Re: [Xen-devel] [PATCH RFC v3 4/8] x86emul: support MOVDIR64B insn

[Jan Beulich <jbeulich@xxxxxxxx>]

On 06.01.2020 20:38, Andrew Cooper wrote:
> On 06/01/2020 16:36, Jan Beulich wrote:
>> Note that SDM revision 070 doesn't specify exception behavior for
>> ModRM.mod != 0b11; assuming #UD here.
>>
>> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
>> ---
>> RFC: Yet to be tested (once SDE supports it).
> 
> Do you have any plans for how to support ENQCMD{,S} which are just
> variations of MOVDIR64B using the F2 and F3 prefixes for behaviour
> modification, and whether those might alter what we do here?
> 
> The underlying write out into the system is going to be largely the
> same, but it can't be shared with MOVDIR64B because it generates a
> different type of bus transaction.  Also, they require ZF to find their
> way back out of the rmw() handler.

To be honest, I hadn't looked at the ENQCMD{,S} details at all yet
(and iirc they weren't even available when I first worked on this).
I will re-consider the approach - thanks for pointing this out.

Jan

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