Re: [Xen-devel] [PATCH for-4.9 v2] hvm/vpt: fix inconsistent views of vIOAPIC in vmx_intr_assist()

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 28.04.17 at 11:09, <chao.gao@xxxxxxxxx> wrote:
> On Fri, Apr 28, 2017 at 02:36:11AM -0600, Jan Beulich wrote:
>>>>> On 27.04.17 at 04:47, <chao.gao@xxxxxxxxx> wrote:
>>> --- a/xen/include/asm-x86/hvm/vpt.h
>>> +++ b/xen/include/asm-x86/hvm/vpt.h
>>> @@ -46,6 +46,12 @@ struct periodic_time {
>>>  #define PTSRC_lapic  2 /* LAPIC time source */
>>>      u8 source;                  /* PTSRC_ */
>>>      u8 irq;
>>> +    /*
>>> +     * Vector set in vIRR in one interrupt delivery. Using this value can
>>> +     * avoid reading the IOAPIC RTE again. Valid only when its source is
>>> +     * 'PTSRC_isa' and handled by vlapic.
>>> +     */
>>> +    int16_t latched_vector;
>>
>>Why is this PTSRC_isa specific? In the description you say
>>"for example, if a periodic timer interrupt is from PIT".
> 
> PTSRC_lapic means the pt is lapic interrupt timer. We can read 'irq'
> field directly from structure periodic_timer. For other cases, namely
> PTSRC_isa, we should get vector from vioapic or vpic.

Oh, I'm sorry - PTSRC_isa covers all of HPET, PIT, and RTC.
This aspect is fine then as is.

Jan


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