diff options
Diffstat (limited to 'arch/x86/kvm/mmu/spte.h')
| -rw-r--r-- | arch/x86/kvm/mmu/spte.h | 139 |
1 files changed, 94 insertions, 45 deletions
diff --git a/arch/x86/kvm/mmu/spte.h b/arch/x86/kvm/mmu/spte.h index a129951c9a88..59746854c0af 100644 --- a/arch/x86/kvm/mmu/spte.h +++ b/arch/x86/kvm/mmu/spte.h @@ -3,6 +3,8 @@ #ifndef KVM_X86_MMU_SPTE_H #define KVM_X86_MMU_SPTE_H +#include <asm/vmx.h> + #include "mmu.h" #include "mmu_internal.h" @@ -149,6 +151,31 @@ static_assert(MMIO_SPTE_GEN_LOW_BITS == 8 && MMIO_SPTE_GEN_HIGH_BITS == 11); #define MMIO_SPTE_GEN_MASK GENMASK_ULL(MMIO_SPTE_GEN_LOW_BITS + MMIO_SPTE_GEN_HIGH_BITS - 1, 0) +/* + * Non-present SPTE value needs to set bit 63 for TDX, in order to suppress + * #VE and get EPT violations on non-present PTEs. We can use the + * same value also without TDX for both VMX and SVM: + * + * For SVM NPT, for non-present spte (bit 0 = 0), other bits are ignored. + * For VMX EPT, bit 63 is ignored if #VE is disabled. (EPT_VIOLATION_VE=0) + * bit 63 is #VE suppress if #VE is enabled. (EPT_VIOLATION_VE=1) + */ +#ifdef CONFIG_X86_64 +#define SHADOW_NONPRESENT_VALUE BIT_ULL(63) +static_assert(!(SHADOW_NONPRESENT_VALUE & SPTE_MMU_PRESENT_MASK)); +#else +#define SHADOW_NONPRESENT_VALUE 0ULL +#endif + + +/* + * True if A/D bits are supported in hardware and are enabled by KVM. When + * enabled, KVM uses A/D bits for all non-nested MMUs. Because L1 can disable + * A/D bits in EPTP12, SP and SPTE variants are needed to handle the scenario + * where KVM is using A/D bits for L1, but not L2. + */ +extern bool __read_mostly kvm_ad_enabled; + extern u64 __read_mostly shadow_host_writable_mask; extern u64 __read_mostly shadow_mmu_writable_mask; extern u64 __read_mostly shadow_nx_mask; @@ -184,24 +211,24 @@ extern u64 __read_mostly shadow_nonpresent_or_rsvd_mask; /* * If a thread running without exclusive control of the MMU lock must perform a - * multi-part operation on an SPTE, it can set the SPTE to REMOVED_SPTE as a + * multi-part operation on an SPTE, it can set the SPTE to FROZEN_SPTE as a * non-present intermediate value. Other threads which encounter this value * should not modify the SPTE. * * Use a semi-arbitrary value that doesn't set RWX bits, i.e. is not-present on * both AMD and Intel CPUs, and doesn't set PFN bits, i.e. doesn't create a L1TF - * vulnerability. Use only low bits to avoid 64-bit immediates. + * vulnerability. * * Only used by the TDP MMU. */ -#define REMOVED_SPTE 0x5a0ULL +#define FROZEN_SPTE (SHADOW_NONPRESENT_VALUE | 0x5a0ULL) -/* Removed SPTEs must not be misconstrued as shadow present PTEs. */ -static_assert(!(REMOVED_SPTE & SPTE_MMU_PRESENT_MASK)); +/* Frozen SPTEs must not be misconstrued as shadow present PTEs. */ +static_assert(!(FROZEN_SPTE & SPTE_MMU_PRESENT_MASK)); -static inline bool is_removed_spte(u64 spte) +static inline bool is_frozen_spte(u64 spte) { - return spte == REMOVED_SPTE; + return spte == FROZEN_SPTE; } /* Get an SPTE's index into its parent's page table (and the spt array). */ @@ -249,9 +276,14 @@ static inline struct kvm_mmu_page *root_to_sp(hpa_t root) return spte_to_child_sp(root); } -static inline bool is_mmio_spte(u64 spte) +static inline bool is_mirror_sptep(tdp_ptep_t sptep) { - return (spte & shadow_mmio_mask) == shadow_mmio_value && + return is_mirror_sp(sptep_to_sp(rcu_dereference(sptep))); +} + +static inline bool is_mmio_spte(struct kvm *kvm, u64 spte) +{ + return (spte & shadow_mmio_mask) == kvm->arch.shadow_mmio_value && likely(enable_mmio_caching); } @@ -260,15 +292,11 @@ static inline bool is_shadow_present_pte(u64 pte) return !!(pte & SPTE_MMU_PRESENT_MASK); } -/* - * Returns true if A/D bits are supported in hardware and are enabled by KVM. - * When enabled, KVM uses A/D bits for all non-nested MMUs. Because L1 can - * disable A/D bits in EPTP12, SP and SPTE variants are needed to handle the - * scenario where KVM is using A/D bits for L1, but not L2. - */ -static inline bool kvm_ad_enabled(void) +static inline bool is_ept_ve_possible(u64 spte) { - return !!shadow_accessed_mask; + return (shadow_present_mask & VMX_EPT_SUPPRESS_VE_BIT) && + !