diff options
Diffstat (limited to 'arch/x86/kvm/mmu/mmu.c')
| -rw-r--r-- | arch/x86/kvm/mmu/mmu.c | 8095 |
1 files changed, 8095 insertions, 0 deletions
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c new file mode 100644 index 000000000000..02c450686b4a --- /dev/null +++ b/arch/x86/kvm/mmu/mmu.c @@ -0,0 +1,8095 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Kernel-based Virtual Machine driver for Linux + * + * This module enables machines with Intel VT-x extensions to run virtual + * machines without emulation or binary translation. + * + * MMU support + * + * Copyright (C) 2006 Qumranet, Inc. + * Copyright 2010 Red Hat, Inc. and/or its affiliates. + * + * Authors: + * Yaniv Kamay <yaniv@qumranet.com> + * Avi Kivity <avi@qumranet.com> + */ +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include "irq.h" +#include "ioapic.h" +#include "mmu.h" +#include "mmu_internal.h" +#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" + +#include <linux/kvm_host.h> +#include <linux/types.h> +#include <linux/string.h> +#include <linux/mm.h> +#include <linux/highmem.h> +#include <linux/moduleparam.h> +#include <linux/export.h> +#include <linux/swap.h> +#include <linux/hugetlb.h> +#include <linux/compiler.h> +#include <linux/srcu.h> +#include <linux/slab.h> +#include <linux/sched/signal.h> +#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 "trace.h" + +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; +#else +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_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 = get_nx_huge_pages, +}; + +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_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); + +/* + * When setting this variable to true it enables Two-Dimensional-Paging + * where the hardware walks 2 page tables: + * 1. the guest-virtual to guest-physical + * 2. while doing 1. it walks guest-physical to host-physical + * If the hardware supports that we don't need to do shadow paging. + */ +bool tdp_enabled = false; + +static bool __ro_after_init tdp_mmu_allowed; + +#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 + +static int max_huge_page_level __read_mostly; +static int tdp_root_level __read_mostly; +static int max_tdp_level __read_mostly; + +#define PTE_PREFETCH_NUM 8 + +#include <trace/events/kvm.h> + +/* 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 { + 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 { + u64 addr; + hpa_t shadow_addr; + u64 *sptep; + int level; + unsigned index; +}; + +#define for_each_shadow_entry_using_root(_vcpu, _root, _addr, _walker) \ + for (shadow_walk_init_using_root(&(_walker), (_vcpu), \ + (_root), (_addr)); \ + shadow_walk_okay(&(_walker)); \ + shadow_walk_next(&(_walker))) + +#define for_each_shadow_entry(_vcpu, _addr, _walker) \ + for (shadow_walk_init(&(_walker), _vcpu, _addr); \ + shadow_walk_okay(&(_walker)); \ + shadow_walk_next(&(_walker))) + +#define for_each_shadow_entry_lockless(_vcpu, _addr, _walker, spte) \ + for (shadow_walk_init(&(_walker), _vcpu, _addr); \ + shadow_walk_okay(&(_walker)) && \ + ({ spte = mmu_spte_get_lockless(_walker.sptep); 1; }); \ + __shadow_walk_next(&(_walker), spte)) + +static struct kmem_cache *pte_list_desc_cache; +struct kmem_cache *mmu_page_header_cache; + +static void mmu_spte_set(u64 *sptep, u64 spte); + +struct kvm_mmu_role_regs { + const unsigned long cr0; + const unsigned long cr4; + const u64 efer; +}; + +#define CREATE_TRACE_POINTS +#include "mmutrace.h" + +/* + * Yes, lot's of underscores. They're a hint that you probably shouldn't be + * 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 __maybe_unused \ +____is_##reg##_##name(const struct kvm_mmu_role_regs *regs) \ +{ \ + return !!(regs->reg & flag); \ +} +BUILD_MMU_ROLE_REGS_ACCESSOR(cr0, pg, X86_CR0_PG); +BUILD_MMU_ROLE_REGS_ACCESSOR(cr0, wp, X86_CR0_WP); +BUILD_MMU_ROLE_REGS_ACCESSOR(cr4, pse, X86_CR4_PSE); +BUILD_MMU_ROLE_REGS_ACCESSOR(cr4, pae, X86_CR4_PAE); +BUILD_MMU_ROLE_REGS_ACCESSOR(cr4, smep, X86_CR4_SMEP); +BUILD_MMU_ROLE_REGS_ACCESSOR(cr4, smap, X86_CR4_SMAP); +BUILD_MMU_ROLE_REGS_ACCESSOR(cr4, pke, X86_CR4_PKE); +BUILD_MMU_ROLE_REGS_ACCESSOR(cr4, la57, X86_CR4_LA57); +BUILD_MMU_ROLE_REGS_ACCESSOR(efer, nx, EFER_NX); +BUILD_MMU_ROLE_REGS_ACCESSOR(efer, lma, EFER_LMA); + +/* + * The MMU itself (with a valid role) is the single source of truth for the + * MMU. Do not use the regs used to build the MMU/role, nor the vCPU. The + * regs don't account for dependencies, e.g. clearing CR4 bits if CR0.PG=1, + * and the vCPU may be incorrect/irrelevant. + */ +#define BUILD_MMU_ROLE_ACCESSOR(base_or_ext, reg, name) \ +static inline bool __maybe_unused is_##reg##_##name(struct kvm_mmu *mmu) \ +{ \ + return !!(mmu->cpu_role. base_or_ext . reg##_##name); \ +} +BUILD_MMU_ROLE_ACCESSOR(base, cr0, wp); +BUILD_MMU_ROLE_ACCESSOR(ext, cr4, pse); +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) +{ + struct kvm_mmu_role_regs regs = { + .cr0 = kvm_read_cr0_bits(vcpu, KVM_MMU_CR0_ROLE_BITS), + .cr4 = kvm_read_cr4_bits(vcpu, KVM_MMU_CR4_ROLE_BITS), + .efer = vcpu->arch.efer, + }; + + return regs; +} + +static unsigned long get_guest_cr3(struct kvm_vcpu *vcpu) +{ + return kvm_read_cr3(vcpu); +} + +static inline unsigned long kvm_mmu_get_guest_pgd(struct kvm_vcpu *vcpu, + struct kvm_mmu *mmu) +{ + 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 inline bool kvm_available_flush_remote_tlbs_range(void) +{ +#if IS_ENABLED(CONFIG_HYPERV) + return kvm_x86_ops.flush_remote_tlbs_range; +#else + return false; +#endif +} + +static gfn_t kvm_mmu_page_get_gfn(struct kvm_mmu_page *sp, int index); + +/* 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_gfn(kvm, gfn, sp->role.level); +} + +static void mark_mmio_spte(struct kvm_vcpu *vcpu, u64 *sptep, u64 gfn, + unsigned int access) +{ + u64 spte = make_mmio_spte(vcpu, gfn, access); + + trace_mark_mmio_spte(sptep, gfn, spte); + mmu_spte_set(sptep, spte); +} + +static gfn_t get_mmio_spte_gfn(u64 spte) +{ + u64 gpa = spte & shadow_nonpresent_or_rsvd_lower_gfn_mask; + + gpa |= (spte >> SHADOW_NONPRESENT_OR_RSVD_MASK_LEN) + & shadow_nonpresent_or_rsvd_mask; + + return gpa >> PAGE_SHIFT; +} + +static unsigned get_mmio_spte_access(u64 spte) +{ + return spte & shadow_mmio_access_mask; +} + +static bool check_mmio_spte(struct kvm_vcpu *vcpu, u64 spte) +{ + u64 kvm_gen, spte_gen, gen; + + gen = kvm_vcpu_memslots(vcpu)->generation; + if (unlikely(gen & KVM_MEMSLOT_GEN_UPDATE_IN_PROGRESS)) + return false; + + kvm_gen = gen & MMIO_SPTE_GEN_MASK; + spte_gen = get_mmio_spte_generation(spte); + + trace_check_mmio_spte(spte, kvm_gen, spte_gen); + return likely(kvm_gen == spte_gen); +} + +static int is_cpuid_PSE36(void) +{ + return 1; +} + +#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); +} + +static u64 __get_spte_lockless(u64 *sptep) +{ + return READ_ONCE(*sptep); +} +#else +union split_spte { + struct { + u32 spte_low; + u32 spte_high; + }; + u64 spte; +}; + +static void count_spte_clear(u64 *sptep, u64 spte) +{ + struct kvm_mmu_page *sp = sptep_to_sp(sptep); + + if (is_shadow_present_pte(spte)) + return; + + /* Ensure the spte is completely set before we increase the count */ + smp_wmb(); + sp->clear_spte_count++; +} + +static void __set_spte(u64 *sptep, u64 spte) +{ + union split_spte *ssptep, sspte; + + ssptep = (union split_spte *)sptep; + sspte = (union split_spte)spte; + + ssptep->spte_high = sspte.spte_high; + + /* + * If we map the spte from nonpresent to present, We should store + * the high bits firstly, then set present bit, so cpu can not + * fetch this spte while we are setting the spte. + */ + smp_wmb(); + + WRITE_ONCE(ssptep->spte_low, sspte.spte_low); +} + +static void __update_clear_spte_fast(u64 *sptep, u64 spte) +{ + union split_spte *ssptep, sspte; + + ssptep = (union split_spte *)sptep; + sspte = (union split_spte)spte; + + WRITE_ONCE(ssptep->spte_low, sspte.spte_low); + + /* + * If we map the spte from present to nonpresent, we should clear + * present bit firstly to avoid vcpu fetch the old high bits. + */ + smp_wmb(); + + ssptep->spte_high = sspte.spte_high; + count_spte_clear(sptep, spte); +} + +static u64 __update_clear_spte_slow(u64 *sptep, u64 spte) +{ + union split_spte *ssptep, sspte, orig; + + ssptep = (union split_spte *)sptep; + sspte = (union split_spte)spte; + + /* xchg acts as a barrier before the setting of the high bits */ + orig.spte_low = xchg(&ssptep->spte_low, sspte.spte_low); + orig.spte_high = ssptep->spte_high; + ssptep->spte_high = sspte.spte_high; + count_spte_clear(sptep, spte); + + return orig.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 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 + * for the high part of the spte. The race is fine for a present->non-present + * change (because the high part of the spte is ignored for non-present spte), + * but for a present->present change we must reread the spte. + * + * All such changes are done in two steps (present->non-present and + * non-present->present), hence it is enough to count the number of + * present->non-present updates: if it changed while reading the spte, + * we might have hit the race. This is done using clear_spte_count. + */ +static u64 __get_spte_lockless(u64 *sptep) +{ + struct kvm_mmu_page *sp = sptep_to_sp(sptep); + union split_spte spte, *orig = (union split_spte *)sptep; + int count; + +retry: + count = sp->clear_spte_count; + smp_rmb(); + + spte.spte_low = orig->spte_low; + smp_rmb(); + + spte.spte_high = orig->spte_high; + smp_rmb(); + + if (unlikely(spte.spte_low != orig->spte_low || + count != sp->clear_spte_count)) + goto retry; + + return spte.spte; +} +#endif + +/* Rules for using mmu_spte_set: + * Set the sptep from nonpresent to present. + * Note: the sptep being assigned *must* be either not present + * or in a state where the hardware will not attempt to update + * the spte. + */ +static void mmu_spte_set(u64 *sptep, u64 new_spte) +{ + WARN_ON_ONCE(is_shadow_present_pte(*sptep)); + __set_spte(sptep, new_spte); +} + +/* 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 bool mmu_spte_update(u64 *sptep, u64 new_spte) +{ + u64 old_spte = *sptep; + + 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 false; + } + + 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_ONCE(!is_shadow_present_pte(old_spte) || + spte_to_pfn(old_spte) != spte_to_pfn(new_spte)); + + 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 the old PTE. + */ +static u64 mmu_spte_clear_track_bits(struct kvm *kvm, u64 *sptep) +{ + u64 old_spte = *sptep; + int level = sptep_to_sp(sptep)->role.level; + + 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, SHADOW_NONPRESENT_VALUE); + + if (!is_shadow_present_pte(old_spte)) + return old_spte; + + kvm_update_page_stats(kvm, level, -1); + return old_spte; +} + +/* + * Rules for using mmu_spte_clear_no_track: + * Directly clear spte without caring the state bits of sptep, + * it is used to set the upper level spte. + */ +static void mmu_spte_clear_no_track(u64 *sptep) +{ + __update_clear_spte_fast(sptep, SHADOW_NONPRESENT_VALUE); +} + +static u64 mmu_spte_get_lockless(u64 *sptep) +{ + return __get_spte_lockless(sptep); +} + +static inline bool is_tdp_mmu_active(struct kvm_vcpu *vcpu) +{ + return tdp_mmu_enabled && vcpu->arch.mmu->root_role.direct; +} + +static void walk_shadow_page_lockless_begin(struct kvm_vcpu *vcpu) +{ + if (is_tdp_mmu_active(vcpu)) { + kvm_tdp_mmu_walk_lockless_begin(); + } else { + /* + * 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) +{ + 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) +{ + int r; + + /* 1 rmap, 1 parent PTE per level, and the prefetched rmaps. */ + r = kvm_mmu_topup_memory_cache(&vcpu->arch.mmu_pte_list_desc_cache, + 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_shadowed_info_cache, + PT64_ROOT_MAX_LEVEL); + if (r) + return r; + } + return kvm_mmu_topup_memory_cache(&vcpu->arch.mmu_page_header_cache, + PT64_ROOT_MAX_LEVEL); +} + +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_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 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.passthrough) + return sp->gfn; + + if (sp->shadowed_translation) + return sp->shadowed_translation[index] >> PAGE_SHIFT; + + return sp->gfn + (index << ((sp->role.level - 1) * SPTE_LEVEL_BITS)); +} + +/* + * 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->shadowed_translation) { + sp->shadowed_translation[index] = (gfn << PAGE_SHIFT) | access; + return; + } + + 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); +} + +/* + * Return the pointer to the large page information for a given gfn, + * handling slots that are not large page aligned. + */ +static struct kvm_lpage_info *lpage_info_slot(gfn_t gfn, + const struct kvm_memory_slot *slot, int level) +{ + unsigned long idx; + + idx = gfn_to_index(gfn, slot->base_gfn, level); + return &slot->arch.lpage_info[level - 2][idx]; +} + +/* + * 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 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_ONCE((old ^ linfo->disallow_lpage) & KVM_LPAGE_MIXED_FLAG); + } +} + +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(const struct kvm_memory_slot *slot, gfn_t gfn) +{ + update_gfn_disallow_lpage_count(slot, gfn, -1); +} + +static void account_shadowed(struct kvm *kvm, struct kvm_mmu_page *sp) +{ + struct kvm_memslots *slots; + struct kvm_memory_slot *slot; + 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_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 track_possible_nx_huge_page(struct kvm *kvm, struct kvm_mmu_page *sp, + enum kvm_mmu_type mmu_type) +{ + /* + * 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; + ++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) +{ + struct kvm_memslots *slots; + struct kvm_memory_slot *slot; + gfn_t gfn; + + kvm->arch.indirect_shadow_pages--; + gfn = sp->gfn; + slots = kvm_memslots_for_spte_role(kvm, sp->role); + slot = __gfn_to_memslot(slots, gfn); + if (sp->role.level > PG_LEVEL_4K) + return __kvm_write_track_remove_gfn(kvm, slot, gfn); + + kvm_mmu_gfn_allow_lpage(slot, gfn); +} + +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; + --kvm->arch.possible_nx_huge_pages[mmu_type].nr_pages; + list_del_init(&sp->possible_nx_huge_page_link); +} + +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; + + slot = kvm_vcpu_gfn_to_memslot(vcpu, gfn); + if (!slot || slot->flags & KVM_MEMSLOT_INVALID) + return NULL; + if (no_dirty_log && kvm_slot_dirty_track_enabled(slot)) + return NULL; + + return slot; +} + +/* + * 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 & ~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 *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 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; + desc->spte_count = 2; + desc->tail_count = 0; + new_val = (unsigned long)desc | KVM_RMAP_MANY; + ++count; + } else { + 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; + } + 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 *kvm, unsigned long *rmap_val, + struct pte_list_desc *desc, int i) +{ + 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); + + /* + * 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; + + /* + * 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 + *rmap_val = (unsigned long)head_desc->more | KVM_RMAP_MANY; + mmu_free_pte_list_desc(head_desc); +} + +static void pte_list_remove(struct kvm *kvm, u64 *spte, + struct kvm_rmap_head *rmap_head) +{ + struct pte_list_desc *desc; + unsigned long rmap_val; + int i; + + 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 { + desc = (struct pte_list_desc *)(rmap_val & ~KVM_RMAP_MANY); + while (desc) { + for (i = 0; i < desc->spte_count; ++i) { + if (desc->sptes[i] == spte) { + pte_list_desc_remove_entry(kvm, &rmap_val, + desc, i); + goto out; + } + } + desc = desc->more; + } + + KVM_BUG_ON_DATA_CORRUPTION(true, kvm); + } + +out: + kvm_rmap_unlock(kvm, rmap_head, rmap_val); +} + +static void kvm_zap_one_rmap_spte(struct kvm *kvm, + struct kvm_rmap_head *rmap_head, u64 *sptep) +{ + mmu_spte_clear_track_bits(kvm, sptep); + pte_list_remove(kvm, sptep, rmap_head); +} + +/* 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) +{ + struct pte_list_desc *desc, *next; + unsigned long rmap_val; + int i; + + rmap_val = kvm_rmap_lock(kvm, rmap_head); + if (!rmap_val) + return false; + + if (!(rmap_val & KVM_RMAP_MANY)) { + mmu_spte_clear_track_bits(kvm, (u64 *)rmap_val); + goto out; + } + + 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; +} + +unsigned int pte_list_count(struct kvm_rmap_head *rmap_head) +{ + unsigned long rmap_val = kvm_rmap_get(rmap_head); + struct pte_list_desc *desc; + + 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 struct kvm_rmap_head *gfn_to_rmap(gfn_t gfn, int level, + const struct kvm_memory_slot *slot) +{ + unsigned long idx; + + 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_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); +} + +/* + * Used by the following functions to iterate through the sptes linked by a + * rmap. All fields are private and not assumed to be used outside. + */ +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 */ +}; + +/* + * Iteration must be started by this function. This should also be used after + * removing/dropping sptes from the rmap link because in such cases the + * information in the iterator may not be valid. + * + * Returns sptep if found, NULL otherwise. + */ +static u64 *rmap_get_first(struct kvm_rmap_head *rmap_head, + struct rmap_iterator *iter) +{ + unsigned long rmap_val = kvm_rmap_get(rmap_head); + + if (!rmap_val) + return NULL; + + if (!(rmap_val & KVM_RMAP_MANY)) { + iter->desc = NULL; + return (u64 *)rmap_val; + } + + iter->desc = (struct pte_list_desc *)(rmap_val & ~KVM_RMAP_MANY); + iter->pos = 0; + return iter->desc->sptes[iter->pos]; +} + +/* + * Must be used with a valid iterator: e.g. after rmap_get_first(). + * + * Returns sptep if found, NULL otherwise. + */ +static u64 *rmap_get_next(struct rmap_iterator *iter) +{ + if (iter->desc) { + if (iter->pos < PTE_LIST_EXT - 1) { + ++iter->pos; + if (iter->desc->sptes[iter->pos]) + return iter->desc->sptes[iter->pos]; + } + + iter->desc = iter->desc->more; + + if (iter->desc) { + iter->pos = 0; + /* desc->sptes[0] cannot be NULL */ + return iter->desc->sptes[iter->pos]; + } + } + + return NULL; +} + +#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) +{ + u64 old_spte = mmu_spte_clear_track_bits(kvm, sptep); + + if (is_shadow_present_pte(old_spte)) + rmap_remove(kvm, sptep); +} + +static void drop_large_spte(struct kvm *kvm, u64 *sptep, bool flush) +{ + struct kvm_mmu_page *sp; + + sp = sptep_to_sp(sptep); + WARN_ON_ONCE(sp->role.level == PG_LEVEL_4K); + + drop_spte(kvm, sptep); + + if (flush) + kvm_flush_remote_tlbs_sptep(kvm, sptep); +} + +/* + * Write-protect on the specified @sptep, @pt_protect indicates whether + * spte write-protection is caused by protecting shadow page table. + * + * Note: write protection is difference between dirty logging and spte + * protection: + * - for dirty logging, the spte can be set to writable at anytime if + * its dirty bitmap is properly set. + * - for spte protection, the spte can be writable only after unsync-ing + * shadow page. + * + * Return true if tlb need be flushed. + */ +static bool spte_write_protect(u64 *sptep, bool pt_protect) +{ + u64 spte = *sptep; + + if (!is_writable_pte(spte) && + !(pt_protect && is_mmu_writable_spte(spte))) + return false; + + if (pt_protect) + spte &= ~shadow_mmu_writable_mask; + spte = spte & ~PT_WRITABLE_MASK; + + return mmu_spte_update(sptep, spte); +} + +static bool rmap_write_protect(struct kvm_rmap_head *rmap_head, + bool pt_protect) +{ + u64 *sptep; + struct rmap_iterator iter; + bool flush = false; + + for_each_rmap_spte(rmap_head, &iter, sptep) + flush |= spte_write_protect(sptep, pt_protect); + + return flush; +} + +static bool spte_clear_dirty(u64 *sptep) +{ + u64 spte = *sptep; + + KVM_MMU_WARN_ON(!spte_ad_enabled(spte)); + spte &= ~shadow_dirty_mask; + return mmu_spte_update(sptep, spte); +} + +/* + * Gets the GFN ready for another round of dirty logging by clearing the + * - D bit on ad-enabled SPTEs, and + * - W bit on ad-disabled SPTEs. + * Returns true iff any D or W bits were cleared. + */ +static bool __rmap_clear_dirty(struct kvm *kvm, struct kvm_rmap_head *rmap_head, + const struct kvm_memory_slot *slot) +{ + u64 *sptep; + struct rmap_iterator iter; + bool flush = false; + + for_each_rmap_spte(rmap_head, &iter, sptep) { + if (spte_ad_need_write_protect(*sptep)) + flush |= test_and_clear_bit(PT_WRITABLE_SHIFT, + (unsigned long *)sptep); + else + flush |= spte_clear_dirty(sptep); + } + + return flush; +} + +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 (tdp_mmu_enabled) + kvm_tdp_mmu_clear_dirty_pt_masked(kvm, slot, + slot->base_gfn + gfn_offset, mask, true); + + if (!kvm_memslots_have_rmaps(kvm)) + return; + + while (mask) { + 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; + } +} + +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 (tdp_mmu_enabled) + kvm_tdp_mmu_clear_dirty_pt_masked(kvm, slot, + slot->base_gfn + gfn_offset, mask, false); + + if (!kvm_memslots_have_rmaps(kvm)) + return; + + while (mask) { + 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 */ + mask &= mask - 1; + } +} + +void kvm_arch_mmu_enable_log_dirty_pt_masked(struct kvm *kvm, + struct kvm_memory_slot *slot, + gfn_t gfn_offset, unsigned long mask) +{ + /* + * 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 + * pages. + */ + if (kvm_dirty_log_manual_protect_and_init_set(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? */ + if (ALIGN(start << PAGE_SHIFT, PMD_SIZE) != + ALIGN(end << PAGE_SHIFT, PMD_SIZE)) + kvm_mmu_slot_gfn_write_protect(kvm, slot, end, + PG_LEVEL_2M); + } + + /* + * (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(struct kvm *kvm) +{ + return kvm->arch.cpu_dirty_log_size; +} + +bool kvm_mmu_slot_gfn_write_protect(struct kvm *kvm, + struct kvm_memory_slot *slot, u64 gfn, + int min_level) +{ + struct kvm_rmap_head *rmap_head; + int i; + bool write_protected = false; + + 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(rmap_head, true); + } + } + + if (tdp_mmu_enabled) + write_protected |= + kvm_tdp_mmu_write_protect_gfn(kvm, slot, gfn, min_level); + + return write_protected; +} + +static bool kvm_vcpu_write_protect_gfn(struct kvm_vcpu *vcpu, u64 gfn) +{ + struct kvm_memory_slot *slot; + + slot = kvm_vcpu_gfn_to_memslot(vcpu, gfn); + return kvm_mmu_slot_gfn_write_protect(vcpu->kvm, slot, gfn, PG_LEVEL_4K); +} + +static bool kvm_zap_rmap(struct kvm *kvm, struct kvm_rmap_head *rmap_head, + const struct kvm_memory_slot *slot) +{ + return kvm_zap_all_rmap_sptes(kvm, rmap_head); +} + +struct slot_rmap_walk_iterator { + /* input fields. */ + const struct kvm_memory_slot *slot; + gfn_t start_gfn; + gfn_t end_gfn; + int start_level; + int end_level; + + /* output fields. */ + gfn_t gfn; + struct kvm_rmap_head *rmap; + int level; + + /* private field. */ + struct kvm_rmap_head *end_rmap; +}; + +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); +} + +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; + iterator->end_level = end_level; + iterator->start_gfn = start_gfn; + iterator->end_gfn = end_gfn; + + rmap_walk_init_level(iterator, iterator->start_level); +} + +static bool slot_rmap_walk_okay(struct slot_rmap_walk_iterator *iterator) +{ + return !!iterator->rmap; +} + +static void slot_rmap_walk_next(struct slot_rmap_walk_iterator *iterator) +{ + 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) { + iterator->rmap = NULL; + return; + } + + rmap_walk_init_level(iterator, iterator->level); +} + +#define for_each_slot_rmap_range(_slot_, _start_level_, _end_level_, \ + _start_gfn, _end_gfn, _iter_) \ + for (slot_rmap_walk_init(_iter_, _slot_, _start_level_, \ + _end_level_, _start_gfn, _end_gfn); \ + slot_rmap_walk_okay(_iter_); \ + slot_rmap_walk_next(_iter_)) + +/* 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 __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; + + lockdep_assert_held_write(&kvm->mmu_lock); + + 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; +} + +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) +{ + 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); +} + +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); +} + +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_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_rmap_zap_gfn_range(kvm, range->slot, + range->start, range->end, + range->may_block, flush); + + 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; +} + +#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) +{ + struct kvm_mmu_page *sp; + struct kvm_rmap_head *rmap_head; + int rmap_count; + + 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); + + 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 void rmap_add(struct kvm_vcpu *vcpu, const struct kvm_memory_slot *slot, + u64 *spte, gfn_t gfn, unsigned int access) +{ + struct kvm_mmu_memory_cache *cache = &vcpu->arch.mmu_pte_list_desc_cache; + + __rmap_add(vcpu->kvm, cache, slot, spte, gfn, access); +} + +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 rmap_iterator iter; + unsigned long rmap_val; + bool young = false; + u64 *sptep; + gfn_t gfn; + int level; + u64 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; + } + + 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_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 (tdp_mmu_enabled) + 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; +} + +bool kvm_test_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range) +{ + bool young = false; + + if (tdp_mmu_enabled) + 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; +} + +static void kvm_mmu_check_sptes_at_free(struct kvm_mmu_page *sp) +{ +#ifdef CONFIG_KVM_PROVE_MMU + int i; + + 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 +} + +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--; + kvm_account_pgtable_pages((void *)sp->spt, -1); +} + +static void kvm_mmu_free_shadow_page(struct kvm_mmu_page *sp) +{ + kvm_mmu_check_sptes_at_free(sp); + + hlist_del(&sp->hash_link); + list_del(&sp->link); + free_page((unsigned long)sp->spt); + free_page((unsigned long)sp->shadowed_translation); + kmem_cache_free(mmu_page_header_cache, sp); +} + +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 *kvm, + struct kvm_mmu_memory_cache *cache, + struct kvm_mmu_page *sp, u64 *parent_pte) +{ + if (!parent_pte) + return; + + pte_list_add(kvm, cache, parent_pte, &sp->parent_ptes); +} + +static void mmu_page_remove_parent_pte(struct kvm *kvm, struct kvm_mmu_page *sp, + u64 *parent_pte) +{ + pte_list_remove(kvm, parent_pte, &sp->parent_ptes); +} + +static void drop_parent_pte(struct kvm *kvm, struct kvm_mmu_page *sp, + u64 *parent_pte) +{ + mmu_page_remove_parent_pte(kvm, sp, parent_pte); + mmu_spte_clear_no_track(parent_pte); +} + +static void mark_unsync(u64 *spte); +static void kvm_mmu_mark_parents_unsync(struct kvm_mmu_page *sp) +{ + u64 *sptep; + struct rmap_iterator iter; + + for_each_rmap_spte(&sp->parent_ptes, &iter, sptep) { + mark_unsync(sptep); + } +} + +static void mark_unsync(u64 *spte) +{ + struct kvm_mmu_page *sp; + + sp = sptep_to_sp(spte); + if (__test_and_set_bit(spte_index(spte), sp->unsync_child_bitmap)) + return; + if (sp->unsync_children++) + return; + kvm_mmu_mark_parents_unsync(sp); +} + +#define KVM_PAGE_ARRAY_NR 16 + +struct kvm_mmu_pages { + struct mmu_page_and_offset { + struct kvm_mmu_page *sp; + unsigned int idx; + } page[KVM_PAGE_ARRAY_NR]; + unsigned int nr; +}; + +static int mmu_pages_add(struct kvm_mmu_pages *pvec, struct kvm_mmu_page *sp, + int idx) +{ + int i; + + if (sp->unsync) + for (i=0; i < pvec->nr; i++) + if (pvec->page[i].sp == sp) + return 0; + + pvec->page[pvec->nr].sp = sp; + pvec->page[pvec->nr].idx = idx; + pvec->nr++; + return (pvec->nr == KVM_PAGE_ARRAY_NR); +} + +static inline void clear_unsync_child_bit(struct kvm_mmu_page *sp, int idx) +{ + --sp->unsync_children; + WARN_ON_ONCE((int)sp->unsync_children < 0); + __clear_bit(idx, sp->unsync_child_bitmap); +} + +static int __mmu_unsync_walk(struct kvm_mmu_page *sp, + struct kvm_mmu_pages *pvec) +{ + int i, ret, nr_unsync_leaf = 0; + + for_each_set_bit(i, sp->unsync_child_bitmap, 512) { + struct kvm_mmu_page *child; + u64 ent = sp->spt[i]; + + if (!is_shadow_present_pte(ent) || is_large_pte(ent)) { + clear_unsync_child_bit(sp, i); + continue; + } + + child = spte_to_child_sp(ent); + + if (child->unsync_children) { + if (mmu_pages_add(pvec, child, i)) + return -ENOSPC; + + ret = __mmu_unsync_walk(child, pvec); + if (!ret) { + clear_unsync_child_bit(sp, i); + continue; + } else if (ret > 0) { + nr_unsync_leaf += ret; + } else + return ret; + } else if (child->unsync) { + nr_unsync_leaf++; + if (mmu_pages_add(pvec, child, i)) + return -ENOSPC; + } else + clear_unsync_child_bit(sp, i); + } + + return nr_unsync_leaf; +} + +#define INVALID_INDEX (-1) + +static int mmu_unsync_walk(struct kvm_mmu_page *sp, + struct kvm_mmu_pages *pvec) +{ + pvec->nr = 0; + if (!sp->unsync_children) + return 0; + + mmu_pages_add(pvec, sp, INVALID_INDEX); + return __mmu_unsync_walk(sp, pvec); +} + +static void kvm_unlink_unsync_page(struct kvm *kvm, struct kvm_mmu_page *sp) +{ + WARN_ON_ONCE(!sp->unsync); + trace_kvm_mmu_sync_page(sp); + sp->unsync = 0; + --kvm->stat.mmu_unsync; +} + +static bool kvm_mmu_prepare_zap_page(struct kvm *kvm, struct kvm_mmu_page *sp, + struct list_head *invalid_list); +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_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_check(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp) +{ + 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) +{ + if (!remote_flush && list_empty(invalid_list)) + return false; + + if (!list_empty(invalid_list)) + kvm_mmu_commit_zap_page(kvm, invalid_list); + else + kvm_flush_remote_tlbs(kvm); + return true; +} + +static bool is_obsolete_sp(struct kvm *kvm, struct kvm_mmu_page *sp) +{ + 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); +} + +struct mmu_page_path { + struct kvm_mmu_page *parent[PT64_ROOT_MAX_LEVEL]; + unsigned int idx[PT64_ROOT_MAX_LEVEL]; +}; + +#define for_each_sp(pvec, sp, parents, i) \ + for (i = mmu_pages_first(&pvec, &parents); \ + i < pvec.nr && ({ sp = pvec.page[i].sp; 1;}); \ + i = mmu_pages_next(&pvec, &parents, i)) + +static int mmu_pages_next(struct kvm_mmu_pages *pvec, + struct mmu_page_path *parents, + int i) +{ + int n; + + for (n = i+1; n < pvec->nr; n++) { + struct kvm_mmu_page *sp = pvec->page[n].sp; + unsigned idx = pvec->page[n].idx; + int level = sp->role.level; + + parents->idx[level-1] = idx; + if (level == PG_LEVEL_4K) + break; + + parents->parent[level-2] = sp; + } + + return n; +} + +static int mmu_pages_first(struct kvm_mmu_pages *pvec, + struct mmu_page_path *parents) +{ + struct kvm_mmu_page *sp; + int level; + + if (pvec->nr == 0) + return 0; + + WARN_ON_ONCE(pvec->page[0].idx != INVALID_INDEX); + + sp = pvec->page[0].sp; + level = sp->role.level; + WARN_ON_ONCE(level == PG_LEVEL_4K); + + parents->parent[level-2] = sp; + + /* Also set up a sentinel. Further entries in pvec are all + * children of sp, so this element is never overwritten. + */ + parents->parent[level-1] = NULL; + return mmu_pages_next(pvec, parents, 0); +} + +static void mmu_pages_clear_parents(struct mmu_page_path *parents) +{ + struct kvm_mmu_page *sp; + unsigned int level = 0; + + do { + unsigned int idx = parents->idx[level]; + sp = parents->parent[level]; + if (!sp) + return; + + WARN_ON_ONCE(idx == INVALID_INDEX); + clear_unsync_child_bit(sp, idx); + level++; + } while (!sp->unsync_children); +} + +static int mmu_sync_children(struct kvm_vcpu *vcpu, + struct kvm_mmu_page *parent, bool can_yield) +{ + int i; + struct kvm_mmu_page *sp; + struct mmu_page_path parents; + struct kvm_mmu_pages pages; + LIST_HEAD(invalid_list); + bool flush = false; + + while (mmu_unsync_walk(parent, &pages)) { + bool protected = false; + + for_each_sp(pages, sp, parents, i) + protected |= kvm_vcpu_write_protect_gfn(vcpu, sp->gfn); + + if (protected) { + 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) > 0; + mmu_pages_clear_parents(&parents); + } + if (need_resched() || rwlock_needbreak(&vcpu->kvm->mmu_lock)) { + 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_remote_flush_or_zap(vcpu->kvm, &invalid_list, flush); + return 0; +} + +static void __clear_sp_write_flooding_count(struct kvm_mmu_page *sp) +{ + atomic_set(&sp->write_flooding_count, 0); +} + +static void clear_sp_write_flooding_count(u64 *spte) +{ + __clear_sp_write_flooding_count(sptep_to_sp(spte)); +} + +/* + * 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) +{ + struct kvm_mmu_page *sp; + int ret; + int collisions = 0; + LIST_HEAD(invalid_list); + + for_each_valid_sp(kvm, sp, sp_list) { + if (sp->gfn != gfn) { + collisions++; + continue; + } + + if (sp->role.word != role.word) { + /* + * If the guest is creating an upper-level page, zap + * unsync pages for the same gfn. While it's possible + * the guest is using recursive page tables, in all + * likelihood the guest has stopped using the unsync + * page and is installing a completely unrelated page. + * Unsync pages must not be left as is, because the new + * upper-level page will be write-protected. + */ + if (role.level > PG_LEVEL_4K && sp->unsync) + kvm_mmu_prepare_zap_page(kvm, sp, + &invalid_list); + continue; + } + + /* 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) + * it doesn't write-protect the page or mark it synchronized! + * This way the validity of the mapping is ensured, but the + * overhead of write protection is not incurred until the + * guest invalidates the TLB mapping. This allows multiple + * SPs for a single gfn to be unsync. + * + * If the sync fails, the page is zapped. If so, break + * in order to rebuild it. + */ + ret = kvm_sync_page(vcpu, sp, &invalid_list); + if (ret < 0) + break; + + WARN_ON_ONCE(!list_empty(&invalid_list)); + if (ret > 0) + kvm_flush_remote_tlbs(kvm); + } + + __clear_sp_write_flooding_count(sp); + + goto out; + } + + 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); + + 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 (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, 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->root_role.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); + + iterator->shadow_addr + = vcpu->arch.mmu->pae_root[(addr >> 30) & 3]; + iterator->shadow_addr &= SPTE_BASE_ADDR_MASK; + --iterator->level; + if (!iterator->shadow_addr) + iterator->level = 0; + } +} + +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, + addr); +} + +static bool shadow_walk_okay(struct kvm_shadow_walk_iterator *iterator) +{ + if (iterator->level < PG_LEVEL_4K) + return false; + + iterator->index = SPTE_INDEX(iterator->addr, iterator->level); + iterator->sptep = ((u64 *)__va(iterator->shadow_addr)) + iterator->index; + return true; +} + +static void __shadow_walk_next(struct kvm_shadow_walk_iterator *iterator, + u64 spte) +{ + if (!is_shadow_present_pte(spte) || is_last_spte(spte, iterator->level)) { + iterator->level = 0; + return; + } + + iterator->shadow_addr = spte & SPTE_BASE_ADDR_MASK; + --iterator->level; +} + +static void shadow_walk_next(struct kvm_shadow_walk_iterator *iterator) +{ + __shadow_walk_next(iterator, *iterator->sptep); +} + +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(kvm, cache, sp, sptep); + + /* + * 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) +{ + if (is_shadow_present_pte(*sptep) && !is_large_pte(*sptep)) { + struct kvm_mmu_page *child; + + /* + * For the direct sp, if the guest pte's dirty bit + * changed form clean to dirty, it will corrupt the + * sp's access: allow writable in the read-only sp, + * so we should update the spte at this point to get + * a new sp with the correct access. + */ + child = spte_to_child_sp(*sptep); + if (child->role.access == direct_access) + return; + + drop_parent_pte(vcpu->kvm, child, sptep); + kvm_flush_remote_tlbs_sptep(vcpu->kvm, sptep); + } +} + +/* Returns the number of zapped non-leaf child shadow pages. */ +static int mmu_page_zap_pte(struct kvm *kvm, struct kvm_mmu_page *sp, + u64 *spte, struct list_head *invalid_list) +{ + u64 pte; + struct kvm_mmu_page *child; + + pte = *spte; + if (is_shadow_present_pte(pte)) { + if (is_last_spte(pte, sp->role.level)) { + drop_spte(kvm, spte); + } else { + child = spte_to_child_sp(pte); + drop_parent_pte(kvm, child, spte); + + /* + * Recursively zap nested TDP SPs, parentless SPs are + * unlikely to be used again in the near future. This + * avoids retaining a large number of stale nested SPs. + */ + if (tdp_enabled && invalid_list && + 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(kvm, pte)) { + mmu_spte_clear_no_track(spte); + } + return 0; +} + +static int kvm_mmu_page_unlink_children(struct kvm *kvm, + struct kvm_mmu_page *sp, + struct list_head *invalid_list) +{ + int zapped = 0; + unsigned i; + + for (i = 0; i < SPTE_ENT_PER_PAGE; ++i) + zapped += mmu_page_zap_pte(kvm, sp, sp->spt + i, invalid_list); + + return zapped; +} + +static void kvm_mmu_unlink_parents(struct kvm *kvm, struct kvm_mmu_page *sp) +{ + u64 *sptep; + struct rmap_iterator iter; + + while ((sptep = rmap_get_first(&sp->parent_ptes, &iter))) + drop_parent_pte(kvm, sp, sptep); +} + +static int mmu_zap_unsync_children(struct kvm *kvm, + struct kvm_mmu_page *parent, + struct list_head *invalid_list) +{ + int i, zapped = 0; + struct mmu_page_path parents; + struct kvm_mmu_pages pages; + + if (parent->role.level == PG_LEVEL_4K) + return 0; + + while (mmu_unsync_walk(parent, &pages)) { + struct kvm_mmu_page *sp; + + for_each_sp(pages, sp, parents, i) { + kvm_mmu_prepare_zap_page(kvm, sp, invalid_list); + mmu_pages_clear_parents(&parents); + zapped++; + } + } + + return zapped; +} + +static bool __kvm_mmu_prepare_zap_page(struct kvm *kvm, + struct kvm_mmu_page *sp, + struct list_head *invalid_list, + int *nr_zapped) +{ + 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); + *nr_zapped += kvm_mmu_page_unlink_children(kvm, sp, invalid_list); + kvm_mmu_unlink_parents(kvm, sp); + + /* Zapping children means active_mmu_pages has become unstable. */ + list_unstable = *nr_zapped; + + if (!sp->role.invalid && sp_has_gptes(sp)) + unaccount_shadowed(kvm, sp); + + if (sp->unsync) + kvm_unlink_unsync_page(kvm, sp); + if (!sp->root_count) { + /* Count self */ + (*nr_zapped)++; + + /* + * Already invalid pages (previously active roots) are not on + * the active page list. See list_del() in the "else" case of + * !sp->root_count. + */ + if (sp->role.invalid) + list_add(&sp->link, invalid_list); + else + list_move(&sp->link, invalid_list); + kvm_unaccount_mmu_page(kvm, sp); + } else { + /* + * Remove the active root from the active page list, the root + * will be explicitly freed when the root_count hits zero. + */ + list_del(&sp->link); + + /* + * Obsolete pages cannot be used on any vCPUs, see the comment + * in kvm_mmu_zap_all_fast(). Note, is_obsolete_sp() also + * treats invalid shadow pages as being obsolete. + */ + zapped_root = !is_obsolete_sp(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; +} + +static bool kvm_mmu_prepare_zap_page(struct kvm *kvm, struct kvm_mmu_page *sp, + struct list_head *invalid_list) +{ + int nr_zapped; + + __kvm_mmu_prepare_zap_page(kvm, sp, invalid_list, &nr_zapped); + return nr_zapped; +} + +static void kvm_mmu_commit_zap_page(struct kvm *kvm, + struct list_head *invalid_list) +{ + struct kvm_mmu_page *sp, *nsp; + + if (list_empty(invalid_list)) + return; + + /* + * We need to make sure everyone sees our modifications to + * the page tables and see changes to vcpu->mode here. The barrier + * in the kvm_flush_remote_tlbs() achieves this. This pairs + * with vcpu_enter_guest and walk_shadow_page_lockless_begin/end. + * + * In addition, kvm_flush_remote_tlbs waits for all vcpus to exit + * guest mode and/or lockless shadow page table walks. + */ + kvm_flush_remote_tlbs(kvm); + + list_for_each_entry_safe(sp, nsp, invalid_list, link) { + WARN_ON_ONCE(!sp->role.invalid || sp->root_count); + kvm_mmu_free_shadow_page(sp); + } +} + +static unsigned long kvm_mmu_zap_oldest_mmu_pages(struct kvm *kvm, + unsigned long nr_to_zap) +{ + unsigned long total_zapped = 0; + struct kvm_mmu_page *sp, *tmp; + LIST_HEAD(invalid_list); + bool unstable; + int nr_zapped; + + if (list_empty(&kvm->arch.active_mmu_pages)) + return 0; + +restart: + list_for_each_entry_safe_reverse(sp, tmp, &kvm->arch.active_mmu_pages, link) { + /* + * Don't zap active root pages, the page itself can't be freed + * and zapping it will just force vCPUs to realloc and reload. + */ + if (sp->root_count) + continue; + + unstable = __kvm_mmu_prepare_zap_page(kvm, sp, &invalid_list, + &nr_zapped); + total_zapped += nr_zapped; + if (total_zapped >= nr_to_zap) + break; + + if (unstable) + goto restart; + } + + kvm_mmu_commit_zap_page(kvm, &invalid_list); + + kvm->stat.mmu_recycled += total_zapped; + return total_zapped; +} + +static inline unsigned long kvm_mmu_available_pages(struct kvm *kvm) +{ + if (kvm->arch.n_max_mmu_pages > kvm->arch.n_used_mmu_pages) + return kvm->arch.n_max_mmu_pages - + kvm->arch.n_used_mmu_pages; + + return 0; +} + +static int make_mmu_pages_available(struct kvm_vcpu *vcpu) +{ + unsigned long avail = kvm_mmu_available_pages(vcpu->kvm); + + if (likely(avail >= KVM_MIN_FREE_MMU_PAGES)) + return 0; + + kvm_mmu_zap_oldest_mmu_pages(vcpu->kvm, KVM_REFILL_PAGES - avail); + + /* + * Note, this check is intentionally soft, it only guarantees that one + * page is available, while the caller may end up allocating as many as + * four pages, e.g. for PAE roots or for 5-level paging. Temporarily + * exceeding the (arbitrary by default) limit will not harm the host, + * being too aggressive may unnecessarily kill the guest, and getting an + * exact count is far more trouble than it's worth, especially in the + * page fault paths. + */ + if (!kvm_mmu_available_pages(vcpu->kvm)) + return -ENOSPC; + return 0; +} + +/* + * Changing the number of mmu pages allocated to the vm + * Note: if goal_nr_mmu_pages is too small, you will get dead lock + */ +void kvm_mmu_change_mmu_pages(struct kvm *kvm, unsigned long goal_nr_mmu_pages) +{ + write_lock(&kvm->mmu_lock); + + if (kvm->arch.n_used_mmu_pages > goal_nr_mmu_pages) { + kvm_mmu_zap_oldest_mmu_pages(kvm, kvm->arch.n_used_mmu_pages - + goal_nr_mmu_pages); + + goal_nr_mmu_pages = kvm->arch.n_used_mmu_pages; + } + + kvm->arch.n_max_mmu_pages = goal_nr_mmu_pages; + + write_unlock(&kvm->mmu_lock); +} + +bool __kvm_mmu_unprotect_gfn_and_retry(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, + bool always_retry) +{ + struct kvm *kvm = vcpu->kvm; + LIST_HEAD(invalid_list); + 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; + } + + write_lock(&kvm->mmu_lock); + 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 void kvm_unsync_page(struct kvm *kvm, struct kvm_mmu_page *sp) +{ + trace_kvm_mmu_unsync_page(sp); + ++kvm->stat.mmu_unsync; + sp->unsync = 1; + + kvm_mmu_mark_parents_unsync(sp); +} + +/* + * Attempt to unsync any shadow pages that can be reached by the specified gfn, + * KVM is creating a writable mapping for said gfn. Returns 0 if all pages + * 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 *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_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. 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_valid_sp_with_gptes(kvm, sp, gfn) { + if (synchronizing) + return -EPERM; + + if (sp->unsync) + continue; + + 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 + * before the SPTE is updated to allow writes because + * kvm_mmu_sync_roots() checks the unsync flags without holding + * the MMU lock and so can race with this. If the SPTE was updated + * before the page had been marked as unsync-ed, something like the + * following could happen: + * + * CPU 1 CPU 2 + * --------------------------------------------------------------------- + * 1.2 Host updates SPTE + * to be writable + * 2.1 Guest writes a GPTE for GVA X. + * (GPTE being in the guest page table shadowed + * by the SP from CPU 1.) + * This reads SPTE during the page table walk. + * Since SPTE.W is read as 1, there is no + * fault. + * + * 2.2 Guest issues TLB flush. + * That causes a VM Exit. + * + * 2.3 Walking of unsync pages sees sp->unsync is + * false and skips the page. + * + * 2.4 Guest accesses GVA X. + * Since the mapping in the SP was not updated, + * so the old mapping for GVA X incorrectly + * gets used. + * 1.1 Host marks SP + * as 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. 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 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 ret = RET_PF_FIXED; + bool flush = false; + bool wrprot; + u64 spte; + + /* 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. + */ + if (level > PG_LEVEL_4K && !is_large_pte(*sptep)) { + struct kvm_mmu_page *child; + u64 pte = *sptep; + + child = spte_to_child_sp(pte); + drop_parent_pte(vcpu->kvm, child, sptep); + flush = true; + } else if (WARN_ON_ONCE(pfn != spte_to_pfn(*sptep))) { + drop_spte(vcpu->kvm, sptep); + flush = true; + } else + was_rmapped = 1; + } + + wrprot = make_spte(vcpu, sp, slot, pte_access, gfn, pfn, *sptep, prefetch, + false, host_writable, &spte); + + if (*sptep == spte) { + ret = RET_PF_SPURIOUS; + } else { + flush |= mmu_spte_update(sptep, spte); + trace_kvm_mmu_set_spte(level, gfn, sptep); + } + + if (wrprot && write_fault) + ret = RET_PF_WRITE_PROTECTED; + + 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 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; + int i; + + if (WARN_ON_ONCE(nr_pages > PTE_PREFETCH_NUM)) + return false; + + slot = gfn_to_memslot_dirty_bitmap(vcpu, gfn, access & ACC_WRITE_MASK); + if (!slot) + return false; + + 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); + + /* + * 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 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, + struct kvm_mmu_page *sp, u64 *sptep) +{ + u64 *spte, *start = NULL; + int i; + + WARN_ON_ONCE(!sp->role.direct); + + 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)) + 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) +{ + struct kvm_mmu_page *sp; + + sp = sptep_to_sp(sptep); + + /* + * Without accessed bits, there's no way to distinguish between + * actually accessed translations and prefetched, so disable pte + * prefetch if accessed bits aren't available. + */ + if (sp_ad_disabled(sp)) + return; + + if (sp->role.level > PG_LEVEL_4K) + return; + + /* + * If addresses are being invalidated, skip prefetching to avoid + * accidentally prefetching those addresses. + */ + if (unlikely(vcpu->kvm->mmu_invalidate_in_progress)) + return; + + __direct_pte_prefetch(vcpu, sp, sptep); +} + +/* + * 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; + 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() + * is not solely for performance, it's also necessary to avoid the + * "writable" check in __gfn_to_hva_many(), which will always fail on + * read-only memslots due to gfn_to_hva() assuming writes. Earlier + * page fault steps have already verified the guest isn't writing a + * read-only memslot. + */ + hva = __gfn_to_hva_memslot(slot, gfn); + + /* + * 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; +} + +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--) { + linfo = lpage_info_slot(gfn, slot, max_level); + if (!linfo->disallow_lpage) + break; + } + + if (max_level == PG_LEVEL_4K) + return PG_LEVEL_4K; + + 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); +} + +void kvm_mmu_hugepage_adjust(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault) +{ + struct kvm_memory_slot *slot = fault->slot; + kvm_pfn_t mask; + + fault->huge_page_disallowed = fault->exec && fault->nx_huge_page_workaround_enabled; + + if (unlikely(fault->max_level == PG_LEVEL_4K)) + return; + + if (is_error_noslot_pfn(fault->pfn)) + return; + + 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. + */ + 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_invalidate_retry() was successful and mmu_lock is held, so + * the pmd can't be split from under us. + */ + 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(struct kvm_page_fault *fault, u64 spte, int cur_level) +{ + if (cur_level > PG_LEVEL_4K && + cur_level == fault->goal_level && + is_shadow_present_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), + * 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(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, struct kvm_page_fault *fault) +{ + struct kvm_shadow_walk_iterator it; + struct kvm_mmu_page *sp; + int ret; + gfn_t base_gfn = fault->gfn; + + kvm_mmu_hugepage_adjust(vcpu, fault); + + 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 (fault->nx_huge_page_workaround_enabled) + disallowed_hugepage_adjust(fault, *it.sptep, it.level); + + base_gfn = gfn_round_for_level(fault->gfn, it.level); + if (it.level == fault->goal_level) + break; + + 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 (fault->huge_page_disallowed) + account_nx_huge_page(vcpu->kvm, sp, + fault->req_level >= it.level); + } + + 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); + return ret; +} + +static void kvm_send_hwpoison_signal(struct kvm_memory_slot *slot, gfn_t gfn) +{ + 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_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 (fault->pfn == KVM_PFN_ERR_RO_FAULT) + return RET_PF_EMULATE; + + if (fault->pfn == KVM_PFN_ERR_HWPOISON) { + kvm_send_hwpoison_signal(fault->slot, fault->gfn); + return RET_PF_RETRY; + } + + return -EFAULT; +} + +static int kvm_handle_noslot_fault(struct kvm_vcpu *vcpu, + struct kvm_page_fault *fault, + unsigned int access) +{ + gva_t gva = fault->is_tdp ? 