On Tue, Apr 23, 2013 at 04:50:43PM -0700, H. Peter Anvin wrote:
> On 04/23/2013 04:41 PM, Borislav Petkov wrote:
> >
> > Btw, in thinking about this more, I'm kinda sceptical we want to use the
> > CPUID layout for this new KVM_GET_EMULATED_* ioctl. And the reason why
> > I'm sceptical is that not every instruction is behind a CPUID capability
> > bit and if we want to tell userspace that we do emulate any insn, even
> > one for which there's no CPUID bit, we're going to have to either
> > simulate a kvm-specific CPUID leaf or, maybe even better, come up with
> > our own format for emulated capabilities. Maybe a bit vector with set
> > bits for the respective capability, or something more nifty.
> >
> > In any case, it doesn't really need to be CPUID-like, IMHO.
> >
> Using CPUID has the major advantage that it is well-defined.
Right, and it is actually a tree of bitvectors of height of 1. :-)
However, in the remote case where we want to state an emulated
capability for which there is no CPUID bit, we probably need something.
>From looking at do_cpuid_ent(), kvm uses the 0x40000000 so we probably
could define such a flag in there. If needed, of course.
So KVM_GET_EMULATED_CPUID it is. :-)
--
Regards/Gruss,
Boris.
Sent from a fat crate under my desk. Formatting is fine.
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