Re: [PATCH 6/6] kvm: x86: do not use KVM_REQ_EVENT for APICv interrupt injection

Paolo Bonzini
2017-02-08T17:22:16Z

On 07/02/2017 20:58, Radim Krčmář wrote:
>> - local_irq_disable();
>> + if (kvm_lapic_enabled(vcpu)) {
>> + /*
>> + * This handles the case where a posted interrupt was
>> + * notified with kvm_vcpu_kick.
>> + */
>> + if (kvm_x86_ops->sync_pir_to_irr)
>> + kvm_x86_ops->sync_pir_to_irr(vcpu);
> Hm, this is not working well when nesting while L1 has assigned devices:
> if the posted interrupt arrives just before local_irq_disable(), then
> we'll just enter L2 instead of doing a nested VM exit (in case we have
> interrupt exiting).
>
> And after reading the code a bit, I think we allow posted interrupts in
> L2 while L1 has assigned devices that use posted interrupts, and that it
> doesn't work.

So you mean the interrupt is delivered to L2? The fix would be to wrap
L2 entry and exit with some subset of pi_pre_block/pi_post_block.

Paolo