0 : fault->addr; + + if (fault->is_private) { + kvm_mmu_prepare_memory_fault_exit(vcpu, fault); + return -EFAULT; + } + + 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(struct kvm *kvm, struct kvm_page_fault *fault) +{ + /* + * 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 (fault->rsvd) + return false; + + /* + * 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 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; + + /* + * 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_page_fault *fault, + u64 *sptep, u64 old_spte, u64 new_spte) +{ + /* + * Theoretically we could also set dirty bit (and flush TLB) here in + * order to eliminate unnecessary PML logging. See comments in + * set_spte. But fast_page_fault is very unlikely to happen with PML + * enabled, so we do not do this. This might result in the same GPA + * to be logged in PML buffer again when the write really happens, and + * eventually to be called by mark_page_dirty twice. But it's also no + * harm. This also avoids the TLB flush needed after setting dirty bit + * so non-PML cases won't be impacted. + * + * Compare with make_spte() where instead shadow_dirty_mask is set. + */ + if (!try_cmpxchg64(sptep, &old_spte, new_spte)) + return false; + + if (is_writable_pte(new_spte) && !is_writable_pte(old_spte)) + mark_page_dirty_in_slot(vcpu->kvm, fault->slot, fault->gfn); + + return true; +} + +/* + * 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) +{ + struct kvm_shadow_walk_iterator iterator; + u64 old_spte; + u64 *sptep = NULL; + + for_each_shadow_entry_lockless(vcpu, gpa, iterator, old_spte) { + sptep = iterator.sptep; + *spte = old_spte; + } + + return sptep; +} + +/* + * Returns one of RET_PF_INVALID, RET_PF_FIXED or RET_PF_SPURIOUS. + */ +static int fast_page_fault(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault) +{ + struct kvm_mmu_page *sp; + int ret = RET_PF_INVALID; + u64 spte; + u64 *sptep; + uint retry_count = 0; + + if (!page_fault_can_be_fast(vcpu->kvm, fault)) + return ret; + + walk_shadow_page_lockless_begin(vcpu); + + do { + u64 new_spte; + + 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(sptep); + if (!is_last_spte(spte, sp->role.level)) + break; + + /* + * Check whether the memory access that caused the fault would + * still cause it if it were to be performed right now. If not, + * then this is a spurious fault caused by TLB lazily flushed, + * or some other CPU has already fixed the PTE after the + * current CPU took the fault. + * + * Need not check the access of upper level table entries since + * they are always ACC_ALL. + */ + if (is_access_allowed(fault, spte)) { + ret = RET_PF_SPURIOUS; + break; + } + + new_spte = 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; + + /* + * 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 (fault->write && is_mmu_writable_spte(spte)) { + new_spte |= PT_WRITABLE_MASK; + + /* + * 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. + */ + 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(fault, new_spte)) + break; + + /* + * Currently, fast page fault only works for direct mapping + * 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, fault, sptep, spte, new_spte)) { + ret = RET_PF_FIXED; + break; + } + + if (++retry_count > 4) { + pr_warn_once("Fast #PF retrying more than 4 times.\n"); + break; + } + + } while (true); + + 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; +} + +static void mmu_free_root_page(struct kvm *kvm, hpa_t *root_hpa, + struct list_head *invalid_list) +{ + struct kvm_mmu_page *sp; + + if (!VALID_PAGE(*root_hpa)) + return; + + sp = root_to_sp(*root_hpa); + if (WARN_ON_ONCE(!sp)) + return; + + 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 *kvm, struct kvm_mmu *mmu, + ulong roots_to_free) +{ + bool is_tdp_mmu = tdp_mmu_enabled && mmu->root_role.direct; + int i; + LIST_HEAD(invalid_list); + 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. */ + 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)) + break; + + if (i == KVM_MMU_NUM_PREV_ROOTS) + return; + } + + 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)) + mmu_free_root_page(kvm, &mmu->prev_roots[i].hpa, + &invalid_list); + + if (free_active_root) { + 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])) + continue; + + mmu_free_root_page(kvm, &mmu->pae_root[i], + &invalid_list); + mmu->pae_root[i] = INVALID_PAE_ROOT; + } + } + mmu->root.hpa = INVALID_PAGE; + mmu->root.pgd = 0; + } + + 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_FOR_KVM_INTERNAL(kvm_mmu_free_roots); + +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; + + /* + * 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->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; + + sp = root_to_sp(root_hpa); + if (!sp || sp->role.guest_mode) + roots_to_free |= KVM_MMU_ROOT_PREVIOUS(i); + } + + kvm_mmu_free_roots(kvm, mmu, roots_to_free); +} +EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_mmu_free_guest_mode_roots); + +static hpa_t mmu_alloc_root(struct kvm_vcpu *vcpu, gfn_t gfn, int quadrant, + u8 level) +{ + union kvm_mmu_page_role role = vcpu->arch.mmu->root_role; + struct kvm_mmu_page *sp; + + role.level = level; + role.quadrant = quadrant; + + WARN_ON_ONCE(quadrant && !role.has_4_byte_gpte); + WARN_ON_ONCE(role.direct && role.has_4_byte_gpte); + + sp = kvm_mmu_get_shadow_page(vcpu, gfn, role); + ++sp->root_count; + + return __pa(sp->spt); +} + +static int mmu_alloc_direct_roots(struct kvm_vcpu *vcpu) +{ + struct kvm_mmu *mmu = vcpu->arch.mmu; + 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 (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; + goto out_unlock; + } + + 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), 0, + PT32_ROOT_LEVEL); + mmu->pae_root[i] = root | PT_PRESENT_MASK | + shadow_me_value; + } + 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; +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; + + root_pgd = kvm_mmu_get_guest_pgd(vcpu, mmu); + root_gfn = (root_pgd & __PT_BASE_ADDR_MASK) >> PAGE_SHIFT; + + 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->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 (!kvm_vcpu_is_visible_gfn(vcpu, pdptrs[i] >> PAGE_SHIFT)) + pdptrs[i] = 0; + } + } + + r = mmu_first_shadow_root_alloc(vcpu->kvm); + if (r) + return r; + + write_lock(&vcpu->kvm->mmu_lock); + r = make_mmu_pages_available(vcpu); + if (r < 0) + goto out_unlock; + + /* + * Do we shadow a long mode page table? If so we need to + * write-protect the guests page table root. + */ + if (mmu->cpu_role.base.level >= PT64_ROOT_4LEVEL) { + root = mmu_alloc_root(vcpu, root_gfn, 0, + mmu->root_role.level); + mmu->root.hpa = root; + goto set_root_pgd; + } + + if (WARN_ON_ONCE(!mmu->pae_root)) { + r = -EIO; + goto out_unlock; + } + + /* + * We shadow a 32 bit page table. This may be a legacy 2-level + * 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_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->cpu_role.base.level == PT32E_ROOT_LEVEL) { + if (!(pdptrs[i] & PT_PRESENT_MASK)) { + mmu->pae_root[i] = INVALID_PAE_ROOT; + continue; + } + root_gfn = pdptrs[i] >> PAGE_SHIFT; + } + + /* + * 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->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); + +set_root_pgd: + mmu->root.pgd = root_pgd; +out_unlock: + write_unlock(&vcpu->kvm->mmu_lock); + + return r; +} + +static int mmu_alloc_special_roots(struct kvm_vcpu *vcpu) +{ + struct kvm_mmu *mmu = vcpu->arch.mmu; + 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 + * tables are allocated and initialized at root creation as there is no + * 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->root_role.direct || + mmu->cpu_role.base.level >= PT64_ROOT_4LEVEL || + mmu->root_role.level < PT64_ROOT_4LEVEL) + return 0; + + /* + * 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 (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 || + (need_pml5 && mmu->pml5_root))) + return -EIO; + + /* + * Unlike 32-bit NPT, the PDP table doesn't need to be in low mem, and + * doesn't need to be decrypted. + */ + pae_root = (void *)get_zeroed_page(GFP_KERNEL_ACCOUNT); + if (!pae_root) + return -ENOMEM; + +#ifdef CONFIG_X86_64 + pml4_root = (void *)get_zeroed_page(GFP_KERNEL_ACCOUNT); + 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) +{ + int i; + struct kvm_mmu_page *sp; + + if (vcpu->arch.mmu->root_role.direct) + return; + + if (!VALID_PAGE(vcpu->arch.mmu->root.hpa)) + return; + + vcpu_clear_mmio_info(vcpu, MMIO_GVA_ANY); + + if (vcpu->arch.mmu->cpu_role.base.level >= PT64_ROOT_4LEVEL) { + hpa_t root = vcpu->arch.mmu->root.hpa; + + if (!is_unsync_root(root)) + return; + + sp = root_to_sp(root); + + 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); + + for (i = 0; i < 4; ++i) { + hpa_t root = vcpu->arch.mmu->pae_root[i]; + + if (IS_VALID_PAE_ROOT(root)) { + sp = spte_to_child_sp(root); + mmu_sync_children(vcpu, sp, true); + } + } + + write_unlock(&vcpu->kvm->mmu_lock); +} + +void kvm_mmu_sync_prev_roots(struct kvm_vcpu *vcpu) +{ + 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(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu, + gpa_t vaddr, u64 access, + struct x86_exception *exception) +{ + if (exception) + exception->error_code = 0; + return kvm_translate_gpa(vcpu, mmu, vaddr, access, exception); +} + +static bool mmio_info_in_cache(struct kvm_vcpu *vcpu, u64 addr, bool direct) +{ + /* + * A nested guest cannot use the MMIO cache if it is using nested + * page tables, because cr2 is a nGPA while the cache stores GPAs. + */ + if (mmu_is_nested(vcpu)) + return false; + + if (direct) + return vcpu_match_mmio_gpa(vcpu, addr); + + return vcpu_match_mmio_gva(vcpu, addr); +} + +/* + * 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) +{ + struct kvm_shadow_walk_iterator iterator; + int leaf = -1; + u64 spte; + + for (shadow_walk_init(&iterator, vcpu, addr), + *root_level = iterator.level; + shadow_walk_okay(&iterator); + __shadow_walk_next(&iterator, spte)) { + leaf = iterator.level; + spte = mmu_spte_get_lockless(iterator.sptep); + + sptes[leaf] = spte; + } + + 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; +} + +/* return true if reserved bit(s) are detected on a valid, non-MMIO SPTE. */ +static bool get_mmio_spte(struct kvm_vcpu *vcpu, u64 addr, u64 *sptep) +{ + u64 sptes[PT64_ROOT_MAX_LEVEL + 1]; + struct rsvd_bits_validate *rsvd_check; + int root, leaf, level; + bool reserved = false; + + leaf = get_sptes_lockless(vcpu, addr, sptes, &root); + if (unlikely(leaf < 0)) { + *sptep = 0ull; + return reserved; + } + + *sptep = sptes[leaf]; + + /* + * Skip reserved bits checks on the terminal leaf if it's not a valid + * SPTE. Note, this also (intentionally) skips MMIO SPTEs, which, by + * design, always have reserved bits set. The purpose of the checks is + * to detect reserved bits on non-MMIO SPTEs. i.e. buggy SPTEs. + */ + if (!is_shadow_present_pte(sptes[leaf])) + leaf++; + + rsvd_check = &vcpu->arch.mmu->shadow_zero_check; + + for (level = root; level >= leaf; level--) + reserved |= is_rsvd_spte(rsvd_check, sptes[level], level); + + if (reserved) { + pr_err("%s: reserved bits set on MMU-present spte, addr 0x%llx, hierarchy:\n", + __func__, addr); + for (level = root; level >= leaf; level--) + pr_err("------ spte = 0x%llx level = %d, rsvd bits = 0x%llx", + sptes[level], level, + get_rsvd_bits(rsvd_check, sptes[level], level)); + } + + return reserved; +} + +static int handle_mmio_page_fault(struct kvm_vcpu *vcpu, u64 addr, bool direct) +{ + u64 spte; + bool reserved; + + if (mmio_info_in_cache(vcpu, addr, direct)) + return RET_PF_EMULATE; + + reserved = get_mmio_spte(vcpu, addr, &spte); + if (WARN_ON_ONCE(reserved)) + return -EINVAL; + + if (is_mmio_spte(vcpu->kvm, spte)) { + gfn_t gfn = get_mmio_spte_gfn(spte); + unsigned int access = get_mmio_spte_access(spte); + + if (!check_mmio_spte(vcpu, spte)) + return RET_PF_INVALID; + + if (direct) + addr = 0; + + trace_handle_mmio_page_fault(addr, gfn, access); + vcpu_cache_mmio_info(vcpu, addr, gfn, access); + return RET_PF_EMULATE; + } + + /* + * If the page table is zapped by other cpus, let CPU fault again on + * the address. + */ + return RET_PF_RETRY; +} + +static bool page_fault_handle_page_track(struct kvm_vcpu *vcpu, + struct kvm_page_fault *fault) +{ + if (unlikely(fault->rsvd)) + return false; + + 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_gfn_is_write_tracked(vcpu->kvm, fault->slot, fault->gfn)) + return true; + + return false; +} + +static void shadow_page_table_clear_flood(struct kvm_vcpu *vcpu, gva_t addr) +{ + struct kvm_shadow_walk_iterator iterator; + u64 spte; + + walk_shadow_page_lockless_begin(vcpu); + for_each_shadow_entry_lockless(vcpu, addr, iterator, spte) + clear_sp_write_flooding_count(iterator.sptep); + walk_shadow_page_lockless_end(vcpu); +} + +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 = 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; + } + + 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 int __kvm_mmu_faultin_pfn(struct kvm_vcpu *vcpu, + struct kvm_page_fault *fault) +{ + 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. 