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SubjectRe: [PATCH v2 1/4] KVM: nSVM: cancel KVM_REQ_GET_NESTED_STATE_PAGES on nested vmexit
Date
On 07/01/21 18:51, Paolo Bonzini wrote:
> On 07/01/21 18:00, Sean Christopherson wrote:
>> Ugh, I assume this is due to one of the "premature"
>> nested_ops->check_events()
>> calls that are necessitated by the event mess?  I'm guessing
>> kvm_vcpu_running()
>> is the culprit?
>>
>> If my assumption is correct, this bug affects nVMX as well.
>
> Yes, though it may be latent.  For SVM it was until we started
> allocating svm->nested on demand.
>
>> Rather than clear the request blindly on any nested VM-Exit, what
>> about something like the following?
>
> I think your patch is overkill, KVM_REQ_GET_NESTED_STATE_PAGES is only
> set from KVM_SET_NESTED_STATE so it cannot happen while the VM runs.

... and when leaving SMM. But in either case, there cannot be something
else causing a nested vmexit before the request is set, because SMM does
not support VMX operation. So I still don't think that it justifies the
extra code and indirection.

Paolo

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