Re: [Xen-devel] [HYBRID]: XEN_EMULATE_PREFIX in user process

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 29.06.12 at 10:07, Ian Campbell <Ian.Campbell@xxxxxxxxxx> wrote:
> On Fri, 2012-06-29 at 08:56 +0100, Jan Beulich wrote:
>> >>> On 29.06.12 at 03:00, Mukesh Rathor <mukesh.rathor@xxxxxxxxxx> wrote:
>> > BTW, for cpuid vmexit, if kernel mode I call pv_cpuid, if user mode, I
>> > just return cpuid values, as that's what would happen without the HVM
>> > container.
>> 
>> Which means you're not leveraging one of the things you could
>> gain from hybrid (after all, returning the native value to user
>> mode is one of the weaknesses of PV).
> 
> cpuid masking could happen in the HVM layer too, couldn't it?

But CPUID masking is rather limited (after all that's why CPUID
faulting got added later).

> Probably "XEN_EMULATE_PREFIX cpuid" and raw "cpuid" ought to return the
> same set of PV values in hybrid?

Yes, that's what I would think.

Jan


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