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KVM: x86/mmu: Don't try to unprotect an INVALID_GPA

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If getting the gpa for a gva fails, e.g. because the gva isn't mapped in
the guest page tables, don't try to unprotect the invalid gfn.  This is
mostly a performance fix (avoids unnecessarily taking mmu_lock), as
for_each_gfn_valid_sp_with_gptes() won't explode on garbage input, it's
simply pointless.

Link: https://lore.kernel.org/r/20240831001538.336683-13-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Sean Christopherson 2024-08-30 17:15:27 -07:00
parent 2df354e37c
commit b7e948898e
1 changed files with 6 additions and 1 deletions
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7
arch/x86/kvm/mmu/mmu.c
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@ -2729,8 +2729,11 @@ bool kvm_mmu_unprotect_gfn_and_retry(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa)
if (!READ_ONCE(vcpu->kvm->arch.indirect_shadow_pages))
return false;
if (!vcpu->arch.mmu->root_role.direct)
if (!vcpu->arch.mmu->root_role.direct) {
gpa = kvm_mmu_gva_to_gpa_write(vcpu, cr2_or_gpa, NULL);
if (gpa == INVALID_GPA)
return false;
}
r = kvm_mmu_unprotect_page(vcpu->kvm, gpa_to_gfn(gpa));
if (r) {
@ -2749,6 +2752,8 @@ static int kvm_mmu_unprotect_page_virt(struct kvm_vcpu *vcpu, gva_t gva)
return 0;
gpa = kvm_mmu_gva_to_gpa_read(vcpu, gva, NULL);
if (gpa == INVALID_GPA)
return 0;
r = kvm_mmu_unprotect_page(vcpu->kvm, gpa >> PAGE_SHIFT);