Re: [Xen-devel] [PATCH v2 10/27] ARM: GICv3: forward pending LPIs to guests

[Julien Grall <julien.grall@xxxxxxx>]

On 03/04/17 15:18, Andre Przywara wrote:
> Hi,
Hi Andre,

> On 24/03/17 12:03, Julien Grall wrote:
> > > +    /* We may have mapped more host LPIs than the guest actually
> > > asked for. */
> > Another way, is the interrupt has been received at the same time the
> > guest is configuring it. What will happen if the interrupt is lost?
> I don't see how this would be our problem. If the guest is still about
> to configure an LPI, then any incoming one is pretty clearly a spurious
> interrupt.
> I take it that you mean "mapping an LPI using ITS commands" when you say
> "configuring" here. If this is not what you mean, please correct me.
>
> I'd expect a guest to first map the LPI, then enable it and send an INV
> command. Doing that differently will not result in any sane behavior (as
> in: a guest cannot expect an LPI to come through), so nothing we need to
> worry about (from a lost IRQ perspective).
>
> Or what do I miss here?
All host LPIs will be enabled when a device is assigned to a guest. So 
technically an LPI can come at anytime before the guest is configuring 
the virtual mapping.
Cheers,

--
Julien Grall

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