vcpu, fault)) goto out_unlock; + r = make_mmu_pages_available(vcpu); if (r) goto out_unlock; - if (is_tdp_mmu_fault) - r = kvm_tdp_mmu_map(vcpu, gpa, error_code, map_writable, max_level, - pfn, prefault); - else - r = __direct_map(vcpu, gpa, error_code, map_writable, max_level, pfn, - prefault, is_tdp); + r = direct_map(vcpu, fault); out_unlock: - if (is_tdp_mmu_fault) - read_unlock(&vcpu->kvm->mmu_lock); - else - write_unlock(&vcpu->kvm->mmu_lock); - kvm_release_pfn_clean(pfn); + kvm_mmu_finish_page_fault(vcpu, fault, r); + write_unlock(&vcpu->kvm->mmu_lock); return r; } -static int nonpaging_page_fault(struct kvm_vcpu *vcpu, gpa_t gpa, - u32 error_code, bool prefault) +static int nonpaging_page_fault(struct kvm_vcpu *vcpu, + struct kvm_page_fault *fault) { - pgprintk("%s: gva %lx error %x\n", __func__, gpa, error_code); - /* This path builds a PAE pagetable, we can map 2mb pages at maximum. */ - return direct_page_fault(vcpu, gpa & PAGE_MASK, error_code, prefault, - PG_LEVEL_2M, false); + fault->max_level = PG_LEVEL_2M; + return direct_page_fault(vcpu, fault); } int kvm_handle_page_fault(struct kvm_vcpu *vcpu, u64 error_code, @@ -3896,13 +4845,24 @@ int kvm_handle_page_fault(struct kvm_vcpu *vcpu, u64 error_code, if (WARN_ON_ONCE(fault_address >> 32)) return -EFAULT; #endif + /* + * Legacy #PF exception only have a 32-bit error code. Simply drop the + * upper bits as KVM doesn't use them for #PF (because they are never + * set), and to ensure there are no collisions with KVM-defined bits. + */ + if (WARN_ON_ONCE(error_code >> 32)) + error_code = lower_32_bits(error_code); + + /* + * Restrict KVM-defined flags to bits 63:32 so that it's impossible for + * them to conflict with #PF error codes, which are limited to 32 bits. + */ + BUILD_BUG_ON(lower_32_bits(PFERR_SYNTHETIC_MASK)); - vcpu->arch.l1tf_flush_l1d = true; + kvm_request_l1tf_flush_l1d(); if (!flags) { - trace_kvm_page_fault(fault_address, error_code); + trace_kvm_page_fault(vcpu, fault_address, error_code); - if (kvm_event_needs_reinjection(vcpu)) - kvm_mmu_unprotect_page_virt(vcpu, fault_address); r = kvm_mmu_page_fault(vcpu, fault_address, error_code, insn, insn_len); } else if (flags & KVM_PV_REASON_PAGE_NOT_PRESENT) { @@ -3916,108 +4876,345 @@ int kvm_handle_page_fault(struct kvm_vcpu *vcpu, u64 error_code, return r; } -EXPORT_SYMBOL_GPL(kvm_handle_page_fault); +EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_handle_page_fault); -int kvm_tdp_page_fault(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code, - bool prefault) +#ifdef CONFIG_X86_64 +static int kvm_tdp_mmu_page_fault(struct kvm_vcpu *vcpu, + struct kvm_page_fault *fault) { - int max_level; + int r; - for (max_level = KVM_MAX_HUGEPAGE_LEVEL; - max_level > PG_LEVEL_4K; - max_level--) { - int page_num = KVM_PAGES_PER_HPAGE(max_level); - gfn_t base = (gpa >> PAGE_SHIFT) & ~(page_num - 1); + if (page_fault_handle_page_track(vcpu, fault)) + return RET_PF_WRITE_PROTECTED; - if (kvm_mtrr_check_gfn_range_consistency(vcpu, base, page_num)) - break; + r = fast_page_fault(vcpu, fault); + if (r != RET_PF_INVALID) + return r; + + r = mmu_topup_memory_caches(vcpu, false); + if (r) + return r; + + r = kvm_mmu_faultin_pfn(vcpu, fault, ACC_ALL); + if (r != RET_PF_CONTINUE) + return r; + + r = RET_PF_RETRY; + read_lock(&vcpu->kvm->mmu_lock); + + if (is_page_fault_stale(vcpu, fault)) + goto out_unlock; + + r = kvm_tdp_mmu_map(vcpu, fault); + +out_unlock: + kvm_mmu_finish_page_fault(vcpu, fault, r); + read_unlock(&vcpu->kvm->mmu_lock); + return r; +} +#endif + +int kvm_tdp_page_fault(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault) +{ +#ifdef CONFIG_X86_64 + if (tdp_mmu_enabled) + return kvm_tdp_mmu_page_fault(vcpu, fault); +#endif + + return direct_page_fault(vcpu, fault); +} + +static int kvm_tdp_page_prefault(struct kvm_vcpu *vcpu, gpa_t gpa, + u64 error_code, u8 *level) +{ + int r; + + /* + * Restrict to TDP page fault, since that's the only case where the MMU + * is indexed by GPA. + */ + if (vcpu->arch.mmu->page_fault != kvm_tdp_page_fault) + return -EOPNOTSUPP; + + do { + if (signal_pending(current)) + return -EINTR; + + if (kvm_check_request(KVM_REQ_VM_DEAD, vcpu)) + return -EIO; + + cond_resched(); + r = kvm_mmu_do_page_fault(vcpu, gpa, error_code, true, NULL, level); + } while (r == RET_PF_RETRY); + + if (r < 0) + return r; + + switch (r) { + case RET_PF_FIXED: + case RET_PF_SPURIOUS: + case RET_PF_WRITE_PROTECTED: + return 0; + + case RET_PF_EMULATE: + return -ENOENT; + + case RET_PF_RETRY: + case RET_PF_CONTINUE: + case RET_PF_INVALID: + default: + WARN_ONCE(1, "could not fix page fault during prefault"); + return -EIO; } +} + +long kvm_arch_vcpu_pre_fault_memory(struct kvm_vcpu *vcpu, + struct kvm_pre_fault_memory *range) +{ + u64 error_code = PFERR_GUEST_FINAL_MASK; + u8 level = PG_LEVEL_4K; + u64 direct_bits; + u64 end; + int r; - return direct_page_fault(vcpu, gpa, error_code, prefault, - max_level, true); + if (!vcpu->kvm->arch.pre_fault_allowed) + return -EOPNOTSUPP; + + if (kvm_is_gfn_alias(vcpu->kvm, gpa_to_gfn(range->gpa))) + return -EINVAL; + + /* + * reload is efficient when called repeatedly, so we can do it on + * every iteration. + */ + r = kvm_mmu_reload(vcpu); + if (r) + return r; + + direct_bits = 0; + if (kvm_arch_has_private_mem(vcpu->kvm) && + kvm_mem_is_private(vcpu->kvm, gpa_to_gfn(range->gpa))) + error_code |= PFERR_PRIVATE_ACCESS; + else + direct_bits = gfn_to_gpa(kvm_gfn_direct_bits(vcpu->kvm)); + + /* + * Shadow paging uses GVA for kvm page fault, so restrict to + * two-dimensional paging. + */ + r = kvm_tdp_page_prefault(vcpu, range->gpa | direct_bits, error_code, &level); + if (r < 0) + return r; + + /* + * If the mapping that covers range->gpa can use a huge page, it + * may start below it or end after range->gpa + range->size. + */ + end = (range->gpa & KVM_HPAGE_MASK(level)) + KVM_HPAGE_SIZE(level); + return min(range->size, end - range->gpa); +} + +#ifdef CONFIG_KVM_GUEST_MEMFD +static void kvm_assert_gmem_invalidate_lock_held(struct kvm_memory_slot *slot) +{ +#ifdef CONFIG_PROVE_LOCKING + if (WARN_ON_ONCE(!kvm_slot_has_gmem(slot)) || + WARN_ON_ONCE(!slot->gmem.file) || + WARN_ON_ONCE(!file_count(slot->gmem.file))) + return; + + lockdep_assert_held(&file_inode(slot->gmem.file)->i_mapping->invalidate_lock); +#endif } +int kvm_tdp_mmu_map_private_pfn(struct kvm_vcpu *vcpu, gfn_t gfn, kvm_pfn_t pfn) +{ + struct kvm_page_fault fault = { + .addr = gfn_to_gpa(gfn), + .error_code = PFERR_GUEST_FINAL_MASK | PFERR_PRIVATE_ACCESS, + .prefetch = true, + .is_tdp = true, + .nx_huge_page_workaround_enabled = is_nx_huge_page_enabled(vcpu->kvm), + + .max_level = PG_LEVEL_4K, + .req_level = PG_LEVEL_4K, + .goal_level = PG_LEVEL_4K, + .is_private = true, + + .gfn = gfn, + .slot = kvm_vcpu_gfn_to_memslot(vcpu, gfn), + .pfn = pfn, + .map_writable = true, + }; + struct kvm *kvm = vcpu->kvm; + int r; + + lockdep_assert_held(&kvm->slots_lock); + + /* + * Mapping a pre-determined private pfn is intended only for use when + * populating a guest_memfd instance. Assert that the slot is backed + * by guest_memfd and that the gmem instance's invalidate_lock is held. + */ + kvm_assert_gmem_invalidate_lock_held(fault.slot); + + if (KVM_BUG_ON(!tdp_mmu_enabled, kvm)) + return -EIO; + + if (kvm_gfn_is_write_tracked(kvm, fault.slot, fault.gfn)) + return -EPERM; + + r = kvm_mmu_reload(vcpu); + if (r) + return r; + + r = mmu_topup_memory_caches(vcpu, false); + if (r) + return r; + + do { + if (signal_pending(current)) + return -EINTR; + + if (kvm_test_request(KVM_REQ_VM_DEAD, vcpu)) + return -EIO; + + cond_resched(); + + guard(read_lock)(&kvm->mmu_lock); + + r = kvm_tdp_mmu_map(vcpu, &fault); + } while (r == RET_PF_RETRY); + + if (r != RET_PF_FIXED) + return -EIO; + + return 0; +} +EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_tdp_mmu_map_private_pfn); +#endif + static void nonpaging_init_context(struct kvm_mmu *context) { context->page_fault = nonpaging_page_fault; context->gva_to_gpa = nonpaging_gva_to_gpa; - context->sync_page = nonpaging_sync_page; - context->invlpg = NULL; - context->direct_map = true; + context->sync_spte = NULL; } static inline bool is_root_usable(struct kvm_mmu_root_info *root, gpa_t pgd, union kvm_mmu_page_role role) { - return (role.direct || pgd == root->pgd) && - VALID_PAGE(root->hpa) && to_shadow_page(root->hpa) && - role.word == to_shadow_page(root->hpa)->role.word; + struct kvm_mmu_page *sp; + + if (!VALID_PAGE(root->hpa)) + return false; + + if (!role.direct && pgd != root->pgd) + return false; + + sp = root_to_sp(root->hpa); + if (WARN_ON_ONCE(!sp)) + return false; + + return role.word == sp->role.word; } /* - * Find out if a previously cached root matching the new pgd/role is available. - * The current root is also inserted into the cache. - * If a matching root was found, it is assigned to kvm_mmu->root_hpa and true is - * returned. - * Otherwise, the LRU root from the cache is assigned to kvm_mmu->root_hpa and - * false is returned. This root should now be freed by the caller. + * Find out if a previously cached root matching the new pgd/role is available, + * and insert the current root as the MRU in the cache. + * If a matching root is found, it is assigned to kvm_mmu->root and + * true is returned. + * If no match is found, kvm_mmu->root is left invalid, the LRU root is + * evicted to make room for the current root, and false is returned. */ -static bool cached_root_available(struct kvm_vcpu *vcpu, gpa_t new_pgd, - union kvm_mmu_page_role new_role) +static bool cached_root_find_and_keep_current(struct kvm *kvm, struct kvm_mmu *mmu, + gpa_t new_pgd, + union kvm_mmu_page_role new_role) { uint i; - struct kvm_mmu_root_info root; - struct kvm_mmu *mmu = vcpu->arch.mmu; - - root.pgd = mmu->root_pgd; - root.hpa = mmu->root_hpa; - if (is_root_usable(&root, new_pgd, new_role)) + if (is_root_usable(&mmu->root, new_pgd, new_role)) return true; for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++) { - swap(root, mmu->prev_roots[i]); - - if (is_root_usable(&root, new_pgd, new_role)) - break; + /* + * The swaps end up rotating the cache like this: + * C 0 1 2 3 (on entry to the function) + * 0 C 1 2 3 + * 1 C 0 2 3 + * 2 C 0 1 3 + * 3 C 0 1 2 (on exit from the loop) + */ + swap(mmu->root, mmu->prev_roots[i]); + if (is_root_usable(&mmu->root, new_pgd, new_role)) + return true; } - mmu->root_hpa = root.hpa; - mmu->root_pgd = root.pgd; - - return i < KVM_MMU_NUM_PREV_ROOTS; + kvm_mmu_free_roots(kvm, mmu, KVM_MMU_ROOT_CURRENT); + return false; } -static bool fast_pgd_switch(struct kvm_vcpu *vcpu, gpa_t new_pgd, - union kvm_mmu_page_role new_role) +/* + * Find out if a previously cached root matching the new pgd/role is available. + * On entry, mmu->root is invalid. + * If a matching root is found, it is assigned to kvm_mmu->root, the LRU entry + * of the cache becomes invalid, and true is returned. + * If no match is found, kvm_mmu->root is left invalid and false is returned. + */ +static bool cached_root_find_without_current(struct kvm *kvm, struct kvm_mmu *mmu, + gpa_t new_pgd, + union kvm_mmu_page_role new_role) { - struct kvm_mmu *mmu = vcpu->arch.mmu; + uint i; + for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++) + if (is_root_usable(&mmu->prev_roots[i], new_pgd, new_role)) + goto hit; + + return false; + +hit: + swap(mmu->root, mmu->prev_roots[i]); + /* Bubble up the remaining roots. */ + for (; i < KVM_MMU_NUM_PREV_ROOTS - 1; i++) + mmu->prev_roots[i] = mmu->prev_roots[i + 1]; + mmu->prev_roots[i].hpa = INVALID_PAGE; + return true; +} + +static bool fast_pgd_switch(struct kvm *kvm, struct kvm_mmu *mmu, + gpa_t new_pgd, union kvm_mmu_page_role new_role) +{ /* - * For now, limit the fast switch to 64-bit hosts+VMs in order to avoid - * having to deal with PDPTEs. We may add support for 32-bit hosts/VMs - * later if necessary. + * Limit reuse to 64-bit hosts+VMs without "special" roots in order to + * avoid having to deal with PDPTEs and other complexities. */ - if (mmu->shadow_root_level >= PT64_ROOT_4LEVEL && - mmu->root_level >= PT64_ROOT_4LEVEL) - return cached_root_available(vcpu, new_pgd, new_role); + if (VALID_PAGE(mmu->root.hpa) && !root_to_sp(mmu->root.hpa)) + kvm_mmu_free_roots(kvm, mmu, KVM_MMU_ROOT_CURRENT); - return false; + if (VALID_PAGE(mmu->root.hpa)) + return cached_root_find_and_keep_current(kvm, mmu, new_pgd, new_role); + else + return cached_root_find_without_current(kvm, mmu, new_pgd, new_role); } -static void __kvm_mmu_new_pgd(struct kvm_vcpu *vcpu, gpa_t new_pgd, - union kvm_mmu_page_role new_role) +void kvm_mmu_new_pgd(struct kvm_vcpu *vcpu, gpa_t new_pgd) { - if (!fast_pgd_switch(vcpu, new_pgd, new_role)) { - kvm_mmu_free_roots(vcpu, vcpu->arch.mmu, KVM_MMU_ROOT_CURRENT); + struct kvm_mmu *mmu = vcpu->arch.mmu; + union kvm_mmu_page_role new_role = mmu->root_role; + + /* + * Return immediately if no usable root was found, kvm_mmu_reload() + * will establish a valid root prior to the next VM-Enter. + */ + if (!fast_pgd_switch(vcpu->kvm, mmu, new_pgd, new_role)) return; - } /* * It's possible that the cached previous root page is obsolete because * of a change in the MMU generation number. However, changing the - * generation number is accompanied by KVM_REQ_MMU_RELOAD, which will - * free the root set here and allocate a new one. + * generation number is accompanied by KVM_REQ_MMU_FREE_OBSOLETE_ROOTS, + * which will free the root set here and allocate a new one. */ kvm_make_request(KVM_REQ_LOAD_MMU_PGD, vcpu); @@ -4038,32 +5235,24 @@ static void __kvm_mmu_new_pgd(struct kvm_vcpu *vcpu, gpa_t new_pgd, * If this is a direct root page, it doesn't have a write flooding * count. Otherwise, clear the write flooding count. */ - if (!new_role.direct) - __clear_sp_write_flooding_count( - to_shadow_page(vcpu->arch.mmu->root_hpa)); -} - -void kvm_mmu_new_pgd(struct kvm_vcpu *vcpu, gpa_t new_pgd) -{ - __kvm_mmu_new_pgd(vcpu, new_pgd, kvm_mmu_calc_root_page_role(vcpu)); -} -EXPORT_SYMBOL_GPL(kvm_mmu_new_pgd); + if (!new_role.direct) { + struct kvm_mmu_page *sp = root_to_sp(vcpu->arch.mmu->root.hpa); -static unsigned long get_cr3(struct kvm_vcpu *vcpu) -{ - return kvm_read_cr3(vcpu); + if (!WARN_ON_ONCE(!sp)) + __clear_sp_write_flooding_count(sp); + } } +EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_mmu_new_pgd); static bool sync_mmio_spte(struct kvm_vcpu *vcpu, u64 *sptep, gfn_t gfn, - unsigned int access, int *nr_present) + unsigned int access) { - if (unlikely(is_mmio_spte(*sptep))) { + if (unlikely(is_mmio_spte(vcpu->kvm, *sptep))) { if (gfn != get_mmio_spte_gfn(*sptep)) { mmu_spte_clear_no_track(sptep); return true; } - (*nr_present)++; mark_mmio_spte(vcpu, sptep, gfn, access); return true; } @@ -4084,10 +5273,9 @@ static bool sync_mmio_spte(struct kvm_vcpu *vcpu, u64 *sptep, gfn_t gfn, #include "paging_tmpl.h" #undef PTTYPE -static void -__reset_rsvds_bits_mask(struct rsvd_bits_validate *rsvd_check, - u64 pa_bits_rsvd, int level, bool nx, bool gbpages, - bool pse, bool amd) +static void __reset_rsvds_bits_mask(struct rsvd_bits_validate *rsvd_check, + u64 pa_bits_rsvd, int level, bool nx, + bool gbpages, bool pse, bool amd) { u64 gbpages_bit_rsvd = 0; u64 nonleaf_bit8_rsvd = 0; @@ -4174,50 +5362,41 @@ __reset_rsvds_bits_mask(struct rsvd_bits_validate *rsvd_check, } } -static bool guest_can_use_gbpages(struct kvm_vcpu *vcpu) -{ - /* - * If TDP is enabled, let the guest use GBPAGES if they're supported in - * hardware. The hardware page walker doesn't let KVM disable GBPAGES, - * i.e. won't treat them as reserved, and KVM doesn't redo the GVA->GPA - * walk for performance and complexity reasons. Not to mention KVM - * _can't_ solve the problem because GVA->GPA walks aren't visible to - * KVM once a TDP translation is installed. Mimic hardware behavior so - * that KVM's is at least consistent, i.e. doesn't randomly inject #PF. - */ - return tdp_enabled ? boot_cpu_has(X86_FEATURE_GBPAGES) : - guest_cpuid_has(vcpu, X86_FEATURE_GBPAGES); -} - -static void reset_rsvds_bits_mask(struct kvm_vcpu *vcpu, - struct kvm_mmu *context) +static void reset_guest_rsvds_bits_mask(struct kvm_vcpu *vcpu, + struct kvm_mmu *context) { __reset_rsvds_bits_mask(&context->guest_rsvd_check, vcpu->arch.reserved_gpa_bits, - context->root_level, is_efer_nx(context), - guest_can_use_gbpages(vcpu), + context->cpu_role.base.level, is_efer_nx(context), + guest_cpu_cap_has(vcpu, X86_FEATURE_GBPAGES), is_cr4_pse(context), - guest_cpuid_is_amd_or_hygon(vcpu)); + guest_cpuid_is_amd_compatible(vcpu)); } -static void -__reset_rsvds_bits_mask_ept(struct rsvd_bits_validate *rsvd_check, - u64 pa_bits_rsvd, bool execonly) +static void __reset_rsvds_bits_mask_ept(struct rsvd_bits_validate *rsvd_check, + u64 pa_bits_rsvd, bool execonly, + int huge_page_level) { u64 high_bits_rsvd = pa_bits_rsvd & rsvd_bits(0, 51); + u64 large_1g_rsvd = 0, large_2m_rsvd = 0; u64 bad_mt_xwr; + if (huge_page_level < PG_LEVEL_1G) + large_1g_rsvd = rsvd_bits(7, 7); + if (huge_page_level < PG_LEVEL_2M) + large_2m_rsvd = rsvd_bits(7, 7); + rsvd_check->rsvd_bits_mask[0][4] = high_bits_rsvd | rsvd_bits(3, 7); rsvd_check->rsvd_bits_mask[0][3] = high_bits_rsvd | rsvd_bits(3, 7); - rsvd_check->rsvd_bits_mask[0][2] = high_bits_rsvd | rsvd_bits(3, 6); - rsvd_check->rsvd_bits_mask[0][1] = high_bits_rsvd | rsvd_bits(3, 6); + rsvd_check->rsvd_bits_mask[0][2] = high_bits_rsvd | rsvd_bits(3, 6) | large_1g_rsvd; + rsvd_check->rsvd_bits_mask[0][1] = high_bits_rsvd | rsvd_bits(3, 6) | large_2m_rsvd; rsvd_check->rsvd_bits_mask[0][0] = high_bits_rsvd; /* large page */ rsvd_check->rsvd_bits_mask[1][4] = rsvd_check->rsvd_bits_mask[0][4]; rsvd_check->rsvd_bits_mask[1][3] = rsvd_check->rsvd_bits_mask[0][3]; - rsvd_check->rsvd_bits_mask[1][2] = high_bits_rsvd | rsvd_bits(12, 29); - rsvd_check->rsvd_bits_mask[1][1] = high_bits_rsvd | rsvd_bits(12, 20); + rsvd_check->rsvd_bits_mask[1][2] = high_bits_rsvd | rsvd_bits(12, 29) | large_1g_rsvd; + rsvd_check->rsvd_bits_mask[1][1] = high_bits_rsvd | rsvd_bits(12, 20) | large_2m_rsvd; rsvd_check->rsvd_bits_mask[1][0] = rsvd_check->rsvd_bits_mask[0][0]; bad_mt_xwr = 0xFFull << (2 * 8); /* bits 3..5 must not be 2 */ @@ -4233,15 +5412,16 @@ __reset_rsvds_bits_mask_ept(struct rsvd_bits_validate *rsvd_check, } static void reset_rsvds_bits_mask_ept(struct kvm_vcpu *vcpu, - struct kvm_mmu *context, bool execonly) + struct kvm_mmu *context, bool execonly, int huge_page_level) { __reset_rsvds_bits_mask_ept(&context->guest_rsvd_check, - vcpu->arch.reserved_gpa_bits, execonly); + vcpu->arch.reserved_gpa_bits, execonly, + huge_page_level); } static inline u64 reserved_hpa_bits(void) { - return rsvd_bits(shadow_phys_bits, 63); + return rsvd_bits(kvm_host.maxphyaddr, 63); } /* @@ -4252,16 +5432,6 @@ static inline u64 reserved_hpa_bits(void) static void reset_shadow_zero_bits_mask(struct kvm_vcpu *vcpu, struct kvm_mmu *context) { - /* - * KVM uses NX when TDP is disabled to handle a variety of scenarios, - * notably for huge SPTEs if iTLB multi-hit mitigation is enabled and - * to generate correct permissions for CR0.WP=0/CR4.SMEP=1/EFER.NX=0. - * The iTLB multi-hit workaround can be toggled at any time, so assume - * NX can be used by any non-nested shadow MMU to avoid having to reset - * MMU contexts. Note, KVM forces EFER.NX=1 when TDP is disabled. - */ - bool uses_nx = is_efer_nx(context) || !tdp_enabled; - /* @amd adds a check on bit of SPTEs, which KVM shouldn't use anyways. */ bool is_amd = true; /* KVM doesn't use 2-level page tables for the shadow MMU. */ @@ -4269,19 +5439,29 @@ static void reset_shadow_zero_bits_mask(struct kvm_vcpu *vcpu, struct rsvd_bits_validate *shadow_zero_check; int i; - WARN_ON_ONCE(context->shadow_root_level < PT32E_ROOT_LEVEL); + WARN_ON_ONCE(context->root_role.level < PT32E_ROOT_LEVEL); shadow_zero_check = &context->shadow_zero_check; __reset_rsvds_bits_mask(shadow_zero_check, reserved_hpa_bits(), - context->shadow_root_level, uses_nx, - guest_can_use_gbpages(vcpu), is_pse, is_amd); + context->root_role.level, + context->root_role.efer_nx, + guest_cpu_cap_has(vcpu, X86_FEATURE_GBPAGES), + is_pse, is_amd); if (!shadow_me_mask) return; - for (i = context->shadow_root_level; --i >= 0;) { - shadow_zero_check->rsvd_bits_mask[0][i] &= ~shadow_me_mask; - shadow_zero_check->rsvd_bits_mask[1][i] &= ~shadow_me_mask; + for (i = context->root_role.level; --i >= 0;) { + /* + * So far shadow_me_value is a constant during KVM's life + * time. Bits in shadow_me_value are allowed to be set. + * Bits in shadow_me_mask but not in shadow_me_value are + * not allowed to be set. + */ + shadow_zero_check->rsvd_bits_mask[0][i] |= shadow_me_mask; + shadow_zero_check->rsvd_bits_mask[1][i] |= shadow_me_mask; + shadow_zero_check->rsvd_bits_mask[0][i] &= ~shadow_me_value; + shadow_zero_check->rsvd_bits_mask[1][i] &= ~shadow_me_value; } } @@ -4296,9 +5476,7 @@ static inline bool boot_cpu_is_amd(void) * the direct page table on host, use as much mmu features as * possible, however, kvm currently does not do execution-protection. */ -static void -reset_tdp_shadow_zero_bits_mask(struct kvm_vcpu *vcpu, - struct kvm_mmu *context) +static void reset_tdp_shadow_zero_bits_mask(struct kvm_mmu *context) { struct rsvd_bits_validate *shadow_zero_check; int i; @@ -4307,17 +5485,18 @@ reset_tdp_shadow_zero_bits_mask(struct kvm_vcpu *vcpu, if (boot_cpu_is_amd()) __reset_rsvds_bits_mask(shadow_zero_check, reserved_hpa_bits(), - context->shadow_root_level, false, + context->root_role.level, true, boot_cpu_has(X86_FEATURE_GBPAGES), false, true); else __reset_rsvds_bits_mask_ept(shadow_zero_check, - reserved_hpa_bits(), false); + reserved_hpa_bits(), false, + max_huge_page_level); if (!shadow_me_mask) return; - for (i = context->shadow_root_level; --i >= 0;) { + for (i = context->root_role.level; --i >= 0;) { shadow_zero_check->rsvd_bits_mask[0][i] &= ~shadow_me_mask; shadow_zero_check->rsvd_bits_mask[1][i] &= ~shadow_me_mask; } @@ -4328,11 +5507,11 @@ reset_tdp_shadow_zero_bits_mask(struct kvm_vcpu *vcpu, * is the shadow page table for intel nested guest. */ static void -reset_ept_shadow_zero_bits_mask(struct kvm_vcpu *vcpu, - struct kvm_mmu *context, bool execonly) +reset_ept_shadow_zero_bits_mask(struct kvm_mmu *context, bool execonly) { __reset_rsvds_bits_mask_ept(&context->shadow_zero_check, - reserved_hpa_bits(), execonly); + reserved_hpa_bits(), execonly, + max_huge_page_level); } #define BYTE_MASK(access) \ @@ -4401,11 +5580,11 @@ static void update_permission_bitmask(struct kvm_mmu *mmu, bool ept) * - X86_CR4_SMAP is set in CR4 * - A user page is accessed * - The access is not a fetch - * - Page fault in kernel mode - * - if CPL = 3 or X86_EFLAGS_AC is clear + * - The access is supervisor mode + * - If implicit supervisor access or X86_EFLAGS_AC is clear * - * Here, we cover the first three conditions. - * The fourth is computed dynamically in permission_fault(); + * Here, we cover the first four conditions. + * The fifth is computed dynamically in permission_fault(); * PFERR_RSVD_MASK bit will be set in PFEC if the access is * *not* subject to SMAP restrictions. */ @@ -4446,10 +5625,10 @@ static void update_pkru_bitmask(struct kvm_mmu *mmu) unsigned bit; bool wp; - if (!is_cr4_pke(mmu)) { - mmu->pkru_mask = 0; + mmu->pkru_mask = 0; + + if (!is_cr4_pke(mmu)) return; - } wp = is_cr0_wp(mmu); @@ -4491,7 +5670,7 @@ static void reset_guest_paging_metadata(struct kvm_vcpu *vcpu, if (!is_cr0_pg(mmu)) return; - reset_rsvds_bits_mask(vcpu, mmu); + reset_guest_rsvds_bits_mask(vcpu, mmu); update_permission_bitmask(mmu, false); update_pkru_bitmask(mmu); } @@ -4500,107 +5679,132 @@ static void paging64_init_context(struct kvm_mmu *context) { context->page_fault = paging64_page_fault; context->gva_to_gpa = paging64_gva_to_gpa; - context->sync_page = paging64_sync_page; - context->invlpg = paging64_invlpg; - context->direct_map = false; + context->sync_spte = paging64_sync_spte; } static void paging32_init_context(struct kvm_mmu *context) { context->page_fault = paging32_page_fault; context->gva_to_gpa = paging32_gva_to_gpa; - context->sync_page = paging32_sync_page; - context->invlpg = paging32_invlpg; - context->direct_map = false; + context->sync_spte = paging32_sync_spte; } -static union kvm_mmu_extended_role kvm_calc_mmu_role_ext(struct kvm_vcpu *vcpu, - struct kvm_mmu_role_regs *regs) +static union kvm_cpu_role kvm_calc_cpu_role(struct kvm_vcpu *vcpu, + const struct kvm_mmu_role_regs *regs) { - union kvm_mmu_extended_role ext = {0}; + union kvm_cpu_role role = {0}; - if (____is_cr0_pg(regs)) { - ext.cr0_pg = 1; - ext.cr4_pae = ____is_cr4_pae(regs); - ext.cr4_smep = ____is_cr4_smep(regs); - ext.cr4_smap = ____is_cr4_smap(regs); - ext.cr4_pse = ____is_cr4_pse(regs); + role.base.access = ACC_ALL; + role.base.smm = is_smm(vcpu); + role.base.guest_mode = is_guest_mode(vcpu); + role.ext.valid = 1; - /* PKEY and LA57 are active iff long mode is active. */ - ext.cr4_pke = ____is_efer_lma(regs) && ____is_cr4_pke(regs); - ext.cr4_la57 = ____is_efer_lma(regs) && ____is_cr4_la57(regs); + if (!____is_cr0_pg(regs)) { + role.base.direct = 1; + return role; } - ext.valid = 1; + role.base.efer_nx = ____is_efer_nx(regs); + role.base.cr0_wp = ____is_cr0_wp(regs); + role.base.smep_andnot_wp = ____is_cr4_smep(regs) && !____is_cr0_wp(regs); + role.base.smap_andnot_wp = ____is_cr4_smap(regs) && !____is_cr0_wp(regs); + role.base.has_4_byte_gpte = !____is_cr4_pae(regs); + + if (____is_efer_lma(regs)) + role.base.level = ____is_cr4_la57(regs) ? PT64_ROOT_5LEVEL + : PT64_ROOT_4LEVEL; + else if (____is_cr4_pae(regs)) + role.base.level = PT32E_ROOT_LEVEL; + else + role.base.level = PT32_ROOT_LEVEL; + + role.ext.cr4_smep = ____is_cr4_smep(regs); + role.ext.cr4_smap = ____is_cr4_smap(regs); + role.ext.cr4_pse = ____is_cr4_pse(regs); - return ext; + /* PKEY and LA57 are active iff long mode is active. */ + role.ext.cr4_pke = ____is_efer_lma(regs) && ____is_cr4_pke(regs); + role.ext.cr4_la57 = ____is_efer_lma(regs) && ____is_cr4_la57(regs); + role.ext.efer_lma = ____is_efer_lma(regs); + return role; } -static union kvm_mmu_role kvm_calc_mmu_role_common(struct kvm_vcpu *vcpu, - struct kvm_mmu_role_regs *regs, - bool base_only) +void __kvm_mmu_refresh_passthrough_bits(struct kvm_vcpu *vcpu, + struct kvm_mmu *mmu) { - union kvm_mmu_role role = {0}; - - role.base.access = ACC_ALL; - if (____is_cr0_pg(regs)) { - role.base.efer_nx = ____is_efer_nx(regs); - role.base.cr0_wp = ____is_cr0_wp(regs); - } - role.base.smm = is_smm(vcpu); - role.base.guest_mode = is_guest_mode(vcpu); + const bool cr0_wp = kvm_is_cr0_bit_set(vcpu, X86_CR0_WP); - if (base_only) - return role; + BUILD_BUG_ON((KVM_MMU_CR0_ROLE_BITS & KVM_POSSIBLE_CR0_GUEST_BITS) != X86_CR0_WP); + BUILD_BUG_ON((KVM_MMU_CR4_ROLE_BITS & KVM_POSSIBLE_CR4_GUEST_BITS)); - role.ext = kvm_calc_mmu_role_ext(vcpu, regs); + if (is_cr0_wp(mmu) == cr0_wp) + return; - return role; + mmu->cpu_role.base.cr0_wp = cr0_wp; + reset_guest_paging_metadata(vcpu, mmu); } static inline int kvm_mmu_get_tdp_level(struct kvm_vcpu *vcpu) { + int maxpa; + + if (vcpu->kvm->arch.vm_type == KVM_X86_TDX_VM) + maxpa = cpuid_query_maxguestphyaddr(vcpu); + else + maxpa = cpuid_maxphyaddr(vcpu); + + /* tdp_root_level is architecture forced level, use it if nonzero */ + if (tdp_root_level) + return tdp_root_level; + /* Use 5-level TDP if and only if it's useful/necessary. */ - if (max_tdp_level == 5 && cpuid_maxphyaddr(vcpu) <= 48) + if (max_tdp_level == 5 && maxpa <= 48) return 4; return max_tdp_level; } -static union kvm_mmu_role +u8 kvm_mmu_get_max_tdp_level(void) +{ + return tdp_root_level ? tdp_root_level : max_tdp_level; +} + +static union kvm_mmu_page_role kvm_calc_tdp_mmu_root_page_role(struct kvm_vcpu *vcpu, - struct kvm_mmu_role_regs *regs, bool base_only) + union kvm_cpu_role cpu_role) { - union kvm_mmu_role role = kvm_calc_mmu_role_common(vcpu, regs, base_only); + union kvm_mmu_page_role role = {0}; - role.base.ad_disabled = (shadow_accessed_mask == 0); - role.base.level = kvm_mmu_get_tdp_level(vcpu); - role.base.direct = true; - role.base.gpte_is_8_bytes = true; + role.access = ACC_ALL; + role.cr0_wp = true; + role.efer_nx = true; + role.smm = cpu_role.base.smm; + role.guest_mode = cpu_role.base.guest_mode; + role.ad_disabled = !kvm_ad_enabled; + role.level = kvm_mmu_get_tdp_level(vcpu); + role.direct = true; + role.has_4_byte_gpte = false; return role; } -static void init_kvm_tdp_mmu(struct kvm_vcpu *vcpu) +static void init_kvm_tdp_mmu(struct kvm_vcpu *vcpu, + union kvm_cpu_role cpu_role) { struct kvm_mmu *context = &vcpu->arch.root_mmu; - struct kvm_mmu_role_regs regs = vcpu_to_role_regs(vcpu); - union kvm_mmu_role new_role = - kvm_calc_tdp_mmu_root_page_role(vcpu, ®s, false); + union kvm_mmu_page_role root_role = kvm_calc_tdp_mmu_root_page_role(vcpu, cpu_role); - if (new_role.as_u64 == context->mmu_role.as_u64) + if (cpu_role.as_u64 == context->cpu_role.as_u64 && + root_role.word == context->root_role.word) return; - context->mmu_role.as_u64 = new_role.as_u64; + context->cpu_role.as_u64 = cpu_role.as_u64; + context->root_role.word = root_role.word; context->page_fault = kvm_tdp_page_fault; - context->sync_page = nonpaging_sync_page; - context->invlpg = NULL; - context->shadow_root_level = kvm_mmu_get_tdp_level(vcpu); - context->direct_map = true; - context->get_guest_pgd = get_cr3; + context->sync_spte = NULL; + context->get_guest_pgd = get_guest_cr3; context->get_pdptr = kvm_pdptr_read; context->inject_page_fault = kvm_inject_page_fault; - context->root_level = role_regs_to_root_level(®s); if (!is_cr0_pg(context)) context->gva_to_gpa = nonpaging_gva_to_gpa; @@ -4610,49 +5814,19 @@ static void init_kvm_tdp_mmu(struct kvm_vcpu *vcpu) context->gva_to_gpa = paging32_gva_to_gpa; reset_guest_paging_metadata(vcpu, context); - reset_tdp_shadow_zero_bits_mask(vcpu, context); -} - -static union kvm_mmu_role -kvm_calc_shadow_root_page_role_common(struct kvm_vcpu *vcpu, - struct kvm_mmu_role_regs *regs, bool base_only) -{ - union kvm_mmu_role role = kvm_calc_mmu_role_common(vcpu, regs, base_only); - - role.base.smep_andnot_wp = role.ext.cr4_smep && !