Re: [Intel-gfx] [PATCH v2 13/15] drm/ttm: Add BO and offset arguments for vm_access and vm_fault ttm handlers.

["Thomas Hellström" <thomas.hellstrom@linux.intel.com>]

+ Christian König

On 5/18/21 10:26 AM, Thomas Hellström wrote:
> From: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
>
> This allows other drivers that may not setup the vma in the same way
> to use the ttm bo helpers.
>
> Also clarify the documentation a bit, especially related to VM_FAULT_RETRY.
>
> Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>

Lgtm. Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>

> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c    |  4 +-
>   drivers/gpu/drm/nouveau/nouveau_ttm.c      |  4 +-
>   drivers/gpu/drm/radeon/radeon_ttm.c        |  4 +-
>   drivers/gpu/drm/ttm/ttm_bo_vm.c            | 84 +++++++++++++---------
>   drivers/gpu/drm/vmwgfx/vmwgfx_page_dirty.c |  8 ++-
>   include/drm/ttm/ttm_bo_api.h               |  9 ++-
>   6 files changed, 75 insertions(+), 38 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> index d5a9d7a88315..89dafe14f828 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> @@ -1919,7 +1919,9 @@ static vm_fault_t amdgpu_ttm_fault(struct vm_fault *vmf)
>   	if (ret)
>   		goto unlock;
>   
> -	ret = ttm_bo_vm_fault_reserved(vmf, vmf->vma->vm_page_prot,
> +	ret = ttm_bo_vm_fault_reserved(bo, vmf,
> +				       drm_vma_node_start(&bo->base.vma_node),
> +				       vmf->vma->vm_page_prot,
>   				       TTM_BO_VM_NUM_PREFAULT, 1);
>   	if (ret == VM_FAULT_RETRY && !(vmf->flags & FAULT_FLAG_RETRY_NOWAIT))
>   		return ret;
> diff --git a/drivers/gpu/drm/nouveau/nouveau_ttm.c b/drivers/gpu/drm/nouveau/nouveau_ttm.c
> index b81ae90b8449..555fb6d8be8b 100644
> --- a/drivers/gpu/drm/nouveau/nouveau_ttm.c
> +++ b/drivers/gpu/drm/nouveau/nouveau_ttm.c
> @@ -144,7 +144,9 @@ static vm_fault_t nouveau_ttm_fault(struct vm_fault *vmf)
>   
>   	nouveau_bo_del_io_reserve_lru(bo);
>   	prot = vm_get_page_prot(vma->vm_flags);
> -	ret = ttm_bo_vm_fault_reserved(vmf, prot, TTM_BO_VM_NUM_PREFAULT, 1);
> +	ret = ttm_bo_vm_fault_reserved(bo, vmf,
> +				       drm_vma_node_start(&bo->base.vma_node),
> +				       prot, TTM_BO_VM_NUM_PREFAULT, 1);
>   	nouveau_bo_add_io_reserve_lru(bo);
>   	if (ret == VM_FAULT_RETRY && !(vmf->flags & FAULT_FLAG_RETRY_NOWAIT))
>   		return ret;
> diff --git a/drivers/gpu/drm/radeon/radeon_ttm.c b/drivers/gpu/drm/radeon/radeon_ttm.c
> index 3361d11769a2..ba48a2acdef0 100644
> --- a/drivers/gpu/drm/radeon/radeon_ttm.c
> +++ b/drivers/gpu/drm/radeon/radeon_ttm.c
> @@ -816,7 +816,9 @@ static vm_fault_t radeon_ttm_fault(struct vm_fault *vmf)
>   	if (ret)
>   		goto unlock_resv;
>   
> -	ret = ttm_bo_vm_fault_reserved(vmf, vmf->vma->vm_page_prot,
> +	ret = ttm_bo_vm_fault_reserved(bo, vmf,
> +				       drm_vma_node_start(&bo->base.vma_node),
> +				       vmf->vma->vm_page_prot,
>   				       TTM_BO_VM_NUM_PREFAULT, 1);
>   	if (ret == VM_FAULT_RETRY && !(vmf->flags & FAULT_FLAG_RETRY_NOWAIT))
>   		goto unlock_mclk;
> diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c b/drivers/gpu/drm/ttm/ttm_bo_vm.c
> index b31b18058965..ed00ccf1376e 100644
> --- a/drivers/gpu/drm/ttm/ttm_bo_vm.c
> +++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c
> @@ -42,7 +42,7 @@
>   #include <linux/mem_encrypt.h>
>   
>   static vm_fault_t ttm_bo_vm_fault_idle(struct ttm_buffer_object *bo,
> -				struct vm_fault *vmf)
> +				       struct vm_fault *vmf)
>   {
>   	vm_fault_t ret = 0;
>   	int err = 0;
> @@ -122,7 +122,8 @@ static unsigned long ttm_bo_io_mem_pfn(struct ttm_buffer_object *bo,
>    * Return:
>    *    0 on success and the bo was reserved.
