Re: [RFC PATCH 03/21] i386/kvm: handle Xen HVM cpuid leaves

[Philippe Mathieu-Daudé]

On 6/12/22 01:18, David Woodhouse wrote:
> On Mon, 2022-12-05 at 22:58 +0100, Philippe Mathieu-Daudé wrote:
> > > diff --git a/target/i386/cpu.c b/target/i386/cpu.c
> > > index 22b681ca37..45aa9e40a5 100644
> > > --- a/target/i386/cpu.c
> > > +++ b/target/i386/cpu.c
> > > @@ -7069,6 +7069,8 @@ static Property x86_cpu_properties[] = {
> > >         * own cache information (see x86_cpu_load_def()).
> > >         */
> > >        DEFINE_PROP_BOOL("legacy-cache", X86CPU, legacy_cache, true),
> > > +    DEFINE_PROP_BOOL("xen", X86CPU, xen, false),
> >
> > Maybe name it 'xen-hvm'?
>
> I think I'd prefer it to go away completely. If the *machine* has the
> Xen feature enabled (which I've made implicit in the 'xen-version'
> property), perhaps we should *always* disable 'expose_kvm' and enable
> the Xen CPUID leaves instead?

It would be silly to run a non-Xen guest on the Xen machine, so it is
not a bad idea :)

> > > +    DEFINE_PROP_BOOL("xen-vapic", X86CPU, xen_vapic, false),
> >
> > What happens if we use -cpu host,-kvm,+xen,-xen-vapic ?
>
> That's sane; it does the Xen CPUID thing but doesn't advertise the
> vAPIC feature in the Xen CPUID leaves.

In which case we don't want to use the vAPIC?

Thanks,

Phil.