[Intel-xe] [PATCH] drm/xe: Disallow pinning dma-bufs in VRAM

[Oded Gabbay]

On Tue, Sep 19, 2023 at 11:46 AM Thomas Hellström
<thomas.hellstrom at linux.intel.com> wrote:
>
> For now only support pinning in TT memory, for two reasons:
> 1) Avoid pinning in a placement not accessible to some importers.
> 2) Pinning in VRAM requires PIN accounting which is a to-do.
>
> Suggested-by: Oded Gabbay <ogabbay at kernel.org>
> Signed-off-by: Thomas Hellström <thomas.hellstrom at linux.intel.com>
> ---
>  drivers/gpu/drm/xe/xe_dma_buf.c | 25 +++++++++++++++++++++----
>  1 file changed, 21 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/xe/xe_dma_buf.c b/drivers/gpu/drm/xe/xe_dma_buf.c
> index 09343b8b3e96..bd8d51e7f93f 100644
> --- a/drivers/gpu/drm/xe/xe_dma_buf.c
> +++ b/drivers/gpu/drm/xe/xe_dma_buf.c
> @@ -49,13 +49,30 @@ static int xe_dma_buf_pin(struct dma_buf_attachment *attach)
>  {
>         struct drm_gem_object *obj = attach->dmabuf->priv;
>         struct xe_bo *bo = gem_to_xe_bo(obj);
> +       struct xe_device *xe = xe_bo_device(bo);
> +       int ret;
>
>         /*
> -        * Migrate to TT first to increase the chance of non-p2p clients
> -        * can attach.
> +        * For now only support pinning in TT memory, for two reasons:
> +        * 1) Avoid pinning in a placement not accessible to some importers.
> +        * 2) Pinning in VRAM requires PIN accounting which is a to-do.
>          */
> -       (void)xe_bo_migrate(bo, XE_PL_TT);
> -       xe_bo_pin_external(bo);
> +       if (xe_bo_is_pinned(bo) && bo->ttm.resource->placement != XE_PL_TT) {
> +               drm_dbg(&xe->drm, "Can't migrate pinned bo for dma-buf pin.\n");
> +               return -EINVAL;
> +       }
> +
> +       ret = xe_bo_migrate(bo, XE_PL_TT);
> +       if (ret) {
> +               if (ret != -EINTR && ret != -ERESTARTSYS)
> +                       drm_dbg(&xe->drm,
> +                               "Failed migrating dma-buf to TT memory: %pe\n",
> +                               ERR_PTR(ret));
> +               return ret;
> +       }
> +
> +       ret = xe_bo_pin_external(bo);
> +       xe_assert(xe, !ret);
>
>         return 0;
>  }
> --
> 2.41.0
>
Reviewed-by: Oded Gabbay <ogabbay at kernel.org>
Thanks,
Oded