[PATCH v7 035/102] KVM: x86/mmu: Explicitly check for MMIO spte in fast page fault

isaku.yamahata
2022-06-27T21:56:14Z

From: Sean Christopherson <sean.j.christopherson@intel.com>

Explicitly check for an MMIO spte in the fast page fault flow. TDX will
use a not-present entry for MMIO sptes, which can be mistaken for an
access-tracked spte since both have SPTE_SPECIAL_MASK set.

MMIO sptes are handled in handle_mmio_page_fault for non-TDX VMs, so this
patch does not affect them. TDX will handle MMIO emulation through a
hypercall instead.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
---
arch/x86/kvm/mmu/mmu.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 17252f39bd7c..51306b80f47c 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -3163,7 +3163,7 @@ static int fast_page_fault(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
else
sptep = fast_pf_get_last_sptep(vcpu, fault->addr, &spte);

- if (!is_shadow_present_pte(spte))
+ if (!is_shadow_present_pte(spte) || is_mmio_spte(spte))
break;

sp = sptep_to_sp(sptep);
--
2.25.1