From d9a8d252adf9c558e257c3611d1bb46d2587d957 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Thu, 20 Jan 2022 01:07:12 +0000 Subject: [PATCH] Revert "KVM: SVM: avoid infinite loop on NPF from bad address" BugLink: https://bugs.launchpad.net/bugs/1959879 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 Cc: stable@vger.kernel.org Signed-off-by: Sean Christopherson Reviewed-by: Liam Merwick Message-Id: <20220120010719.711476-3-seanjc@google.com> Signed-off-by: Paolo Bonzini Signed-off-by: Greg Kroah-Hartman Signed-off-by: Paolo Pisati --- arch/x86/kvm/svm/svm.c | 7 ------- virt/kvm/kvm_main.c | 1 - 2 files changed, 8 deletions(-) diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index e64f16237b60..f7e9cdee0d8d 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -4456,13 +4456,6 @@ static bool svm_can_emulate_instruction(struct kvm_vcpu *vcpu, void *insn, int i 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; diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index c6bfd4e15d28..13aff136e6ee 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -2104,7 +2104,6 @@ struct kvm_memory_slot *kvm_vcpu_gfn_to_memslot(struct kvm_vcpu *vcpu, gfn_t gfn return NULL; } -EXPORT_SYMBOL_GPL(kvm_vcpu_gfn_to_memslot); bool kvm_is_visible_gfn(struct kvm *kvm, gfn_t gfn) { -- 2.39.5