Re: [Xen-devel] [PATCH 10/24] xen: mask XSAVE from cpuid

Andi Kleen
2009-03-17T11:56:20Z

> The point is YOU DON'T KNOW. In particular, there might be new traps,
> there might be new state, there might be new MSRs, there might be new
> control bits... anything. Therefore, you cannot blindly pass the bit
> on, even though XSAVE solves one part of the problem.

I think what will happen if you don't expose it is that there will
be always hypervisors which are behind and applications/OS will end up
doing probing for opcodes instead of trusting CPUID bits.

Probably not what you intended.

-Andi
--
ak@linux.intel.com -- Speaking for myself only.