Re: [PATCH 6/6] drm/amdgpu: Do bo_va ref counting for KFD BOs

["Chen, Xiaogang" <xiaogang.chen@amd.com>]

Reviewed-by: Xiaogang Chen <Xiaoganng.Chen@amd.com>

Regards

Xiaogang

On 1/11/2023 7:31 PM, Felix Kuehling wrote:
> This is needed to correctly handle BOs imported into the GEM API, which
> would otherwise get added twice to the same VM.
>
> Signed-off-by: Felix Kuehling <Felix.Kuehling@amd.com>
> ---
>   .../gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c  | 28 +++++++++++++++----
>   1 file changed, 22 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
> index df08e84f01d7..8b5ba2e04a79 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c
> @@ -370,9 +370,17 @@ static int amdgpu_amdkfd_bo_validate_and_fence(struct amdgpu_bo *bo,
>   		return ret;
>   
>   	ret = amdgpu_amdkfd_bo_validate(bo, domain, true);
> -	if (!ret)
> -		dma_resv_add_fence(bo->tbo.base.resv, fence,
> -				   DMA_RESV_USAGE_BOOKKEEP);
> +	if (ret)
> +		goto unreserve_out;
> +
> +	ret = dma_resv_reserve_fences(bo->tbo.base.resv, 1);
> +	if (ret)
> +		goto unreserve_out;
> +
> +	dma_resv_add_fence(bo->tbo.base.resv, fence,
> +			   DMA_RESV_USAGE_BOOKKEEP);
> +
> +unreserve_out:
>   	amdgpu_bo_unreserve(bo);
>   
>   	return ret;
> @@ -785,6 +793,7 @@ static int kfd_mem_attach(struct amdgpu_device *adev, struct kgd_mem *mem,
>   	uint64_t va = mem->va;
>   	struct kfd_mem_attachment *attachment[2] = {NULL, NULL};
>   	struct amdgpu_bo *bo[2] = {NULL, NULL};
> +	struct amdgpu_bo_va *bo_va;
>   	bool same_hive = false;
>   	int i, ret;
>   
> @@ -871,7 +880,12 @@ static int kfd_mem_attach(struct amdgpu_device *adev, struct kgd_mem *mem,
>   			pr_debug("Unable to reserve BO during memory attach");
>   			goto unwind;
>   		}
> -		attachment[i]->bo_va = amdgpu_vm_bo_add(adev, vm, bo[i]);
> +		bo_va = amdgpu_vm_bo_find(vm, bo[i]);
> +		if (!bo_va)
> +			bo_va = amdgpu_vm_bo_add(adev, vm, bo[i]);
> +		else
> +			++bo_va->ref_count;
> +		attachment[i]->bo_va = bo_va;
>   		amdgpu_bo_unreserve(bo[i]);
>   		if (unlikely(!attachment[i]->bo_va)) {
>   			ret = -ENOMEM;
> @@ -895,7 +909,8 @@ static int kfd_mem_attach(struct amdgpu_device *adev, struct kgd_mem *mem,
>   			continue;
>   		if (attachment[i]->bo_va) {
>   			amdgpu_bo_reserve(bo[i], true);
> -			amdgpu_vm_bo_del(adev, attachment[i]->bo_va);
> +			if (--attachment[i]->bo_va->ref_count == 0)
> +				amdgpu_vm_bo_del(adev, attachment[i]->bo_va);
>   			amdgpu_bo_unreserve(bo[i]);
>   			list_del(&attachment[i]->list);
>   		}
> @@ -912,7 +927,8 @@ static void kfd_mem_detach(struct kfd_mem_attachment *attachment)
>   
>   	pr_debug("\t remove VA 0x%llx in entry %p\n",
>   			attachment->va, attachment);
> -	amdgpu_vm_bo_del(attachment->adev, attachment->bo_va);
> +	if (--attachment->bo_va->ref_count == 0)
> +		amdgpu_vm_bo_del(attachment->adev, attachment->bo_va);
>   	drm_gem_object_put(&bo->tbo.base);
>   	list_del(&attachment->list);
>   	kfree(attachment);