>    *    VM_FAULT_RETRY if blocking wait.
> - *    VM_FAULT_NOPAGE if blocking wait and retrying was not allowed.
> + *    VM_FAULT_NOPAGE if blocking wait and retrying was not allowed, or wait interrupted.
> + *    VM_FAULT_SIGBUS if wait on bo->moving failed for reason other than a signal.
>    */
>   vm_fault_t ttm_bo_vm_reserve(struct ttm_buffer_object *bo,
>   			     struct vm_fault *vmf)
> @@ -254,7 +255,9 @@ static vm_fault_t ttm_bo_vm_insert_huge(struct vm_fault *vmf,
>   
>   /**
>    * ttm_bo_vm_fault_reserved - TTM fault helper
> + * @bo: The buffer object
>    * @vmf: The struct vm_fault given as argument to the fault callback
> + * @mmap_base: The base of the mmap, to which the @vmf fault is relative to.
>    * @prot: The page protection to be used for this memory area.
>    * @num_prefault: Maximum number of prefault pages. The caller may want to
>    * specify this based on madvice settings and the size of the GPU object
> @@ -265,19 +268,28 @@ static vm_fault_t ttm_bo_vm_insert_huge(struct vm_fault *vmf,
>    * memory backing the buffer object, and then returns a return code
>    * instructing the caller to retry the page access.
>    *
> + * This function ensures any pipelined wait is finished.
> + *
> + * WARNING:
> + * On VM_FAULT_RETRY, the bo will be unlocked by this function when
> + * #FAULT_FLAG_RETRY_NOWAIT is not set inside @vmf->flags. In this
> + * case, the caller should not unlock the @bo.
> + *
>    * Return:
> - *   VM_FAULT_NOPAGE on success or pending signal
> + *   0 on success.
> + *   VM_FAULT_NOPAGE on pending signal
>    *   VM_FAULT_SIGBUS on unspecified error
>    *   VM_FAULT_OOM on out-of-memory
> - *   VM_FAULT_RETRY if retryable wait
> + *   VM_FAULT_RETRY if retryable wait, see WARNING above.
>    */
> -vm_fault_t ttm_bo_vm_fault_reserved(struct vm_fault *vmf,
> +vm_fault_t ttm_bo_vm_fault_reserved(struct ttm_buffer_object *bo,
> +				    struct vm_fault *vmf,
> +				    unsigned long mmap_base,
>   				    pgprot_t prot,
>   				    pgoff_t num_prefault,
>   				    pgoff_t fault_page_size)
>   {
>   	struct vm_area_struct *vma = vmf->vma;
> -	struct ttm_buffer_object *bo = vma->vm_private_data;
>   	struct ttm_device *bdev = bo->bdev;
>   	unsigned long page_offset;
>   	unsigned long page_last;
> @@ -286,15 +298,11 @@ vm_fault_t ttm_bo_vm_fault_reserved(struct vm_fault *vmf,
>   	struct page *page;
>   	int err;
>   	pgoff_t i;
> -	vm_fault_t ret = VM_FAULT_NOPAGE;
> +	vm_fault_t ret;
>   	unsigned long address = vmf->address;
>   
> -	/*
> -	 * Wait for buffer data in transit, due to a pipelined
> -	 * move.
