On 20/01/2022 01:07, Sean Christopherson wrote:
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@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
Reviewed-by: Liam Merwick <liam.merwick@xxxxxxxxxx>
---
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 aa1649b8cd8f..85703145eb0a 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -4311,13 +4311,6 @@ 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 5a1164483e6c..0bacecda79cf 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -2248,7 +2248,6 @@ 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)
{
