Re: [PATCH v5 3/3] drm/xe/guc/tlb: Flush g2h worker in case of tlb timeout

[Nirmoy Das <nirmoy.das@intel.com>]

On 11/1/2024 7:51 PM, John Harrison wrote:
> On 10/29/2024 05:01, Nirmoy Das wrote:
>> Flush the g2h worker explicitly if TLB timeout happens which is
>> observed on LNL and that points to the recent scheduling issue with
>> E-cores on LNL.
>>
>> This is similar to the recent fix:
>> commit e51527233804 ("drm/xe/guc/ct: Flush g2h worker in case of g2h
>> response timeout") and should be removed once there is E core
>> scheduling fix.
>>
>> v2: Add platform check(Himal)
>> v3: Remove gfx platform check as the issue related to cpu
>>      platform(John)
>>      Use the common WA macro(John) and print when the flush
>>      resolves timeout(Matt B)
>> v4: Remove the resolves log and do the flush before taking
>>      pending_lock(Matt A)
>>
>> Cc: Badal Nilawar <badal.nilawar@intel.com>
>> Cc: Matthew Brost <matthew.brost@intel.com>
>> Cc: Matthew Auld <matthew.auld@intel.com>
>> Cc: John Harrison <John.C.Harrison@Intel.com>
>> Cc: Himal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>
>> Cc: Lucas De Marchi <lucas.demarchi@intel.com>
>> Cc: <stable@vger.kernel.org> # v6.11+
>> Link: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/2687
>> Signed-off-by: Nirmoy Das <nirmoy.das@intel.com>
>> ---
>>   drivers/gpu/drm/xe/xe_gt_tlb_invalidation.c | 2 ++
>>   1 file changed, 2 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/xe/xe_gt_tlb_invalidation.c b/drivers/gpu/drm/xe/xe_gt_tlb_invalidation.c
>> index 773de1f08db9..3cb228c773cd 100644
>> --- a/drivers/gpu/drm/xe/xe_gt_tlb_invalidation.c
>> +++ b/drivers/gpu/drm/xe/xe_gt_tlb_invalidation.c
>> @@ -72,6 +72,8 @@ static void xe_gt_tlb_fence_timeout(struct work_struct *work)
>>       struct xe_device *xe = gt_to_xe(gt);
>>       struct xe_gt_tlb_invalidation_fence *fence, *next;
>>   +    LNL_FLUSH_WORK(&gt->uc.guc.ct.g2h_worker);
>> +
> Do we not want some kind of 'success required flush' message here as per the other instances?


This flush resolves TLB timeout but in this function, I can't think of a simple way to detect that and log a message.


Regards,

Nirmoy

> John.
>
>>       spin_lock_irq(&gt->tlb_invalidation.pending_lock);
>>       list_for_each_entry_safe(fence, next,
>>                    &gt->tlb_invalidation.pending_fences, link) {
>