Commit 5f8a7cf2 authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini
Browse files

KVM: x86/mmu: Skip mmu_notifier check when handling MMIO page fault 



Don't retry a page fault due to an mmu_notifier invalidation when
handling a page fault for a GPA that did not resolve to a memslot, i.e.
an MMIO page fault.  Invalidations from the mmu_notifier signal a change
in a host virtual address (HVA) mapping; without a memslot, there is no
HVA and thus no possibility that the invalidation is relevant to the
page fault being handled.

Note, the MMIO vs. memslot generation checks handle the case where a
pending memslot will create a memslot overlapping the faulting GPA.  The
mmu_notifier checks are orthogonal to memslot updates.

Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
Message-Id: <20210222024522.1751719-2-stevensd@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 356c7558

arch/x86/kvm/mmu/mmu.c

+1 −1
Original line number Diff line number Diff line
@@ -3712,7 +3712,7 @@ static int direct_page_fault(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code, 
	else

		write_lock(&vcpu->kvm->mmu_lock);



	if (mmu_notifier_retry(vcpu->kvm, mmu_seq))

	if (!is_noslot_pfn(pfn) && mmu_notifier_retry(vcpu->kvm, mmu_seq))

		goto out_unlock;

	r = make_mmu_pages_available(vcpu);

	if (r)

arch/x86/kvm/mmu/paging_tmpl.h

+1 −1
Original line number Diff line number Diff line
@@ -869,7 +869,7 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gpa_t addr, u32 error_code, 


	r = RET_PF_RETRY;

	write_lock(&vcpu->kvm->mmu_lock);

	if (mmu_notifier_retry(vcpu->kvm, mmu_seq))

	if (!is_noslot_pfn(pfn) && mmu_notifier_retry(vcpu->kvm, mmu_seq))

		goto out_unlock;



	kvm_mmu_audit(vcpu, AUDIT_PRE_PAGE_FAULT);