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

[Melody Wang <huibo.wang@amd.com>]

Hi Tom,

On 4/28/26 12:24 PM, Tom Lendacky wrote:
> 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@amd.com>
>> Signed-off-by: Thomas Lendacky <thomas.lendacky@amd.com>
>> Signed-off-by: Melody Wang <huibo.wang@amd.com>
>> ---
>>   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?
> 
Yes, I will update the comment.

Thanks,
Melody
> 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:

-- 
Thanks,
Melody