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->flags & KVM_MEMSLOT_INVALID) { + if (fault->prefetch) + return -EAGAIN; + + return RET_PF_RETRY; + } + + 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 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; + } + + /* + * 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; +} + +/* + * 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) +{ + struct kvm_mmu_page *sp = root_to_sp(vcpu->arch.mmu->root.hpa); + + /* 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; + + /* 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 (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; + + 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_page_fault_stale(vcpu, fault)) + goto out_unlock; + + r = make_mmu_pages_available(vcpu); + if (r) + goto out_unlock; + + r = direct_map(vcpu, fault); + +out_unlock: + 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, + struct kvm_page_fault *fault) +{ + /* This path builds a PAE pagetable, we can map 2mb pages at maximum. */ + fault->max_level = PG_LEVEL_2M; + return direct_page_fault(vcpu, fault); +} + +int kvm_handle_page_fault(struct kvm_vcpu *vcpu, u64 error_code, + u64 fault_address, char *insn, int insn_len) +{ + int r = 1; + u32 flags = vcpu->arch.apf.host_apf_flags; + +#ifndef CONFIG_X86_64 + /* A 64-bit CR2 should be impossible on 32-bit KVM. */ + 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)); + + kvm_request_l1tf_flush_l1d(); + if (!flags) { + trace_kvm_page_fault(vcpu, fault_address, error_code); + + r = kvm_mmu_page_fault(vcpu, fault_address, error_code, insn, + insn_len); + } else if (flags & KVM_PV_REASON_PAGE_NOT_PRESENT) { + vcpu->arch.apf.host_apf_flags = 0; + local_irq_disable(); + kvm_async_pf_task_wait_schedule(fault_address); + local_irq_enable(); + } else { + WARN_ONCE(1, "Unexpected host async PF flags: %x\n", flags); + } + + return r; +} +EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_handle_page_fault); + +#ifdef CONFIG_X86_64 +static int kvm_tdp_mmu_page_fault(struct kvm_vcpu *vcpu, + struct kvm_page_fault *fault) +{ + int 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; + + 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; + + 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_spte = NULL; +} + +static inline bool is_root_usable(struct kvm_mmu_root_info *root, gpa_t pgd, + union kvm_mmu_page_role role) +{ + 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, + * 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_find_and_keep_current(struct kvm *kvm, struct kvm_mmu *mmu, + gpa_t new_pgd, + union kvm_mmu_page_role new_role) +{ + uint i; + + if (is_root_usable(&mmu->root, new_pgd, new_role)) + return true; + + for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++) { + /* + * 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; + } + + kvm_mmu_free_roots(kvm, mmu, KVM_MMU_ROOT_CURRENT); + return false; +} + +/* + * 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) +{ + 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) +{ + /* + * Limit reuse to 64-bit hosts+VMs without "special" roots in order to + * avoid having to deal with PDPTEs and other complexities. + */ + if (VALID_PAGE(mmu->root.hpa) && !root_to_sp(mmu->root.hpa)) + kvm_mmu_free_roots(kvm, mmu, KVM_MMU_ROOT_CURRENT); + + 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); +} + +void kvm_mmu_new_pgd(struct kvm_vcpu *vcpu, gpa_t new_pgd) +{ + 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_FREE_OBSOLETE_ROOTS, + * which will free the root set here and allocate a new one. + */ + kvm_make_request(KVM_REQ_LOAD_MMU_PGD, vcpu); + + if (force_flush_and_sync_on_reuse) { + kvm_make_request(KVM_REQ_MMU_SYNC, vcpu); + kvm_make_request(KVM_REQ_TLB_FLUSH_CURRENT, vcpu); + } + + /* + * The last MMIO access's GVA and GPA are cached in the VCPU. When + * switching to a new CR3, that GVA->GPA mapping may no longer be + * valid. So clear any cached MMIO info even when we don't need to sync + * the shadow page tables. + */ + vcpu_clear_mmio_info(vcpu, MMIO_GVA_ANY); + + /* + * 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) { + struct kvm_mmu_page *sp = root_to_sp(vcpu->arch.mmu->root.hpa); + + 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) +{ + if (unlikely(is_mmio_spte(vcpu->kvm, *sptep))) { + if (gfn != get_mmio_spte_gfn(*sptep)) { + mmu_spte_clear_no_track(sptep); + return true; + } + + mark_mmio_spte(vcpu, sptep, gfn, access); + return true; + } + + return false; +} + +#define PTTYPE_EPT 18 /* arbitrary */ +#define PTTYPE PTTYPE_EPT +#include "paging_tmpl.h" +#undef PTTYPE + +#define PTTYPE 64 +#include "paging_tmpl.h" +#undef PTTYPE + +#define PTTYPE 32 +#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) +{ + u64 gbpages_bit_rsvd = 0; + u64 nonleaf_bit8_rsvd = 0; + u64 high_bits_rsvd; + + rsvd_check->bad_mt_xwr = 0; + + if (!gbpages) + gbpages_bit_rsvd = rsvd_bits(7, 7); + + if (level == PT32E_ROOT_LEVEL) + high_bits_rsvd = pa_bits_rsvd & rsvd_bits(0, 62); + else + high_bits_rsvd = pa_bits_rsvd & rsvd_bits(0, 51); + + /* Note, NX doesn't exist in PDPTEs, this is handled below. */ + if (!nx) + high_bits_rsvd |= rsvd_bits(63, 63); + + /* + * Non-leaf PML4Es and PDPEs reserve bit 8 (which would be the G bit for + * leaf entries) on AMD CPUs only. + */ + if (amd) + nonleaf_bit8_rsvd = rsvd_bits(8, 8); + + switch (level) { + case PT32_ROOT_LEVEL: + /* no rsvd bits for 2 level 4K page table entries */ + rsvd_check->rsvd_bits_mask[0][1] = 0; + rsvd_check->rsvd_bits_mask[0][0] = 0; + rsvd_check->rsvd_bits_mask[1][0] = + rsvd_check->rsvd_bits_mask[0][0]; + + if (!pse) { + rsvd_check->rsvd_bits_mask[1][1] = 0; + break; + } + + if (is_cpuid_PSE36()) + /* 36bits PSE 4MB page */ + rsvd_check->rsvd_bits_mask[1][1] = rsvd_bits(17, 21); + else + /* 32 bits PSE 4MB page */ + rsvd_check->rsvd_bits_mask[1][1] = rsvd_bits(13, 21); + break; + case PT32E_ROOT_LEVEL: + rsvd_check->rsvd_bits_mask[0][2] = rsvd_bits(63, 63) | + high_bits_rsvd | + rsvd_bits(5, 8) | + rsvd_bits(1, 2); /* PDPTE */ + rsvd_check->rsvd_bits_mask[0][1] = high_bits_rsvd; /* PDE */ + rsvd_check->rsvd_bits_mask[0][0] = high_bits_rsvd; /* PTE */ + rsvd_check->rsvd_bits_mask[1][1] = high_bits_rsvd | + rsvd_bits(13, 20); /* large page */ + rsvd_check->rsvd_bits_mask[1][0] = + rsvd_check->rsvd_bits_mask[0][0]; + break; + case PT64_ROOT_5LEVEL: + rsvd_check->rsvd_bits_mask[0][4] = high_bits_rsvd | + nonleaf_bit8_rsvd | + rsvd_bits(7, 7); + rsvd_check->rsvd_bits_mask[1][4] = + rsvd_check->rsvd_bits_mask[0][4]; + fallthrough; + case PT64_ROOT_4LEVEL: + rsvd_check->rsvd_bits_mask[0][3] = high_bits_rsvd | + nonleaf_bit8_rsvd | + rsvd_bits(7, 7); + rsvd_check->rsvd_bits_mask[0][2] = high_bits_rsvd | + gbpages_bit_rsvd; + rsvd_check->rsvd_bits_mask[0][1] = high_bits_rsvd; + rsvd_check->rsvd_bits_mask[0][0] = high_bits_rsvd; + rsvd_check->rsvd_bits_mask[1][3] = + rsvd_check->rsvd_bits_mask[0][3]; + rsvd_check->rsvd_bits_mask[1][2] = high_bits_rsvd | + gbpages_bit_rsvd | + rsvd_bits(13, 29); + rsvd_check->rsvd_bits_mask[1][1] = high_bits_rsvd | + rsvd_bits(13, 20); /* large page */ + rsvd_check->rsvd_bits_mask[1][0] = + rsvd_check->rsvd_bits_mask[0][0]; + break; + } +} + +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->cpu_role.base.level, is_efer_nx(context), + guest_cpu_cap_has(vcpu, X86_FEATURE_GBPAGES), + is_cr4_pse(context), + 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, + 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) | 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) | 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 */ + bad_mt_xwr |= 0xFFull << (3 * 8); /* bits 3..5 must not be 3 */ + bad_mt_xwr |= 0xFFull << (7 * 8); /* bits 3..5 must not be 7 */ + bad_mt_xwr |= REPEAT_BYTE(1ull << 2); /* bits 0..2 must not be 010 */ + bad_mt_xwr |= REPEAT_BYTE(1ull << 6); /* bits 0..2 must not be 110 */ + if (!execonly) { + /* bits 0..2 must not be 100 unless VMX capabilities allow it */ + bad_mt_xwr |= REPEAT_BYTE(1ull << 4); + } + rsvd_check->bad_mt_xwr = bad_mt_xwr; +} + +static void reset_rsvds_bits_mask_ept(struct kvm_vcpu *vcpu, + 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, + huge_page_level); +} + +static inline u64 reserved_hpa_bits(void) +{ + return rsvd_bits(kvm_host.maxphyaddr, 63); +} + +/* + * the page table on host is the shadow page table for the page + * table in guest or amd nested guest, its mmu features completely + * follow the features in guest. + */ +static void reset_shadow_zero_bits_mask(struct kvm_vcpu *vcpu, + struct kvm_mmu *context) +{ + /* @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. */ + bool is_pse = false; + struct rsvd_bits_validate *shadow_zero_check; + int i; + + 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->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->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; + } + +} + +static inline bool boot_cpu_is_amd(void) +{ + WARN_ON_ONCE(!tdp_enabled); + return shadow_x_mask == 0; +} + +/* + * 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_mmu *context) +{ + struct rsvd_bits_validate *shadow_zero_check; + int i; + + shadow_zero_check = &context->shadow_zero_check; + + if (boot_cpu_is_amd()) + __reset_rsvds_bits_mask(shadow_zero_check, reserved_hpa_bits(), + 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, + max_huge_page_level); + + if (!shadow_me_mask) + return; + + 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; + } +} + +/* + * as the comments in reset_shadow_zero_bits_mask() except it + * is the shadow page table for intel nested guest. + */ +static void +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, + max_huge_page_level); +} + +#define BYTE_MASK(access) \ + ((1 & (access) ? 2 : 0) | \ + (2 & (access) ? 4 : 0) | \ + (3 & (access) ? 8 : 0) | \ + (4 & (access) ? 16 : 0) | \ + (5 & (access) ? 32 : 0) | \ + (6 & (access) ? 64 : 0) | \ + (7 & (access) ? 128 : 0)) + + +static void update_permission_bitmask(struct kvm_mmu *mmu, bool ept) +{ + unsigned byte; + + const u8 x = BYTE_MASK(ACC_EXEC_MASK); + const u8 w = BYTE_MASK(ACC_WRITE_MASK); + const u8 u = BYTE_MASK(ACC_USER_MASK); + + bool cr4_smep = is_cr4_smep(mmu); + bool cr4_smap = is_cr4_smap(mmu); + bool cr0_wp = is_cr0_wp(mmu); + bool efer_nx = is_efer_nx(mmu); + + for (byte = 0; byte < ARRAY_SIZE(mmu->permissions); ++byte) { + unsigned pfec = byte << 1; + + /* + * Each "*f" variable has a 1 bit for each UWX value + * that causes a fault with the given PFEC. + */ + + /* Faults from writes to non-writable pages */ + u8 wf = (pfec & PFERR_WRITE_MASK) ? (u8)~w : 0; + /* Faults from user mode accesses to supervisor pages */ + u8 uf = (pfec & PFERR_USER_MASK) ? (u8)~u : 0; + /* Faults from fetches of non-executable pages*/ + u8 ff = (pfec & PFERR_FETCH_MASK) ? (u8)~x : 0; + /* Faults from kernel mode fetches of user pages */ + u8 smepf = 0; + /* Faults from kernel mode accesses of user pages */ + u8 smapf = 0; + + if (!ept) { + /* Faults from kernel mode accesses to user pages */ + u8 kf = (pfec & PFERR_USER_MASK) ? 0 : u; + + /* Not really needed: !nx will cause pte.nx to fault */ + if (!efer_nx) + ff = 0; + + /* Allow supervisor writes if !cr0.wp */ + if (!cr0_wp) + wf = (pfec & PFERR_USER_MASK) ? wf : 0; + + /* Disallow supervisor fetches of user code if cr4.smep */ + if (cr4_smep) + smepf = (pfec & PFERR_FETCH_MASK) ? kf : 0; + + /* + * SMAP:kernel-mode data accesses from user-mode + * mappings should fault. A fault is considered + * as a SMAP violation if all of the following + * conditions are true: + * - X86_CR4_SMAP is set in CR4 + * - A user page is accessed + * - The access is not a fetch + * - The access is supervisor mode + * - If implicit supervisor access or X86_EFLAGS_AC is clear + * + * 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. + */ + if (cr4_smap) + smapf = (pfec & (PFERR_RSVD_MASK|PFERR_FETCH_MASK)) ? 0 : kf; + } + + mmu->permissions[byte] = ff | uf | wf | smepf | smapf; + } +} + +/* +* PKU is an additional mechanism by which the paging controls access to +* user-mode addresses based on the value in the PKRU register. Protection +* key violations are reported through a bit in the page fault error code. +* Unlike other bits of the error code, the PK bit is not known at the +* call site of e.g. gva_to_gpa; it must be computed directly in +* permission_fault based on two bits of PKRU, on some machine state (CR4, +* CR0, EFER, CPL), and on other bits of the error code and the page tables. +* +* In particular the following conditions come from the error code, the +* page tables and the machine state: +* - PK is always zero unless CR4.PKE=1 and EFER.LMA=1 +* - PK is always zero if RSVD=1 (reserved bit set) or F=1 (instruction fetch) +* - PK is always zero if U=0 in the page tables +* - PKRU.WD is ignored if CR0.WP=0 and the access is a supervisor access. +* +* The PKRU bitmask caches the result of these four conditions. The error +* code (minus the P bit) and the page table's U bit form an index into the +* PKRU bitmask. Two bits of the PKRU bitmask are then extracted and ANDed +* with the two bits of the PKRU register corresponding to the protection key. +* For the first three conditions above the bits will be 00, thus masking +* away both AD and WD. For all reads or if the last condition holds, WD +* only will be masked away. +*/ +static void update_pkru_bitmask(struct kvm_mmu *mmu) +{ + unsigned bit; + bool wp; + + mmu->pkru_mask = 0; + + if (!is_cr4_pke(mmu)) + return; + + wp = is_cr0_wp(mmu); + + for (bit = 0; bit < ARRAY_SIZE(mmu->permissions); ++bit) { + unsigned pfec, pkey_bits; + bool check_pkey, check_write, ff, uf, wf, pte_user; + + pfec = bit << 1; + ff = pfec & PFERR_FETCH_MASK; + uf = pfec & PFERR_USER_MASK; + wf = pfec & PFERR_WRITE_MASK; + + /* PFEC.RSVD is replaced by ACC_USER_MASK. */ + pte_user = pfec & PFERR_RSVD_MASK; + + /* + * Only need to check the access which is not an + * instruction fetch and is to a user page. + */ + check_pkey = (!ff && pte_user); + /* + * write access is controlled by PKRU if it is a + * user access or CR0.WP = 1. + */ + check_write = check_pkey && wf && (uf || wp); + + /* PKRU.AD stops both read and write access. */ + pkey_bits = !!check_pkey; + /* PKRU.WD stops write access. */ + pkey_bits |= (!!check_write) << 1; + + mmu->pkru_mask |= (pkey_bits & 3) << pfec; + } +} + +static void reset_guest_paging_metadata(struct kvm_vcpu *vcpu, + struct kvm_mmu *mmu) +{ + if (!is_cr0_pg(mmu)) + return; + + reset_guest_rsvds_bits_mask(vcpu, mmu); + update_permission_bitmask(mmu, false); + update_pkru_bitmask(mmu); +} + +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_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_spte = paging32_sync_spte; +} + +static union kvm_cpu_role kvm_calc_cpu_role(struct kvm_vcpu *vcpu, + const struct kvm_mmu_role_regs *regs) +{ + union kvm_cpu_role role = {0}; + + role.base.access = ACC_ALL; + role.base.smm = is_smm(vcpu); + role.base.guest_mode = is_guest_mode(vcpu); + role.ext.valid = 1; + + if (!