RE: [PATCH] KVM: x86: Sync the pending Posted-Interrupts

[Kang, Luwei]

> > However, you should at least change the comment in vcpu_enter_guest to
> > mention "before reading PIR" instead of "before reading PIR.ON".
> 
> Will do that. I think the "checking PIR.ON" should be PID.ON. I will fix it.
> 
Hi Paolo,
    I reconsidered the comment in vcpu_enter_guest() and think it may don't need to change. The original comment as below:
         * 2) For APICv, we should set ->mode before checking  PIR.ON.  This
         * pairs with the memory barrier implicit in pi_test_and_set_on
         * (see vmx_deliver_posted_interrupt).

    I think "before checking PIR.ON" is mean "before checking PID.PIR and PID.ON". Because there indeed have this two flag check in  vmx_deliver_posted_interrupt() function. If PID.ON is already Set at the time of hardware posting an interrupt to PIR field, notification event is not generated (from VT-d spec 9.12).

Thanks,
Luwei Kang