On 15/06/2017 14:38, Ladi Prosek wrote:
> On Thu, Jun 15, 2017 at 2:05 PM, Paolo Bonzini <pbonzini@xxxxxxxxxx> wrote:
>>
>>
>> On 15/06/2017 13:20, Ladi Prosek wrote:
>>> @@ -4823,6 +4826,22 @@ static void svm_vcpu_run(struct kvm_vcpu *vcpu)
>>> if (unlikely(svm->nested.exit_required))
>>> return;
>>>
>>> + /*
>>> + * Disable singlestep if we're injecting an interrupt/exception.
>>> + * We don't want our modified rflags to be pushed on the stack where
>>> + * we might not be able to easily reset them if we disabled NMI
>>> + * singlestep later.
>>> + */
>>> + if (svm->nmi_singlestep && svm->vmcb->control.event_inj) {
>>> + /*
>>> + * We enabled NMI singlestepping because the NMI window was
>>> + * closed. It's unlikely that injecting another event will make
>>> + * it any better. Try again later, on next iret at the latest.
>>> + */
>>> + disable_nmi_singlestep(svm);
>>> + set_intercept(svm, INTERCEPT_IRET);
>>> + }
>>> +
>>> pre_svm_run(svm);
>>>
>>> sync_lapic_to_cr8(vcpu);
>>>
>>
>> I wonder if we could just force an immediate vmexit instead of asking
>> for one at the next IRET. Based on the AMD manual, event injection
>> happens before external interrupts cause a vmexit.
>>
>> Interrupts here are disabled (through either IF or GIF) until VMRUN, so
>> just a
>>
>> smp_send_reschedule(vcpu->cpu);
>>
>> should be enough after disable_nmi_singlestep. Or if you put the code
>> in pre_svm_run you have a cpu local variable.
>
> Yup, this seems to work. Thanks!
Make sure to add a comment. :)
Paolo
