[libvirt] xsave-related CPU features implementation

[Jiri Denemark]

On Thu, May 19, 2016 at 19:56:18 +0300, Alexander Burluka wrote:
> Hello,
> 
> I would like to add support for the next CPU features which presents in
> QEMU - xsaveopt, xsavec, xgetbv1, xsaves. These features were introduced
> in QEMU commit 0bb0b2d2fe7f645ddaf1f0ff40ac669c9feb4aa1.
> I was confused by comment in src/cpu/cpu_map.xml:
> ...
> <!-- We support only ecx 0x0 now as it's done by a workaround -->
> ...
> Is this comment is still actual? This feature set needs ecx 0x1.
> I can see that it was a temporary solution in commit by Peter Krempa
> 012f9b19ef3812884e207dc431571502de4cebce. Does these features addtion
> require CPU detection improvement? Or can I simply put them into 
> src/cpu/cpu_map.xml?

Yeah, the CPU detection code needs to be improved to support features
which require more than just eax set when running CPUID instruction.

I'm currently working on adding more CPUID tests (and data) to libvirt
and I'll take that as the opportunity to add support for these new
features.

Jirka