[libvirt] ARM KVM GICv3 Support

[Peter Maydell]

On 6 January 2016 at 12:49, Andrea Bolognani <abologna at redhat.com> wrote:
> That's correct, having a QMP command that lists the values gic-version
> can have on the current host would be just great.
>
> If we had that, we could validate the GIC version chosen for a guest,
> and expose it in the capabilities XML so that higher-level tools can
> provide a list of choices to the user.
>
> Please note that this QMP command would have to work regardless of the
> machine type selected on QEMU's command line, because libvirt always
> runs a QEMU binary with '-M none' when probing its capabilities.

On the other hand, if you don't tell us the machine type you care
about then we can't tell you:
 (a) "this machine type doesn't support setting this property at all"
     (which applies to machines like vexpress-a15 which you can use with
     KVM on 32-bit hosts, and of course also to all the non-KVM models)
 (b) "this machine type only supports GIC versions X and Y even if the
      host supports more" (this is currently only hypothetical, though,
      since we only have the property on 'virt'. it would only happen
      if in the future we needed something other than '2' or '3' or
      'host' I think.)

If you use -M none then we can only tell you information you
could have got yourself by directly asking the kernel about it.

thanks
-- PMM