Re: [PATCH 3/4] drm/amdgpu: drm/amdgpu: Handle IOMMU enabled case

["Christian König" <ckoenig.leichtzumerken@gmail.com>]

Am 24.08.21 um 23:01 schrieb Andrey Grodzovsky:
> Handle all DMA IOMMU group related dependencies before the
> group is removed and we try to access it after free.
>
> Signed-off-by: Andrey Grodzovsky <andrey.grodzovsky@amd.com>
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_device.c |  2 +
>   drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c    | 50 ++++++++++++++++++++++
>   drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h    |  1 +
>   3 files changed, 53 insertions(+)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> index 0b5764aa98a4..288a465b8101 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> @@ -3860,6 +3860,8 @@ void amdgpu_device_fini_hw(struct amdgpu_device *adev)
>   
>   	amdgpu_device_ip_fini_early(adev);
>   
> +	amdgpu_ttm_clear_dma_mappings(adev);
> +
>   	amdgpu_gart_dummy_page_fini(adev);
>   
>   	amdgpu_device_unmap_mmio(adev);
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> index 446943e32e3e..f73d807db3b0 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> @@ -64,6 +64,7 @@
>   static int amdgpu_ttm_backend_bind(struct ttm_device *bdev,
>   				   struct ttm_tt *ttm,
>   				   struct ttm_resource *bo_mem);
> +
>   static void amdgpu_ttm_backend_unbind(struct ttm_device *bdev,
>   				      struct ttm_tt *ttm);
>   
> @@ -2293,6 +2294,55 @@ static ssize_t amdgpu_iomem_write(struct file *f, const char __user *buf,
>   	return result;
>   }
>   
> +void amdgpu_ttm_clear_dma_mappings(struct amdgpu_device *adev)

I strongly think that this function should be part of TTM. Something 
like ttm_device_force_unpopulate.

> +{
> +	struct ttm_device *bdev = &adev->mman.bdev;
> +	struct ttm_resource_manager *man;
> +	struct ttm_buffer_object *bo;
> +	unsigned int i, j;
> +
> +	spin_lock(&bdev->lru_lock);
> +	for (i = TTM_PL_SYSTEM; i < TTM_NUM_MEM_TYPES; ++i) {
> +		man = ttm_manager_type(bdev, i);
> +		if (!man || !man->use_tt)
> +			continue;
> +
> +		while (!list_empty(&man->pinned)) {
> +			bo = list_first_entry(&man->pinned, struct ttm_buffer_object, lru);
> +			/* Take ref against racing releases once lru_lock is unlocked */
> +			ttm_bo_get(bo);
> +			list_del_init(&bo->lru);
> +			spin_unlock(&bdev->lru_lock);
> +
> +			if (bo->ttm) {
> +				amdgpu_ttm_backend_unbind(bo->bdev, bo->ttm);
> +				ttm_tt_destroy_common(bo->bdev, bo->ttm);

Then you can also cleanly use ttm_tt_unpopulate here, cause this will 
result in incorrect statistics inside TTM atm.

Regards,
Christian.

> +			}
> +
> +			ttm_bo_put(bo);
> +			spin_lock(&bdev->lru_lock);
> +		}
> +
> +		for (j = 0; j < TTM_MAX_BO_PRIORITY; ++j) {
> +			while (!list_empty(&man->lru[j])) {
> +				bo = list_first_entry(&man->lru[j], struct ttm_buffer_object, lru);
> +				ttm_bo_get(bo);
> +				list_del_init(&bo->lru);
> +				spin_unlock(&bdev->lru_lock);
> +
> +				if (bo->ttm) {
> +					amdgpu_ttm_backend_unbind(bo->bdev, bo->ttm);
> +					ttm_tt_destroy_common(bo->bdev, bo->ttm);
> +				}
> +				ttm_bo_put(bo);
> +				spin_lock(&bdev->lru_lock);
> +			}
> +		}
> +	}
> +	spin_unlock(&bdev->lru_lock);
> +
> +}
> +
>   static const struct file_operations amdgpu_ttm_iomem_fops = {
>   	.owner = THIS_MODULE,
>   	.read = amdgpu_iomem_read,
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h
> index e69f3e8e06e5..02c8eac48a64 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.h
> @@ -190,6 +190,7 @@ bool amdgpu_ttm_tt_is_readonly(struct ttm_tt *ttm);
>   uint64_t amdgpu_ttm_tt_pde_flags(struct ttm_tt *ttm, struct ttm_resource *mem);
>   uint64_t amdgpu_ttm_tt_pte_flags(struct amdgpu_device *adev, struct ttm_tt *ttm,
>   				 struct ttm_resource *mem);
> +void amdgpu_ttm_clear_dma_mappings(struct amdgpu_device *adev);
>   
>   void amdgpu_ttm_debugfs_init(struct amdgpu_device *adev);
>