On 25/11/2014 21:02, Paolo Bonzini wrote:
> > > +static const char *cpuid_xsave_feature_name[] = {
> > > + "xsaveopt", "xsavec", "xgetbv1", "xsaves",
> >
> > None of the above features introduce any new state that might need to be
> > migrated, or will require other changes in QEMU to work, right?
> >
> > It looks like they don't introduce any extra state, but if they do, they
> > need to be added to unmigratable_flags until migration support is
> > implemented.
> >
> > If they require other QEMU changes, it would be nice if KVM reported
> > them using KVM_CHECK_EXTENSION instead of GET_SUPPORTED_CPUID, so it
> > wouldn't break "-cpu host".
>
> No, they don't.
Actually, xsaves does but I don't think KVM_CHECK_EXTENSION is right.
It's just another MSR, and we haven't used KVM_CHECK_EXTENSION for new
MSRs and new XSAVE areas (last example: avx512).
Since no hardware really exists for it, and KVM does not support it
anyway, I think it's simplest to leave xsaves out for now. Is this right?
Paolo
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