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Re: [Xen-devel] [PATCH 2/2] xen/arm: initialize the GIC irq properties of interrupts routed to guests

On Wed, 9 Jan 2013, Ian Campbell wrote:
> On Wed, 2013-01-09 at 16:17 +0000, Stefano Stabellini wrote:
> > We are currently initializing GIC irq properties (ITARGETSR, IPRIORITYR,
> > and GICD_ICFGR) only in gic_route_irq, that is not called for guest
> > interrupts at all.
> > Move the initialization into a separate function
> > (gic_set_irq_properties) and call it from gic_route_irq_to_guest.
> Should this all be done in response to emulating the writes to the GICD
> which the guest itself makes?

I don't think so: no matter what the guest does we ought to provide a
sensible default to make sure that the GIC behaves correctly.
Of course we should also emulate those registers correctly and maybe set
the hardware in response to a guest write too.

> e.g. ITARGETSR needs to be emulated to map to VCPUs etc. Or maybe we
> want such interrupts to always come to any PCPU and we then take VCPUs
> based purely on an emulated ITARGETSR?

Yeah, we might as well do that until we do direct interrupt injection.

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