RE: [PATCH v4 0/3] AMDGPU / RADEON / DRM Fix mapping of user pages

[Ruhl, Michael J]

>-----Original Message-----
>From: dri-devel <dri-devel-bounces@xxxxxxxxxxxxxxxxxxxxx> On Behalf Of
>Shane Francis
>Sent: Wednesday, March 25, 2020 5:08 AM
>To: dri-devel@xxxxxxxxxxxxxxxxxxxxx
>Cc: airlied@xxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; bigbeeshane@xxxxxxxxx;
>amd-gfx-request@xxxxxxxxxxxxxxxxxxxxx; alexander.deucher@xxxxxxx;
>christian.koenig@xxxxxxx
>Subject: [PATCH v4 0/3] AMDGPU / RADEON / DRM Fix mapping of user pages
>
>This patch set is to fix a bug in amdgpu / radeon drm that results in
>a crash when dma_map_sg combines elemnets within a scatterlist table.

s/elemnets/elements

>There are 2 shortfalls in the current kernel.
>
>1) AMDGPU / RADEON assumes that the requested and created scatterlist
>   table lengths using from dma_map_sg are equal. This may not be the
>   case using the newer dma-iommu implementation
>
>2) drm_prime does not fetch the length of the scatterlist
>   via the correct dma macro, this can use the incorrect length
>   being used (>0) in places where dma_map_sg has updated the table
>   elements.
>
>   The sg_dma_len macro is representative of the length of the sg item
>   after dma_map_sg
>
>Example Crash :
>> [drm:amdgpu_ttm_backend_bind [amdgpu]] *ERROR* failed to pin userptr
>
>This happens in OpenCL applications, causing them to crash or hang, on
>either amdgpu-pro or ROCm OpenCL implementations
>
>I have verified this fixes the above on kernel 5.5 and 5.5rc using an
>AMD Vega 64 GPU
>
>Shane Francis (3):
>  drm/prime: use dma length macro when mapping sg to arrays
>  drm/amdgpu: fix scatter-gather mapping with user pages
>  drm/radeon: fix scatter-gather mapping with user pages
>
> drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 2 +-
> drivers/gpu/drm/drm_prime.c             | 2 +-
> drivers/gpu/drm/radeon/radeon_ttm.c     | 2 +-
> 3 files changed, 3 insertions(+), 3 deletions(-)
>
>--
>2.26.0
>
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