____is_cr0_wp(regs); - role.base.smap_andnot_wp = role.ext.cr4_smap && !____is_cr0_wp(regs); - role.base.gpte_is_8_bytes = ____is_cr0_pg(regs) && ____is_cr4_pae(regs); - - return role; -} - -static union kvm_mmu_role -kvm_calc_shadow_mmu_root_page_role(struct kvm_vcpu *vcpu, - struct kvm_mmu_role_regs *regs, bool base_only) -{ - union kvm_mmu_role role = - kvm_calc_shadow_root_page_role_common(vcpu, regs, base_only); - - role.base.direct = !____is_cr0_pg(regs); - - if (!____is_efer_lma(regs)) - role.base.level = PT32E_ROOT_LEVEL; - else if (____is_cr4_la57(regs)) - role.base.level = PT64_ROOT_5LEVEL; - else - role.base.level = PT64_ROOT_4LEVEL; - - return role; + reset_tdp_shadow_zero_bits_mask(context); } static void shadow_mmu_init_context(struct kvm_vcpu *vcpu, struct kvm_mmu *context, - struct kvm_mmu_role_regs *regs, - union kvm_mmu_role new_role) + union kvm_cpu_role cpu_role, + union kvm_mmu_page_role root_role) { - if (new_role.as_u64 == context->mmu_role.as_u64) + if (cpu_role.as_u64 == context->cpu_role.as_u64 && + root_role.word == context->root_role.word) return; - context->mmu_role.as_u64 = new_role.as_u64; + context->cpu_role.as_u64 = cpu_role.as_u64; + context->root_role.word = root_role.word; if (!is_cr0_pg(context)) nonpaging_init_context(context); @@ -4660,35 +5834,34 @@ static void shadow_mmu_init_context(struct kvm_vcpu *vcpu, struct kvm_mmu *conte paging64_init_context(context); else paging32_init_context(context); - context->root_level = role_regs_to_root_level(regs); reset_guest_paging_metadata(vcpu, context); - context->shadow_root_level = new_role.base.level; - reset_shadow_zero_bits_mask(vcpu, context); } static void kvm_init_shadow_mmu(struct kvm_vcpu *vcpu, - struct kvm_mmu_role_regs *regs) + union kvm_cpu_role cpu_role) { struct kvm_mmu *context = &vcpu->arch.root_mmu; - union kvm_mmu_role new_role = - kvm_calc_shadow_mmu_root_page_role(vcpu, regs, false); + union kvm_mmu_page_role root_role; - shadow_mmu_init_context(vcpu, context, regs, new_role); -} + root_role = cpu_role.base; -static union kvm_mmu_role -kvm_calc_shadow_npt_root_page_role(struct kvm_vcpu *vcpu, - struct kvm_mmu_role_regs *regs) -{ - union kvm_mmu_role role = - kvm_calc_shadow_root_page_role_common(vcpu, regs, false); + /* KVM uses PAE paging whenever the guest isn't using 64-bit paging. */ + root_role.level = max_t(u32, root_role.level, PT32E_ROOT_LEVEL); - role.base.direct = false; - role.base.level = kvm_mmu_get_tdp_level(vcpu); + /* + * KVM forces EFER.NX=1 when TDP is disabled, reflect it in the MMU role. + * KVM uses NX when TDP is disabled to handle a variety of scenarios, + * notably for huge SPTEs if iTLB multi-hit mitigation is enabled and + * to generate correct permissions for CR0.WP=0/CR4.SMEP=1/EFER.NX=0. + * The iTLB multi-hit workaround can be toggled at any time, so assume + * NX can be used by any non-nested shadow MMU to avoid having to reset + * MMU contexts. + */ + root_role.efer_nx = true; - return role; + shadow_mmu_init_context(vcpu, context, cpu_role, root_role); } void kvm_init_shadow_npt_mmu(struct kvm_vcpu *vcpu, unsigned long cr0, @@ -4697,36 +5870,44 @@ void kvm_init_shadow_npt_mmu(struct kvm_vcpu *vcpu, unsigned long cr0, struct kvm_mmu *context = &vcpu->arch.guest_mmu; struct kvm_mmu_role_regs regs = { .cr0 = cr0, - .cr4 = cr4, + .cr4 = cr4 & ~X86_CR4_PKE, .efer = efer, }; - union kvm_mmu_role new_role; + union kvm_cpu_role cpu_role = kvm_calc_cpu_role(vcpu, ®s); + union kvm_mmu_page_role root_role; - new_role = kvm_calc_shadow_npt_root_page_role(vcpu, ®s); + /* NPT requires CR0.PG=1. */ + WARN_ON_ONCE(cpu_role.base.direct || !cpu_role.base.guest_mode); - __kvm_mmu_new_pgd(vcpu, nested_cr3, new_role.base); + root_role = cpu_role.base; + root_role.level = kvm_mmu_get_tdp_level(vcpu); + if (root_role.level == PT64_ROOT_5LEVEL && + cpu_role.base.level == PT64_ROOT_4LEVEL) + root_role.passthrough = 1; - shadow_mmu_init_context(vcpu, context, ®s, new_role); + shadow_mmu_init_context(vcpu, context, cpu_role, root_role); + kvm_mmu_new_pgd(vcpu, nested_cr3); } -EXPORT_SYMBOL_GPL(kvm_init_shadow_npt_mmu); +EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_init_shadow_npt_mmu); -static union kvm_mmu_role +static union kvm_cpu_role kvm_calc_shadow_ept_root_page_role(struct kvm_vcpu *vcpu, bool accessed_dirty, bool execonly, u8 level) { - union kvm_mmu_role role = {0}; - - /* SMM flag is inherited from root_mmu */ - role.base.smm = vcpu->arch.root_mmu.mmu_role.base.smm; + union kvm_cpu_role role = {0}; + /* + * KVM does not support SMM transfer monitors, and consequently does not + * support the "entry to SMM" control either. role.base.smm is always 0. + */ + WARN_ON_ONCE(is_smm(vcpu)); role.base.level = level; - role.base.gpte_is_8_bytes = true; + role.base.has_4_byte_gpte = false; role.base.direct = false; role.base.ad_disabled = !accessed_dirty; role.base.guest_mode = true; role.base.access = ACC_ALL; - /* EPT, and thus nested EPT, does not consume CR0, CR4, nor EFER. */ role.ext.word = 0; role.ext.execonly = execonly; role.ext.valid = 1; @@ -4735,87 +5916,64 @@ kvm_calc_shadow_ept_root_page_role(struct kvm_vcpu *vcpu, bool accessed_dirty, } void kvm_init_shadow_ept_mmu(struct kvm_vcpu *vcpu, bool execonly, - bool accessed_dirty, gpa_t new_eptp) + int huge_page_level, bool accessed_dirty, + gpa_t new_eptp) { struct kvm_mmu *context = &vcpu->arch.guest_mmu; u8 level = vmx_eptp_page_walk_level(new_eptp); - union kvm_mmu_role new_role = + union kvm_cpu_role new_mode = kvm_calc_shadow_ept_root_page_role(vcpu, accessed_dirty, execonly, level); - __kvm_mmu_new_pgd(vcpu, new_eptp, new_role.base); - - if (new_role.as_u64 == context->mmu_role.as_u64) - return; - - context->mmu_role.as_u64 = new_role.as_u64; + if (new_mode.as_u64 != context->cpu_role.as_u64) { + /* EPT, and thus nested EPT, does not consume CR0, CR4, nor EFER. */ + context->cpu_role.as_u64 = new_mode.as_u64; + context->root_role.word = new_mode.base.word; - context->shadow_root_level = level; + context->page_fault = ept_page_fault; + context->gva_to_gpa = ept_gva_to_gpa; + context->sync_spte = ept_sync_spte; - context->ept_ad = accessed_dirty; - context->page_fault = ept_page_fault; - context->gva_to_gpa = ept_gva_to_gpa; - context->sync_page = ept_sync_page; - context->invlpg = ept_invlpg; - context->root_level = level; - context->direct_map = false; + update_permission_bitmask(context, true); + context->pkru_mask = 0; + reset_rsvds_bits_mask_ept(vcpu, context, execonly, huge_page_level); + reset_ept_shadow_zero_bits_mask(context, execonly); + } - update_permission_bitmask(context, true); - update_pkru_bitmask(context); - reset_rsvds_bits_mask_ept(vcpu, context, execonly); - reset_ept_shadow_zero_bits_mask(vcpu, context, execonly); + kvm_mmu_new_pgd(vcpu, new_eptp); } -EXPORT_SYMBOL_GPL(kvm_init_shadow_ept_mmu); +EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_init_shadow_ept_mmu); -static void init_kvm_softmmu(struct kvm_vcpu *vcpu) +static void init_kvm_softmmu(struct kvm_vcpu *vcpu, + union kvm_cpu_role cpu_role) { struct kvm_mmu *context = &vcpu->arch.root_mmu; - struct kvm_mmu_role_regs regs = vcpu_to_role_regs(vcpu); - kvm_init_shadow_mmu(vcpu, ®s); + kvm_init_shadow_mmu(vcpu, cpu_role); - context->get_guest_pgd = get_cr3; + context->get_guest_pgd = get_guest_cr3; context->get_pdptr = kvm_pdptr_read; context->inject_page_fault = kvm_inject_page_fault; } -static union kvm_mmu_role -kvm_calc_nested_mmu_role(struct kvm_vcpu *vcpu, struct kvm_mmu_role_regs *regs) +static void init_kvm_nested_mmu(struct kvm_vcpu *vcpu, + union kvm_cpu_role new_mode) { - union kvm_mmu_role role; - - role = kvm_calc_shadow_root_page_role_common(vcpu, regs, false); - - /* - * Nested MMUs are used only for walking L2's gva->gpa, they never have - * shadow pages of their own and so "direct" has no meaning. Set it - * to "true" to try to detect bogus usage of the nested MMU. - */ - role.base.direct = true; - role.base.level = role_regs_to_root_level(regs); - return role; -} - -static void init_kvm_nested_mmu(struct kvm_vcpu *vcpu) -{ - struct kvm_mmu_role_regs regs = vcpu_to_role_regs(vcpu); - union kvm_mmu_role new_role = kvm_calc_nested_mmu_role(vcpu, ®s); struct kvm_mmu *g_context = &vcpu->arch.nested_mmu; - if (new_role.as_u64 == g_context->mmu_role.as_u64) + if (new_mode.as_u64 == g_context->cpu_role.as_u64) return; - g_context->mmu_role.as_u64 = new_role.as_u64; - g_context->get_guest_pgd = get_cr3; + g_context->cpu_role.as_u64 = new_mode.as_u64; + g_context->get_guest_pgd = get_guest_cr3; g_context->get_pdptr = kvm_pdptr_read; g_context->inject_page_fault = kvm_inject_page_fault; - g_context->root_level = new_role.base.level; /* * L2 page tables are never shadowed, so there is no need to sync * SPTEs. */ - g_context->invlpg = NULL; + g_context->sync_spte = NULL; /* * Note that arch.mmu->gva_to_gpa translates l2_gpa to l1_gpa using @@ -4826,72 +5984,58 @@ static void init_kvm_nested_mmu(struct kvm_vcpu *vcpu) * the gva_to_gpa functions between mmu and nested_mmu are swapped. */ if (!is_paging(vcpu)) - g_context->gva_to_gpa = nonpaging_gva_to_gpa_nested; + g_context->gva_to_gpa = nonpaging_gva_to_gpa; else if (is_long_mode(vcpu)) - g_context->gva_to_gpa = paging64_gva_to_gpa_nested; + g_context->gva_to_gpa = paging64_gva_to_gpa; else if (is_pae(vcpu)) - g_context->gva_to_gpa = paging64_gva_to_gpa_nested; + g_context->gva_to_gpa = paging64_gva_to_gpa; else - g_context->gva_to_gpa = paging32_gva_to_gpa_nested; + g_context->gva_to_gpa = paging32_gva_to_gpa; reset_guest_paging_metadata(vcpu, g_context); } void kvm_init_mmu(struct kvm_vcpu *vcpu) { - if (mmu_is_nested(vcpu)) - init_kvm_nested_mmu(vcpu); - else if (tdp_enabled) - init_kvm_tdp_mmu(vcpu); - else - init_kvm_softmmu(vcpu); -} -EXPORT_SYMBOL_GPL(kvm_init_mmu); - -static union kvm_mmu_page_role -kvm_mmu_calc_root_page_role(struct kvm_vcpu *vcpu) -{ struct kvm_mmu_role_regs regs = vcpu_to_role_regs(vcpu); - union kvm_mmu_role role; + union kvm_cpu_role cpu_role = kvm_calc_cpu_role(vcpu, ®s); - if (tdp_enabled) - role = kvm_calc_tdp_mmu_root_page_role(vcpu, ®s, true); + if (mmu_is_nested(vcpu)) + init_kvm_nested_mmu(vcpu, cpu_role); + else if (tdp_enabled) + init_kvm_tdp_mmu(vcpu, cpu_role); else - role = kvm_calc_shadow_mmu_root_page_role(vcpu, ®s, true); - - return role.base; + init_kvm_softmmu(vcpu, cpu_role); } +EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_init_mmu); void kvm_mmu_after_set_cpuid(struct kvm_vcpu *vcpu) { /* * Invalidate all MMU roles to force them to reinitialize as CPUID * information is factored into reserved bit calculations. + * + * Correctly handling multiple vCPU models with respect to paging and + * physical address properties) in a single VM would require tracking + * all relevant CPUID information in kvm_mmu_page_role. That is very + * undesirable as it would increase the memory requirements for + * gfn_write_track (see struct kvm_mmu_page_role comments). For now + * that problem is swept under the rug; KVM's CPUID API is horrific and + * it's all but impossible to solve it without introducing a new API. */ - vcpu->arch.root_mmu.mmu_role.ext.valid = 0; - vcpu->arch.guest_mmu.mmu_role.ext.valid = 0; - vcpu->arch.nested_mmu.mmu_role.ext.valid = 0; + vcpu->arch.root_mmu.root_role.invalid = 1; + vcpu->arch.guest_mmu.root_role.invalid = 1; + vcpu->arch.nested_mmu.root_role.invalid = 1; + vcpu->arch.root_mmu.cpu_role.ext.valid = 0; + vcpu->arch.guest_mmu.cpu_role.ext.valid = 0; + vcpu->arch.nested_mmu.cpu_role.ext.valid = 0; kvm_mmu_reset_context(vcpu); /* - * KVM does not correctly handle changing guest CPUID after KVM_RUN, as - * MAXPHYADDR, GBPAGES support, AMD reserved bit behavior, etc.. aren't - * tracked in kvm_mmu_page_role. As a result, KVM may miss guest page - * faults due to reusing SPs/SPTEs. Alert userspace, but otherwise - * sweep the problem under the rug. - * - * KVM's horrific CPUID ABI makes the problem all but impossible to - * solve, as correctly handling multiple vCPU models (with respect to - * paging and physical address properties) in a single VM would require - * tracking all relevant CPUID information in kvm_mmu_page_role. That - * is very undesirable as it would double the memory requirements for - * gfn_track (see struct kvm_mmu_page_role comments), and in practice - * no sane VMM mucks with the core vCPU model on the fly. + * Changing guest CPUID after KVM_RUN is forbidden, see the comment in + * kvm_arch_vcpu_ioctl(). */ - if (vcpu->arch.last_vmentry_cpu != -1) { - pr_warn_ratelimited("KVM: KVM_SET_CPUID{,2} after KVM_RUN may cause guest instability\n"); - pr_warn_ratelimited("KVM: KVM_SET_CPUID{,2} will fail after KVM_RUN starting with Linux 5.16\n"); - } + KVM_BUG_ON(kvm_vcpu_has_run(vcpu), vcpu->kvm); } void kvm_mmu_reset_context(struct kvm_vcpu *vcpu) @@ -4899,19 +6043,19 @@ void kvm_mmu_reset_context(struct kvm_vcpu *vcpu) kvm_mmu_unload(vcpu); kvm_init_mmu(vcpu); } -EXPORT_SYMBOL_GPL(kvm_mmu_reset_context); +EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_mmu_reset_context); int kvm_mmu_load(struct kvm_vcpu *vcpu) { int r; - r = mmu_topup_memory_caches(vcpu, !vcpu->arch.mmu->direct_map); + r = mmu_topup_memory_caches(vcpu, !vcpu->arch.mmu->root_role.direct); if (r) goto out; r = mmu_alloc_special_roots(vcpu); if (r) goto out; - if (vcpu->arch.mmu->direct_map) + if (vcpu->arch.mmu->root_role.direct) r = mmu_alloc_direct_roots(vcpu); else r = mmu_alloc_shadow_roots(vcpu); @@ -4921,32 +6065,81 @@ int kvm_mmu_load(struct kvm_vcpu *vcpu) kvm_mmu_sync_roots(vcpu); kvm_mmu_load_pgd(vcpu); - static_call(kvm_x86_tlb_flush_current)(vcpu); + + /* + * Flush any TLB entries for the new root, the provenance of the root + * is unknown. Even if KVM ensures there are no stale TLB entries + * for a freed root, in theory another hypervisor could have left + * stale entries. Flushing on alloc also allows KVM to skip the TLB + * flush when freeing a root (see kvm_tdp_mmu_put_root()). + */ + kvm_x86_call(flush_tlb_current)(vcpu); out: return r; } void kvm_mmu_unload(struct kvm_vcpu *vcpu) { - kvm_mmu_free_roots(vcpu, &vcpu->arch.root_mmu, KVM_MMU_ROOTS_ALL); - WARN_ON(VALID_PAGE(vcpu->arch.root_mmu.root_hpa)); - kvm_mmu_free_roots(vcpu, &vcpu->arch.guest_mmu, KVM_MMU_ROOTS_ALL); - WARN_ON(VALID_PAGE(vcpu->arch.guest_mmu.root_hpa)); + struct