[PATCH 21/24] KVM: x86/mmu: Tweak auditing WARN for A/D bits to !PRESENT (was MMIO)

[Sean Christopherson]

Tweak the MMU_WARN that guards against weirdness when querying A/D status
to fire on a !MMU_PRESENT SPTE, as opposed to a MMIO SPTE.  Attempting to
query A/D status on any kind of !MMU_PRESENT SPTE, MMIO or otherwise,
indicates a KVM bug.  Case in point, several now-fixed bugs were
identified by enabling this new WARN.

Signed-off-by: Sean Christopherson <sea...@google.com>
---
 arch/x86/kvm/mmu/spte.h | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/arch/x86/kvm/mmu/spte.h b/arch/x86/kvm/mmu/spte.h
index 645e9bc2d4a2..2fad4ccd3679 100644
--- a/arch/x86/kvm/mmu/spte.h
+++ b/arch/x86/kvm/mmu/spte.h
@@ -209,6 +209,11 @@ static inline bool is_mmio_spte(u64 spte)
               likely(shadow_mmio_value);
 }
 
+static inline bool is_shadow_present_pte(u64 pte)
+{
+       return !!(pte & SPTE_MMU_PRESENT_MASK);
+}
+
 static inline bool sp_ad_disabled(struct kvm_mmu_page *sp)
 {
        return sp->role.ad_disabled;
@@ -216,13 +221,13 @@ static inline bool sp_ad_disabled(struct kvm_mmu_page *sp)
 
 static inline bool spte_ad_enabled(u64 spte)
 {
-       MMU_WARN_ON(is_mmio_spte(spte));
+       MMU_WARN_ON(!is_shadow_present_pte(spte));
        return (spte & SPTE_TDP_AD_MASK) != SPTE_TDP_AD_DISABLED_MASK;
 }
 
 static inline bool spte_ad_need_write_protect(u64 spte)
 {
-       MMU_WARN_ON(is_mmio_spte(spte));
+       MMU_WARN_ON(!is_shadow_present_pte(spte));
        /*
         * This is benign for non-TDP SPTEs as SPTE_TDP_AD_ENABLED_MASK is '0',
         * and non-TDP SPTEs will never set these bits.  Optimize for 64-bit
@@ -233,13 +238,13 @@ static inline bool spte_ad_need_write_protect(u64 spte)
 
 static inline u64 spte_shadow_accessed_mask(u64 spte)
 {
-       MMU_WARN_ON(is_mmio_spte(spte));
+       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)
 {
-       MMU_WARN_ON(is_mmio_spte(spte));
+       MMU_WARN_ON(!is_shadow_present_pte(spte));
        return spte_ad_enabled(spte) ? shadow_dirty_mask : 0;
 }
 
@@ -248,11 +253,6 @@ static inline bool is_access_track_spte(u64 spte)
        return !spte_ad_enabled(spte) && (spte & shadow_acc_track_mask) == 0;
 }
 
-static inline bool is_shadow_present_pte(u64 pte)
-{
-       return !!(pte & SPTE_MMU_PRESENT_MASK);
-}
-
 static inline bool is_large_pte(u64 pte)
 {
        return pte & PT_PAGE_SIZE_MASK;
-- 
2.30.1.766.gb4fecdf3b7-goog