[PATCH] drm/amdgpu: disable userptr if swiotlb is active

[Kuehling, Felix]

I guess we'll need something similar for KFD? I don't think we've ever 
intentionally tested KFD with swiotlb. But I've seen some backtraces 
with swiotlb in them before. I wonder how badly broken it is ...

Regards,
   Felix

On 2019-02-20 8:46 a.m., Christian König wrote:
> Otherwise we can't be sure that we won't end up with a bounce buffer.
>
> Signed-off-by: Christian König <christian.koenig at amd.com>
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c | 4 ++++
>   1 file changed, 4 insertions(+)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
> index d21dd2f369da..abc65633119b 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
> @@ -289,6 +289,10 @@ int amdgpu_gem_userptr_ioctl(struct drm_device *dev, void *data,
>   	if (offset_in_page(args->addr | args->size))
>   		return -EINVAL;
>   
> +	/* We can't do this when swiotlb is active */
> +	if (adev->needs_swiotlb)
> +		return -ENXIO;
> +
>   	/* reject unknown flag values */
>   	if (args->flags & ~(AMDGPU_GEM_USERPTR_READONLY |
>   	    AMDGPU_GEM_USERPTR_ANONONLY | AMDGPU_GEM_USERPTR_VALIDATE |