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

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>

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index e24de1f3d1db1becbe42ad5cd662976ea951a434..bafec04b07ea1b1b679a00e3f99bb563b36ea31b 100644 (file)
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -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);