[PATCH] drm/amdgpu: Check BO's requested pinning domains against its preferred_domains

[Christian König]

Am 12.07.22 um 00:44 schrieb sunpeng.li at amd.com:
> From: Leo Li <sunpeng.li at amd.com>
>
> When pinning a buffer, we should check to see if there are any
> additional restrictions imposed by bo->preferred_domains. This will
> prevent the BO from being moved to an invalid domain when pinning.
>
> For example, this can happen if the user requests to create a BO in GTT
> domain for display scanout. amdgpu_dm will allow pinning to either VRAM
> or GTT domains, since DCN can scanout from either or. However, in
> amdgpu_bo_pin_restricted(), pinning to VRAM is preferred if there is
> adequate carveout. This can lead to pinning to VRAM despite the user
> requesting GTT placement for the BO.
>
> Signed-off-by: Leo Li <sunpeng.li at amd.com>
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_object.c | 3 +++
>   1 file changed, 3 insertions(+)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
> index 8a7b0f6162da..50400d70ef12 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
> @@ -883,6 +883,9 @@ int amdgpu_bo_pin_restricted(struct amdgpu_bo *bo, u32 domain,
>   	if (WARN_ON_ONCE(min_offset > max_offset))
>   		return -EINVAL;
>   
> +	/* Check domain to be pinned to against preferred domains */
> +	domain = bo->preferred_domains & domain

Please guard that with an "if (bo->preferred_domains & domain)" to 
handle the case when the kernel needs to override the pin domain. That 
can happen when we export a BO to a V4L camera (for example).

Apart from that looks like a rather nice bugfix.

Alex should we add a CC stable to this?

Regards,
Christian.

> +
>   	/* A shared bo cannot be migrated to VRAM */
>   	if (bo->tbo.base.import_attach) {
>   		if (domain & AMDGPU_GEM_DOMAIN_GTT)