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KVM: x86/mmu: Set Dirty bit for new SPTEs, even if _hardware_ A/D bits are disabled

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When making a SPTE, set the Dirty bit in the SPTE as appropriate, even if
hardware A/D bits are disabled.  Only EPT allows A/D bits to be disabled,
and for EPT, the bits are software-available (ignored by hardware) when
A/D bits are disabled, i.e. it is perfectly legal for KVM to use the Dirty
to track dirty pages in software.

Link: https://lore.kernel.org/r/20241011021051.1557902-17-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Sean Christopherson
2024-10-10 19:10:48 -07:00
parent c9b625625b
commit 8564911751
2 changed files with 1 additions and 7 deletions
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2
arch/x86/kvm/mmu/spte.c
View File

@@ -237,7 +237,7 @@ bool make_spte(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
wrprot = true;
else
spte |= PT_WRITABLE_MASK | shadow_mmu_writable_mask |
spte_shadow_dirty_mask(spte);
shadow_dirty_mask;
}
if (prefetch && !synchronizing)

6
arch/x86/kvm/mmu/spte.h
View File

@@ -316,12 +316,6 @@ 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_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;