Re: [Intel-gfx] [RFC 1/2] drm/i915/ttm: Add extra pages for handling ccs data

["Das, Nirmoy" <nirmoy.das@linux.intel.com>]

On 07/02/2022 10:37, Ramalingam C wrote:
> While evicting the local memory data on flat-ccs capable platform we
> need to evict the ccs data associated to the data. For this, we are
> adding extra pages ((size / 256) >> PAGE_SIZE) into the ttm_tt.
>
> To achieve this we are adding a new param into the ttm_tt_init as
> ccs_pages_needed, which will be added into the ttm_tt->num_pages.
>
> Signed-off-by: Ramalingam C <ramalingam.c@intel.com>
> Suggested-by: Thomas Hellstorm <thomas.hellstrom@intel.com>
> ---
>   drivers/gpu/drm/drm_gem_vram_helper.c      |  2 +-
>   drivers/gpu/drm/i915/gem/i915_gem_ttm.c    | 23 +++++++++++++++++++++-
>   drivers/gpu/drm/qxl/qxl_ttm.c              |  2 +-
>   drivers/gpu/drm/ttm/ttm_agp_backend.c      |  2 +-
>   drivers/gpu/drm/ttm/ttm_tt.c               | 12 ++++++-----
>   drivers/gpu/drm/vmwgfx/vmwgfx_ttm_buffer.c |  2 +-
>   include/drm/ttm/ttm_tt.h                   |  4 +++-
>   7 files changed, 36 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_gem_vram_helper.c b/drivers/gpu/drm/drm_gem_vram_helper.c
> index 3f00192215d1..eef1f4dc7232 100644
> --- a/drivers/gpu/drm/drm_gem_vram_helper.c
> +++ b/drivers/gpu/drm/drm_gem_vram_helper.c
> @@ -864,7 +864,7 @@ static struct ttm_tt *bo_driver_ttm_tt_create(struct ttm_buffer_object *bo,
>   	if (!tt)
>   		return NULL;
>   
> -	ret = ttm_tt_init(tt, bo, page_flags, ttm_cached);
> +	ret = ttm_tt_init(tt, bo, page_flags, ttm_cached, 0);
>   	if (ret < 0)
>   		goto err_ttm_tt_init;
>   
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
> index 84cae740b4a5..bb71aa6d66c0 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
> @@ -16,6 +16,7 @@
>   #include "gem/i915_gem_ttm.h"
>   #include "gem/i915_gem_ttm_move.h"
>   #include "gem/i915_gem_ttm_pm.h"
> +#include "gt/intel_gpu_commands.h"
>   
>   #define I915_TTM_PRIO_PURGE     0
>   #define I915_TTM_PRIO_NO_PAGES  1
> @@ -242,12 +243,27 @@ static const struct i915_refct_sgt_ops tt_rsgt_ops = {
>   	.release = i915_ttm_tt_release
>   };
>   
> +static inline bool
> +i915_gem_object_has_lmem_placement(struct drm_i915_gem_object *obj)
> +{
> +	int i;
> +
> +	for (i = 0; i < obj->mm.n_placements; i++)
> +		if (obj->mm.placements[i]->type == INTEL_MEMORY_LOCAL)
> +			return true;
> +
> +	return false;
> +}
> +
>   static struct ttm_tt *i915_ttm_tt_create(struct ttm_buffer_object *bo,
>   					 uint32_t page_flags)
>   {
> +	struct drm_i915_private *i915 = container_of(bo->bdev, typeof(*i915),
> +						     bdev);
>   	struct ttm_resource_manager *man =
>   		ttm_manager_type(bo->bdev, bo->resource->mem_type);
>   	struct drm_i915_gem_object *obj = i915_ttm_to_gem(bo);
> +	unsigned long ccs_pages_needed = 0;
>   	enum ttm_caching caching;
>   	struct i915_ttm_tt *i915_tt;
>   	int ret;
> @@ -270,7 +286,12 @@ static struct ttm_tt *i915_ttm_tt_create(struct ttm_buffer_object *bo,
>   		i915_tt->is_shmem = true;
>   	}
>   
> -	ret = ttm_tt_init(&i915_tt->ttm, bo, page_flags, caching);
> +	if (HAS_FLAT_CCS(i915) && i915_gem_object_has_lmem_placement(obj))
> +		ccs_pages_needed = DIV_ROUND_UP(DIV_ROUND_UP(bo->base.size,
> +					       NUM_CCS_BYTES_PER_BLOCK), PAGE_SIZE);
> +
> +	ret = ttm_tt_init(&i915_tt->ttm, bo, page_flags,
> +			  caching, ccs_pages_needed);

I am wondering if we should do this in the driver itself and pass 
ttm->num_pages with CCS size included.


