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.
Paolo