kvm *kvm = vcpu->kvm; + + kvm_mmu_free_roots(kvm, &vcpu->arch.root_mmu, KVM_MMU_ROOTS_ALL); + WARN_ON_ONCE(VALID_PAGE(vcpu->arch.root_mmu.root.hpa)); + kvm_mmu_free_roots(kvm, &vcpu->arch.guest_mmu, KVM_MMU_ROOTS_ALL); + WARN_ON_ONCE(VALID_PAGE(vcpu->arch.guest_mmu.root.hpa)); + vcpu_clear_mmio_info(vcpu, MMIO_GVA_ANY); } -static bool need_remote_flush(u64 old, u64 new) +static bool is_obsolete_root(struct kvm *kvm, hpa_t root_hpa) { - if (!is_shadow_present_pte(old)) + struct kvm_mmu_page *sp; + + if (!VALID_PAGE(root_hpa)) return false; - if (!is_shadow_present_pte(new)) - return true; - if ((old ^ new) & PT64_BASE_ADDR_MASK) - return true; - old ^= shadow_nx_mask; - new ^= shadow_nx_mask; - return (old & ~new & PT64_PERM_MASK) != 0; + + /* + * When freeing obsolete roots, treat roots as obsolete if they don't + * have an associated shadow page, as it's impossible to determine if + * such roots are fresh or stale. This does mean KVM will get false + * positives and free roots that don't strictly need to be freed, but + * such false positives are relatively rare: + * + * (a) only PAE paging and nested NPT have roots without shadow pages + * (or any shadow paging flavor with a dummy root, see note below) + * (b) remote reloads due to a memslot update obsoletes _all_ roots + * (c) KVM doesn't track previous roots for PAE paging, and the guest + * is unlikely to zap an in-use PGD. + * + * Note! Dummy roots are unique in that they are obsoleted by memslot + * _creation_! See also FNAME(fetch). + */ + sp = root_to_sp(root_hpa); + return !sp || is_obsolete_sp(kvm, sp); } +static void __kvm_mmu_free_obsolete_roots(struct kvm *kvm, struct kvm_mmu *mmu) +{ + unsigned long roots_to_free = 0; + int i; + + if (is_obsolete_root(kvm, mmu->root.hpa)) + roots_to_free |= KVM_MMU_ROOT_CURRENT; + + for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++) { + if (is_obsolete_root(kvm, mmu->prev_roots[i].hpa)) + roots_to_free |= KVM_MMU_ROOT_PREVIOUS(i); + } + + if (roots_to_free) + kvm_mmu_free_roots(kvm, mmu, roots_to_free); +} + +void kvm_mmu_free_obsolete_roots(struct kvm_vcpu *vcpu) +{ + __kvm_mmu_free_obsolete_roots(vcpu->kvm, &vcpu->arch.root_mmu); + __kvm_mmu_free_obsolete_roots(vcpu->kvm, &vcpu->arch.guest_mmu); +} +EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_mmu_free_obsolete_roots); + static u64 mmu_pte_write_fetch_gpte(struct kvm_vcpu *vcpu, gpa_t *gpa, int *bytes) { @@ -4999,11 +6192,8 @@ static bool detect_write_misaligned(struct kvm_mmu_page *sp, gpa_t gpa, { unsigned offset, pte_size, misaligned; - pgprintk("misaligned: gpa %llx bytes %d role %x\n", - gpa, bytes, sp->role.word); - offset = offset_in_page(gpa); - pte_size = sp->role.gpte_is_8_bytes ? 8 : 4; + pte_size = sp->role.has_4_byte_gpte ? 4 : 8; /* * Sometimes, the OS only writes the last one bytes to update status @@ -5027,7 +6217,7 @@ static u64 *get_written_sptes(struct kvm_mmu_page *sp, gpa_t gpa, int *nspte) page_offset = offset_in_page(gpa); level = sp->role.level; *nspte = 1; - if (!sp->role.gpte_is_8_bytes) { + if (sp->role.has_4_byte_gpte) { page_offset <<= 1; /* 32->64 */ /* * A 32-bit pde maps 4MB while the shadow pdes map @@ -5049,43 +6239,35 @@ static u64 *get_written_sptes(struct kvm_mmu_page *sp, gpa_t gpa, int *nspte) return spte; } -static void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa, - const u8 *new, int bytes, - struct kvm_page_track_notifier_node *node) +void kvm_mmu_track_write(struct kvm_vcpu *vcpu, gpa_t gpa, const u8 *new, + int bytes) { gfn_t gfn = gpa >> PAGE_SHIFT; struct kvm_mmu_page *sp; LIST_HEAD(invalid_list); u64 entry, gentry, *spte; int npte; - bool remote_flush, local_flush; + bool flush = false; /* - * If we don't have indirect shadow pages, it means no page is - * write-protected, so we can exit simply. + * When emulating guest writes, ensure the written value is visible to + * any task that is handling page faults before checking whether or not + * KVM is shadowing a guest PTE. This ensures either KVM will create + * the correct SPTE in the page fault handler, or this task will see + * a non-zero indirect_shadow_pages. Pairs with the smp_mb() in + * account_shadowed(). */ - if (!READ_ONCE(vcpu->kvm->arch.indirect_shadow_pages)) + smp_mb(); + if (!vcpu->kvm->arch.indirect_shadow_pages) return; - remote_flush = local_flush = false; - - pgprintk("%s: gpa %llx bytes %d\n", __func__, gpa, bytes); - - /* - * No need to care whether allocation memory is successful - * or not since pte prefetch is skipped if it does not have - * enough objects in the cache. - */ - mmu_topup_memory_caches(vcpu, true); - write_lock(&vcpu->kvm->mmu_lock); gentry = mmu_pte_write_fetch_gpte(vcpu, &gpa, &bytes); ++vcpu->kvm->stat.mmu_pte_write; - kvm_mmu_audit(vcpu, AUDIT_PRE_PTE_WRITE); - for_each_gfn_indirect_valid_sp(vcpu->kvm, sp, gfn) { + for_each_gfn_valid_sp_with_gptes(vcpu->kvm, sp, gfn) { if (detect_write_misaligned(sp, gpa, bytes) || detect_write_flooding(sp)) { kvm_mmu_prepare_zap_page(vcpu->kvm, sp, &invalid_list); @@ -5097,151 +6279,310 @@ static void kvm_mmu_pte_write(struct kvm_vcpu *vcpu, gpa_t gpa, if (!spte) continue; - local_flush = true; while (npte--) { entry = *spte; mmu_page_zap_pte(vcpu->kvm, sp, spte, NULL); if (gentry && sp->role.level != PG_LEVEL_4K) ++vcpu->kvm->stat.mmu_pde_zapped; - if (need_remote_flush(entry, *spte)) - remote_flush = true; + if (is_shadow_present_pte(entry)) + flush = true; ++spte; } } - kvm_mmu_flush_or_zap(vcpu, &invalid_list, remote_flush, local_flush); - kvm_mmu_audit(vcpu, AUDIT_POST_PTE_WRITE); + kvm_mmu_remote_flush_or_zap(vcpu->kvm, &invalid_list, flush); write_unlock(&vcpu->kvm->mmu_lock); } -int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, u64 error_code, +static bool is_write_to_guest_page_table(u64 error_code) +{ + const u64 mask = PFERR_GUEST_PAGE_MASK | PFERR_WRITE_MASK | PFERR_PRESENT_MASK; + + return (error_code & mask) == mask; +} + +static int kvm_mmu_write_protect_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, + u64 error_code, int *emulation_type) +{ + bool direct = vcpu->arch.mmu->root_role.direct; + + /* + * Do not try to unprotect and retry if the vCPU re-faulted on the same + * RIP with the same address that was previously unprotected, as doing + * so will likely put the vCPU into an infinite. E.g. if the vCPU uses + * a non-page-table modifying instruction on the PDE that points to the + * instruction, then unprotecting the gfn will unmap the instruction's + * code, i.e. make it impossible for the instruction to ever complete. + */ + if (vcpu->arch.last_retry_eip == kvm_rip_read(vcpu) && + vcpu->arch.last_retry_addr == cr2_or_gpa) + return RET_PF_EMULATE; + + /* + * Reset the unprotect+retry values that guard against infinite loops. + * The values will be refreshed if KVM explicitly unprotects a gfn and + * retries, in all other cases it's safe to retry in the future even if + * the next page fault happens on the same RIP+address. + */ + vcpu->arch.last_retry_eip = 0; + vcpu->arch.last_retry_addr = 0; + + /* + * It should be impossible to reach this point with an MMIO cache hit, + * as RET_PF_WRITE_PROTECTED is returned if and only if there's a valid, + * writable memslot, and creating a memslot should invalidate the MMIO + * cache by way of changing the memslot generation. WARN and disallow + * retry if MMIO is detected, as retrying MMIO emulation is pointless + * and could put the vCPU into an infinite loop because the processor + * will keep faulting on the non-existent MMIO address. + */ + if (WARN_ON_ONCE(mmio_info_in_cache(vcpu, cr2_or_gpa, direct))) + return RET_PF_EMULATE; + + /* + * Before emulating the instruction, check to see if the access was due + * to a read-only violation while the CPU was walking non-nested NPT + * page tables, i.e. for a direct MMU, for _guest_ page tables in L1. + * If L1 is sharing (a subset of) its page tables with L2, e.g. by + * having nCR3 share lower level page tables with hCR3, then when KVM + * (L0) write-protects the nested NPTs, i.e. npt12 entries, KVM is also + * unknowingly write-protecting L1's guest page tables, which KVM isn't + * shadowing. + * + * Because the CPU (by default) walks NPT page tables using a write + * access (to ensure the CPU can do A/D updates), page walks in L1 can + * trigger write faults for the above case even when L1 isn't modifying + * PTEs. As a result, KVM will unnecessarily emulate (or at least, try + * to emulate) an excessive number of L1 instructions; because L1's MMU + * isn't shadowed by KVM, there is no need to write-protect L1's gPTEs + * and thus no need to emulate in order to guarantee forward progress. + * + * Try to unprotect the gfn, i.e. zap any shadow pages, so that L1 can + * proceed without triggering emulation. If one or more shadow pages + * was zapped, skip emulation and resume L1 to let it natively execute + * the instruction. If no shadow pages were zapped, then the write- + * fault is due to something else entirely, i.e. KVM needs to emulate, + * as resuming the guest will put it into an infinite loop. + * + * Note, this code also applies to Intel CPUs, even though it is *very* + * unlikely that an L1 will share its page tables (IA32/PAE/paging64 + * format) with L2's page tables (EPT format). + * + * For indirect MMUs, i.e. if KVM is shadowing the current MMU, try to + * unprotect the gfn and retry if an event is awaiting reinjection. If + * KVM emulates multiple instructions before completing event injection, + * the event could be delayed beyond what is architecturally allowed, + * e.g. KVM could inject an IRQ after the TPR has been raised. + */ + if (((direct && is_write_to_guest_page_table(error_code)) || + (!direct && kvm_event_needs_reinjection(vcpu))) && + kvm_mmu_unprotect_gfn_and_retry(vcpu, cr2_or_gpa)) + return RET_PF_RETRY; + + /* + * The gfn is write-protected, but if KVM detects its emulating an + * instruction that is unlikely to be used to modify page tables, or if + * emulation fails, KVM can try to unprotect the gfn and let the CPU + * re-execute the instruction that caused the page fault. Do not allow + * retrying an instruction from a nested guest as KVM is only explicitly + * shadowing L1's page tables, i.e. unprotecting something for L1 isn't + * going to magically fix whatever issue caused L2 to fail. + */ + if (!is_guest_mode(vcpu)) + *emulation_type |= EMULTYPE_ALLOW_RETRY_PF; + + return RET_PF_EMULATE; +} + +int noinline kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, u64 error_code, void *insn, int insn_len) { int r, emulation_type = EMULTYPE_PF; - bool direct = vcpu->arch.mmu->direct_map; + bool direct = vcpu->arch.mmu->root_role.direct; - if (WARN_ON(!VALID_PAGE(vcpu->arch.mmu->root_hpa))) + if (WARN_ON_ONCE(!VALID_PAGE(vcpu->arch.mmu->root.hpa))) return RET_PF_RETRY; + /* + * Except for reserved faults (emulated MMIO is shared-only), set the + * PFERR_PRIVATE_ACCESS flag for software-protected VMs based on the gfn's + * current attributes, which are the source of truth for such VMs. Note, + * this wrong for nested MMUs as the GPA is an L2 GPA, but KVM doesn't + * currently supported nested virtualization (among many other things) + * for software-protected VMs. + */ + if (IS_ENABLED(CONFIG_KVM_SW_PROTECTED_VM) && + !(error_code & PFERR_RSVD_MASK) && + vcpu->kvm->arch.vm_type == KVM_X86_SW_PROTECTED_VM && + kvm_mem_is_private(vcpu->kvm, gpa_to_gfn(cr2_or_gpa))) + error_code |= PFERR_PRIVATE_ACCESS; + r = RET_PF_INVALID; if (unlikely(error_code & PFERR_RSVD_MASK)) { + if (WARN_ON_ONCE(error_code & PFERR_PRIVATE_ACCESS)) + return -EFAULT; + r = handle_mmio_page_fault(vcpu, cr2_or_gpa, direct); if (r == RET_PF_EMULATE) goto emulate; } if (r == RET_PF_INVALID) { - r = kvm_mmu_do_page_fault(vcpu, cr2_or_gpa, - lower_32_bits(error_code), false); - if (WARN_ON_ONCE(r == RET_PF_INVALID)) + vcpu->stat.pf_taken++; + + r = kvm_mmu_do_page_fault(vcpu, cr2_or_gpa, error_code, false, + &emulation_type, NULL); + if (KVM_BUG_ON(r == RET_PF_INVALID, vcpu->kvm)) return -EIO; } if (r < 0) return r; - if (r != RET_PF_EMULATE) - return 1; + + if (r == RET_PF_WRITE_PROTECTED) + r = kvm_mmu_write_protect_fault(vcpu, cr2_or_gpa, error_code, + &emulation_type); + + if (r == RET_PF_FIXED) + vcpu->stat.pf_fixed++; + else if (r == RET_PF_EMULATE) + vcpu->stat.pf_emulate++; + else if (r == RET_PF_SPURIOUS) + vcpu->stat.pf_spurious++; /* - * Before emulating the instruction, check if the error code - * was due to a RO violation while translating the guest page. - * This can occur when using nested virtualization with nested - * paging in both guests. If true, we simply unprotect the page - * and resume the guest. + * None of handle_mmio_page_fault(), kvm_mmu_do_page_fault(), or + * kvm_mmu_write_protect_fault() return RET_PF_CONTINUE. + * kvm_mmu_do_page_fault() only uses RET_PF_CONTINUE internally to + * indicate continuing the page fault handling until to the final + * page table mapping phase. */ - if (vcpu->arch.mmu->direct_map && - (error_code & PFERR_NESTED_GUEST_PAGE) == PFERR_NESTED_GUEST_PAGE) { - kvm_mmu_unprotect_page(vcpu->kvm, gpa_to_gfn(cr2_or_gpa)); - return 1; - } + WARN_ON_ONCE(r == RET_PF_CONTINUE); + if (r != RET_PF_EMULATE) + return r; - /* - * vcpu->arch.mmu.page_fault returned RET_PF_EMULATE, but we can still - * optimistically try to just unprotect the page and let the processor - * re-execute the instruction that caused the page fault. Do not allow - * retrying MMIO emulation, as it's not only pointless but could also - * cause us to enter an infinite loop because the processor will keep - * faulting on the non-existent MMIO address. Retrying an instruction - * from a nested guest is also pointless and dangerous as we are only - * explicitly shadowing L1's page tables, i.e. unprotecting something - * for L1 isn't going to magically fix whatever issue cause L2 to fail. - */ - if (!mmio_info_in_cache(vcpu, cr2_or_gpa, direct) && !is_guest_mode(vcpu)) - emulation_type |= EMULTYPE_ALLOW_RETRY_PF; emulate: return x86_emulate_instruction(vcpu, cr2_or_gpa, emulation_type, insn, insn_len); } -EXPORT_SYMBOL_GPL(kvm_mmu_page_fault); +EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_mmu_page_fault); + +void kvm_mmu_print_sptes(struct kvm_vcpu *vcpu, gpa_t gpa, const char *msg) +{ + u64 sptes[PT64_ROOT_MAX_LEVEL + 1]; + int root_level, leaf, level; + + leaf = get_sptes_lockless(vcpu, gpa, sptes, &root_level); + if (unlikely(leaf < 0)) + return; + + pr_err("%s %llx", msg, gpa); + for (level = root_level; level >= leaf; level--) + pr_cont(", spte[%d] = 0x%llx", level, sptes[level]); + pr_cont("\n"); +} +EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_mmu_print_sptes); + +static