[PATCH] drm/amdgpu: fix max_entries calculation

[Pan, Xinhui]

> 2020年9月2日 20:05，Christian König <ckoenig.leichtzumerken at gmail.com> 写道：
> 
> Calculate the correct value for max_entries or we might run after the
> page_address array.
> 
> Signed-off-by: Christian König <christian.koenig at amd.com>
> Fixes: 1e691e244487 drm/amdgpu: stop allocating dummy GTT nodes
> ---
> drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> index 8bc2253939be..8aa9584c184f 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> @@ -1697,7 +1697,8 @@ static int amdgpu_vm_bo_split_mapping(struct amdgpu_device *adev,
> 				AMDGPU_GPU_PAGES_IN_CPU_PAGE;
> 		} else {
> 			addr = 0;
> -			max_entries = S64_MAX;
> +			max_entries = ((mapping->last - mapping->start) >>
> +				       AMDGPU_GPU_PAGE_SHIFT) + 1;

should it be like below?
max_entries = (mapping->last - mapping->start + 1 - pfn) * AMDGPU_GPU_PAGES_IN_CPU_PAGE;

last and start are already pfns. why still >> AMDGPU_GPU_PAGE_SHIFT? Am I missing something?

> 		}
> 
> 		if (pages_addr) {
> -- 
> 2.17.1
>