> -	 */
>   	ret = ttm_bo_vm_fault_idle(bo, vmf);
> -	if (unlikely(ret != 0))
> +	if (ret)
>   		return ret;
>   
>   	err = ttm_mem_io_reserve(bdev, &bo->mem);
> @@ -302,9 +310,8 @@ vm_fault_t ttm_bo_vm_fault_reserved(struct vm_fault *vmf,
>   		return VM_FAULT_SIGBUS;
>   
>   	page_offset = ((address - vma->vm_start) >> PAGE_SHIFT) +
> -		vma->vm_pgoff - drm_vma_node_start(&bo->base.vma_node);
> -	page_last = vma_pages(vma) + vma->vm_pgoff -
> -		drm_vma_node_start(&bo->base.vma_node);
> +		vma->vm_pgoff - mmap_base;
> +	page_last = vma_pages(vma) + vma->vm_pgoff - mmap_base;
>   
>   	if (unlikely(page_offset >= bo->mem.num_pages))
>   		return VM_FAULT_SIGBUS;
> @@ -344,8 +351,7 @@ vm_fault_t ttm_bo_vm_fault_reserved(struct vm_fault *vmf,
>   			} else if (unlikely(!page)) {
>   				break;
>   			}
> -			page->index = drm_vma_node_start(&bo->base.vma_node) +
> -				page_offset;
> +			page->index = mmap_base + page_offset;
>   			pfn = page_to_pfn(page);
>   		}
>   
> @@ -392,7 +398,10 @@ vm_fault_t ttm_bo_vm_fault(struct vm_fault *vmf)
>   		return ret;
>   
>   	prot = vma->vm_page_prot;
> -	ret = ttm_bo_vm_fault_reserved(vmf, prot, TTM_BO_VM_NUM_PREFAULT, 1);
> +	ret = ttm_bo_vm_fault_reserved(bo, vmf,
> +				       drm_vma_node_start(&bo->base.vma_node),
> +				       prot, TTM_BO_VM_NUM_PREFAULT, 1);
> +
>   	if (ret == VM_FAULT_RETRY && !(vmf->flags & FAULT_FLAG_RETRY_NOWAIT))
>   		return ret;
>   
> @@ -460,22 +469,16 @@ static int ttm_bo_vm_access_kmap(struct ttm_buffer_object *bo,
>   	return len;
>   }
>   
> -int ttm_bo_vm_access(struct vm_area_struct *vma, unsigned long addr,
> -		     void *buf, int len, int write)
> +int ttm_bo_vm_access_reserved(struct ttm_buffer_object *bo,
> +			      struct vm_area_struct *vma,
> +			      unsigned long offset,
> +			      void *buf, int len, int write)
>   {
> -	struct ttm_buffer_object *bo = vma->vm_private_data;
> -	unsigned long offset = (addr) - vma->vm_start +
> -		((vma->vm_pgoff - drm_vma_node_start(&bo->base.vma_node))
> -		 << PAGE_SHIFT);
>   	int ret;
>   
>   	if (len < 1 || (offset + len) >> PAGE_SHIFT > bo->mem.num_pages)
>   		return -EIO;
>   
> -	ret = ttm_bo_reserve(bo, true, false, NULL);
> -	if (ret)
> -		return ret;
> -
>   	switch (bo->mem.mem_type) {
>   	case TTM_PL_SYSTEM:
>   		if (unlikely(bo->ttm->page_flags & TTM_PAGE_FLAG_SWAPPED)) {
> @@ -485,16 +488,33 @@ int ttm_bo_vm_access(struct vm_area_struct *vma, unsigned long addr,
>   		}
>   		fallthrough;
>   	case TTM_PL_TT:
> -		ret = ttm_bo_vm_access_kmap(bo, offset, buf, len, write);
> -		break;
> +		return ttm_bo_vm_access_kmap(bo, offset, buf, len, write);
>   	default:
>   		if (bo->bdev->funcs->access_memory)
> -			ret = bo->bdev->funcs->access_memory(
> +			return bo->bdev->funcs->access_memory(
>   				bo, offset, buf, len, write);
>   		else
> -			ret = -EIO;
> +			return -EIO;
>   	}
>   
> +	return ret;
> +}
> +EXPORT_SYMBOL(ttm_bo_vm_access_reserved);
> +