void __kvm_mmu_invalidate_addr(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu, + u64 addr, hpa_t root_hpa) +{ + struct kvm_shadow_walk_iterator iterator; + + vcpu_clear_mmio_info(vcpu, addr); + + /* + * Walking and synchronizing SPTEs both assume they are operating in + * the context of the current MMU, and would need to be reworked if + * this is ever used to sync the guest_mmu, e.g. to emulate INVEPT. + */ + if (WARN_ON_ONCE(mmu != vcpu->arch.mmu)) + return; + + if (!VALID_PAGE(root_hpa)) + return; + + write_lock(&vcpu->kvm->mmu_lock); + for_each_shadow_entry_using_root(vcpu, root_hpa, addr, iterator) { + struct kvm_mmu_page *sp = sptep_to_sp(iterator.sptep); + + if (sp->unsync) { + int ret = kvm_sync_spte(vcpu, sp, iterator.index); + + if (ret < 0) + mmu_page_zap_pte(vcpu->kvm, sp, iterator.sptep, NULL); + if (ret) + kvm_flush_remote_tlbs_sptep(vcpu->kvm, iterator.sptep); + } + + if (!sp->unsync_children) + break; + } + write_unlock(&vcpu->kvm->mmu_lock); +} -void kvm_mmu_invalidate_gva(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu, - gva_t gva, hpa_t root_hpa) +void kvm_mmu_invalidate_addr(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu, + u64 addr, unsigned long roots) { int i; + WARN_ON_ONCE(roots & ~KVM_MMU_ROOTS_ALL); + /* It's actually a GPA for vcpu->arch.guest_mmu. */ if (mmu != &vcpu->arch.guest_mmu) { /* INVLPG on a non-canonical address is a NOP according to the SDM. */ - if (is_noncanonical_address(gva, vcpu)) + if (is_noncanonical_invlpg_address(addr, vcpu)) return; - static_call(kvm_x86_tlb_flush_gva)(vcpu, gva); + kvm_x86_call(flush_tlb_gva)(vcpu, addr); } - if (!mmu->invlpg) + if (!mmu->sync_spte) return; - if (root_hpa == INVALID_PAGE) { - mmu->invlpg(vcpu, gva, mmu->root_hpa); + if (roots & KVM_MMU_ROOT_CURRENT) + __kvm_mmu_invalidate_addr(vcpu, mmu, addr, mmu->root.hpa); - /* - * INVLPG is required to invalidate any global mappings for the VA, - * irrespective of PCID. Since it would take us roughly similar amount - * of work to determine whether any of the prev_root mappings of the VA - * is marked global, or to just sync it blindly, so we might as well - * just always sync it. - * - * Mappings not reachable via the current cr3 or the prev_roots will be - * synced when switching to that cr3, so nothing needs to be done here - * for them. - */ - for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++) - if (VALID_PAGE(mmu->prev_roots[i].hpa)) - mmu->invlpg(vcpu, gva, mmu->prev_roots[i].hpa); - } else { - mmu->invlpg(vcpu, gva, root_hpa); + for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++) { + if (roots & KVM_MMU_ROOT_PREVIOUS(i)) + __kvm_mmu_invalidate_addr(vcpu, mmu, addr, mmu->prev_roots[i].hpa); } } +EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_mmu_invalidate_addr); void kvm_mmu_invlpg(struct kvm_vcpu *vcpu, gva_t gva) { - kvm_mmu_invalidate_gva(vcpu, vcpu->arch.mmu, gva, INVALID_PAGE); + /* + * INVLPG is required to invalidate any global mappings for the VA, + * irrespective of PCID. Blindly sync all roots as it would take + * roughly the same amount of work/time to determine whether any of the + * previous roots have a global mapping. + * + * Mappings not reachable via the current or previous cached roots will + * be synced when switching to that new cr3, so nothing needs to be + * done here for them. + */ + kvm_mmu_invalidate_addr(vcpu, vcpu->arch.walk_mmu, gva, KVM_MMU_ROOTS_ALL); ++vcpu->stat.invlpg; } -EXPORT_SYMBOL_GPL(kvm_mmu_invlpg); +EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_mmu_invlpg); void kvm_mmu_invpcid_gva(struct kvm_vcpu *vcpu, gva_t gva, unsigned long pcid) { struct kvm_mmu *mmu = vcpu->arch.mmu; - bool tlb_flush = false; + unsigned long roots = 0; uint i; - if (pcid == kvm_get_active_pcid(vcpu)) { - mmu->invlpg(vcpu, gva, mmu->root_hpa); - tlb_flush = true; - } + if (pcid == kvm_get_active_pcid(vcpu)) + roots |= KVM_MMU_ROOT_CURRENT; for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++) { if (VALID_PAGE(mmu->prev_roots[i].hpa) && - pcid == kvm_get_pcid(vcpu, mmu->prev_roots[i].pgd)) { - mmu->invlpg(vcpu, gva, mmu->prev_roots[i].hpa); - tlb_flush = true; - } + pcid == kvm_get_pcid(vcpu, mmu->prev_roots[i].pgd)) + roots |= KVM_MMU_ROOT_PREVIOUS(i); } - if (tlb_flush) - static_call(kvm_x86_tlb_flush_gva)(vcpu, gva); - + if (roots) + kvm_mmu_invalidate_addr(vcpu, mmu, gva, roots); ++vcpu->stat.invlpg; /* @@ -5251,12 +6592,16 @@ void kvm_mmu_invpcid_gva(struct kvm_vcpu *vcpu, gva_t gva, unsigned long pcid) */ } -void kvm_configure_mmu(bool enable_tdp, int tdp_max_root_level, - int tdp_huge_page_level) +void kvm_configure_mmu(bool enable_tdp, int tdp_forced_root_level, + int tdp_max_root_level, int tdp_huge_page_level) { tdp_enabled = enable_tdp; + tdp_root_level = tdp_forced_root_level; max_tdp_level = tdp_max_root_level; +#ifdef CONFIG_X86_64 + tdp_mmu_enabled = tdp_mmu_allowed && tdp_enabled; +#endif /* * max_huge_page_level reflects KVM's MMU capabilities irrespective * of kernel support, e.g. KVM may be capable of using 1GB pages when @@ -5271,58 +6616,7 @@ void kvm_configure_mmu(bool enable_tdp, int tdp_max_root_level, else max_huge_page_level = PG_LEVEL_2M; } -EXPORT_SYMBOL_GPL(kvm_configure_mmu); - -/* The return value indicates if tlb flush on all vcpus is needed. */ -typedef bool (*slot_level_handler) (struct kvm *kvm, struct kvm_rmap_head *rmap_head, - struct kvm_memory_slot *slot); - -/* The caller should hold mmu-lock before calling this function. */ -static __always_inline bool -slot_handle_level_range(struct kvm *kvm, struct kvm_memory_slot *memslot, - slot_level_handler fn, int start_level, int end_level, - gfn_t start_gfn, gfn_t end_gfn, bool flush_on_yield, - bool flush) -{ - struct slot_rmap_walk_iterator iterator; - - for_each_slot_rmap_range(memslot, start_level, end_level, start_gfn, - end_gfn, &iterator) { - if (iterator.rmap) - flush |= fn(kvm, iterator.rmap, memslot); - - if (need_resched() || rwlock_needbreak(&kvm->mmu_lock)) { - if (flush && flush_on_yield) { - kvm_flush_remote_tlbs_with_address(kvm, - start_gfn, - iterator.gfn - start_gfn + 1); - flush = false; - } - cond_resched_rwlock_write(&kvm->mmu_lock); - } - } - - return flush; -} - -static __always_inline bool -slot_handle_level(struct kvm *kvm, struct kvm_memory_slot *memslot, - slot_level_handler fn, int start_level, int end_level, - bool flush_on_yield) -{ - return slot_handle_level_range(kvm, memslot, fn, start_level, - end_level, memslot->base_gfn, - memslot->base_gfn + memslot->npages - 1, - flush_on_yield, false); -} - -static __always_inline bool -slot_handle_leaf(struct kvm *kvm, struct kvm_memory_slot *memslot, - slot_level_handler fn, bool flush_on_yield) -{ - return slot_handle_level(kvm, memslot, fn, PG_LEVEL_4K, - PG_LEVEL_4K, flush_on_yield); -} +EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_configure_mmu); static void free_mmu_pages(struct kvm_mmu *mmu) { @@ -5330,6 +6624,7 @@ static void free_mmu_pages(struct kvm_mmu *mmu) set_memory_encrypted((unsigned long)mmu->pae_root, 1); free_page((unsigned long)mmu->pae_root); free_page((unsigned long)mmu->pml4_root); + free_page((unsigned long)mmu->pml5_root); } static int __kvm_mmu_create(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu) @@ -5337,12 +6632,16 @@ static int __kvm_mmu_create(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu) struct page *page; int i; - mmu->root_hpa = INVALID_PAGE; - mmu->root_pgd = 0; - mmu->translate_gpa = translate_gpa; + mmu->root.hpa = INVALID_PAGE; + mmu->root.pgd = 0; + mmu->mirror_root_hpa = INVALID_PAGE; for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++) mmu->prev_roots[i] = KVM_MMU_ROOT_INFO_INVALID; + /* vcpu->arch.guest_mmu isn't used when !tdp_enabled. */ + if (!tdp_enabled && mmu == &vcpu->arch.guest_mmu) + return 0; + /* * When using PAE paging, the four PDPTEs are treated as 'root' pages, * while the PDP table is a per-vCPU construct that's allocated at MMU @@ -5352,7 +6651,7 @@ static int __kvm_mmu_create(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu) * generally doesn't use PAE paging and can skip allocating the PDP * table. The main exception, handled here, is SVM's 32-bit NPT. The * other exception is for shadowing L1's 32-bit or PAE NPT on 64-bit - * KVM; that horror is handled on-demand by mmu_alloc_shadow_roots(). + * KVM; that horror is handled on-demand by mmu_alloc_special_roots(). */ if (tdp_enabled && kvm_mmu_get_tdp_level(vcpu) > PT32E_ROOT_LEVEL) return 0; @@ -5374,7 +6673,7 @@ static int __kvm_mmu_create(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu) if (!tdp_enabled) set_memory_decrypted((unsigned long)mmu->pae_root, 1); else - WARN_ON_ONCE(shadow_me_mask); + WARN_ON_ONCE(shadow_me_value); for (i = 0; i < 4; ++i) mmu->pae_root[i] = INVALID_PAE_ROOT; @@ -5392,13 +6691,14 @@ int kvm_mmu_create(struct kvm_vcpu *vcpu) vcpu->arch.mmu_page_header_cache.kmem_cache = mmu_page_header_cache; vcpu->arch.mmu_page_header_cache.gfp_zero = __GFP_ZERO; - vcpu->arch.mmu_shadow_page_cache.gfp_zero = __GFP_ZERO; + vcpu->arch.mmu_shadow_page_cache.init_value = + SHADOW_NONPRESENT_VALUE; + if (!vcpu->arch.mmu_shadow_page_cache.init_value) + vcpu->arch.mmu_shadow_page_cache.gfp_zero = __GFP_ZERO; vcpu->arch.mmu = &vcpu->arch.root_mmu; vcpu->arch.walk_mmu = &vcpu->arch.root_mmu; - vcpu->arch.nested_mmu.translate_gpa = translate_nested_gpa; - ret = __kvm_mmu_create(vcpu, &vcpu->arch.guest_mmu); if (ret) return ret; @@ -5418,6 +6718,10 @@ static void kvm_zap_obsolete_pages(struct kvm *kvm) { struct kvm_mmu_page *sp, *node; int nr_zapped, batch = 0; + LIST_HEAD(invalid_list); + bool unstable; + + lockdep_assert_held(&kvm->slots_lock); restart: list_for_each_entry_safe_reverse(sp, node, @@ -5434,7 +6738,7 @@ restart: * pages. Skip the bogus page, otherwise we'll get stuck in an * infinite loop if the page gets put back on the list (again). */ - if (WARN_ON(sp->role.invalid)) + if (WARN_ON_ONCE(sp->role.invalid)) continue; /* @@ -5449,19 +6753,24 @@ restart: goto restart; } - if (__kvm_mmu_prepare_zap_page(kvm, sp, - &kvm->arch.zapped_obsolete_pages, &nr_zapped)) { - batch += nr_zapped; + unstable = __kvm_mmu_prepare_zap_page(kvm, sp, + &invalid_list, &nr_zapped); + batch += nr_zapped; + + if (unstable) goto restart; - } } /* - * Trigger a remote TLB flush before freeing the page tables to ensure - * KVM is not in the middle of a lockless shadow page table walk, which - * may reference the pages. + * Kick all vCPUs (via remote TLB flush) before freeing the page tables + * to ensure KVM is not in the middle of a lockless shadow page table + * walk, which may reference the pages. The remote TLB flush itself is + * not required and is simply a convenient way to kick vCPUs as needed. + * KVM performs a local TLB flush when allocating a new root (see + * kvm_mmu_load()), and the reload in the caller ensure no vCPUs are + * running with an obsolete MMU. */ - kvm_mmu_commit_zap_page(kvm, &kvm->arch.zapped_obsolete_pages); + kvm_mmu_commit_zap_page(kvm, &invalid_list); } /* @@ -5489,14 +6798,19 @@ static void kvm_mmu_zap_all_fast(struct kvm *kvm) */ kvm->arch.mmu_valid_gen = kvm->arch.mmu_valid_gen ? 0 : 1; - /* In order to ensure all threads see this change when - * handling the MMU reload signal, this must happen in the - * same critical section as kvm_reload_remote_mmus, and - * before kvm_zap_obsolete_pages as kvm_zap_obsolete_pages - * could drop the MMU lock and yield. + /* + * In order to ensure all vCPUs drop their soon-to-be invalid roots, + * invalidating TDP MMU roots must be done while holding mmu_lock for + * write and in the same critical section as making the reload request, + * e.g. before kvm_zap_obsolete_pages() could drop mmu_lock and yield. */ - if (is_tdp_mmu_enabled(kvm)) - kvm_tdp_mmu_invalidate_all_roots(kvm); + if (tdp_mmu_enabled) { + /* + * External page tables don't support fast zapping, therefore + * their mirrors must be invalidated separately by the caller. + */ + kvm_tdp_mmu_invalidate_roots(kvm, KVM_DIRECT_ROOTS); + } /* * Notify all vcpus to reload its shadow page table and flush TLB. @@ -5506,158 +6820,447 @@ static void kvm_mmu_zap_all_fast(struct kvm *kvm) * Note: we need to do this under the protection of mmu_lock, * otherwise, vcpu would purge shadow page but miss tlb flush. */ - kvm_reload_remote_mmus(kvm); + kvm_make_all_cpus_request(kvm, KVM_REQ_MMU_FREE_OBSOLETE_ROOTS); kvm_zap_obsolete_pages(kvm); write_unlock(&kvm->mmu_lock); - if (is_tdp_mmu_enabled(kvm)) { + /* + * Zap the invalidated TDP MMU roots, all SPTEs must be dropped before + * returning to the caller, e.g. if the zap is in response to a memslot + * deletion, mmu_notifier callbacks will be unable to reach the SPTEs + * associated with the deleted memslot once the update completes, and + * Deferring the zap until the final reference to the root is put would + * lead to use-after-free. + */ + if (tdp_mmu_enabled) + kvm_tdp_mmu_zap_invalidated_roots(kvm, true); +} + +int kvm_mmu_init_vm(struct kvm *kvm) +{ + int r, i; + + kvm->arch.shadow_mmio_value = shadow_mmio_value; + INIT_LIST_HEAD(&kvm->arch.active_mmu_pages); + for (i = 0; i < KVM_NR_MMU_TYPES; ++i) + INIT_LIST_HEAD(&kvm->arch.possible_nx_huge_pages[i].pages); + spin_lock_init(&kvm->arch.mmu_unsync_pages_lock); + + if (tdp_mmu_enabled) { + kvm_mmu_init_tdp_mmu(kvm); + } else { + r = kvm_mmu_alloc_page_hash(kvm); + if (r) + return r; + } + + kvm->arch.split_page_header_cache.kmem_cache = mmu_page_header_cache; + kvm->arch.split_page_header_cache.gfp_zero = __GFP_ZERO; + + kvm->arch.split_shadow_page_cache.gfp_zero = __GFP_ZERO; + + kvm->arch.split_desc_cache.kmem_cache = pte_list_desc_cache; + kvm->arch.split_desc_cache.gfp_zero = __GFP_ZERO; + return 0; +} + +static void mmu_free_vm_memory_caches(struct kvm *kvm) +{ + kvm_mmu_free_memory_cache(&kvm->arch.split_desc_cache); + kvm_mmu_free_memory_cache(&kvm->arch.split_page_header_cache); + kvm_mmu_free_memory_cache(&kvm->arch.split_shadow_page_cache); +} + +void kvm_mmu_uninit_vm(struct kvm *kvm) +{ + kvfree(kvm->arch.mmu_page_hash); + + if (tdp_mmu_enabled) + kvm_mmu_uninit_tdp_mmu(kvm); + + mmu_free_vm_memory_caches(kvm); +} + +static bool kvm_rmap_zap_gfn_range(struct kvm *kvm, gfn_t gfn_start, gfn_t gfn_end) +{ + const struct kvm_memory_slot *memslot; + struct kvm_memslots *slots; + struct kvm_memslot_iter iter; + bool flush = false; + gfn_t start, end; + int i; + + if (!kvm_memslots_have_rmaps(kvm)) + return flush; + + for (i = 0; i < kvm_arch_nr_memslot_as_ids(kvm); i++) { + slots = __kvm_memslots(kvm, i); + + kvm_for_each_memslot_in_gfn_range(&iter, slots, gfn_start, gfn_end) { + memslot = iter.slot; + start = max(gfn_start, memslot->base_gfn); + end = min(gfn_end, memslot->base_gfn + memslot->npages); + if (WARN_ON_ONCE(start >= end)) + continue; + + flush = __kvm_rmap_zap_gfn_range(kvm, memslot, start, + end, true, flush); + } + } + + return flush; +} + +/* + * Invalidate (zap) SPTEs that cover GFNs from gfn_start and up to gfn_end + * (not including it) + */ +void kvm_zap_gfn_range(struct kvm *kvm, gfn_t gfn_start, gfn_t gfn_end) +{ + bool flush; + + if (WARN_ON_ONCE(gfn_end <= gfn_start)) + return; + + write_lock(&kvm->mmu_lock); + + kvm_mmu_invalidate_begin(kvm); + + kvm_mmu_invalidate_range_add(kvm, gfn_start, gfn_end); + + flush = kvm_rmap_zap_gfn_range(kvm, gfn_start, gfn_end); + + if (tdp_mmu_enabled) + flush = kvm_tdp_mmu_zap_leafs(kvm, gfn_start, gfn_end, flush); + + if (flush) + kvm_flush_remote_tlbs_range(kvm, gfn_start, gfn_end - gfn_start); + + kvm_mmu_invalidate_end(kvm); + + write_unlock(&kvm->mmu_lock); +} +EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_zap_gfn_range); + +static bool slot_rmap_write_protect(struct kvm *kvm, + struct kvm_rmap_head *rmap_head, + const struct kvm_memory_slot *slot) +{ + return rmap_write_protect(rmap_head, false); +} + +void kvm_mmu_slot_remove_write_access(struct kvm *kvm, + const struct kvm_memory_slot *memslot, + int start_level) +{ + if (kvm_memslots_have_rmaps(kvm)) { + write_lock(&kvm->mmu_lock); + walk_slot_rmaps(kvm, memslot, slot_rmap_write_protect, + start_level, KVM_MAX_HUGEPAGE_LEVEL, false); + write_unlock(&kvm->mmu_lock); + } + + if (tdp_mmu_enabled) { read_lock(&kvm->mmu_lock); - kvm_tdp_mmu_zap_invalidated_roots(kvm); + kvm_tdp_mmu_wrprot_slot(kvm, memslot, start_level); read_unlock(&kvm->mmu_lock); } } -static bool kvm_has_zapped_obsolete_pages(struct kvm *kvm) +static inline bool need_topup(struct kvm_mmu_memory_cache *cache, int min) { - return unlikely(!list_empty_careful(&kvm->arch.zapped_obsolete_pages)); + return kvm_mmu_memory_cache_nr_free_objects(cache) < min; } -static void kvm_mmu_invalidate_zap_pages_in_memslot(struct kvm *kvm, - struct kvm_memory_slot *slot, - struct kvm_page_track_notifier_node *node) +static bool need_topup_split_caches_or_resched(struct kvm *kvm) { - kvm_mmu_zap_all_fast(kvm); + if (need_resched() || rwlock_needbreak(&kvm->mmu_lock)) + return true; + + /* + * In the worst case, SPLIT_DESC_CACHE_MIN_NR_OBJECTS descriptors are needed + * to split a single huge page. Calculating how many are actually needed + * is possible but not worth the complexity. + */ + return need_topup(&kvm->arch.split_desc_cache, SPLIT_DESC_CACHE_MIN_NR_OBJECTS) || + need_topup(&kvm->arch.split_page_header_cache, 1) || + need_topup(&kvm->arch.split_shadow_page_cache, 1); } -void kvm_mmu_init_vm(struct kvm *kvm) +static int topup_split_caches(struct kvm *kvm) { - struct kvm_page_track_notifier_node *node = &kvm->arch.mmu_sp_tracker; + /* + * Allocating rmap list entries when splitting huge pages for nested + * MMUs is uncommon as KVM needs to use a list if and only if there is + * more than one rmap entry for a gfn, i.e. requires an L1 gfn to be + * aliased by multiple L2 gfns and/or from multiple nested roots with + * different roles. Aliasing gfns when using TDP is atypical for VMMs; + * a few gfns are often aliased during boot, e.g. when remapping BIOS, + * but aliasing rarely occurs post-boot or for many gfns. If there is + * only one rmap entry, rmap->val points directly at that one entry and + * doesn't need to allocate a list. Buffer the cache by the default + * capacity so that KVM doesn't have to drop mmu_lock to topup if KVM + * encounters an aliased gfn or two. + */ + const int capacity = SPLIT_DESC_CACHE_MIN_NR_OBJECTS + + KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE; + int r; - if (!kvm_mmu_init_tdp_mmu(kvm)) - /* - * No smp_load/store wrappers needed here as we are in - * VM init and there cannot be any memslots / other threads - * accessing this struct kvm yet. - */ - kvm->arch.memslots_have_rmaps = true; + lockdep_assert_held(&kvm->slots_lock); + + r = __kvm_mmu_topup_memory_cache(&kvm->arch.split_desc_cache, capacity, + SPLIT_DESC_CACHE_MIN_NR_OBJECTS); + if (r) + return r; - node->track_write = kvm_mmu_pte_write; - node->track_flush_slot = kvm_mmu_invalidate_zap_pages_in_memslot; - kvm_page_track_register_notifier(kvm, node); + r = kvm_mmu_topup_memory_cache(&kvm->arch.split_page_header_cache, 1); + if (r) + return r; + + return kvm_mmu_topup_memory_cache(&kvm->arch.split_shadow_page_cache, 1); } -void kvm_mmu_uninit_vm(struct kvm *kvm) +static struct kvm_mmu_page *shadow_mmu_get_sp_for_split(struct kvm *kvm, u64 *huge_sptep) { - struct kvm_page_track_notifier_node *node = &kvm->arch.mmu_sp_tracker; + struct kvm_mmu_page *huge_sp = sptep_to_sp(huge_sptep); + struct shadow_page_caches caches = {}; + union kvm_mmu_page_role role; + unsigned int access; + gfn_t gfn; + + gfn = kvm_mmu_page_get_gfn(huge_sp, spte_index(huge_sptep)); + access = kvm_mmu_page_get_access(huge_sp, spte_index(huge_sptep)); + + /* + * Note, huge page splitting always uses direct shadow pages, regardless + * of whether the huge page itself is mapped by a direct or indirect + * shadow page, since the huge page region itself is being directly + * mapped with smaller pages. + */ + role = kvm_mmu_child_role(huge_sptep, /*direct=*/true, access); - kvm_page_track_unregister_notifier(kvm, node); + /* Direct SPs do not require a shadowed_info_cache. */ + caches.page_header_cache = &kvm->arch.split_page_header_cache; + caches.shadow_page_cache = &kvm->arch.split_shadow_page_cache; - kvm_mmu_uninit_tdp_mmu(kvm); + /* Safe to pass NULL for vCPU since requesting a direct SP. */ + return __kvm_mmu_get_shadow_page(kvm, NULL, &caches, gfn, role); } -void kvm_zap_gfn_range(struct kvm *kvm, gfn_t gfn_start, gfn_t gfn_end) +static void shadow_mmu_split_huge_page(struct kvm *kvm, + const struct kvm_memory_slot *slot, + u64 *huge_sptep) + { - struct kvm_memslots *slots; - struct kvm_memory_slot *memslot; - int i; + struct kvm_mmu_memory_cache *cache = &kvm->arch.split_desc_cache; + u64 huge_spte = READ_ONCE(*huge_sptep); + struct kvm_mmu_page *sp; bool flush = false; + u64 *sptep, spte; + gfn_t gfn; + int index; - if (kvm_memslots_have_rmaps(kvm)) { - write_lock(&kvm->mmu_lock); - for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) { - slots = __kvm_memslots(kvm, i); - kvm_for_each_memslot(memslot, slots) { - gfn_t start, end; - - start = max(gfn_start, memslot->base_gfn); - end = min(gfn_end, memslot->base_gfn + memslot->npages); - if (start >= end) - continue; + sp = shadow_mmu_get_sp_for_split(kvm, huge_sptep); - flush = slot_handle_level_range(kvm, memslot, - kvm_zap_rmapp, PG_LEVEL_4K, - KVM_MAX_HUGEPAGE_LEVEL, start, - end - 1, true, flush); - } + for (index = 0; index < SPTE_ENT_PER_PAGE; index++) { + sptep = &sp->spt[index]; + gfn = kvm_mmu_page_get_gfn(sp, index); + + /* + * The SP may already have populated SPTEs, e.g. if this huge + * page is aliased by multiple sptes with the same access + * permissions. These entries are guaranteed to map the same + * gfn-to-pfn translation since the SP is direct, so no need to + * modify them. + * + * However, if a given SPTE points to a lower level page table, + * that lower level page table may only be partially populated. + * Installing such SPTEs would effectively unmap a potion of the + * huge page. Unmapping guest memory always requires a TLB flush + * since a subsequent operation on the unmapped regions would + * fail to detect the need to flush. + */ + if (is_shadow_present_pte(*sptep)) { + flush |= !is_last_spte(*sptep, sp->role.level); + continue; } - if (flush) - kvm_flush_remote_tlbs_with_address(kvm, gfn_start, gfn_end); + + spte = make_small_spte(kvm, huge_spte, sp->role, index); + mmu_spte_set(sptep, spte); + __rmap_add(kvm, cache, slot, sptep, gfn, sp->role.access); + } + + __link_shadow_page(kvm, cache, huge_sptep, sp, flush); +} + +static int shadow_mmu_try_split_huge_page(struct kvm *kvm, + const struct kvm_memory_slot *slot, + u64 *huge_sptep) +{ + struct kvm_mmu_page *huge_sp = sptep_to_sp(huge_sptep); + int level, r = 0; + gfn_t gfn; + u64 spte; + + /* Grab information for the tracepoint before dropping the MMU lock. */ + gfn = kvm_mmu_page_get_gfn(huge_sp, spte_index(huge_sptep)); + level = huge_sp->role.level; + spte = *huge_sptep; + + if (kvm_mmu_available_pages(kvm) <= KVM_MIN_FREE_MMU_PAGES) { + r = -ENOSPC; + goto out; + } + + if (need_topup_split_caches_or_resched(kvm)) { write_unlock(&kvm->mmu_lock); + cond_resched(); + /* + * If the topup succeeds, return -EAGAIN to indicate that the + * rmap iterator should be restarted because the MMU lock was + * dropped. + */ + r = topup_split_caches(kvm) ?: -EAGAIN; + write_lock(&kvm->mmu_lock); + goto out; } - if (is_tdp_mmu_enabled(kvm)) { - flush = false; + shadow_mmu_split_huge_page(kvm, slot, huge_sptep); - read_lock(&kvm->mmu_lock); - for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) - flush = kvm_tdp_mmu_zap_gfn_range(kvm, i, gfn_start, - gfn_end, flush, true); - if (flush) - kvm_flush_remote_tlbs_with_address(kvm, gfn_start, - gfn_end); +out: + trace_kvm_mmu_split_huge_page(gfn, spte, level, r); + return r; +} - read_unlock(&kvm->mmu_lock); +static bool shadow_mmu_try_split_huge_pages(struct kvm *kvm, + struct kvm_rmap_head *rmap_head, + const struct kvm_memory_slot *slot) +{ + struct rmap_iterator iter; + struct kvm_mmu_page *sp; + u64 *huge_sptep; + int r; + +restart: + for_each_rmap_spte(rmap_head, &iter, huge_sptep) { + sp = sptep_to_sp(huge_sptep); + + /* TDP MMU is enabled, so rmap only contains nested MMU SPs. */ + if (WARN_ON_ONCE(!sp->role.guest_mode)) + continue; + + /* The rmaps should never contain non-leaf SPTEs. */ + if (WARN_ON_ONCE(!is_large_pte(*huge_sptep))) + continue; + + /* SPs with level >PG_LEVEL_4K should never by unsync. */ + if (WARN_ON_ONCE(sp->unsync)) + continue; + + /* Don't bother splitting huge pages on invalid SPs. */ + if (sp->role.invalid) + continue; + + r = shadow_mmu_try_split_huge_page(kvm, slot, huge_sptep); + + /* + * The split succeeded or needs to be retried because the MMU + * lock was dropped. Either way, restart the iterator to get it + * back into a consistent state. + */ + if (!r || r == -EAGAIN) + goto restart; + + /* The split failed and shouldn't be retried (e.g. -ENOMEM). */ + break; } + + return false; } -static bool slot_rmap_write_protect(struct kvm *kvm, - struct kvm_rmap_head *rmap_head, - struct kvm_memory_slot *slot) +static void kvm_shadow_mmu_try_split_huge_pages(struct kvm *kvm, + const struct kvm_memory_slot *slot, + gfn_t start, gfn_t end, + int target_level) { - return __rmap_write_protect(kvm, rmap_head, false); + int level; + + /* + * Split huge pages starting with KVM_MAX_HUGEPAGE_LEVEL and working + * down to the target level. This ensures pages are recursively split + * all the way to the target level. There's no need to split pages + * already at the target level. + */ + for (level = KVM_MAX_HUGEPAGE_LEVEL; level > target_level; level--) + __walk_slot_rmaps(kvm, slot, shadow_mmu_try_split_huge_pages, + level, level, start, end - 1, true, true, false); } -void kvm_mmu_slot_remove_write_access(struct kvm *kvm, - struct kvm_memory_slot *memslot, - int start_level) +/* Must be called with the mmu_lock held in write-mode. */ +void kvm_mmu_try_split_huge_pages(struct kvm *kvm, + const struct kvm_memory_slot *memslot, + u64 start, u64 end, + int target_level) { - bool flush = false; + if (!tdp_mmu_enabled) + return; + + if (kvm_memslots_have_rmaps(kvm)) + kvm_shadow_mmu_try_split_huge_pages(kvm, memslot, start, end, target_level); + + kvm_tdp_mmu_try_split_huge_pages(kvm, memslot, start, end, target_level, false); + + /* + * A TLB flush is unnecessary at this point for the same reasons as in + * kvm_mmu_slot_try_split_huge_pages(). + */ +} + +void kvm_mmu_slot_try_split_huge_pages(struct kvm *kvm, + const struct kvm_memory_slot *memslot, + int target_level) +{ + u64 start = memslot->base_gfn; + u64 end = start + memslot->npages; + + if (!tdp_mmu_enabled) + return; if (kvm_memslots_have_rmaps(kvm)) { write_lock(&kvm->mmu_lock); - flush = slot_handle_level(kvm, memslot, slot_rmap_write_protect, - start_level, KVM_MAX_HUGEPAGE_LEVEL, - false); + kvm_shadow_mmu_try_split_huge_pages(kvm, memslot, start, end, target_level); write_unlock(&kvm->mmu_lock); } - if (is_tdp_mmu_enabled(kvm)) { - read_lock(&kvm->mmu_lock); - flush |= kvm_tdp_mmu_wrprot_slot(kvm, memslot, start_level); - read_unlock(&kvm->mmu_lock); - } + read_lock(&kvm->mmu_lock); + kvm_tdp_mmu_try_split_huge_pages(kvm, memslot, start, end, target_level, true); + read_unlock(&kvm->mmu_lock); /* - * We can flush all the TLBs out of the mmu lock without TLB - * corruption since we just change the spte from writable to - * readonly so that we only need to care the case of changing - * spte from present to present (changing the spte from present - * to nonpresent will flush all the TLBs immediately), in other - * words, the only case we care is mmu_spte_update() where we - * have checked Host-writable | MMU-writable instead of - * PT_WRITABLE_MASK, that means it does not depend on PT_WRITABLE_MASK - * anymore. + * No TLB flush is necessary here. KVM will flush TLBs after + * write-protecting and/or clearing dirty on the newly split SPTEs to + * ensure that guest writes are reflected in the dirty log before the + * ioctl to enable dirty logging on this memslot completes. Since the + * split SPTEs retain the write and dirty bits of the huge SPTE, it is + * safe for KVM to decide if a TLB flush is necessary based on the split + * SPTEs. */ - if (flush) - kvm_arch_flush_remote_tlbs_memslot(kvm, memslot); } static bool kvm_mmu_zap_collapsible_spte(struct kvm *kvm, struct kvm_rmap_head *rmap_head, - struct kvm_memory_slot *slot) + const struct kvm_memory_slot *slot) { u64 *sptep; struct rmap_iterator iter; int need_tlb_flush = 0; - kvm_pfn_t pfn; struct kvm_mmu_page *sp; restart: for_each_rmap_spte(rmap_head, &iter, sptep) { sp = sptep_to_sp(sptep); - pfn = spte_to_pfn(*sptep); /* * We cannot do huge page mapping for indirect shadow pages, @@ -5666,14 +7269,12 @@ restart: * the guest, and the guest page table is using 4K page size * mapping if the indirect sp has level = 1. */ - if (sp->role.direct && !kvm_is_reserved_pfn(pfn) && - sp->role.level < kvm_mmu_max_mapping_level(kvm, slot, sp->gfn, - pfn, PG_LEVEL_NUM)) { - pte_list_remove(rmap_head, sptep); - - if (kvm_available_flush_tlb_with_range()) - kvm_flush_remote_tlbs_with_address(kvm, sp->gfn, - KVM_PAGES_PER_HPAGE(sp->role.level)); + if (sp->role.direct && + sp->role.level < kvm_mmu_max_mapping_level(kvm, NULL, slot, sp->gfn)) { + kvm_zap_one_rmap_spte(kvm, rmap_head, sptep); + + if (kvm_available_flush_remote_tlbs_range()) + kvm_flush_remote_tlbs_sptep(kvm, sptep); else need_tlb_flush = 1; @@ -5684,74 +7285,64 @@ restart: return need_tlb_flush; } -void