____is_cr0_pg(regs)) { + role.base.direct = 1; + return role; + } + + 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); + + /* 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; +} + +void __kvm_mmu_refresh_passthrough_bits(struct kvm_vcpu *vcpu, + struct kvm_mmu *mmu) +{ + const bool cr0_wp = kvm_is_cr0_bit_set(vcpu, X86_CR0_WP); + + 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)); + + if (is_cr0_wp(mmu) == cr0_wp) + return; + + 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 && maxpa <= 48) + return 4; + + return max_tdp_level; +} + +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, + union kvm_cpu_role cpu_role) +{ + union kvm_mmu_page_role role = {0}; + + 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, + union kvm_cpu_role cpu_role) +{ + struct kvm_mmu *context = &vcpu->arch.root_mmu; + union kvm_mmu_page_role root_role = kvm_calc_tdp_mmu_root_page_role(vcpu, cpu_role); + + if (cpu_role.as_u64 == context->cpu_role.as_u64 && + root_role.word == context->root_role.word) + return; + + 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_spte = NULL; + context->get_guest_pgd = get_guest_cr3; + context->get_pdptr = kvm_pdptr_read; + context->inject_page_fault = kvm_inject_page_fault; + + if (!is_cr0_pg(context)) + context->gva_to_gpa = nonpaging_gva_to_gpa; + else if (is_cr4_pae(context)) + context->gva_to_gpa = paging64_gva_to_gpa; + else + context->gva_to_gpa = paging32_gva_to_gpa; + + reset_guest_paging_metadata(vcpu, context); + reset_tdp_shadow_zero_bits_mask(context); +} + +static void shadow_mmu_init_context(struct kvm_vcpu *vcpu, struct kvm_mmu *context, + union kvm_cpu_role cpu_role, + union kvm_mmu_page_role root_role) +{ + if (cpu_role.as_u64 == context->cpu_role.as_u64 && + root_role.word == context->root_role.word) + return; + + 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); + else if (is_cr4_pae(context)) + paging64_init_context(context); + else + paging32_init_context(context); + + reset_guest_paging_metadata(vcpu, context); + reset_shadow_zero_bits_mask(vcpu, context); +} + +static void kvm_init_shadow_mmu(struct kvm_vcpu *vcpu, + union kvm_cpu_role cpu_role) +{ + struct kvm_mmu *context = &vcpu->arch.root_mmu; + union kvm_mmu_page_role root_role; + + root_role = cpu_role.base; + + /* 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); + + /* + * 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; + + shadow_mmu_init_context(vcpu, context, cpu_role, root_role); +} + +void kvm_init_shadow_npt_mmu(struct kvm_vcpu *vcpu, unsigned long cr0, + unsigned long cr4, u64 efer, gpa_t nested_cr3) +{ + struct kvm_mmu *context = &vcpu->arch.guest_mmu; + struct kvm_mmu_role_regs regs = { + .cr0 = cr0, + .cr4 = cr4 & ~X86_CR4_PKE, + .efer = efer, + }; + union kvm_cpu_role cpu_role = kvm_calc_cpu_role(vcpu, ®s); + union kvm_mmu_page_role root_role; + + /* NPT requires CR0.PG=1. */ + WARN_ON_ONCE(cpu_role.base.direct || !cpu_role.base.guest_mode); + + 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, cpu_role, root_role); + kvm_mmu_new_pgd(vcpu, nested_cr3); +} +EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_init_shadow_npt_mmu); + +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_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.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; + + role.ext.word = 0; + role.ext.execonly = execonly; + role.ext.valid = 1; + + return role; +} + +void kvm_init_shadow_ept_mmu(struct kvm_vcpu *vcpu, bool execonly, + 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_cpu_role new_mode = + kvm_calc_shadow_ept_root_page_role(vcpu, accessed_dirty, + execonly, level); + + 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->page_fault = ept_page_fault; + context->gva_to_gpa = ept_gva_to_gpa; + context->sync_spte = ept_sync_spte; + + 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); + } + + kvm_mmu_new_pgd(vcpu, new_eptp); +} +EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_init_shadow_ept_mmu); + +static void init_kvm_softmmu(struct kvm_vcpu *vcpu, + union kvm_cpu_role cpu_role) +{ + struct kvm_mmu *context = &vcpu->arch.root_mmu; + + kvm_init_shadow_mmu(vcpu, cpu_role); + + context->get_guest_pgd = get_guest_cr3; + context->get_pdptr = kvm_pdptr_read; + context->inject_page_fault = kvm_inject_page_fault; +} + +static void init_kvm_nested_mmu(struct kvm_vcpu *vcpu, + union kvm_cpu_role new_mode) +{ + struct kvm_mmu *g_context = &vcpu->arch.nested_mmu; + + if (new_mode.as_u64 == g_context->cpu_role.as_u64) + return; + + 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; + + /* + * L2 page tables are never shadowed, so there is no need to sync + * SPTEs. + */ + g_context->sync_spte = NULL; + + /* + * Note that arch.mmu->gva_to_gpa translates l2_gpa to l1_gpa using + * L1's nested page tables (e.g. EPT12). The nested translation + * of l2_gva to l1_gpa is done by arch.nested_mmu.gva_to_gpa using + * L2's page tables as the first level of translation and L1's + * nested page tables as the second level of translation. Basically + * 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; + else if (is_long_mode(vcpu)) + g_context->gva_to_gpa = paging64_gva_to_gpa; + else if (is_pae(vcpu)) + g_context->gva_to_gpa = paging64_gva_to_gpa; + else + g_context->gva_to_gpa = paging32_gva_to_gpa; + + reset_guest_paging_metadata(vcpu, g_context); +} + +void kvm_init_mmu(struct kvm_vcpu *vcpu) +{ + struct kvm_mmu_role_regs regs = vcpu_to_role_regs(vcpu); + union kvm_cpu_role cpu_role = kvm_calc_cpu_role(vcpu, ®s); + + if (mmu_is_nested(vcpu)) + init_kvm_nested_mmu(vcpu, cpu_role); + else if (tdp_enabled) + init_kvm_tdp_mmu(vcpu, cpu_role); + else + 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.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); + + /* + * Changing guest CPUID after KVM_RUN is forbidden, see the comment in + * kvm_arch_vcpu_ioctl(). + */ + KVM_BUG_ON(kvm_vcpu_has_run(vcpu), vcpu->kvm); +} + +void kvm_mmu_reset_context(struct kvm_vcpu *vcpu) +{ + kvm_mmu_unload(vcpu); + kvm_init_mmu(vcpu); +} +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->root_role.direct); + if (r) + goto out; + r = mmu_alloc_special_roots(vcpu); + if (r) + goto out; + if (vcpu->arch.mmu->root_role.direct) + r = mmu_alloc_direct_roots(vcpu); + else + r = mmu_alloc_shadow_roots(vcpu); + if (r) + goto out; + + kvm_mmu_sync_roots(vcpu); + + kvm_mmu_load_pgd(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) +{ + 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 is_obsolete_root(struct kvm *kvm, hpa_t root_hpa) +{ + struct kvm_mmu_page *sp; + + if (!VALID_PAGE(root_hpa)) + return false; + + /* + * 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) +{ + u64 gentry = 0; + int r; + + /* + * Assume that the pte write on a page table of the same type + * as the current vcpu paging mode since we update the sptes only + * when they have the same mode. + */ + if (is_pae(vcpu) && *bytes == 4) { + /* Handle a 32-bit guest writing two halves of a 64-bit gpte */ + *gpa &= ~(gpa_t)7; + *bytes = 8; + } + + if (*bytes == 4 || *bytes == 8) { + r = kvm_vcpu_read_guest_atomic(vcpu, *gpa, &gentry, *bytes); + if (r) + gentry = 0; + } + + return gentry; +} + +/* + * If we're seeing too many writes to a page, it may no longer be a page table, + * or we may be forking, in which case it is better to unmap the page. + */ +static bool detect_write_flooding(struct kvm_mmu_page *sp) +{ + /* + * Skip write-flooding detected for the sp whose level is 1, because + * it can become unsync, then the guest page is not write-protected. + */ + if (sp->role.level == PG_LEVEL_4K) + return false; + + atomic_inc(&sp->write_flooding_count); + return atomic_read(&sp->write_flooding_count) >= 3; +} + +/* + * Misaligned accesses are too much trouble to fix up; also, they usually + * indicate a page is not used as a page table. + */ +static bool detect_write_misaligned(struct kvm_mmu_page *sp, gpa_t gpa, + int bytes) +{ + unsigned offset, pte_size, misaligned; + + offset = offset_in_page(gpa); + pte_size = sp->role.has_4_byte_gpte ? 4 : 8; + + /* + * Sometimes, the OS only writes the last one bytes to update status + * bits, for example, in linux, andb instruction is used in clear_bit(). + */ + if (!(offset & (pte_size - 1)) && bytes == 1) + return false; + + misaligned = (offset ^ (offset + bytes - 1)) & ~(pte_size - 1); + misaligned |= bytes < 4; + + return misaligned; +} + +static u64 *get_written_sptes(struct kvm_mmu_page *sp, gpa_t gpa, int *nspte) +{ + unsigned page_offset, quadrant; + u64 *spte; + int level; + + page_offset = offset_in_page(gpa); + level = sp->role.level; + *nspte = 1; + if (sp->role.has_4_byte_gpte) { + page_offset <<= 1; /* 32->64 */ + /* + * A 32-bit pde maps 4MB while the shadow pdes map + * only 2MB. So we need to double the offset again + * and zap two pdes instead of one. + */ + if (level == PT32_ROOT_LEVEL) { + page_offset &= ~7; /* kill rounding error */ + page_offset <<= 1; + *nspte = 2; + } + quadrant = page_offset >> PAGE_SHIFT; + page_offset &= ~PAGE_MASK; + if (quadrant != sp->role.quadrant) + return NULL; + } + + spte = &sp->spt[page_offset / sizeof(*spte)]; + return spte; +} + +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 flush = false; + + /* + * 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(). + */ + smp_mb(); + if (!vcpu->kvm->arch.indirect_shadow_pages) + return; + + write_lock(&vcpu->kvm->mmu_lock); + + gentry = mmu_pte_write_fetch_gpte(vcpu, &gpa, &bytes); + + ++vcpu->kvm->stat.mmu_pte_write; + + 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); + ++vcpu->kvm->stat.mmu_flooded; + continue; + } + + spte = get_written_sptes(sp, gpa, &npte); + if (!spte) + continue; + + 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 (is_shadow_present_pte(entry)) + flush = true; + ++spte; + } + } + kvm_mmu_remote_flush_or_zap(vcpu->kvm, &invalid_list, flush); + write_unlock(&vcpu->kvm->mmu_lock); +} + +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->root_role.direct; + + 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) { + 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_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++; + + /* + * 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. + */ + WARN_ON_ONCE(r == RET_PF_CONTINUE); + if (r != RET_PF_EMULATE) + return r; + +emulate: + return x86_emulate_instruction(vcpu, cr2_or_gpa, emulation_type, insn, + insn_len); +} +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_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_invlpg_address(addr, vcpu)) + return; + + kvm_x86_call(flush_tlb_gva)(vcpu, addr); + } + + if (!mmu->sync_spte) + return; + + if (roots & KVM_MMU_ROOT_CURRENT) + __kvm_mmu_invalidate_addr(vcpu, mmu, addr, mmu->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) +{ + /* + * 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_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; + unsigned long roots = 0; + uint i; + + 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)) + roots |= KVM_MMU_ROOT_PREVIOUS(i); + } + + if (roots) + kvm_mmu_invalidate_addr(vcpu, mmu, gva, roots); + ++vcpu->stat.invlpg; + + /* + * 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. + */ +} + +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 + * the kernel is not. But, KVM never creates a page size greater than + * what is used by the kernel for any given HVA, i.e. the kernel's + * capabilities are ultimately consulted by kvm_mmu_hugepage_adjust(). + */ + if (tdp_enabled) + max_huge_page_level = tdp_huge_page_level; + else if (boot_cpu_has(X86_FEATURE_GBPAGES)) + max_huge_page_level = PG_LEVEL_1G; + else + max_huge_page_level = PG_LEVEL_2M; +} +EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_configure_mmu); + +static void free_mmu_pages(struct kvm_mmu *mmu) +{ + if (!tdp_enabled && mmu->pae_root) + 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) +{ + struct page *page; + int i; + + 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 + * creation. When emulating 32-bit mode, cr3 is only 32 bits even on + * x86_64. Therefore we need to allocate the PDP table in the first + * 4GB of memory, which happens to fit the DMA32 zone. TDP paging + * 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_special_roots(). + */ + if (tdp_enabled && kvm_mmu_get_tdp_level(vcpu) > PT32E_ROOT_LEVEL) + return 0; + + page = alloc_page(GFP_KERNEL_ACCOUNT | __GFP_DMA32); + if (!page) + return -ENOMEM; + + mmu->pae_root = page_address(page); + + /* + * CR3 is only 32 bits when PAE paging is used, thus it's impossible to + * get the CPU to treat the PDPTEs as encrypted. Decrypt the page so + * that KVM's writes and the CPU's reads get along. Note, this is + * only necessary when using shadow paging, as 64-bit NPT can get at + * the C-bit even when shadowing 32-bit NPT, and SME isn't supported + * by 32-bit kernels (when KVM itself uses 32-bit NPT). + */ + if (!tdp_enabled) + set_memory_decrypted((unsigned long)mmu->pae_root, 1); + else + WARN_ON_ONCE(shadow_me_value); + + for (i = 0; i < 4; ++i) + mmu->pae_root[i] = INVALID_PAE_ROOT; + + return 0; +} + +int kvm_mmu_create(struct kvm_vcpu *vcpu) +{ + int ret; + + vcpu->arch.mmu_pte_list_desc_cache.kmem_cache = pte_list_desc_cache; + vcpu->arch.mmu_pte_list_desc_cache.gfp_zero = __GFP_ZERO; + + 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.