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

Jan Beulich
2009-03-16T14:17:12Z

>>> Arjan van de Ven <arjan@infradead.org> 16.03.09 01:09 >>>
>Well.. pretty much all new instructions need Xen modifications due to
>the need to be emulate to deal with traps/vmexits/etc right?
>So I don't quite see many cpuid bits that would NOT involve some Xen
>modification or another ;)

No, new (user-mode accessible) instructions represent precisely the kind
of extension that do not require hypervisor (or OS) awareness (see SSE2
etc, AES, FMA). New registers otoh are examples of where awareness is
needed (SSE, AVX), as would be new privileged instructions.

Jan