On Thu, Nov 13, 2025 at 02:56:20PM -0800, Sean Christopherson wrote:
> Limit KVM's incorrect check for VMXEXIT_INVALID, a.k.a. SVM_EXIT_ERR, to
> running as a VM, as detected by X86_FEATURE_HYPERVISOR. The exit_code and
> all failure codes, e.g. VMXEXIT_INVALID, are 64-bit values, and so checking
> only bits 31:0 could result in false positives when running on non-broken
> hardware, e.g. in the extremely unlikely scenario exit code 0xffffffffull
> is ever generated by hardware.
>
> Keep the 32-bit check to play nice with running on broken KVM (for years,
> KVM has not set bits 63:32 when synthesizing nested SVM VM-Exits).
>
> Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Yosry Ahmed <yosry.ahmed@linux.dev>
> ---
> arch/x86/kvm/svm/svm.h | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
> index 31ee4f65dcc2..801dcfc64d0b 100644
> --- a/arch/x86/kvm/svm/svm.h
> +++ b/arch/x86/kvm/svm/svm.h
> @@ -427,7 +427,10 @@ static __always_inline struct vcpu_svm *to_svm(struct kvm_vcpu *vcpu)
>
> static inline bool svm_is_vmrun_failure(u64 exit_code)
> {
> - return (u32)exit_code == (u32)SVM_EXIT_ERR;
> + if (cpu_feature_enabled(X86_FEATURE_HYPERVISOR))
> + return (u32)exit_code == (u32)SVM_EXIT_ERR;
> +
> + return exit_code == SVM_EXIT_ERR;
> }
>
> /*
> --
> 2.52.0.rc1.455.g30608eb744-goog
>