Re: [Xen-devel] [PATCH v3 13/24] xen/arm: Implement hypercall PHYSDEVOP_{, un}map_pirq

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

On Mon, 2015-02-23 at 15:53 +0000, Julien Grall wrote:
> Hi Ian,
> 
> On 23/02/15 15:28, Ian Campbell wrote:
> > On Mon, 2015-02-23 at 09:33 +0000, Jan Beulich wrote:
> >>>>> On 20.02.15 at 17:53, <ian.campbell@xxxxxxxxxx> wrote:
> >>> Jan, do you have any feeling for how this is going to play out on x86
> >>> with the vapic stuff?
> >>
> >> The vapic logic shouldn't require any physdevop involvement, so if
> >> I read right what you propose (not having such a requirement /
> >> connection on ARM) either, I agree that a new domctl should be all
> >> that's needed (if XEN_DOMCTL_{,un}bind_pt_irq can't be re-used).
> > 
> > Actually, I think bind_pt_irq with a new PT_IRQ_TYPE_* would be a good
> > option.
> > 
> > An ARM SPI is a bit like an ISA IRQ, but not close enough to reuse IMHO
> > (and the datatype would need widening).
> 
> We have to think about MSI and other type too...
> 
> In any case a DOMCTL is not suitable here because a guest kernel may
> need to map/unmap IRQ too (think about ACPI or device passthrough).

I don't follow, setting up device passthrough is very much a toolstack
operation, isn't it? Where does the guest kernel get involved?

As for ACPI, I think dom0 propagating ACPI derived platform info to Xen
should be handled differently (at the hypercall interface at least)
separate from passthrough.

Ian.


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