Re: [PATCH v10 2/9] x86emul: rework CMP and TEST emulation

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 29/05/2020 14:41, Jan Beulich wrote:
> On 29.05.2020 14:24, Andrew Cooper wrote:
>> On 25/05/2020 15:26, Jan Beulich wrote:
>>> Unlike similarly encoded insns these don't write their memory operands,
>> "write to their".
>>
>>> and hence x86_is_mem_write() should return false for them. However,
>>> rather than adding special logic there, rework how their emulation gets
>>> done, by making decoding attributes properly describe the r/o nature of
>>> their memory operands.
>> Describe how?  I see you've change the order of operands encoding, but
>> then override it back?
> There's no overriding back, I don't think: I change the table entries
> for opcodes 0x38 and 0x39, with no other adjustments the the attributes
> later on. For the other opcodes I leave the table entries as they are,
> and override the attributes for the specific sub-cases (identified by
> ModRM.reg).
>
> For opcodes 0x38 and 0x39 the change of the table entries implies
> changing the order of operands as passed to emulate_2op_SrcV(), hence
> the splitting of the cases in the main switch().
> I didn't think this was necessary to spell out in the commit message,
> but of course I can re-use most of the text above and add it into
> there, if you think that would help.

Yes please.  With something suitable, Acked-by: Andrew Cooper
<andrew.cooper3@xxxxxxxxxx>

~Andrew