Re: [PATCH v5 05/10] drm/ttm: Add vmap/vunmap to TTM and TTM GEM helpers

["Christian König" <christian.koenig@amd.com>]

Am 20.10.20 um 14:20 schrieb Thomas Zimmermann:
> The new functions ttm_bo_{vmap,vunmap}() map and unmap a TTM BO in kernel
> address space. The mapping's address is returned as struct dma_buf_map.
> Each function is a simplified version of TTM's existing kmap code. Both
> functions respect the memory's location ani/or writecombine flags.
>
> On top TTM's functions, GEM TTM helpers got drm_gem_ttm_{vmap,vunmap}(),
> two helpers that convert a GEM object into the TTM BO and forward the call
> to TTM's vmap/vunmap. These helpers can be dropped into the rsp GEM object
> callbacks.
>
> v5:
> 	* use size_t for storing mapping size (Christian)
> 	* ignore premapped memory areas correctly in ttm_bo_vunmap()
> 	* rebase onto latest TTM interfaces (Christian)
> 	* remove BUG() from ttm_bo_vmap() (Christian)
> v4:
> 	* drop ttm_kmap_obj_to_dma_buf() in favor of vmap helpers (Daniel,
> 	  Christian)
>
> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
> Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> Tested-by: Sam Ravnborg <sam@ravnborg.org>

Reviewed-by: Christian König <christian.koenig@amd.com>

> ---
>   drivers/gpu/drm/drm_gem_ttm_helper.c | 38 +++++++++++++++
>   drivers/gpu/drm/ttm/ttm_bo_util.c    | 72 ++++++++++++++++++++++++++++
>   include/drm/drm_gem_ttm_helper.h     |  6 +++
>   include/drm/ttm/ttm_bo_api.h         | 28 +++++++++++
>   include/linux/dma-buf-map.h          | 20 ++++++++
>   5 files changed, 164 insertions(+)
>
> diff --git a/drivers/gpu/drm/drm_gem_ttm_helper.c b/drivers/gpu/drm/drm_gem_ttm_helper.c
> index 0e4fb9ba43ad..db4c14d78a30 100644
> --- a/drivers/gpu/drm/drm_gem_ttm_helper.c
> +++ b/drivers/gpu/drm/drm_gem_ttm_helper.c
> @@ -49,6 +49,44 @@ void drm_gem_ttm_print_info(struct drm_printer *p, unsigned int indent,
>   }
>   EXPORT_SYMBOL(drm_gem_ttm_print_info);
>   
> +/**
> + * drm_gem_ttm_vmap() - vmap &ttm_buffer_object
> + * @gem: GEM object.
> + * @map: [out] returns the dma-buf mapping.
> + *
> + * Maps a GEM object with ttm_bo_vmap(). This function can be used as
> + * &drm_gem_object_funcs.vmap callback.
> + *
> + * Returns:
> + * 0 on success, or a negative errno code otherwise.
> + */
> +int drm_gem_ttm_vmap(struct drm_gem_object *gem,
> +		     struct dma_buf_map *map)
> +{
> +	struct ttm_buffer_object *bo = drm_gem_ttm_of_gem(gem);
> +
> +	return ttm_bo_vmap(bo, map);
> +
> +}
> +EXPORT_SYMBOL(drm_gem_ttm_vmap);
> +
> +/**
> + * drm_gem_ttm_vunmap() - vunmap &ttm_buffer_object
> + * @gem: GEM object.
> + * @map: dma-buf mapping.
> + *
> + * Unmaps a GEM object with ttm_bo_vunmap(). This function can be used as
> + * &drm_gem_object_funcs.vmap callback.
> + */
> +void drm_gem_ttm_vunmap(struct drm_gem_object *gem,
> +			struct dma_buf_map *map)
> +{
> +	struct ttm_buffer_object *bo = drm_gem_ttm_of_gem(gem);
> +
> +	ttm_bo_vunmap(bo, map);
> +}
> +EXPORT_SYMBOL(drm_gem_ttm_vunmap);
> +
>   /**
>    * drm_gem_ttm_mmap() - mmap &ttm_buffer_object
>    * @gem: GEM object.
