From: Sean Christopherson seanjc@google.com
When injecting an exception into a vCPU in Real Mode, suppress the error code by clearing the flag that tracks whether the error code is valid, not by clearing the error code itself. The "typo" was introduced by recent fix for SVM's funky Paged Real Mode.
Opportunistically hoist the logic above the tracepoint so that the trace is coherent with respect to what is actually injected (this was also the behavior prior to the buggy commit).
Fixes: b97f07458373 ("KVM: x86: determine if an exception has an error code only when injecting it.") Cc: stable@vger.kernel.org Cc: Maxim Levitsky mlevitsk@redhat.com Signed-off-by: Sean Christopherson seanjc@google.com Message-Id: 20230322143300.2209476-2-seanjc@google.com Signed-off-by: Paolo Bonzini pbonzini@redhat.com (cherry picked from commit 6c41468c7c12d74843bb414fc00307ea8a6318c3) [nsaenz: backport to 5.10.y] Signed-off-by: Nicolas Saenz Julienne nsaenz@amazon.com
Conflicts: arch/x86/kvm/x86.c: Patch offsets had to be corrected. --- Testing: Kernel build and VM launch with KVM. Unfortunately I don't have a repro for the issue this solves, but the patch is straightforward, so I believe the testing above is good enough.
arch/x86/kvm/x86.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 8e0b957c6219..bc295439360e 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -8501,13 +8501,20 @@ static void update_cr8_intercept(struct kvm_vcpu *vcpu)
static void kvm_inject_exception(struct kvm_vcpu *vcpu) { + /* + * Suppress the error code if the vCPU is in Real Mode, as Real Mode + * exceptions don't report error codes. The presence of an error code + * is carried with the exception and only stripped when the exception + * is injected as intercepted #PF VM-Exits for AMD's Paged Real Mode do + * report an error code despite the CPU being in Real Mode. + */ + vcpu->arch.exception.has_error_code &= is_protmode(vcpu); + trace_kvm_inj_exception(vcpu->arch.exception.nr, vcpu->arch.exception.has_error_code, vcpu->arch.exception.error_code, vcpu->arch.exception.injected);
- if (vcpu->arch.exception.error_code && !is_protmode(vcpu)) - vcpu->arch.exception.error_code = false; kvm_x86_ops.queue_exception(vcpu); }