| From | Greg Kroah-Hartman <> | Subject | [PATCH 5.15 026/171] Revert "KVM: SVM: avoid infinite loop on NPF from bad address" | Date | Mon, 31 Jan 2022 11:54:51 +0100 |
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From: Sean Christopherson <seanjc@google.com>
commit 31c25585695abdf03d6160aa6d829e855b256329 upstream.
Revert a completely broken check on an "invalid" RIP in SVM's workaround for the DecodeAssists SMAP errata. kvm_vcpu_gfn_to_memslot() obviously expects a gfn, i.e. operates in the guest physical address space, whereas RIP is a virtual (not even linear) address. The "fix" worked for the problematic KVM selftest because the test identity mapped RIP.
Fully revert the hack instead of trying to translate RIP to a GPA, as the non-SEV case is now handled earlier, and KVM cannot access guest page tables to translate RIP.
This reverts commit e72436bc3a5206f95bb384e741154166ddb3202e.
Fixes: e72436bc3a52 ("KVM: SVM: avoid infinite loop on NPF from bad address") Reported-by: Liam Merwick <liam.merwick@oracle.com> Cc: stable@vger.kernel.org Signed-off-by: Sean Christopherson <seanjc@google.com> Reviewed-by: Liam Merwick <liam.merwick@oracle.com> Message-Id: <20220120010719.711476-3-seanjc@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- arch/x86/kvm/svm/svm.c | 7 ------- virt/kvm/kvm_main.c | 1 - 2 files changed, 8 deletions(-)
--- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -4456,13 +4456,6 @@ static bool svm_can_emulate_instruction( if (likely(!insn || insn_len)) return true; - /* - * 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; - cr4 = kvm_read_cr4(vcpu); smep = cr4 & X86_CR4_SMEP; smap = cr4 & X86_CR4_SMAP; --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -2104,7 +2104,6 @@ struct kvm_memory_slot *kvm_vcpu_gfn_to_ return NULL; } -EXPORT_SYMBOL_GPL(kvm_vcpu_gfn_to_memslot); bool kvm_is_visible_gfn(struct kvm *kvm, gfn_t gfn) {
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