> diff --git a/drivers/gpu/drm/ttm/ttm_bo_util.c b/drivers/gpu/drm/ttm/ttm_bo_util.c
> index ba7ab5ed85d0..5c79418405ea 100644
> --- a/drivers/gpu/drm/ttm/ttm_bo_util.c
> +++ b/drivers/gpu/drm/ttm/ttm_bo_util.c
> @@ -32,6 +32,7 @@
>   #include <drm/ttm/ttm_bo_driver.h>
>   #include <drm/ttm/ttm_placement.h>
>   #include <drm/drm_vma_manager.h>
> +#include <linux/dma-buf-map.h>
>   #include <linux/io.h>
>   #include <linux/highmem.h>
>   #include <linux/wait.h>
> @@ -527,6 +528,77 @@ void ttm_bo_kunmap(struct ttm_bo_kmap_obj *map)
>   }
>   EXPORT_SYMBOL(ttm_bo_kunmap);
>   
> +int ttm_bo_vmap(struct ttm_buffer_object *bo, struct dma_buf_map *map)
> +{
> +	struct ttm_resource *mem = &bo->mem;
> +	int ret;
> +
> +	ret = ttm_mem_io_reserve(bo->bdev, mem);
> +	if (ret)
> +		return ret;
> +
> +	if (mem->bus.is_iomem) {
> +		void __iomem *vaddr_iomem;
> +		size_t size = bo->num_pages << PAGE_SHIFT;
> +
> +		if (mem->bus.addr)
> +			vaddr_iomem = (void __iomem *)mem->bus.addr;
> +		else if (mem->bus.caching == ttm_write_combined)
> +			vaddr_iomem = ioremap_wc(mem->bus.offset, size);
> +		else
> +			vaddr_iomem = ioremap(mem->bus.offset, size);
> +
> +		if (!vaddr_iomem)
> +			return -ENOMEM;
> +
> +		dma_buf_map_set_vaddr_iomem(map, vaddr_iomem);
> +
> +	} else {
> +		struct ttm_operation_ctx ctx = {
> +			.interruptible = false,
> +			.no_wait_gpu = false
> +		};
> +		struct ttm_tt *ttm = bo->ttm;
> +		pgprot_t prot;
> +		void *vaddr;
> +
> +		ret = ttm_tt_populate(bo->bdev, ttm, &ctx);
> +		if (ret)
> +			return ret;
> +
> +		/*
> +		 * We need to use vmap to get the desired page protection
> +		 * or to make the buffer object look contiguous.
> +		 */
> +		prot = ttm_io_prot(bo, mem, PAGE_KERNEL);
> +		vaddr = vmap(ttm->pages, bo->num_pages, 0, prot);
> +		if (!vaddr)
> +			return -ENOMEM;
> +
> +		dma_buf_map_set_vaddr(map, vaddr);
> +	}
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL(ttm_bo_vmap);
> +
> +void ttm_bo_vunmap(struct ttm_buffer_object *bo, struct dma_buf_map *map)
> +{
> +	struct ttm_resource *mem = &bo->mem;
> +
> +	if (dma_buf_map_is_null(map))
> +		return;
> +
> +	if (!map->is_iomem)
> +		vunmap(map->vaddr);
> +	else if (!mem->bus.addr)
> +		iounmap(map->vaddr_iomem);
> +	dma_buf_map_clear(map);
> +
> +	ttm_mem_io_free(bo->bdev, &bo->mem);
> +}
> +EXPORT_SYMBOL(ttm_bo_vunmap);
> +
>   static int ttm_bo_wait_free_node(struct ttm_buffer_object *bo,
>   				 bool dst_use_tt)
>   {
> diff --git a/include/drm/drm_gem_ttm_helper.h b/include/drm/drm_gem_ttm_helper.h
> index 118cef76f84f..7c6d874910b8 100644
> --- a/include/drm/drm_gem_ttm_helper.h
> +++ b/include/drm/drm_gem_ttm_helper.h
> @@ -10,11 +10,17 @@
>   #include <drm/ttm/ttm_bo_api.h>
>   #include <drm/ttm/ttm_bo_driver.h>
>   
> +struct dma_buf_map;
> +
>   #define drm_gem_ttm_of_gem(gem_obj) \
>   	container_of(gem_obj, struct ttm_buffer_object, base)
>   
>   void drm_gem_ttm_print_info(struct drm_printer *p, unsigned int indent,
