On 28/01/19 09:08, Kang, Luwei wrote:
>> 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.
Yes.
>> Alternatively, would it be possible to instead set ON when SN is
>> cleared? The clearing of SN is in pi_clear_sn, and you would have instead
>> something like
>
> SN is cleared when the corresponding vCPU is running on pCPU. I think we
> can't set ON when SN is cleared. Because there have some words in VT-d spec
> 9.12:
> If ON is set at the time of hardware posting an interrupt to PIR field,
> notification event is not generated.
This is okay, because you are setting ON and vmx_sync_pir_to_irr will
read ON before the next vCPU entry and move the interrupts from PIR to IRR.
Paolo
>>
>> WRITE_ONCE(u16 *)&pi_desc->on_sn, POSTED_INTR_ON);
>
> We already have a function (pi_test_on) to check the bit of POSTED_INTR_ON.
> So I think it is unnecessary.
>
> Thanks,
> Luwei Kang
>
>>
>> where on_sn is added to struct pi_desc like this:
>>
>> @@ -61,4 +60,5 @@ struct pi_desc {
>> u32 ndst;
>> };
>> + u16 on_sn;
>> u64 control;
>> };
>>
>> Paolo