kvm_mmu_zap_collapsible_sptes(struct kvm *kvm, - const struct kvm_memory_slot *memslot) +static void kvm_rmap_zap_collapsible_sptes(struct kvm *kvm, + const struct kvm_memory_slot *slot) { - /* FIXME: const-ify all uses of struct kvm_memory_slot. */ - struct kvm_memory_slot *slot = (struct kvm_memory_slot *)memslot; - bool flush = false; + /* + * Note, use KVM_MAX_HUGEPAGE_LEVEL - 1 since there's no need to zap + * pages that are already mapped at the maximum hugepage level. + */ + if (walk_slot_rmaps(kvm, slot, kvm_mmu_zap_collapsible_spte, + PG_LEVEL_4K, KVM_MAX_HUGEPAGE_LEVEL - 1, true)) + kvm_flush_remote_tlbs_memslot(kvm, slot); +} +void kvm_mmu_recover_huge_pages(struct kvm *kvm, + const struct kvm_memory_slot *slot) +{ if (kvm_memslots_have_rmaps(kvm)) { write_lock(&kvm->mmu_lock); - flush = slot_handle_leaf(kvm, slot, kvm_mmu_zap_collapsible_spte, true); - if (flush) - kvm_arch_flush_remote_tlbs_memslot(kvm, slot); + kvm_rmap_zap_collapsible_sptes(kvm, slot); write_unlock(&kvm->mmu_lock); } - if (is_tdp_mmu_enabled(kvm)) { + if (tdp_mmu_enabled) { read_lock(&kvm->mmu_lock); - flush = kvm_tdp_mmu_zap_collapsible_sptes(kvm, slot, flush); - if (flush) - kvm_arch_flush_remote_tlbs_memslot(kvm, slot); + kvm_tdp_mmu_recover_huge_pages(kvm, slot); read_unlock(&kvm->mmu_lock); } } -void kvm_arch_flush_remote_tlbs_memslot(struct kvm *kvm, - const struct kvm_memory_slot *memslot) -{ - /* - * All current use cases for flushing the TLBs for a specific memslot - * related to dirty logging, and many do the TLB flush out of mmu_lock. - * The interaction between the various operations on memslot must be - * serialized by slots_locks to ensure the TLB flush from one operation - * is observed by any other operation on the same memslot. - */ - lockdep_assert_held(&kvm->slots_lock); - kvm_flush_remote_tlbs_with_address(kvm, memslot->base_gfn, - memslot->npages); -} - void kvm_mmu_slot_leaf_clear_dirty(struct kvm *kvm, - struct kvm_memory_slot *memslot) + const struct kvm_memory_slot *memslot) { - bool flush = false; - if (kvm_memslots_have_rmaps(kvm)) { write_lock(&kvm->mmu_lock); - flush = slot_handle_leaf(kvm, memslot, __rmap_clear_dirty, - false); + /* + * Clear dirty bits only on 4k SPTEs since the legacy MMU only + * support dirty logging at a 4k granularity. + */ + walk_slot_rmaps_4k(kvm, memslot, __rmap_clear_dirty, false); write_unlock(&kvm->mmu_lock); } - if (is_tdp_mmu_enabled(kvm)) { + if (tdp_mmu_enabled) { read_lock(&kvm->mmu_lock); - flush |= kvm_tdp_mmu_clear_dirty_slot(kvm, memslot); + kvm_tdp_mmu_clear_dirty_slot(kvm, memslot); read_unlock(&kvm->mmu_lock); } /* + * The caller will flush the TLBs after this function returns. + * * It's also safe to flush TLBs out of mmu lock here as currently this * function is only used for dirty logging, in which case flushing TLB * out of mmu lock also guarantees no dirty pages will be lost in * dirty_bitmap. */ - if (flush) - kvm_arch_flush_remote_tlbs_memslot(kvm, memslot); } -void kvm_mmu_zap_all(struct kvm *kvm) +static void kvm_mmu_zap_all(struct kvm *kvm) { struct kvm_mmu_page *sp, *node; LIST_HEAD(invalid_list); @@ -5760,7 +7351,7 @@ void kvm_mmu_zap_all(struct kvm *kvm) write_lock(&kvm->mmu_lock); restart: list_for_each_entry_safe(sp, node, &kvm->arch.active_mmu_pages, link) { - if (WARN_ON(sp->role.invalid)) + if (WARN_ON_ONCE(sp->role.invalid)) continue; if (__kvm_mmu_prepare_zap_page(kvm, sp, &invalid_list, &ign)) goto restart; @@ -5770,15 +7361,90 @@ restart: kvm_mmu_commit_zap_page(kvm, &invalid_list); - if (is_tdp_mmu_enabled(kvm)) + if (tdp_mmu_enabled) kvm_tdp_mmu_zap_all(kvm); write_unlock(&kvm->mmu_lock); } +void kvm_arch_flush_shadow_all(struct kvm *kvm) +{ + kvm_mmu_zap_all(kvm); +} + +static void kvm_mmu_zap_memslot_pages_and_flush(struct kvm *kvm, + struct kvm_memory_slot *slot, + bool flush) +{ + LIST_HEAD(invalid_list); + unsigned long i; + + if (list_empty(&kvm->arch.active_mmu_pages)) + goto out_flush; + + /* + * Since accounting information is stored in struct kvm_arch_memory_slot, + * all MMU pages that are shadowing guest PTEs must be zapped before the + * memslot is deleted, as freeing such pages after the memslot is freed + * will result in use-after-free, e.g. in unaccount_shadowed(). + */ + for (i = 0; i < slot->npages; i++) { + struct kvm_mmu_page *sp; + gfn_t gfn = slot->base_gfn + i; + + for_each_gfn_valid_sp_with_gptes(kvm, sp, gfn) + kvm_mmu_prepare_zap_page(kvm, sp, &invalid_list); + + if (need_resched() || rwlock_needbreak(&kvm->mmu_lock)) { + kvm_mmu_remote_flush_or_zap(kvm, &invalid_list, flush); + flush = false; + cond_resched_rwlock_write(&kvm->mmu_lock); + } + } + +out_flush: + kvm_mmu_remote_flush_or_zap(kvm, &invalid_list, flush); +} + +static void kvm_mmu_zap_memslot(struct kvm *kvm, + struct kvm_memory_slot *slot) +{ + struct kvm_gfn_range range = { + .slot = slot, + .start = slot->base_gfn, + .end = slot->base_gfn + slot->npages, + .may_block = true, + .attr_filter = KVM_FILTER_PRIVATE | KVM_FILTER_SHARED, + }; + bool flush; + + write_lock(&kvm->mmu_lock); + flush = kvm_unmap_gfn_range(kvm, &range); + kvm_mmu_zap_memslot_pages_and_flush(kvm, slot, flush); + write_unlock(&kvm->mmu_lock); +} + +static inline bool kvm_memslot_flush_zap_all(struct kvm *kvm) +{ + return kvm->arch.vm_type == KVM_X86_DEFAULT_VM && + kvm_check_has_quirk(kvm, KVM_X86_QUIRK_SLOT_ZAP_ALL); +} + +void kvm_arch_flush_shadow_memslot(struct kvm *kvm, + struct kvm_memory_slot *slot) +{ + if (kvm_memslot_flush_zap_all(kvm)) + kvm_mmu_zap_all_fast(kvm); + else + kvm_mmu_zap_memslot(kvm, slot); +} + void kvm_mmu_invalidate_mmio_sptes(struct kvm *kvm, u64 gen) { - WARN_ON(gen & KVM_MEMSLOT_GEN_UPDATE_IN_PROGRESS); + WARN_ON_ONCE(gen & KVM_MEMSLOT_GEN_UPDATE_IN_PROGRESS); + + if (!enable_mmio_caching) + return; gen &= MMIO_SPTE_GEN_MASK; @@ -5789,93 +7455,43 @@ void kvm_mmu_invalidate_mmio_sptes(struct kvm *kvm, u64 gen) * modifier prior to checking for a wrap of the MMIO generation so * that a wrap in any address space is detected. */ - gen &= ~((u64)KVM_ADDRESS_SPACE_NUM - 1); + gen &= ~((u64)kvm_arch_nr_memslot_as_ids(kvm) - 1); /* * The very rare case: if the MMIO generation number has wrapped, * zap all shadow pages. */ if (unlikely(gen == 0)) { - kvm_debug_ratelimited("kvm: zapping shadow pages for mmio generation wraparound\n"); + kvm_debug_ratelimited("zapping shadow pages for mmio generation wraparound\n"); kvm_mmu_zap_all_fast(kvm); } } -static unsigned long -mmu_shrink_scan(struct shrinker *shrink, struct shrink_control *sc) +static void mmu_destroy_caches(void) { - struct kvm *kvm; - int nr_to_scan = sc->nr_to_scan; - unsigned long freed = 0; - - mutex_lock(&kvm_lock); - - list_for_each_entry(kvm, &vm_list, vm_list) { - int idx; - LIST_HEAD(invalid_list); - - /* - * Never scan more than sc->nr_to_scan VM instances. - * Will not hit this condition practically since we do not try - * to shrink more than one VM and it is very unlikely to see - * !n_used_mmu_pages so many times. - */ - if (!nr_to_scan--) - break; - /* - * n_used_mmu_pages is accessed without holding kvm->mmu_lock - * here. We may skip a VM instance errorneosly, but we do not - * want to shrink a VM that only started to populate its MMU - * anyway. - */ - if (!kvm->arch.n_used_mmu_pages && - !kvm_has_zapped_obsolete_pages(kvm)) - continue; - - idx = srcu_read_lock(&kvm->srcu); - write_lock(&kvm->mmu_lock); - - if (kvm_has_zapped_obsolete_pages(kvm)) { - kvm_mmu_commit_zap_page(kvm, - &kvm->arch.zapped_obsolete_pages); - goto unlock; - } - - freed = kvm_mmu_zap_oldest_mmu_pages(kvm, sc->nr_to_scan); - -unlock: - write_unlock(&kvm->mmu_lock); - srcu_read_unlock(&kvm->srcu, idx); - - /* - * unfair on small ones - * per-vm shrinkers cry out - * sadness comes quickly - */ - list_move_tail(&kvm->vm_list, &vm_list); - break; - } - - mutex_unlock(&kvm_lock); - return freed; + kmem_cache_destroy(pte_list_desc_cache); + kmem_cache_destroy(mmu_page_header_cache); } -static unsigned long -mmu_shrink_count(struct shrinker *shrink, struct shrink_control *sc) +static void kvm_wake_nx_recovery_thread(struct kvm *kvm) { - return percpu_counter_read_positive(&kvm_total_used_mmu_pages); -} + /* + * The NX recovery thread is spawned on-demand at the first KVM_RUN and + * may not be valid even though the VM is globally visible. Do nothing, + * as such a VM can't have any possible NX huge pages. + */ + struct vhost_task *nx_thread = READ_ONCE(kvm->arch.nx_huge_page_recovery_thread); -static struct shrinker mmu_shrinker = { - .count_objects = mmu_shrink_count, - .scan_objects = mmu_shrink_scan, - .seeks = DEFAULT_SEEKS * 10, -}; + if (nx_thread) + vhost_task_wake(nx_thread); +} -static void mmu_destroy_caches(void) +static int get_nx_huge_pages(char *buffer, const struct kernel_param *kp) { - kmem_cache_destroy(pte_list_desc_cache); - kmem_cache_destroy(mmu_page_header_cache); + if (nx_hugepage_mitigation_hard_disabled) + return sysfs_emit(buffer, "never\n"); + + return param_get_bool(buffer, kp); } static bool get_nx_auto_mode(void) @@ -5894,15 +7510,29 @@ static int set_nx_huge_pages(const char *val, const struct kernel_param *kp) bool old_val = nx_huge_pages; bool new_val; + if (nx_hugepage_mitigation_hard_disabled) + return -EPERM; + /* In "auto" mode deploy workaround only if CPU has the bug. */ - if (sysfs_streq(val, "off")) + if (sysfs_streq(val, "off")) { new_val = 0; - else if (sysfs_streq(val, "force")) + } else if (sysfs_streq(val, "force")) { new_val = 1; - else if (sysfs_streq(val, "auto")) + } else if (sysfs_streq(val, "auto")) { new_val = get_nx_auto_mode(); - else if (strtobool(val, &new_val) < 0) + } else if (sysfs_streq(val, "never")) { + new_val = 0; + + mutex_lock(&kvm_lock); + if (!list_empty(&vm_list)) { + mutex_unlock(&kvm_lock); + return -EBUSY; + } + nx_hugepage_mitigation_hard_disabled = true; + mutex_unlock(&kvm_lock); + } else if (kstrtobool(val, &new_val) < 0) { return -EINVAL; + } __set_nx_huge_pages(new_val); @@ -5916,7 +7546,7 @@ static int set_nx_huge_pages(const char *val, const struct kernel_param *kp) kvm_mmu_zap_all_fast(kvm); mutex_unlock(&kvm->slots_lock); - wake_up_process(kvm->arch.nx_lpage_recovery_thread); + kvm_wake_nx_recovery_thread(kvm); } mutex_unlock(&kvm_lock); } @@ -5924,14 +7554,37 @@ static int set_nx_huge_pages(const char *val, const struct kernel_param *kp) return 0; } -int kvm_mmu_module_init(void) +/* + * nx_huge_pages needs to be resolved to true/false when kvm.ko is loaded, as + * its default value of -1 is technically undefined behavior for a boolean. + * Forward the module init call to SPTE code so that it too can handle module + * params that need to be resolved/snapshot. + */ +void __init kvm_mmu_x86_module_init(void) { - int ret = -ENOMEM; - if (nx_huge_pages == -1) __set_nx_huge_pages(get_nx_auto_mode()); /* + * Snapshot userspace's desire to enable the TDP MMU. Whether or not the + * TDP MMU is actually enabled is determined in kvm_configure_mmu() + * when the vendor module is loaded. + */ + tdp_mmu_allowed = tdp_mmu_enabled; + + kvm_mmu_spte_module_init(); +} + +/* + * The bulk of the MMU initialization is deferred until the vendor module is + * loaded as many of the masks/values may be modified by VMX or SVM, i.e. need + * to be reset when a potentially different vendor module is loaded. + */ +int kvm_mmu_vendor_module_init(void) +{ + int ret = -ENOMEM; + + /* * MMU roles use union aliasing which is, generally speaking, an * undefined behavior. However, we supposedly know how compilers behave * and the current status quo is unlikely to change. Guardians below are @@ -5939,13 +7592,11 @@ int kvm_mmu_module_init(void) */ BUILD_BUG_ON(sizeof(union kvm_mmu_page_role) != sizeof(u32)); BUILD_BUG_ON(sizeof(union kvm_mmu_extended_role) != sizeof(u32)); - BUILD_BUG_ON(sizeof(union kvm_mmu_role) != sizeof(u64)); + BUILD_BUG_ON(sizeof(union kvm_cpu_role) != sizeof(u64)); kvm_mmu_reset_all_pte_masks(); - pte_list_desc_cache = kmem_cache_create("pte_list_desc", - sizeof(struct pte_list_desc), - 0, SLAB_ACCOUNT, NULL); + pte_list_desc_cache = KMEM_CACHE(pte_list_desc, SLAB_ACCOUNT); if (!pte_list_desc_cache) goto out; @@ -5955,13 +7606,6 @@ int kvm_mmu_module_init(void) if (!mmu_page_header_cache) goto out; - if (percpu_counter_init(&kvm_total_used_mmu_pages, 0, GFP_KERNEL)) - goto out; - - ret = register_shrinker(&mmu_shrinker); - if (ret) - goto out; - return 0; out: @@ -5969,64 +7613,75 @@ out: return ret; } -/* - * Calculate mmu pages needed for kvm. - */ -unsigned long kvm_mmu_calculate_default_mmu_pages(struct kvm *kvm) -{ - unsigned long nr_mmu_pages; - unsigned long nr_pages = 0; - struct kvm_memslots *slots; - struct kvm_memory_slot *memslot; - int i; - - for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) { - slots = __kvm_memslots(kvm, i); - - kvm_for_each_memslot(memslot, slots) - nr_pages += memslot->npages; - } - - nr_mmu_pages = nr_pages * KVM_PERMILLE_MMU_PAGES / 1000; - nr_mmu_pages = max(nr_mmu_pages, KVM_MIN_ALLOC_MMU_PAGES); - - return nr_mmu_pages; -} - void kvm_mmu_destroy(struct kvm_vcpu *vcpu) { kvm_mmu_unload(vcpu); + if (tdp_mmu_enabled) { + read_lock(&vcpu->kvm->mmu_lock); + mmu_free_root_page(vcpu->kvm, &vcpu->arch.mmu->mirror_root_hpa, + NULL); + read_unlock(&vcpu->kvm->mmu_lock); + } free_mmu_pages(&vcpu->arch.root_mmu); free_mmu_pages(&vcpu->arch.guest_mmu); mmu_free_memory_caches(vcpu); } -void kvm_mmu_module_exit(void) +void kvm_mmu_vendor_module_exit(void) { mmu_destroy_caches(); - percpu_counter_destroy(&kvm_total_used_mmu_pages); - unregister_shrinker(&mmu_shrinker); - mmu_audit_disable(); } -static int set_nx_huge_pages_recovery_ratio(const char *val, const struct kernel_param *kp) +/* + * Calculate the effective recovery period, accounting for '0' meaning "let KVM + * select a halving time of 1 hour". Returns true if recovery is enabled. + */ +static bool calc_nx_huge_pages_recovery_period(uint *period) +{ + /* + * Use READ_ONCE to get the params, this may be called outside of the + * param setters, e.g. by the kthread to compute its next timeout. + */ + bool enabled = READ_ONCE(nx_huge_pages); + uint ratio = READ_ONCE(nx_huge_pages_recovery_ratio); + + if (!enabled || !ratio) + return false; + + *period = READ_ONCE(nx_huge_pages_recovery_period_ms); + if (!