From: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
Ignore bits 63 and 62 when checking for present SPTEs to allow setting
said bits in not-present SPTEs. TDX will set bit 63 in "zero" SPTEs to
suppress #VEs (TDX-SEAM unconditionally enables EPT Violation #VE), and
will use bit 62 to track zapped private SPTEs.
Signed-off-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
---
arch/x86/kvm/mmu/paging_tmpl.h | 2 +-
arch/x86/kvm/mmu/spte.h | 17 +++++++++++++++--
2 files changed, 16 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kvm/mmu/paging_tmpl.h b/arch/x86/kvm/mmu/paging_tmpl.h
index 5d4e9f404018..06659d5c8ba0 100644
--- a/arch/x86/kvm/mmu/paging_tmpl.h
+++ b/arch/x86/kvm/mmu/paging_tmpl.h
@@ -1039,7 +1039,7 @@ static int FNAME(sync_page)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp)
gpa_t pte_gpa;
gfn_t gfn;
- if (!sp->spt[i])
+ if (!__is_shadow_present_pte(sp->spt[i]))
continue;
pte_gpa = first_pte_gpa + i * sizeof(pt_element_t);
diff --git a/arch/x86/kvm/mmu/spte.h b/arch/x86/kvm/mmu/spte.h
index e5c94848ade1..22256cc8cce6 100644
--- a/arch/x86/kvm/mmu/spte.h
+++ b/arch/x86/kvm/mmu/spte.h
@@ -174,9 +174,22 @@ static inline bool is_access_track_spte(u64 spte)
return !spte_ad_enabled(spte) && (spte & shadow_acc_track_mask) == 0;
}
-static inline int is_shadow_present_pte(u64 pte)
+static inline bool __is_shadow_present_pte(u64 pte)
{
- return (pte != 0) && !is_mmio_spte(pte);
+ /*
+ * Ignore bits 63 and 62 so that they can be set in SPTEs that are well
+ * and truly not present. We can't use the sane/obvious approach of
+ * querying bits 2:0 (RWX or P) because EPT without A/D bits will clear
+ * RWX of a "present" SPTE to do access tracking. Tracking updates can
+ * be done out of mmu_lock, so even the flushing logic needs to treat
+ * such SPTEs as present.
+ */
+ return !!(pte << 2);
+}
+
+static inline bool is_shadow_present_pte(u64 pte)
+{
+ return __is_shadow_present_pte(pte) && !is_mmio_spte(pte);
}
static inline int is_large_pte(u64 pte)
--
2.17.1
