Re: [PATCH 2/2] drm/amdkfd: Clear MODE.VSKIP in gfx9 trap handler

[Lancelot SIX <Lancelot.Six@amd.com>]

On 10/01/2025 19:37, Jay Cornwall wrote:
> On 1/10/2025 12:14, Six, Lancelot wrote:
> 
>>> If user shader issues S_SETVSKIP then this state will persist when
>>> executing the trap handler, causing vector instructions to be
>>> skipped.
>>>
>>> Restore VSKIP state before resuming the user shader.
>>
>> Hi,
>>
>> I agree with the patch, I just find the text above confusing.
>>
>> Reading this, I'd expect to see vskip to be resumed before s_rfe in 
>> the "non-save"
>> path.  However, that patch touches the save path (disable vskip as 
>> soon as MODE
>> has been saved) so the rest of the save procedure can work as 
>> expected.  VSKIP
>> will eventually be restored in the restore path when restoring MODE 
>> (no change
>> needed), which is done after any instruction that could have been 
>> impacted by
>> VSKIP has already been executed.
> 
> How about:
> 
> VSKIP state is already saved/restored through the MODE register.

Perfect, that works for me.

Thanks,
Lancelot.