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; + + ret = __kvm_mmu_create(vcpu, &vcpu->arch.guest_mmu); + if (ret) + return ret; + + ret = __kvm_mmu_create(vcpu, &vcpu->arch.root_mmu); + if (ret) + goto fail_allocate_root; + + return ret; + fail_allocate_root: + free_mmu_pages(&vcpu->arch.guest_mmu); + return ret; +} + +#define BATCH_ZAP_PAGES 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, + &kvm->arch.active_mmu_pages, link) { + /* + * No obsolete valid page exists before a newly created page + * since active_mmu_pages is a FIFO list. + */ + if (!is_obsolete_sp(kvm, sp)) + break; + + /* + * Invalid pages should never land back on the list of active + * 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_ONCE(sp->role.invalid)) + continue; + + /* + * No need to flush the TLB since we're only zapping shadow + * pages with an obsolete generation number and all vCPUS have + * loaded a new root, i.e. the shadow pages being zapped cannot + * be in active use by the guest. + */ + if (batch >= BATCH_ZAP_PAGES && + cond_resched_rwlock_write(&kvm->mmu_lock)) { + batch = 0; + goto restart; + } + + unstable = __kvm_mmu_prepare_zap_page(kvm, sp, + &invalid_list, &nr_zapped); + batch += nr_zapped; + + if (unstable) + goto restart; + } + + /* + * 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, &invalid_list); +} + +/* + * Fast invalidate all shadow pages and use lock-break technique + * to zap obsolete pages. + * + * It's required when memslot is being deleted or VM is being + * destroyed, in these cases, we should ensure that KVM MMU does + * not use any resource of the being-deleted slot or all slots + * after calling the function. + */ +static void kvm_mmu_zap_all_fast(struct kvm *kvm) +{ + lockdep_assert_held(&kvm->slots_lock); + + write_lock(&kvm->mmu_lock); + trace_kvm_mmu_zap_all_fast(kvm); + + /* + * Toggle mmu_valid_gen between '0' and '1'. Because slots_lock is + * held for the entire duration of zapping obsolete pages, it's + * impossible for there to be multiple invalid generations associated + * with *valid* shadow pages at any given time, i.e. there is exactly + * one valid generation and (at most) one invalid generation. + */ + kvm->arch.mmu_valid_gen = kvm->arch.mmu_valid_gen ? 0 : 1; + + /* + * 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 (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. + * Then all vcpus will switch to new shadow page table with the new + * mmu_valid_gen. + * + * Note: we need to do this under the protection of mmu_lock, + * otherwise, vcpu would purge shadow page but miss tlb flush. + */ + kvm_make_all_cpus_request(kvm, KVM_REQ_MMU_FREE_OBSOLETE_ROOTS); + + kvm_zap_obsolete_pages(kvm); + + write_unlock(&kvm->mmu_lock); + + /* + * 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_wrprot_slot(kvm, memslot, start_level); + read_unlock(&kvm->mmu_lock); + } +} + +static inline bool need_topup(struct kvm_mmu_memory_cache *cache, int min) +{ + return kvm_mmu_memory_cache_nr_free_objects(cache) < min; +} + +static bool need_topup_split_caches_or_resched(struct kvm *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); +} + +static int topup_split_caches(struct kvm *kvm) +{ + /* + * 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; + + 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; + + 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); +} + +static struct kvm_mmu_page *shadow_mmu_get_sp_for_split(struct kvm *kvm, u64 *huge_sptep) +{ + 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); + + /* 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; + + /* Safe to pass NULL for vCPU since requesting a direct SP. */ + return __kvm_mmu_get_shadow_page(kvm, NULL, &caches, gfn, role); +} + +static void shadow_mmu_split_huge_page(struct kvm *kvm, + const struct kvm_memory_slot *slot, + u64 *huge_sptep) + +{ + 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; + + sp = shadow_mmu_get_sp_for_split(kvm, huge_sptep); + + 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; + } + + 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; + } + + shadow_mmu_split_huge_page(kvm, slot, huge_sptep); + +out: + trace_kvm_mmu_split_huge_page(gfn, spte, level, r); + return r; +} + +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 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) +{ + 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); +} + +/* 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) +{ + 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); + kvm_shadow_mmu_try_split_huge_pages(kvm, memslot, start, end, target_level); + write_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); + + /* + * 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. + */ +} + +static bool kvm_mmu_zap_collapsible_spte(struct kvm *kvm, + struct kvm_rmap_head *rmap_head, + const struct kvm_memory_slot *slot) +{ + u64 *sptep; + struct rmap_iterator iter; + int need_tlb_flush = 0; + struct kvm_mmu_page *sp; + +restart: + for_each_rmap_spte(rmap_head, &iter, sptep) { + sp = sptep_to_sp(sptep); + + /* + * We cannot do huge page mapping for indirect shadow pages, + * which are found on the last rmap (level = 1) when not using + * tdp; such shadow pages are synced with the page table in + * the guest, and the guest page table is using 4K page size + * mapping if the indirect sp has level = 1. + */ + 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; + + goto restart; + } + } + + return need_tlb_flush; +} + +static void kvm_rmap_zap_collapsible_sptes(struct kvm *kvm, + const struct kvm_memory_slot *slot) +{ + /* + * 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); + kvm_rmap_zap_collapsible_sptes(kvm, slot); + write_unlock(&kvm->mmu_lock); + } + + if (tdp_mmu_enabled) { + read_lock(&kvm->mmu_lock); + kvm_tdp_mmu_recover_huge_pages(kvm, slot); + read_unlock(&kvm->mmu_lock); + } +} + +void kvm_mmu_slot_leaf_clear_dirty(struct kvm *kvm, + const struct kvm_memory_slot *memslot) +{ + if (kvm_memslots_have_rmaps(kvm)) { + write_lock(&kvm->mmu_lock); + /* + * 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 (tdp_mmu_enabled) { + read_lock(&kvm->mmu_lock); + 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. + */ +} + +static void kvm_mmu_zap_all(struct kvm *kvm) +{ + struct kvm_mmu_page *sp, *node; + LIST_HEAD(invalid_list); + int ign; + + write_lock(&kvm->mmu_lock); +restart: + list_for_each_entry_safe(sp, node, &kvm->arch.active_mmu_pages, link) { + if (WARN_ON_ONCE(sp->role.invalid)) + continue; + if (__kvm_mmu_prepare_zap_page(kvm, sp, &invalid_list, &ign)) + goto restart; + if (cond_resched_rwlock_write(&kvm->mmu_lock)) + goto restart; + } + + kvm_mmu_commit_zap_page(kvm, &invalid_list); + + 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_ONCE(gen & KVM_MEMSLOT_GEN_UPDATE_IN_PROGRESS); + + if (!enable_mmio_caching) + return; + + gen &= MMIO_SPTE_GEN_MASK; + + /* + * Generation numbers are incremented in multiples of the number of + * address spaces in order to provide unique generations across all + * address spaces. Strip what is effectively the address space + * modifier prior to checking for a wrap of the MMIO generation so + * that a wrap in any address space is detected. + */ + 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("zapping shadow pages for mmio generation wraparound\n"); + kvm_mmu_zap_all_fast(kvm); + } +} + +static void mmu_destroy_caches(void) +{ + kmem_cache_destroy(pte_list_desc_cache); + kmem_cache_destroy(mmu_page_header_cache); +} + +static void kvm_wake_nx_recovery_thread(struct kvm *kvm) +{ + /* + * 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); + + if (nx_thread) + vhost_task_wake(nx_thread); +} + +static int get_nx_huge_pages(char *buffer, const struct kernel_param *kp) +{ + 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) +{ + /* Return true when CPU has the bug, and mitigations are ON */ + return boot_cpu_has_bug(X86_BUG_ITLB_MULTIHIT) && !cpu_mitigations_off(); +} + +static void __set_nx_huge_pages(bool val) +{ + nx_huge_pages = itlb_multihit_kvm_mitigation = val; +} + +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")) { + new_val = 0; + } else if (sysfs_streq(val, "force")) { + new_val = 1; + } else if (sysfs_streq(val, "auto")) { + new_val = get_nx_auto_mode(); + } 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); + + if (new_val != old_val) { + struct kvm *kvm; + + mutex_lock(&kvm_lock); + + list_for_each_entry(kvm, &vm_list, vm_list) { + mutex_lock(&kvm->slots_lock); + kvm_mmu_zap_all_fast(kvm); + mutex_unlock(&kvm->slots_lock); + + kvm_wake_nx_recovery_thread(kvm); + } + mutex_unlock(&kvm_lock); + } + + return 0; +} + +/* + * 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) +{ + 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 + * supposed to let us know if the assumption becomes false. + */ + 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_cpu_role) != sizeof(u64)); + + kvm_mmu_reset_all_pte_masks(); + + pte_list_desc_cache = KMEM_CACHE(pte_list_desc, SLAB_ACCOUNT); + if (!pte_list_desc_cache) + goto out; + + mmu_page_header_cache = kmem_cache_create("kvm_mmu_page_header", + sizeof(struct kvm_mmu_page), + 0, SLAB_ACCOUNT, NULL); + if (!mmu_page_header_cache) + goto out; + + return 0; + +out: + mmu_destroy_caches(); + return ret; +} + +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_vendor_module_exit(void) +{ + mmu_destroy_caches(); +} + +/* + * 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) +{ + bool was_recovery_enabled, is_recovery_enabled; + uint old_period, new_period; + int err; + + 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; + + 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) + kvm_wake_nx_recovery_thread(kvm); + + mutex_unlock(&kvm_lock); + } + + return err; +} + +static unsigned long nx_huge_pages_to_zap(struct kvm *kvm, + enum kvm_mmu_type mmu_type) +{ + 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; + LIST_HEAD(invalid_list); + bool flush = false; + int rcu_idx; + + nx_huge_pages = &kvm->arch.possible_nx_huge_pages[mmu_type].pages; + + rcu_idx = srcu_read_lock(&kvm->srcu); + 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(); + + for ( ; to_zap; --to_zap) { + 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 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(nx_huge_pages, + struct kvm_mmu_page, + 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); + 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); + + 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 void kvm_nx_huge_page_recovery_worker_kill(void *data) +{ +} + +static bool kvm_nx_huge_page_recovery_worker(void *data) +{ + struct kvm *kvm = data; + long remaining_time; + bool enabled; + uint period; + int i; + + enabled = calc_nx_huge_pages_recovery_period(&period); + if (!enabled) + return false; + + 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); + 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; +} + +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->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) +{ + if (nx_hugepage_mitigation_hard_disabled) + return 0; + + 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_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 |