[PATCH 11/18] KVM: x86/mmu: Set shadow_dirty_mask for EPT even if A/D bits disabled

Sean Christopherson
2024-10-11T02:11:15Z

Set shadow_dirty_mask to the architectural EPT Dirty bit value even if
A/D bits are disabled at the module level, i.e. even if KVM will never
enable A/D bits in hardware. Doing so provides consistent behavior for
Accessed and Dirty bits, i.e. doesn't leave KVM in a state where it sets
shadow_accessed_mask but not shadow_dirty_mask.

Functionally, this should be one big nop, as consumption of
shadow_dirty_mask is always guarded by a check that hardware A/D bits are
enabled.

Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/x86/kvm/mmu/spte.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kvm/mmu/spte.c b/arch/x86/kvm/mmu/spte.c
index e352d1821319..54d8c9b76050 100644
--- a/arch/x86/kvm/mmu/spte.c
+++ b/arch/x86/kvm/mmu/spte.c
@@ -420,7 +420,7 @@ void kvm_mmu_set_ept_masks(bool has_ad_bits, bool has_exec_only)

shadow_user_mask = VMX_EPT_READABLE_MASK;
shadow_accessed_mask = VMX_EPT_ACCESS_BIT;
- shadow_dirty_mask = has_ad_bits ? VMX_EPT_DIRTY_BIT : 0ull;
+ shadow_dirty_mask = VMX_EPT_DIRTY_BIT;
shadow_nx_mask = 0ull;
shadow_x_mask = VMX_EPT_EXECUTABLE_MASK;
/* VMX_EPT_SUPPRESS_VE_BIT is needed for W or X violation. */
--
2.47.0.rc1.288.g06298d1525-goog