*period) { + /* Make sure the period is not less than one second. */ + ratio = min(ratio, 3600u); + *period = 60 * 60 * 1000 / ratio; + } + return true; +} + +static int set_nx_huge_pages_recovery_param(const char *val, const struct kernel_param *kp) { - unsigned int old_val; + bool was_recovery_enabled, is_recovery_enabled; + uint old_period, new_period; int err; - old_val = nx_huge_pages_recovery_ratio; + if (nx_hugepage_mitigation_hard_disabled) + return -EPERM; + + was_recovery_enabled = calc_nx_huge_pages_recovery_period(&old_period); + err = param_set_uint(val, kp); if (err) return err; - if (READ_ONCE(nx_huge_pages) && - !old_val && nx_huge_pages_recovery_ratio) { + is_recovery_enabled = calc_nx_huge_pages_recovery_period(&new_period); + + if (is_recovery_enabled && + (!was_recovery_enabled || old_period > new_period)) { struct kvm *kvm; mutex_lock(&kvm_lock); list_for_each_entry(kvm, &vm_list, vm_list) - wake_up_process(kvm->arch.nx_lpage_recovery_thread); + kvm_wake_nx_recovery_thread(kvm); mutex_unlock(&kvm_lock); } @@ -6034,100 +7689,407 @@ static int set_nx_huge_pages_recovery_ratio(const char *val, const struct kernel return err; } -static void kvm_recover_nx_lpages(struct kvm *kvm) +static unsigned long nx_huge_pages_to_zap(struct kvm *kvm, + enum kvm_mmu_type mmu_type) { - unsigned long nx_lpage_splits = kvm->stat.nx_lpage_splits; - int rcu_idx; + unsigned long pages = READ_ONCE(kvm->arch.possible_nx_huge_pages[mmu_type].nr_pages); + unsigned int ratio = READ_ONCE(nx_huge_pages_recovery_ratio); + + return ratio ? DIV_ROUND_UP(pages, ratio) : 0; +} + +static bool kvm_mmu_sp_dirty_logging_enabled(struct kvm *kvm, + struct kvm_mmu_page *sp) +{ + struct kvm_memory_slot *slot; + + /* + * Skip the memslot lookup if dirty tracking can't possibly be enabled, + * as memslot lookups are relatively expensive. + * + * If a memslot update is in progress, reading an incorrect value of + * kvm->nr_memslots_dirty_logging is not a problem: if it is becoming + * zero, KVM will do an unnecessary memslot lookup; if it is becoming + * nonzero, the page will be zapped unnecessarily. Either way, this + * only affects efficiency in racy situations, and not correctness. + */ + if (!atomic_read(&kvm->nr_memslots_dirty_logging)) + return false; + + slot = __gfn_to_memslot(kvm_memslots_for_spte_role(kvm, sp->role), sp->gfn); + if (WARN_ON_ONCE(!slot)) + return false; + + return kvm_slot_dirty_track_enabled(slot); +} + +static void kvm_recover_nx_huge_pages(struct kvm *kvm, + const enum kvm_mmu_type mmu_type) +{ +#ifdef CONFIG_X86_64 + const bool is_tdp_mmu = mmu_type == KVM_TDP_MMU; + spinlock_t *tdp_mmu_pages_lock = &kvm->arch.tdp_mmu_pages_lock; +#else + const bool is_tdp_mmu = false; + spinlock_t *tdp_mmu_pages_lock = NULL; +#endif + unsigned long to_zap = nx_huge_pages_to_zap(kvm, mmu_type); + struct list_head *nx_huge_pages; struct kvm_mmu_page *sp; - unsigned int ratio; LIST_HEAD(invalid_list); bool flush = false; - ulong to_zap; + int rcu_idx; + + nx_huge_pages = &kvm->arch.possible_nx_huge_pages[mmu_type].pages; rcu_idx = srcu_read_lock(&kvm->srcu); - write_lock(&kvm->mmu_lock); + if (is_tdp_mmu) + read_lock(&kvm->mmu_lock); + else + write_lock(&kvm->mmu_lock); + + /* + * Zapping TDP MMU shadow pages, including the remote TLB flush, must + * be done under RCU protection, because the pages are freed via RCU + * callback. + */ + rcu_read_lock(); - ratio = READ_ONCE(nx_huge_pages_recovery_ratio); - to_zap = ratio ? DIV_ROUND_UP(nx_lpage_splits, ratio) : 0; for ( ; to_zap; --to_zap) { - if (list_empty(&kvm->arch.lpage_disallowed_mmu_pages)) + if (is_tdp_mmu) + spin_lock(tdp_mmu_pages_lock); + + if (list_empty(nx_huge_pages)) { + if (is_tdp_mmu) + spin_unlock(tdp_mmu_pages_lock); break; + } /* * We use a separate list instead of just using active_mmu_pages - * because the number of lpage_disallowed pages is expected to - * be relatively small compared to the total. + * because the number of shadow pages that be replaced with an + * NX huge page is expected to be relatively small compared to + * the total number of shadow pages. And because the TDP MMU + * doesn't use active_mmu_pages. */ - sp = list_first_entry(&kvm->arch.lpage_disallowed_mmu_pages, + sp = list_first_entry(nx_huge_pages, struct kvm_mmu_page, - lpage_disallowed_link); - WARN_ON_ONCE(!sp->lpage_disallowed); - if (is_tdp_mmu_page(sp)) { - flush |= kvm_tdp_mmu_zap_sp(kvm, sp); - } else { - kvm_mmu_prepare_zap_page(kvm, sp, &invalid_list); - WARN_ON_ONCE(sp->lpage_disallowed); + possible_nx_huge_page_link); + WARN_ON_ONCE(!sp->nx_huge_page_disallowed); + WARN_ON_ONCE(!sp->role.direct); + + unaccount_nx_huge_page(kvm, sp); + + if (is_tdp_mmu) + spin_unlock(tdp_mmu_pages_lock); + + /* + * Do not attempt to recover any NX Huge Pages that are being + * dirty tracked, as they would just be faulted back in as 4KiB + * pages. The NX Huge Pages in this slot will be recovered, + * along with all the other huge pages in the slot, when dirty + * logging is disabled. + */ + if (!kvm_mmu_sp_dirty_logging_enabled(kvm, sp)) { + if (is_tdp_mmu) + flush |= kvm_tdp_mmu_zap_possible_nx_huge_page(kvm, sp); + else + kvm_mmu_prepare_zap_page(kvm, sp, &invalid_list); + } + WARN_ON_ONCE(sp->nx_huge_page_disallowed); + if (need_resched() || rwlock_needbreak(&kvm->mmu_lock)) { kvm_mmu_remote_flush_or_zap(kvm, &invalid_list, flush); - cond_resched_rwlock_write(&kvm->mmu_lock); + rcu_read_unlock(); + + if (is_tdp_mmu) + cond_resched_rwlock_read(&kvm->mmu_lock); + else + cond_resched_rwlock_write(&kvm->mmu_lock); + flush = false; + rcu_read_lock(); } } kvm_mmu_remote_flush_or_zap(kvm, &invalid_list, flush); - write_unlock(&kvm->mmu_lock); + rcu_read_unlock(); + + if (is_tdp_mmu) + read_unlock(&kvm->mmu_lock); + else + write_unlock(&kvm->mmu_lock); srcu_read_unlock(&kvm->srcu, rcu_idx); } -static long get_nx_lpage_recovery_timeout(u64 start_time) +static void kvm_nx_huge_page_recovery_worker_kill(void *data) { - return READ_ONCE(nx_huge_pages) && READ_ONCE(nx_huge_pages_recovery_ratio) - ? start_time + 60 * HZ - get_jiffies_64() - : MAX_SCHEDULE_TIMEOUT; } -static int kvm_nx_lpage_recovery_worker(struct kvm *kvm, uintptr_t data) +static bool kvm_nx_huge_page_recovery_worker(void *data) { - u64 start_time; + struct kvm *kvm = data; long remaining_time; + bool enabled; + uint period; + int i; - while (true) { - start_time = get_jiffies_64(); - remaining_time = get_nx_lpage_recovery_timeout(start_time); + enabled = calc_nx_huge_pages_recovery_period(&period); + if (!enabled) + return false; - set_current_state(TASK_INTERRUPTIBLE); - while (!kthread_should_stop() && remaining_time > 0) { - schedule_timeout(remaining_time); - remaining_time = get_nx_lpage_recovery_timeout(start_time); - set_current_state(TASK_INTERRUPTIBLE); - } + remaining_time = kvm->arch.nx_huge_page_last + msecs_to_jiffies(period) + - get_jiffies_64(); + if (remaining_time > 0) { + schedule_timeout(remaining_time); + /* check for signals and come back */ + return true; + } - set_current_state(TASK_RUNNING); + __set_current_state(TASK_RUNNING); + for (i = 0; i < KVM_NR_MMU_TYPES; ++i) + kvm_recover_nx_huge_pages(kvm, i); + kvm->arch.nx_huge_page_last = get_jiffies_64(); + return true; +} - if (kthread_should_stop()) - return 0; +static int kvm_mmu_start_lpage_recovery(struct once *once) +{ + struct kvm_arch *ka = container_of(once, struct kvm_arch, nx_once); + struct kvm *kvm = container_of(ka, struct kvm, arch); + struct vhost_task *nx_thread; - kvm_recover_nx_lpages(kvm); - } + kvm->arch.nx_huge_page_last = get_jiffies_64(); + nx_thread = vhost_task_create(kvm_nx_huge_page_recovery_worker, + kvm_nx_huge_page_recovery_worker_kill, + kvm, "kvm-nx-lpage-recovery"); + + if (IS_ERR(nx_thread)) + return PTR_ERR(nx_thread); + + vhost_task_start(nx_thread); + + /* Make the task visible only once it is fully started. */ + WRITE_ONCE(kvm->arch.nx_huge_page_recovery_thread, nx_thread); + return 0; } int kvm_mmu_post_init_vm(struct kvm *kvm) { - int err; - - err = kvm_vm_create_worker_thread(kvm, kvm_nx_lpage_recovery_worker, 0, - "kvm-nx-lpage-recovery", - &kvm->arch.nx_lpage_recovery_thread); - if (!err) - kthread_unpark(kvm->arch.nx_lpage_recovery_thread); + if (nx_hugepage_mitigation_hard_disabled) + return 0; - return err; + return call_once(&kvm->arch.nx_once, kvm_mmu_start_lpage_recovery); } void kvm_mmu_pre_destroy_vm(struct kvm *kvm) { - if (kvm->arch.nx_lpage_recovery_thread) - kthread_stop(kvm->arch.nx_lpage_recovery_thread); + if (kvm->arch.nx_huge_page_recovery_thread) + vhost_task_stop(kvm->arch.nx_huge_page_recovery_thread); +} + +#ifdef CONFIG_KVM_GENERIC_MEMORY_ATTRIBUTES +static bool hugepage_test_mixed(struct kvm_memory_slot *slot, gfn_t gfn, + int level) +{ + return lpage_info_slot(gfn, slot, level)->disallow_lpage & KVM_LPAGE_MIXED_FLAG; } + +static void hugepage_clear_mixed(struct kvm_memory_slot *slot, gfn_t gfn, + int level) +{ + lpage_info_slot(gfn, slot, level)->disallow_lpage &= ~KVM_LPAGE_MIXED_FLAG; +} + +static void hugepage_set_mixed(struct kvm_memory_slot *slot, gfn_t gfn, + int level) +{ + lpage_info_slot(gfn, slot, level)->disallow_lpage |= KVM_LPAGE_MIXED_FLAG; +} + +bool kvm_arch_pre_set_memory_attributes(struct kvm *kvm, + struct kvm_gfn_range *range) +{ + struct kvm_memory_slot *slot = range->slot; + int level; + + /* + * Zap SPTEs even if the slot can't be mapped PRIVATE. KVM x86 only + * supports KVM_MEMORY_ATTRIBUTE_PRIVATE, and so it *seems* like KVM + * can simply ignore such slots. But if userspace is making memory + * PRIVATE, then KVM must prevent the guest from accessing the memory + * as shared. And if userspace is making memory SHARED and this point + * is reached, then at least one page within the range was previously + * PRIVATE, i.e. the slot's possible hugepage ranges are changing. + * Zapping SPTEs in this case ensures KVM will reassess whether or not + * a hugepage can be used for affected ranges. + */ + if (WARN_ON_ONCE(!kvm_arch_has_private_mem(kvm))) + return false; + + if (WARN_ON_ONCE(range->end <= range->start)) + return false; + + /* + * If the head and tail pages of the range currently allow a hugepage, + * i.e. reside fully in the slot and don't have mixed attributes, then + * add each corresponding hugepage range to the ongoing invalidation, + * e.g. to prevent KVM from creating a hugepage in response to a fault + * for a gfn whose attributes aren't changing. Note, only the range + * of gfns whose attributes are being modified needs to be explicitly + * unmapped, as that will unmap any existing hugepages. + */ + for (level = PG_LEVEL_2M; level <= KVM_MAX_HUGEPAGE_LEVEL; level++) { + gfn_t start = gfn_round_for_level(range->start, level); + gfn_t end = gfn_round_for_level(range->end - 1, level); + gfn_t nr_pages = KVM_PAGES_PER_HPAGE(level); + + if ((start != range->start || start + nr_pages > range->end) && + start >= slot->base_gfn && + start + nr_pages <= slot->base_gfn + slot->npages && + !hugepage_test_mixed(slot, start, level)) + kvm_mmu_invalidate_range_add(kvm, start, start + nr_pages); + + if (end == start) + continue; + + if ((end + nr_pages) > range->end && + (end + nr_pages) <= (slot->base_gfn + slot->npages) && + !hugepage_test_mixed(slot, end, level)) + kvm_mmu_invalidate_range_add(kvm, end, end + nr_pages); + } + + /* Unmap the old attribute page. */ + if (range->arg.attributes & KVM_MEMORY_ATTRIBUTE_PRIVATE) + range->attr_filter = KVM_FILTER_SHARED; + else + range->attr_filter = KVM_FILTER_PRIVATE; + + return kvm_unmap_gfn_range(kvm, range); +} + + + +static bool hugepage_has_attrs(struct kvm *kvm, struct kvm_memory_slot *slot, + gfn_t gfn, int level, unsigned long attrs) +{ + const unsigned long start = gfn; + const unsigned long end = start + KVM_PAGES_PER_HPAGE(level); + + if (level == PG_LEVEL_2M) + return kvm_range_has_memory_attributes(kvm, start, end, ~0, attrs); + + for (gfn = start; gfn < end; gfn += KVM_PAGES_PER_HPAGE(level - 1)) { + if (hugepage_test_mixed(slot, gfn, level - 1) || + attrs != kvm_get_memory_attributes(kvm, gfn)) + return false; + } + return true; +} + +bool kvm_arch_post_set_memory_attributes(struct kvm *kvm, + struct kvm_gfn_range *range) +{ + unsigned long attrs = range->arg.attributes; + struct kvm_memory_slot *slot = range->slot; + int level; + + lockdep_assert_held_write(&kvm->mmu_lock); + lockdep_assert_held(&kvm->slots_lock); + + /* + * Calculate which ranges can be mapped with hugepages even if the slot + * can't map memory PRIVATE. KVM mustn't create a SHARED hugepage over + * a range that has PRIVATE GFNs, and conversely converting a range to + * SHARED may now allow hugepages. + */ + if (WARN_ON_ONCE(!kvm_arch_has_private_mem(kvm))) + return false; + + /* + * The sequence matters here: upper levels consume the result of lower + * level's scanning. + */ + for (level = PG_LEVEL_2M; level <= KVM_MAX_HUGEPAGE_LEVEL; level++) { + gfn_t nr_pages = KVM_PAGES_PER_HPAGE(level); + gfn_t gfn = gfn_round_for_level(range->start, level); + + /* Process the head page if it straddles the range. */ + if (gfn != range->start || gfn + nr_pages > range->end) { + /* + * Skip mixed tracking if the aligned gfn isn't covered + * by the memslot, KVM can't use a hugepage due to the + * misaligned address regardless of memory attributes. + */ + if (gfn >= slot->base_gfn && + gfn + nr_pages <= slot->base_gfn + slot->npages) { + if (hugepage_has_attrs(kvm, slot, gfn, level, attrs)) + hugepage_clear_mixed(slot, gfn, level); + else + hugepage_set_mixed(slot, gfn, level); + } + gfn += nr_pages; + } + + /* + * Pages entirely covered by the range are guaranteed to have + * only the attributes which were just set. + */ + for ( ; gfn + nr_pages <= range->end; gfn += nr_pages) + hugepage_clear_mixed(slot, gfn, level); + + /* + * Process the last tail page if it straddles the range and is + * contained by the memslot. Like the head page, KVM can't + * create a hugepage if the slot size is misaligned. + */ + if (gfn < range->end && + (gfn + nr_pages) <= (slot->base_gfn + slot->npages)) { + if (hugepage_has_attrs(kvm, slot, gfn, level, attrs)) + hugepage_clear_mixed(slot, gfn, level); + else + hugepage_set_mixed(slot, gfn, level); + } + } + return false; +} + +void kvm_mmu_init_memslot_memory_attributes(struct kvm *kvm, + struct kvm_memory_slot *slot) +{ + int level; + + if (!kvm_arch_has_private_mem(kvm)) + return; + + for (level = PG_LEVEL_2M; level <= KVM_MAX_HUGEPAGE_LEVEL; level++) { + /* + * Don't bother tracking mixed attributes for pages that can't + * be huge due to alignment, i.e. process only pages that are + * entirely contained by the memslot. + */ + gfn_t end = gfn_round_for_level(slot->base_gfn + slot->npages, level); + gfn_t start = gfn_round_for_level(slot->base_gfn, level); + gfn_t nr_pages = KVM_PAGES_PER_HPAGE(level); + gfn_t gfn; + + if (start < slot->base_gfn) + start += nr_pages; + + /* + * Unlike setting attributes, every potential hugepage needs to + * be manually checked as the attributes may already be mixed. + */ + for (gfn = start; gfn < end; gfn += nr_pages) { + unsigned long attrs = kvm_get_memory_attributes(kvm, gfn); + + if (hugepage_has_attrs(kvm, slot, gfn, level, attrs)) + hugepage_clear_mixed(slot, gfn, level); + else + hugepage_set_mixed(slot, gfn, level); + } + } +} +#endif |