Re: [PATCH v4 5/7] KVM: SVM: Inject MCEs when Restricted Injection is active

[Tom Lendacky]

On 4/24/26 12:42, Melody Wang wrote:
> When Restricted Injection is active, only #HV exceptions can be injected
> into the SEV-SNP guest.
> 
> Detect that, and then follow the #HV doorbell communication from the
> GHCB specification to inject the MCEs.
> 
> Co-developed-by: Thomas Lendacky <thomas.lendacky@xxxxxxx>
> Signed-off-by: Thomas Lendacky <thomas.lendacky@xxxxxxx>
> Signed-off-by: Melody Wang <huibo.wang@xxxxxxx>
> ---
>  arch/x86/include/asm/kvm-x86-ops.h |  1 +
>  arch/x86/include/asm/kvm_host.h    |  1 +
>  arch/x86/kvm/svm/sev.c             | 16 ++++++++++++++--
>  arch/x86/kvm/svm/svm.c             | 17 +++++++++++++++++
>  arch/x86/kvm/svm/svm.h             |  2 ++
>  arch/x86/kvm/vmx/main.c            | 10 ++++++++++
>  arch/x86/kvm/vmx/vmx.c             |  5 +++++
>  arch/x86/kvm/vmx/x86_ops.h         |  1 +
>  arch/x86/kvm/x86.c                 |  7 +++++++
>  9 files changed, 58 insertions(+), 2 deletions(-)
> 


> diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
> index 61e1e54deb07..2483357bdd97 100644
> --- a/arch/x86/kvm/svm/sev.c
> +++ b/arch/x86/kvm/svm/sev.c
> @@ -5371,6 +5371,8 @@ static void __sev_snp_inject(enum inject_type type, struct kvm_vcpu *vcpu)
>  
>  	if (type == INJECT_NMI)
>  		hvdb->events.nmi = 1;
> +	else if (type == INJECT_MCE)
> +		hvdb->events.mce = 1;
>  	else
>  		hvdb->events.vector = vcpu->arch.interrupt.nr;
>  
> @@ -5386,6 +5388,11 @@ bool sev_snp_queue_exception(struct kvm_vcpu *vcpu)
>  	if (!sev_snp_is_rinj_active(vcpu))
>  		return false;
>  
> +	if (vcpu->arch.exception.vector == MC_VECTOR) {
> +		__sev_snp_inject(INJECT_MCE, vcpu);
> +		return true;
> +	}
> +
>  	/*
>  	 * Restricted Injection is enabled, only #HV is supported.
>  	 * If the vector is not HV_VECTOR, do not inject the exception,
> @@ -5454,7 +5461,7 @@ void sev_snp_cancel_injection(struct kvm_vcpu *vcpu)
>  
>  	/*
>  	 * KVM only injects a single event each time (prepare_hv_injection),
> -	 * so when events.nmi is true, the vector will be zero
> +	 * so when events.nmi is true, the MCE and vector will be zero.

This is confusing. I think you mean to say

so when events.nmi or events.mce is true, the vector will be zero.

correct?

Thanks,
Tom

>  	 */
>  	if (hvdb->events.vector)
>  		svm->vmcb->control.event_inj |= hvdb->events.vector |
> @@ -5463,6 +5470,9 @@ void sev_snp_cancel_injection(struct kvm_vcpu *vcpu)
>  	if (hvdb->events.nmi)
>  		svm->vmcb->control.event_inj |= SVM_EVTINJ_TYPE_NMI;
>  
> +	if (hvdb->events.mce)
> +		svm->vmcb->control.event_inj |= MC_VECTOR | SVM_EVTINJ_TYPE_EXEPT;
> +
>  	hvdb->events.pending_events = 0;
>  
>  out: