[PATCH] drm/amdgpu: skip huge page for PRT mapping

[Christian König]

Hi Jerry,

Am 05.06.2018 um 03:50 schrieb Zhang, Jerry (Junwei):
> [SNIP]
>>
>> Can you check if the problem also vanishes when you disable the 
>> following
>> optimization in amdgpu_vm_update_ptes?
>>>                 /* We don't need to update PTEs for huge pages */
>>>                 if (entry->huge)
>>>                         continue;
>> Just comment this out for a test.
>
> Thanks to point it out.
> That indeed works well too.
>
> The issue happened by missing to update PTE for reserved PRT range, if 
> huge page is introduced.
>
> Not sure if below change is expected to save the huge page for PRT 
> support.
> That updates the huge page and fills the correct PTE for PRT as well, 
> different from current fix patch.
> {{{
>                 /* We don't need to update PTEs for huge pages */
> -               if (entry->huge)
> +               if (entry->huge && !(flags & AMDGPU_PTE_PRT))
>                         continue;
>
> }}}

problem is that not only affects PRT, but all mappings.

See the patch here if you currently can't receive mails from amd-gfx: 
https://patchwork.freedesktop.org/patch/227336/

Essentially I made a wrong assumption in the clear all code path. Please 
also note that I hadn't time to fully test this patch yet.

Christian.

>
>
> Jerry