[PATCH] drm/amdgpu: Ignore KFD eviction fences invalidating preemptible DMABuf imports

[Christian König]

Am 13.04.23 um 03:01 schrieb Felix Kuehling:
> Am 2023-04-12 um 18:25 schrieb Eric Huang:
>> It is to avoid redundant eviction for KFD's DMAbuf import
>> bo when dmaunmapping DMAbuf. The DMAbuf import bo has
>> been set as AMDGPU_PL_PREEMPT in KFD when mapping.
>>
>> Signed-off-by: Eric Huang <jinhuieric.huang at amd.com>
>
> Reviewed-by: Felix Kuehling <Felix.Kuehling at amd.com>
>
> I'd like to get an Acked-by from Christian as well before submitting 
> this.

I have to admit that I only partially followed the internal discussion, 
but in general you need a *really* good explanation for this.

E.g. add code comment and explain in the commit message extensively why 
this is needed and why there are no alternatives.

Regards,
Christian.

>
> Thanks,
>   Felix
>
>
>> ---
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 7 ++++++-
>>   1 file changed, 6 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c 
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
>> index 2430f3e9f3a7..64795fe9eecb 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
>> @@ -526,7 +526,12 @@ static int amdgpu_bo_move(struct 
>> ttm_buffer_object *bo, bool evict,
>>       if ((old_mem->mem_type == TTM_PL_TT ||
>>            old_mem->mem_type == AMDGPU_PL_PREEMPT) &&
>>           new_mem->mem_type == TTM_PL_SYSTEM) {
>> -        r = ttm_bo_wait_ctx(bo, ctx);
>> +        if (old_mem->mem_type == AMDGPU_PL_PREEMPT)
>> +            r = amdgpu_bo_sync_wait(abo,
>> +                        AMDGPU_FENCE_OWNER_KFD,
>> +                        ctx->interruptible);
>> +        else
>> +            r = ttm_bo_wait_ctx(bo, ctx);
>>           if (r)
>>               return r;