Re: [Xen-devel] [PATCH v8 15/17] vmx: VT-d posted-interrupt core logic handling

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 27.10.15 at 06:19, <feng.wu@xxxxxxxxx> wrote:
>> From: Dario Faggioli [mailto:dario.faggioli@xxxxxxxxxx]
>> Sent: Monday, October 26, 2015 10:40 PM
>> In any case, it would have been nice, given the situation, if you'd have put 
>> a few
>> words about, e.g., which solution you ended up implementing and why, either 
>> in
>> the cover or here (e.g., in the '---' area).
> 
> Thanks for the suggestion. As I mentioned before, updating the PI descriptor 
> needs
> to be atomic, I think it should be a little expensive. So doing it every 
> VM-exit seems
> not a good idea to me.

You could check whether any update is needed before doing the
(atomic) cmpxchg16b.

Jan


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