Re: [Xen-devel] [PATCH 1/6] x86emul: CMPXCHG{8, 16}B ignore prefixes

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 13/12/16 14:01, Jan Beulich wrote:
> This removes 0F C7 from the list of two-byte opcodes treating prefixes
> 66, F3, and F2 as opcode extensions. We better manually handle this in
> the opcode specific code:
> - CMPXCHG8B ignores all these prefixes (its handling is being adjusted
>   accordingly, with a respective test case added as well, to avoid
>   re-introducing the subject of XSA-200),
> - RDRAND/RDSEED (support to be added subsequently) honor 66, but treat
>   F3 and F2 as opcode extensions (resolving to RDPID in the RDSEED
>   case, which in turn ignores 66).
>
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

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