KVM: x86/mmu: Set shadow_dirty_mask for EPT even if A/D bits disabled

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.

Link: https://lore.kernel.org/r/20241011021051.1557902-12-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

diff --git a/arch/x86/kvm/mmu/spte.c b/arch/x86/kvm/mmu/spte.c
index e352d182131903d82dee4f9b18a06b2af1945f6a..54d8c9b76050606e65da57f2bd9134abaf78c1f3 100644 (file)
--- 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. */