Re: [Xen-devel] [PATCH] x86/emul: Correctly annotate all push/pop %sreg instructions

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 24/10/16 10:54, Wei Liu wrote:
> On Mon, Oct 24, 2016 at 03:23:01AM -0600, Jan Beulich wrote:
>>>>> On 19.10.16 at 18:30, <andrew.cooper3@xxxxxxxxxx> wrote:
>>> c/s 373923ed9c2 "x86emul: fix pushing of selector registers" redirected
>>> all push %sreg instructions into the general push path.  However, this
>>> ends up hitting the assertion at the head of the push path.
>>>
>>> Annotate All push and pop %sreg instructions as Mov, indicating that
>>> they do not read the destination operand.
>>>
>>> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
>> Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
>>
>> I wonder how this passed both my and osstest's testing...
>>
> OSSTest Cambridge instance (with rather old hardware) caught this IIRC.

It only showed up in the VGABIOS running on Gen-1 VT-x without
unrestricted_guest.  Under those circumstances, we emulate far more.

~Andrew

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