Re: [Xen-devel] [PATCH v3 18/39] ARM: new VGIC: Add CTLR, TYPER and IIDR handlers

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Wed, 28 Mar 2018, Andre Przywara wrote:
> On 27/03/18 21:38, Stefano Stabellini wrote:
> > On Wed, 21 Mar 2018, Andre Przywara wrote:
> >> Those three registers are v2 emulation specific, so their implementation
> >> lives entirely in vgic-mmio-v2.c. Also they are handled in one function,
> >> as their implementation is pretty simple.
> >> We choose to piggy-back on the existing KVM identification registers,
> >> but use a different variant (major revision).
> > 
> > CC'ing Marc.
> > 
> > Reusing the KVM product ID could cause issues, for instance we could
> > clash with KVM if Linux changes the Major number. If we were to actually
> > reuse KVM's PRODUCT_ID we would need a better coordination in place.
> 
> Marc is aware of this, as this approach was decided after a brief
> discussion with Julien and him last week.
> If we need a quirk on the (guest) GIC driver side for the KVM VGIC, KVM
> would bump the revision number, not the variant.
> This is a good as coordination can realistically ever get.

Sure, as long as it gets documented. It needs to be written down
somewhere and committed.

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