(spte & VMX_EPT_SUPPRESS_VE_BIT) && + (spte & VMX_EPT_RWX_MASK) != VMX_EPT_MISCONFIG_WX_VALUE; } static inline bool sp_ad_disabled(struct kvm_mmu_page *sp) @@ -293,18 +321,6 @@ static inline bool spte_ad_need_write_protect(u64 spte) return (spte & SPTE_TDP_AD_MASK) != SPTE_TDP_AD_ENABLED; } -static inline u64 spte_shadow_accessed_mask(u64 spte) -{ - KVM_MMU_WARN_ON(!is_shadow_present_pte(spte)); - return spte_ad_enabled(spte) ? shadow_accessed_mask : 0; -} - -static inline u64 spte_shadow_dirty_mask(u64 spte) -{ - KVM_MMU_WARN_ON(!is_shadow_present_pte(spte)); - return spte_ad_enabled(spte) ? shadow_dirty_mask : 0; -} - static inline bool is_access_track_spte(u64 spte) { return !spte_ad_enabled(spte) && (spte & shadow_acc_track_mask) == 0; @@ -332,17 +348,7 @@ static inline kvm_pfn_t spte_to_pfn(u64 pte) static inline bool is_accessed_spte(u64 spte) { - u64 accessed_mask = spte_shadow_accessed_mask(spte); - - return accessed_mask ? spte & accessed_mask - : !is_access_track_spte(spte); -} - -static inline bool is_dirty_spte(u64 spte) -{ - u64 dirty_mask = spte_shadow_dirty_mask(spte); - - return dirty_mask ? spte & dirty_mask : spte & PT_WRITABLE_MASK; + return spte & shadow_accessed_mask; } static inline u64 get_rsvd_bits(struct rsvd_bits_validate *rsvd_check, u64 pte, @@ -460,6 +466,50 @@ static inline bool is_mmu_writable_spte(u64 spte) return spte & shadow_mmu_writable_mask; } +/* + * Returns true if the access indicated by @fault is allowed by the existing + * SPTE protections. Note, the caller is responsible for checking that the + * SPTE is a shadow-present, leaf SPTE (either before or after). + */ +static inline bool is_access_allowed(struct kvm_page_fault *fault, u64 spte) +{ + if (fault->exec) + return is_executable_pte(spte); + + if (fault->write) + return is_writable_pte(spte); + + /* Fault was on Read access */ + return spte & PT_PRESENT_MASK; +} + +/* + * If the MMU-writable flag is cleared, i.e. the SPTE is write-protected for + * write-tracking, remote TLBs must be flushed, even if the SPTE was read-only, + * as KVM allows stale Writable TLB entries to exist. When dirty logging, KVM + * flushes TLBs based on whether or not dirty bitmap/ring entries were reaped, + * not whether or not SPTEs were modified, i.e. only the write-tracking case + * needs to flush at the time the SPTEs is modified, before dropping mmu_lock. + * + * Don't flush if the Accessed bit is cleared, as access tracking tolerates + * false negatives, e.g. KVM x86 omits TLB flushes even when aging SPTEs for a + * mmu_notifier.clear_flush_young() event. + * + * Lastly, don't flush if the Dirty bit is cleared, as KVM unconditionally + * flushes when enabling dirty logging (see kvm_mmu_slot_apply_flags()), and + * when clearing dirty logs, KVM flushes based on whether or not dirty entries + * were reaped from the bitmap/ring, not whether or not dirty SPTEs were found. + * + * Note, this logic only applies to shadow-present leaf SPTEs. The caller is + * responsible for checking that the old SPTE is shadow-present, and is also + * responsible for determining whether or not a TLB flush is required when + * modifying a shadow-present non-leaf SPTE. + */ +static inline bool leaf_spte_change_needs_tlb_flush(u64 old_spte, u64 new_spte) +{ + return is_mmu_writable_spte(old_spte) && !is_mmu_writable_spte(new_spte); +} + static inline u64 get_mmio_spte_generation(u64 spte) { u64 gen; @@ -474,10 +524,11 @@ bool spte_has_volatile_bits(u64 spte); bool make_spte(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp, const struct kvm_memory_slot *slot, unsigned int pte_access, gfn_t gfn, kvm_pfn_t pfn, - u64 old_spte, bool prefetch, bool can_unsync, + u64 old_spte, bool prefetch, bool synchronizing, bool host_writable, u64 *new_spte); -u64 make_huge_page_split_spte(struct kvm *kvm, u64 huge_spte, - union kvm_mmu_page_role role, int index); +u64 make_small_spte(struct kvm *kvm, u64 huge_spte, + union kvm_mmu_page_role role, int index); +u64 make_huge_spte(struct kvm *kvm, u64 small_spte, int level); u64 make_nonleaf_spte(u64 *child_pt, bool ad_disabled); u64 make_mmio_spte(struct kvm_vcpu *vcpu, u64 gfn, unsigned int access); u64 mark_spte_for_access_track(u64 spte); @@ -496,8 +547,6 @@ static inline u64 restore_acc_track_spte(u64 spte) return spte; } -u64 kvm_mmu_changed_pte_notifier_make_spte(u64 old_spte, kvm_pfn_t new_pfn); - void __init kvm_mmu_spte_module_init(void); void kvm_mmu_reset_all_pte_masks(void); |