>   			    const struct drm_gem_object *gem);
> +int drm_gem_ttm_vmap(struct drm_gem_object *gem,
> +		     struct dma_buf_map *map);
> +void drm_gem_ttm_vunmap(struct drm_gem_object *gem,
> +			struct dma_buf_map *map);
>   int drm_gem_ttm_mmap(struct drm_gem_object *gem,
>   		     struct vm_area_struct *vma);
>   
> diff --git a/include/drm/ttm/ttm_bo_api.h b/include/drm/ttm/ttm_bo_api.h
> index 37102e45e496..2c59a785374c 100644
> --- a/include/drm/ttm/ttm_bo_api.h
> +++ b/include/drm/ttm/ttm_bo_api.h
> @@ -48,6 +48,8 @@ struct ttm_bo_global;
>   
>   struct ttm_bo_device;
>   
> +struct dma_buf_map;
> +
>   struct drm_mm_node;
>   
>   struct ttm_placement;
> @@ -494,6 +496,32 @@ int ttm_bo_kmap(struct ttm_buffer_object *bo, unsigned long start_page,
>    */
>   void ttm_bo_kunmap(struct ttm_bo_kmap_obj *map);
>   
> +/**
> + * ttm_bo_vmap
> + *
> + * @bo: The buffer object.
> + * @map: pointer to a struct dma_buf_map representing the map.
> + *
> + * Sets up a kernel virtual mapping, using ioremap or vmap to the
> + * data in the buffer object. The parameter @map returns the virtual
> + * address as struct dma_buf_map. Unmap the buffer with ttm_bo_vunmap().
> + *
> + * Returns
> + * -ENOMEM: Out of memory.
> + * -EINVAL: Invalid range.
> + */
> +int ttm_bo_vmap(struct ttm_buffer_object *bo, struct dma_buf_map *map);
> +
> +/**
> + * ttm_bo_vunmap
> + *
> + * @bo: The buffer object.
> + * @map: Object describing the map to unmap.
> + *
> + * Unmaps a kernel map set up by ttm_bo_vmap().
> + */
> +void ttm_bo_vunmap(struct ttm_buffer_object *bo, struct dma_buf_map *map);
> +
>   /**
>    * ttm_bo_mmap_obj - mmap memory backed by a ttm buffer object.
>    *
> diff --git a/include/linux/dma-buf-map.h b/include/linux/dma-buf-map.h
> index fd1aba545fdf..2e8bbecb5091 100644
> --- a/include/linux/dma-buf-map.h
> +++ b/include/linux/dma-buf-map.h
> @@ -45,6 +45,12 @@
>    *
>    *	dma_buf_map_set_vaddr(&map. 0xdeadbeaf);
>    *
> + * To set an address in I/O memory, use dma_buf_map_set_vaddr_iomem().
> + *
> + * .. code-block:: c
> + *
> + *	dma_buf_map_set_vaddr_iomem(&map. 0xdeadbeaf);
> + *
>    * Test if a mapping is valid with either dma_buf_map_is_set() or
>    * dma_buf_map_is_null().
>    *
> @@ -118,6 +124,20 @@ static inline void dma_buf_map_set_vaddr(struct dma_buf_map *map, void *vaddr)
>   	map->is_iomem = false;
>   }
>   
> +/**
> + * dma_buf_map_set_vaddr_iomem - Sets a dma-buf mapping structure to an address in I/O memory
> + * @map:		The dma-buf mapping structure
> + * @vaddr_iomem:	An I/O-memory address
> + *
> + * Sets the address and the I/O-memory flag.
> + */
> +static inline void dma_buf_map_set_vaddr_iomem(struct dma_buf_map *map,
> +					       void __iomem *vaddr_iomem)
> +{
> +	map->vaddr_iomem = vaddr_iomem;
> +	map->is_iomem = true;
> +}
> +
>   /**
>    * dma_buf_map_is_equal - Compares two dma-buf mapping structures for equality
>    * @lhs:	The dma-buf mapping structure