On Thu, May 05, 2022 at 11:14:30AM -0700, isaku.yamahata@xxxxxxxxx wrote: > From: Sean Christopherson <sean.j.christopherson@xxxxxxxxx> > > 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@xxxxxxxxx> > Signed-off-by: Isaku Yamahata <isaku.yamahata@xxxxxxxxx> > --- > 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 d1c37295bb6e..4a12d862bbb6 100644 > --- a/arch/x86/kvm/mmu/mmu.c > +++ b/arch/x86/kvm/mmu/mmu.c > @@ -3184,7 +3184,7 @@ 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)) I wonder if this patch is really necessary. is_shadow_present_pte() checks if SPTE_MMU_PRESENT_MASK is set (which is bit 11, not shadow_present_mask). Do TDX VMs set bit 11 in MMIO SPTEs? > break; > > sp = sptep_to_sp(sptep); > -- > 2.25.1 >
