Re: [PATCH v7 15/17] vmx: VT-d posted-interrupt core logic handling

[Dario Faggioli <dario.faggioli@citrix.com>]

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On Thu, 2015-09-17 at 12:44 +0100, George Dunlap wrote:
> On 09/17/2015 10:38 AM, George Dunlap wrote:
> > Is it the case that the interrupt is not actually delivered to the
> > processor, but that the pending bit will be set in the pi field, so that
> > the interrupt will be delivered the next time the hypervisor returns
> > into the guest?
> > 
> > (I am assuming that is the case, because if the hypervisor *does* get an
> > interrupt, then it can just unblock it there.)
> 
> Actually, it looks like you *do* in fact get a
> pi_notification_interrupt() in this case.  Could we to check to see if
> the current vcpu is blocked and unblock it?
> 
> I haven't yet decided whether I prefer my original suggestion of
> switching the interrupt and putting things on the wake-up list in
> vcpu_block(), or of deferring adding things to the wake-up list until
> the actual context switch.
> 
Sorry but I don't get what you mean with the latter.

I particular, I don't think I understand what you mean with and how it
would work to "defer[ring] adding things to the wake-up list until
actual context switch"... In what case would you defer stuff to context
switch?

Dario
-- 
<<This happens because I choose it to happen!>> (Raistlin Majere)
-----------------------------------------------------------------
Dario Faggioli, Ph.D, http://about.me/dario.faggioli
Senior Software Engineer, Citrix Systems R&D Ltd., Cambridge (UK)

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