On Thu, Nov 13, 2025 at 02:56:13PM -0800, Sean Christopherson wrote:
> Explicitly clear exit_code_hi in the VMCB when synthesizing "normal"
> nested VM-Exits, as the full exit code is a 64-bit value (spoiler alert),
> and all exit codes for non-failing VMRUN use only bits 31:0.
>
> Cc: Jim Mattson <jmattson@google.com>
> Cc: Yosry Ahmed <yosry.ahmed@linux.dev>
> Cc: stable@vger.kernel.org
> Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Yosry Ahmed <yosry.ahmed@linux.dev>
> ---
> arch/x86/kvm/svm/svm.c | 2 ++
> arch/x86/kvm/svm/svm.h | 7 ++++---
> 2 files changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
> index fc42bcdbb520..7ea034ee6b6c 100644
> --- a/arch/x86/kvm/svm/svm.c
> +++ b/arch/x86/kvm/svm/svm.c
> @@ -2433,6 +2433,7 @@ static bool check_selective_cr0_intercepted(struct kvm_vcpu *vcpu,
>
> if (cr0 ^ val) {
> svm->vmcb->control.exit_code = SVM_EXIT_CR0_SEL_WRITE;
> + svm->vmcb->control.exit_code_hi = 0;
> ret = (nested_svm_exit_handled(svm) == NESTED_EXIT_DONE);
> }
>
> @@ -4608,6 +4609,7 @@ static int svm_check_intercept(struct kvm_vcpu *vcpu,
> if (static_cpu_has(X86_FEATURE_NRIPS))
> vmcb->control.next_rip = info->next_rip;
> vmcb->control.exit_code = icpt_info.exit_code;
> + vmcb->control.exit_code_hi = 0;
> vmexit = nested_svm_exit_handled(svm);
>
> ret = (vmexit == NESTED_EXIT_DONE) ? X86EMUL_INTERCEPTED
> diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
> index c2acaa49ee1c..253a8dca412c 100644
> --- a/arch/x86/kvm/svm/svm.h
> +++ b/arch/x86/kvm/svm/svm.h
> @@ -763,9 +763,10 @@ int nested_svm_vmexit(struct vcpu_svm *svm);
>
> static inline int nested_svm_simple_vmexit(struct vcpu_svm *svm, u32 exit_code)
> {
> - svm->vmcb->control.exit_code = exit_code;
> - svm->vmcb->control.exit_info_1 = 0;
> - svm->vmcb->control.exit_info_2 = 0;
> + svm->vmcb->control.exit_code = exit_code;
> + svm->vmcb->control.exit_code_hi = 0;
> + svm->vmcb->control.exit_info_1 = 0;
> + svm->vmcb->control.exit_info_2 = 0;
> return nested_svm_vmexit(svm);
> }
>
> --
> 2.52.0.rc1.455.g30608eb744-goog
>