Commit a2843b3b authored by Chris Wilson's avatar Chris Wilson
Browse files

drm/i915/gem: Limit lmem scatterlist elements to UINT_MAX 



Adhere to the i915_sg_max_segment() limit on the lengths of individual
scatterlist elements, and in doing so split up very large chunks of lmem
into manageable pieces for the dma-mapping backend.

Reported-by: default avatarVenkata Sandeep Dhanalakota <venkata.s.dhanalakota@intel.com>
Suggested-by: default avatarMatthew Auld <matthew.auld@intel.com>
Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Cc: Venkata Sandeep Dhanalakota <venkata.s.dhanalakota@intel.com>
Cc: Matthew Auld <matthew.auld@intel.com>
Reviewed-by: default avatarMatthew Auld <matthew.auld@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20201202173444.14903-1-chris@chris-wilson.co.uk
parent 840291a7

drivers/gpu/drm/i915/gem/i915_gem_region.c

+20 −16
Original line number Diff line number Diff line
@@ -22,6 +22,7 @@ i915_gem_object_put_pages_buddy(struct drm_i915_gem_object *obj, 
int

i915_gem_object_get_pages_buddy(struct drm_i915_gem_object *obj)

{

	const u64 max_segment = i915_sg_segment_size();

	struct intel_memory_region *mem = obj->mm.region;

	struct list_head *blocks = &obj->mm.blocks;

	resource_size_t size = obj->base.size;
@@ -37,7 +38,7 @@ i915_gem_object_get_pages_buddy(struct drm_i915_gem_object *obj) 
	if (!st)

		return -ENOMEM;



	if (sg_alloc_table(st, size >> ilog2(mem->mm.chunk_size), GFP_KERNEL)) {

	if (sg_alloc_table(st, size >> PAGE_SHIFT, GFP_KERNEL)) {

		kfree(st);

		return -ENOMEM;

	}
@@ -64,27 +65,30 @@ i915_gem_object_get_pages_buddy(struct drm_i915_gem_object *obj) 
				   i915_buddy_block_size(&mem->mm, block));

		offset = i915_buddy_block_offset(block);



		GEM_BUG_ON(overflows_type(block_size, sg->length));

		while (block_size) {

			u64 len;



		if (offset != prev_end ||

		    add_overflows_t(typeof(sg->length), sg->length, block_size)) {

			if (offset != prev_end || sg->length >= max_segment) {

				if (st->nents) {

					sg_page_sizes |= sg->length;

					sg = __sg_next(sg);

				}



				sg_dma_address(sg) = mem->region.start + offset;

			sg_dma_len(sg) = block_size;



			sg->length = block_size;



				sg_dma_len(sg) = 0;

				sg->length = 0;

				st->nents++;

		} else {

			sg->length += block_size;

			sg_dma_len(sg) += block_size;

			}



		prev_end = offset + block_size;

			len = min(block_size, max_segment - sg->length);

			sg->length += len;

			sg_dma_len(sg) += len;



			offset += len;

			block_size -= len;



			prev_end = offset;

		}

	}



	sg_page_sizes |= sg->length;

drivers/gpu/drm/i915/selftests/intel_memory_region.c

+21 −6
Original line number Diff line number Diff line
@@ -129,6 +129,21 @@ static void igt_object_release(struct drm_i915_gem_object *obj) 
	i915_gem_object_put(obj);

}



static bool is_contiguous(struct drm_i915_gem_object *obj)

{

	struct scatterlist *sg;

	dma_addr_t addr = -1;



	for (sg = obj->mm.pages->sgl; sg; sg = sg_next(sg)) {

		if (addr != -1 && sg_dma_address(sg) != addr)

			return false;



		addr = sg_dma_address(sg) + sg_dma_len(sg);

	}



	return true;

}



static int igt_mock_contiguous(void *arg)

{

	struct intel_memory_region *mem = arg;
@@ -150,8 +165,8 @@ static int igt_mock_contiguous(void *arg) 
	if (IS_ERR(obj))

		return PTR_ERR(obj);



	if (obj->mm.pages->nents != 1) {

		pr_err("%s min object spans multiple sg entries\n", __func__);

	if (!is_contiguous(obj)) {

		pr_err("%s min object spans disjoint sg entries\n", __func__);

		err = -EINVAL;

		goto err_close_objects;

	}
@@ -163,8 +178,8 @@ static int igt_mock_contiguous(void *arg) 
	if (IS_ERR(obj))

		return PTR_ERR(obj);



	if (obj->mm.pages->nents != 1) {

		pr_err("%s max object spans multiple sg entries\n", __func__);

	if (!is_contiguous(obj)) {

		pr_err("%s max object spans disjoint sg entries\n", __func__);

		err = -EINVAL;

		goto err_close_objects;

	}
@@ -189,8 +204,8 @@ static int igt_mock_contiguous(void *arg) 
		goto err_close_objects;

	}



	if (obj->mm.pages->nents != 1) {

		pr_err("%s object spans multiple sg entries\n", __func__);

	if (!is_contiguous(obj)) {

		pr_err("%s object spans disjoint sg entries\n", __func__);

		err = -EINVAL;

		goto err_close_objects;

	}