[Linaro-mm-sig] [PATCH AUTOSEL 6.13 15/34] drm/amdgpu: allow pinning DMA-bufs into VRAM if all importers can do P2P

[Alex Deucher]

On Mon, Apr 14, 2025 at 9:28 AM Sasha Levin <sashal at kernel.org> wrote:
>
> From: Christian König <christian.koenig at amd.com>
>
> [ Upstream commit f5e7fabd1f5c65b2e077efcdb118cfa67eae7311 ]
>
> Try pinning into VRAM to allow P2P with RDMA NICs without ODP
> support if all attachments can do P2P. If any attachment can't do
> P2P just pin into GTT instead.
>
> Acked-by: Simona Vetter <simona.vetter at ffwll.ch>
> Signed-off-by: Christian König <christian.koenig at amd.com>
> Signed-off-by: Felix Kuehling <felix.kuehling at amd.com>
> Reviewed-by: Felix Kuehling <felix.kuehling at amd.com>
> Tested-by: Pak Nin Lui <pak.lui at amd.com>
> Cc: Simona Vetter <simona.vetter at ffwll.ch>
> Signed-off-by: Alex Deucher <alexander.deucher at amd.com>
> Signed-off-by: Sasha Levin <sashal at kernel.org>

This should not go to stable.  It depends on dmem cgroups.

Alex


> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c | 25 +++++++++++++++------
>  1 file changed, 18 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c
> index 8e81a83d37d84..83390143c2e9f 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c
> @@ -72,11 +72,25 @@ static int amdgpu_dma_buf_attach(struct dma_buf *dmabuf,
>   */
>  static int amdgpu_dma_buf_pin(struct dma_buf_attachment *attach)
>  {
> -       struct drm_gem_object *obj = attach->dmabuf->priv;
> -       struct amdgpu_bo *bo = gem_to_amdgpu_bo(obj);
> +       struct dma_buf *dmabuf = attach->dmabuf;
> +       struct amdgpu_bo *bo = gem_to_amdgpu_bo(dmabuf->priv);
> +       u32 domains = bo->preferred_domains;
>
> -       /* pin buffer into GTT */
> -       return amdgpu_bo_pin(bo, AMDGPU_GEM_DOMAIN_GTT);
> +       dma_resv_assert_held(dmabuf->resv);
> +
> +       /*
> +        * Try pinning into VRAM to allow P2P with RDMA NICs without ODP
> +        * support if all attachments can do P2P. If any attachment can't do
> +        * P2P just pin into GTT instead.
> +        */
> +       list_for_each_entry(attach, &dmabuf->attachments, node)
> +               if (!attach->peer2peer)
> +                       domains &= ~AMDGPU_GEM_DOMAIN_VRAM;
> +
> +       if (domains & AMDGPU_GEM_DOMAIN_VRAM)
> +               bo->flags |= AMDGPU_GEM_CREATE_CPU_ACCESS_REQUIRED;
> +
> +       return amdgpu_bo_pin(bo, domains);
>  }
>
>  /**
> @@ -131,9 +145,6 @@ static struct sg_table *amdgpu_dma_buf_map(struct dma_buf_attachment *attach,
>                 r = ttm_bo_validate(&bo->tbo, &bo->placement, &ctx);
>                 if (r)
>                         return ERR_PTR(r);
> -
> -       } else if (bo->tbo.resource->mem_type != TTM_PL_TT) {
> -               return ERR_PTR(-EBUSY);
>         }
>
>         switch (bo->tbo.resource->mem_type) {
> --
> 2.39.5
>
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