Re: [PATCH v2 08/10] KVM: x86: Switch KVM guest to using interrupts for page ready APF delivery

[Paolo Bonzini]

On 10/06/20 22:51, Vivek Goyal wrote:
>> KVM now supports using interrupt for 'page ready' APF event delivery and
>> legacy mechanism was deprecated. Switch KVM guests to the new one.
> Hi Vitaly,
> 
> I see we have all this code in guest which tries to take care of
> cases where PAGE_READY can be delivered before PAGE_NOT_PRESENT. In
> this new schedume of things, can it still happen. We are using
> an exception to deliver PAGE_NOT_PRESENT while using interrupt to
> deliver PAGE_READY.
> 
> If re-ordeing is not possible, then it will be good to get rid of
> that extra complexity in guest.

It is perhaps less likely but still possible, because the interrupt
might be delivered to another CPU and race against the exception.

Paolo