Re: [Qemu-devel] [PATCH] x86: Skip check apic_id_limit for Xen

["Michael S. Tsirkin" <mst@redhat.com>]

On Thu, Oct 26, 2017 at 02:19:43PM +0200, Eduardo Habkost wrote:
> On Mon, Aug 21, 2017 at 10:22:15AM +0800, Lan Tianyu wrote:
> > On 2017年08月19日 00:38, Eduardo Habkost wrote:
> > > On Thu, Aug 17, 2017 at 09:37:10AM +0800, Lan Tianyu wrote:
> > >> On 2017年08月16日 19:21, Paolo Bonzini wrote:
> > >>> On 16/08/2017 02:22, Lan Tianyu wrote:
> > >>>> Xen vIOMMU device model will be in Xen hypervisor. Skip vIOMMU
> > >>>> check for Xen here when vcpu number is more than 255.
> > >>>
> > >>> I think you still need to do a check for vIOMMU being enabled.
> > >>
> > >> Yes, this will be done in the Xen tool stack and Qemu doesn't have such
> > >> knowledge. Operations of create, destroy Xen vIOMMU will be done in the
> > >> Xen tool stack.
> > > 
> > > Shouldn't we make QEMU have knowledge of the vIOMMU device, then?
> > > Won't QEMU need to know about it eventually?
> > > 
> > 
> > Hi Eduardo:
> >      Thanks for your review.
> >      Xen has some guest modes which doesn't use Qemu and we tried to
> > make Xen vIOMMU framework compatible with all guest modes. So far, we
> > are adding interrupt remapping function for Xen vIOMMU and find qemu
> > doesn't need to know Xen vIOMMU. The check of vcpu number > 255 here
> > will be done in Xen side and so skip the check in Qemu to avoid blocking
> > Xen creating >255 vcpus.
> >      We may make Qemu have knowledge of the vIOMMU device if it's
> > necessary when adding new function.
> 
> I was expecting it to go through the PC tree, but I will queue it
> on x86-next instead.

I was waiting for an ack from you or Paolo as you participated in the
discussion. But sure, go ahead

Acked-by: Michael S. Tsirkin <mst@redhat.com>



> -- 
> Eduardo