> +int ttm_bo_vm_access(struct vm_area_struct *vma, unsigned long addr,
> +		     void *buf, int len, int write)
> +{
> +	struct ttm_buffer_object *bo = vma->vm_private_data;
> +	unsigned long offset = (addr) - vma->vm_start +
> +		((vma->vm_pgoff - drm_vma_node_start(&bo->base.vma_node))
> +		 << PAGE_SHIFT);
> +	int ret;
> +
> +	ret = ttm_bo_reserve(bo, true, false, NULL);
> +	if (ret)
> +		return ret;
> +
> +	ret = ttm_bo_vm_access_reserved(bo, vma, offset, buf, len, write);
>   	ttm_bo_unreserve(bo);
>   
>   	return ret;
> diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_page_dirty.c b/drivers/gpu/drm/vmwgfx/vmwgfx_page_dirty.c
> index 45c9c6a7f1d6..56ecace0cf5c 100644
> --- a/drivers/gpu/drm/vmwgfx/vmwgfx_page_dirty.c
> +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_page_dirty.c
> @@ -477,7 +477,9 @@ vm_fault_t vmw_bo_vm_fault(struct vm_fault *vmf)
>   	else
>   		prot = vm_get_page_prot(vma->vm_flags);
>   
> -	ret = ttm_bo_vm_fault_reserved(vmf, prot, num_prefault, 1);
> +	ret = ttm_bo_vm_fault_reserved(bo, vmf,
> +				       drm_vma_node_start(&bo->base.vma_node),
> +				       prot, num_prefault, 1);
>   	if (ret == VM_FAULT_RETRY && !(vmf->flags & FAULT_FLAG_RETRY_NOWAIT))
>   		return ret;
>   
> @@ -546,7 +548,9 @@ vm_fault_t vmw_bo_vm_huge_fault(struct vm_fault *vmf,
>   		prot = vm_get_page_prot(vma->vm_flags);
>   	}
>   
> -	ret = ttm_bo_vm_fault_reserved(vmf, prot, 1, fault_page_size);
> +	ret = ttm_bo_vm_fault_reserved(bo, vmf,
> +				       drm_vma_node_start(&bo->base.vma_node),
> +				       prot, 1, fault_page_size);
>   	if (ret == VM_FAULT_RETRY && !(vmf->flags & FAULT_FLAG_RETRY_NOWAIT))
>   		return ret;
>   
> diff --git a/include/drm/ttm/ttm_bo_api.h b/include/drm/ttm/ttm_bo_api.h
> index 639521880c29..434f91f1fdbf 100644
> --- a/include/drm/ttm/ttm_bo_api.h
> +++ b/include/drm/ttm/ttm_bo_api.h
> @@ -605,7 +605,9 @@ int ttm_mem_evict_first(struct ttm_device *bdev,
>   vm_fault_t ttm_bo_vm_reserve(struct ttm_buffer_object *bo,
>   			     struct vm_fault *vmf);
>   
> -vm_fault_t ttm_bo_vm_fault_reserved(struct vm_fault *vmf,
> +vm_fault_t ttm_bo_vm_fault_reserved(struct ttm_buffer_object *bo,
> +				    struct vm_fault *vmf,
> +				    unsigned long mmap_base,
>   				    pgprot_t prot,
>   				    pgoff_t num_prefault,
>   				    pgoff_t fault_page_size);
> @@ -616,6 +618,11 @@ void ttm_bo_vm_open(struct vm_area_struct *vma);
>   
>   void ttm_bo_vm_close(struct vm_area_struct *vma);
>   
> +int ttm_bo_vm_access_reserved(struct ttm_buffer_object *bo,
> +			      struct vm_area_struct *vma,
> +			      unsigned long offset,
> +			      void *buf, int len, int write);
> +
>   int ttm_bo_vm_access(struct vm_area_struct *vma, unsigned long addr,
>   		     void *buf, int len, int write);
>   bool ttm_bo_delayed_delete(struct ttm_device *bdev, bool remove_all);
_______________________________________________
Intel-gfx mailing list
Intel-gfx@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/intel-gfx