[PATCH 1/2] drm/amdgpu: fix start calculation in amdgpu_vram_mgr_new

[Arunpravin Paneer Selvam]

Hi Christian,

On 5/10/2022 5:06 PM, Christian König wrote:
> We still need to calculate a virtual start address for the resource to
> aid checking of it is visible or not.
>
> Signed-off-by: Christian König <christian.koenig at amd.com>
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c | 22 +++++++++++++-------
>   1 file changed, 14 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
> index 49e4092f447f..51d9d3a4456c 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
> @@ -496,16 +496,22 @@ static int amdgpu_vram_mgr_new(struct ttm_resource_manager *man,
>   			list_splice_tail(trim_list, &vres->blocks);
>   	}
>   
> -	list_for_each_entry(block, &vres->blocks, link)
> -		vis_usage += amdgpu_vram_mgr_vis_size(adev, block);
> +	vres->base.start = 0;
> +	list_for_each_entry(block, &vres->blocks, link) {
> +		unsigned long start;
>   
> -	block = amdgpu_vram_mgr_first_block(&vres->blocks);
> -	if (!block) {
> -		r = -EINVAL;
> -		goto error_fini;
> -	}
> +		start = amdgpu_vram_mgr_block_start(block) +
> +			amdgpu_vram_mgr_block_size(block);
> +		start >>= PAGE_SHIFT;
>   
> -	vres->base.start = amdgpu_vram_mgr_block_start(block) >> PAGE_SHIFT;
> +		if (start > vres->base.num_pages)
> +			start -= vres->base.num_pages;
I think this works for continuous blocks of addresses, but for a non 
continuous blocks allocated at different
locations and linked together using list, this might fetch an invalid 
address. I will check this patch on my
setup and inform you.

Regards,
Arun
> +		else
> +			start = 0;
> +		vres->base.start = max(vres->base.start, start);
> +
> +		vis_usage += amdgpu_vram_mgr_vis_size(adev, block);
> +	}
>   
>   	if (amdgpu_is_vram_mgr_blocks_contiguous(&vres->blocks))
>   		vres->base.placement |= TTM_PL_FLAG_CONTIGUOUS;