Re: [Xen-devel] Using IRQ_GUEST|IRQ_PER_CPU to signal "delivery to current vcpu"?

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 10.11.15 at 11:48, <ian.campbell@xxxxxxxxxx> wrote:
> So, I was considering using a new bit in the common desc->status bit. Upon
> checking xen/irq.h I found there was already IRQ_PER_CPU which appears to
> be completely unused in the current code base (it looks to have been used
> by IA64 and PPC, but never by x86 and not currently used AFAICT by ARM, x86
> or common code.)
> 
> It seems like IRQ_GUEST|IRQ_PER_CPU is a pretty good fit for the semantics
> I want, but I think it would be confusing to define it as meaning such only
> on ARM and having either common code or other architectures ascribe a
> different meaning (other than "meaningless on this arch") to it.
> 
> I think the other possible use case of this scenario (routing a PPI to a
> specific guest) seems rather unlikely (since it would imply pinning in
> various odd ways). I think that use case can also be dealt with by the
> context switching code which can reroute the interrupt as needed (i.e.
> unmask only when the relevant vcpu is running).
> 
> Any thoughts?

Sounds reasonable.

Jan


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