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| author | Paolo Bonzini <pbonzini@redhat.com> | 2020-04-17 19:21:06 +0300 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2020-04-21 16:13:13 +0300 |
| commit | e72436bc3a5206f95bb384e741154166ddb3202e (patch) | |
| tree | 3bbd58436dcb3900f1f0c276e497b8381d0b169b | |
| parent | 997b7e98990cd44243651827e4efa366d9885907 (diff) | |
| download | linux-e72436bc3a5206f95bb384e741154166ddb3202e.tar.xz | |
KVM: SVM: avoid infinite loop on NPF from bad address
When a nested page fault is taken from an address that does not have
a memslot associated to it, kvm_mmu_do_page_fault returns RET_PF_EMULATE
(via mmu_set_spte) and kvm_mmu_page_fault then invokes svm_need_emulation_on_page_fault.
The default answer there is to return false, but in this case this just
causes the page fault to be retried ad libitum. Since this is not a
fast path, and the only other case where it is taken is an erratum,
just stick a kvm_vcpu_gfn_to_memslot check in there to detect the
common case where the erratum is not happening.
This fixes an infinite loop in the new set_memory_region_test.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
| -rw-r--r-- | arch/x86/kvm/svm/svm.c | 7 | ||||
| -rw-r--r-- | virt/kvm/kvm_main.c | 1 |
2 files changed, 8 insertions, 0 deletions
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index a6f4e1bdb045..eb95283ab68d 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -3838,6 +3838,13 @@ static bool svm_need_emulation_on_page_fault(struct kvm_vcpu *vcpu) bool is_user = svm_get_cpl(vcpu) == 3; /* + * If RIP is invalid, go ahead with emulation which will cause an + * internal error exit. + */ + if (!kvm_vcpu_gfn_to_memslot(vcpu, kvm_rip_read(vcpu) >> PAGE_SHIFT)) + return true; + + /* * Detect and workaround Errata 1096 Fam_17h_00_0Fh. * * Errata: diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index e2f60e313c87..e7436d054305 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -1602,6 +1602,7 @@ struct kvm_memory_slot *kvm_vcpu_gfn_to_memslot(struct kvm_vcpu *vcpu, gfn_t gfn { return __gfn_to_memslot(kvm_vcpu_memslots(vcpu), gfn); } +EXPORT_SYMBOL_GPL(kvm_vcpu_gfn_to_memslot); bool kvm_is_visible_gfn(struct kvm *kvm, gfn_t gfn) { |