Regards,

Nirmoy


>   	if (ret)
>   		goto err_free;
>   
> diff --git a/drivers/gpu/drm/qxl/qxl_ttm.c b/drivers/gpu/drm/qxl/qxl_ttm.c
> index b2e33d5ba5d0..52156b54498f 100644
> --- a/drivers/gpu/drm/qxl/qxl_ttm.c
> +++ b/drivers/gpu/drm/qxl/qxl_ttm.c
> @@ -113,7 +113,7 @@ static struct ttm_tt *qxl_ttm_tt_create(struct ttm_buffer_object *bo,
>   	ttm = kzalloc(sizeof(struct ttm_tt), GFP_KERNEL);
>   	if (ttm == NULL)
>   		return NULL;
> -	if (ttm_tt_init(ttm, bo, page_flags, ttm_cached)) {
> +	if (ttm_tt_init(ttm, bo, page_flags, ttm_cached, 0)) {
>   		kfree(ttm);
>   		return NULL;
>   	}
> diff --git a/drivers/gpu/drm/ttm/ttm_agp_backend.c b/drivers/gpu/drm/ttm/ttm_agp_backend.c
> index 6ddc16f0fe2b..d27691f2e451 100644
> --- a/drivers/gpu/drm/ttm/ttm_agp_backend.c
> +++ b/drivers/gpu/drm/ttm/ttm_agp_backend.c
> @@ -134,7 +134,7 @@ struct ttm_tt *ttm_agp_tt_create(struct ttm_buffer_object *bo,
>   	agp_be->mem = NULL;
>   	agp_be->bridge = bridge;
>   
> -	if (ttm_tt_init(&agp_be->ttm, bo, page_flags, ttm_write_combined)) {
> +	if (ttm_tt_init(&agp_be->ttm, bo, page_flags, ttm_write_combined, 0)) {
>   		kfree(agp_be);
>   		return NULL;
>   	}
> diff --git a/drivers/gpu/drm/ttm/ttm_tt.c b/drivers/gpu/drm/ttm/ttm_tt.c
> index 79c870a3bef8..80355465f717 100644
> --- a/drivers/gpu/drm/ttm/ttm_tt.c
> +++ b/drivers/gpu/drm/ttm/ttm_tt.c
> @@ -134,9 +134,10 @@ void ttm_tt_destroy(struct ttm_device *bdev, struct ttm_tt *ttm)
>   static void ttm_tt_init_fields(struct ttm_tt *ttm,
>   			       struct ttm_buffer_object *bo,
>   			       uint32_t page_flags,
> -			       enum ttm_caching caching)
> +			       enum ttm_caching caching,
> +			       unsigned long ccs_pages)
>   {
> -	ttm->num_pages = PAGE_ALIGN(bo->base.size) >> PAGE_SHIFT;
> +	ttm->num_pages = (PAGE_ALIGN(bo->base.size) >> PAGE_SHIFT) + ccs_pages;
>   	ttm->caching = ttm_cached;
>   	ttm->page_flags = page_flags;
>   	ttm->dma_address = NULL;
> @@ -146,9 +147,10 @@ static void ttm_tt_init_fields(struct ttm_tt *ttm,
>   }
>   
>   int ttm_tt_init(struct ttm_tt *ttm, struct ttm_buffer_object *bo,
> -		uint32_t page_flags, enum ttm_caching caching)
> +		uint32_t page_flags, enum ttm_caching caching,
> +		unsigned long ccs_pages)
>   {
> -	ttm_tt_init_fields(ttm, bo, page_flags, caching);
> +	ttm_tt_init_fields(ttm, bo, page_flags, caching, ccs_pages);
>   
>   	if (ttm_tt_alloc_page_directory(ttm)) {
>   		pr_err("Failed allocating page table\n");
> @@ -180,7 +182,7 @@ int ttm_sg_tt_init(struct ttm_tt *ttm, struct ttm_buffer_object *bo,
>   {
>   	int ret;
>   
> -	ttm_tt_init_fields(ttm, bo, page_flags, caching);
> +	ttm_tt_init_fields(ttm, bo, page_flags, caching, 0);
>   
>   	if (page_flags & TTM_TT_FLAG_EXTERNAL)
>   		ret = ttm_sg_tt_alloc_page_directory(ttm);
> diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_buffer.c b/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_buffer.c
> index b84ecc6d6611..4e3938e62c08 100644
> --- a/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_buffer.c
> +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_ttm_buffer.c
> @@ -517,7 +517,7 @@ static struct ttm_tt *vmw_ttm_tt_create(struct ttm_buffer_object *bo,
>   				     ttm_cached);
>   	else
>   		ret = ttm_tt_init(&vmw_be->dma_ttm, bo, page_flags,
> -				  ttm_cached);
> +				  ttm_cached, 0);
>   	if (unlikely(ret != 0))
>   		goto out_no_init;
>   
> diff --git a/include/drm/ttm/ttm_tt.h b/include/drm/ttm/ttm_tt.h
> index f20832139815..2c4ff08ea354 100644
> --- a/include/drm/ttm/ttm_tt.h
> +++ b/include/drm/ttm/ttm_tt.h
> @@ -140,6 +140,7 @@ int ttm_tt_create(struct ttm_buffer_object *bo, bool zero_alloc);
>    * @bo: The buffer object we create the ttm for.
>    * @page_flags: Page flags as identified by TTM_TT_FLAG_XX flags.
>    * @caching: the desired caching state of the pages
> + * @ccs_pages_needed: Extra pages needed for the ccs data of compression.
>    *
>    * Create a struct ttm_tt to back data with system memory pages.
>    * No pages are actually allocated.
> @@ -147,7 +148,8 @@ int ttm_tt_create(struct ttm_buffer_object *bo, bool zero_alloc);
>    * NULL: Out of memory.
>    */
>   int ttm_tt_init(struct ttm_tt *ttm, struct ttm_buffer_object *bo,
> -		uint32_t page_flags, enum ttm_caching caching);
> +		uint32_t page_flags, enum ttm_caching caching,
> +		unsigned long ccs_pages_needed);
>   int ttm_sg_tt_init(struct ttm_tt *ttm_dma, struct ttm_buffer_object *bo,
>   		   uint32_t page_flags, enum ttm_caching caching);
>