drm: improve drm_buddy_alloc function

- Make drm_buddy_alloc a single function to handle
  range allocation and non-range allocation demands

- Implemented a new function alloc_range() which allocates
  the requested power-of-two block comply with range limitations

- Moved order computation and memory alignment logic from
  i915 driver to drm buddy

v2:
  merged below changes to keep the build unbroken
   - drm_buddy_alloc_range() becomes obsolete and may be removed
   - enable ttm range allocation (fpfn / lpfn) support in i915 driver
   - apply enhanced drm_buddy_alloc() function to i915 driver

v3(Matthew Auld):
  - Fix alignment issues and remove unnecessary list_empty check
  - add more validation checks for input arguments
  - make alloc_range() block allocations as bottom-up
  - optimize order computation logic
  - replace uint64_t with u64, which is preferred in the kernel

v4(Matthew Auld):
  - keep drm_buddy_alloc_range() function implementation for generic
    actual range allocations
  - keep alloc_range() implementation for end bias allocations

v5(Matthew Auld):
  - modify drm_buddy_alloc() passing argument place->lpfn to lpfn
    as place->lpfn will currently always be zero for i915

v6(Matthew Auld):
  - fixup potential uaf - If we are unlucky and can't allocate
    enough memory when splitting blocks, where we temporarily
    end up with the given block and its buddy on the respective
    free list, then we need to ensure we delete both blocks,
    and no just the buddy, before potentially freeing them

  - fix warnings reported by kernel test robot <lkp@intel.com>

v7(Matthew Auld):
  - revert fixup potential uaf
  - keep __alloc_range() add node to the list logic same as
    drm_buddy_alloc_blocks() by having a temporary list variable
  - at drm_buddy_alloc_blocks() keep i915 range_overflows macro
    and add a new check for end variable

v8:
  - fix warnings reported by kernel test robot <lkp@intel.com>

v9(Matthew Auld):
  - remove DRM_BUDDY_RANGE_ALLOCATION flag
  - remove unnecessary function description

v10:
   - keep DRM_BUDDY_RANGE_ALLOCATION flag as removing the flag
     and replacing with (end < size) logic fails amdgpu driver load

Signed-off-by: Arunpravin <Arunpravin.PaneerSelvam@amd.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Signed-off-by: Christian König <christian.koenig@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220221164552.2434-1-Arunpravin.PaneerSelvam@amd.com

1 files changed, 33 insertions, 34 deletions

diff --git a/drivers/gpu/drm/i915/i915_ttm_buddy_manager.c b/drivers/gpu/drm/i915/i915_ttm_buddy_manager.c
index 247714bab044..a328a38fab07 100644
--- a/drivers/gpu/drm/i915/i915_ttm_buddy_manager.c
+++ b/drivers/gpu/drm/i915/i915_ttm_buddy_manager.c
@@ -36,13 +36,14 @@ static int i915_ttm_buddy_man_alloc(struct ttm_resource_manager *man,
 	struct i915_ttm_buddy_manager *bman = to_buddy_manager(man);
 	struct i915_ttm_buddy_resource *bman_res;
 	struct drm_buddy *mm = &bman->mm;
-	unsigned long n_pages;
-	unsigned int min_order;
+	unsigned long n_pages, lpfn;
 	u64 min_page_size;
 	u64 size;
 	int err;
 
-	GEM_BUG_ON(place->fpfn || place->lpfn);
+	lpfn = place->lpfn;
+	if (!lpfn)
+		lpfn = man->size;
 
 	bman_res = kzalloc(sizeof(*bman_res), GFP_KERNEL);
 	if (!bman_res)
@@ -52,6 +53,9 @@ static int i915_ttm_buddy_man_alloc(struct ttm_resource_manager *man,
 	INIT_LIST_HEAD(&bman_res->blocks);
 	bman_res->mm = mm;
 
+	if (place->fpfn || lpfn != man->size)
+		bman_res->flags |= DRM_BUDDY_RANGE_ALLOCATION;
+
 	GEM_BUG_ON(!bman_res->base.num_pages);
 	size = bman_res->base.num_pages << PAGE_SHIFT;
 
@@ -60,10 +64,16 @@ static int i915_ttm_buddy_man_alloc(struct ttm_resource_manager *man,
 		min_page_size = bo->page_alignment << PAGE_SHIFT;
 
 	GEM_BUG_ON(min_page_size < mm->chunk_size);
-	min_order = ilog2(min_page_size) - ilog2(mm->chunk_size);
+
 	if (place->flags & TTM_PL_FLAG_CONTIGUOUS) {
+		unsigned long pages;
+
 		size = roundup_pow_of_two(size);
-		min_order = ilog2(size) - ilog2(mm->chunk_size);
+		min_page_size = size;
+
+		pages = size >> ilog2(mm->chunk_size);
+		if (pages > lpfn)
+			lpfn = pages;
 	}
 
 	if (size > mm->size) {
@@ -73,34 +83,16 @@ static int i915_ttm_buddy_man_alloc(struct ttm_resource_manager *man,
 
 	n_pages = size >> ilog2(mm->chunk_size);
 
-	do {
-		struct drm_buddy_block *block;
-		unsigned int order;
-
-		order = fls(n_pages) - 1;
-		GEM_BUG_ON(order > mm->max_order);
-		GEM_BUG_ON(order < min_order);
-
-		do {
-			mutex_lock(&bman->lock);
-			block = drm_buddy_alloc_blocks(mm, order);
-			mutex_unlock(&bman->lock);
-			if (!IS_ERR(block))
-				break;
-
-			if (order-- == min_order) {
-				err = -ENOSPC;
-				goto err_free_blocks;
-			}
-		} while (1);
-
-		n_pages -= BIT(order);
-
-		list_add_tail(&block->link, &bman_res->blocks);
-
-		if (!n_pages)
-			break;
-	} while (1);
+	mutex_lock(&bman->lock);
+	err = drm_buddy_alloc_blocks(mm, (u64)place->fpfn << PAGE_SHIFT,
+				     (u64)lpfn << PAGE_SHIFT,
+				     (u64)n_pages << PAGE_SHIFT,
+				     min_page_size,
+				     &bman_res->blocks,
+				     bman_res->flags);
+	mutex_unlock(&bman->lock);
+	if (unlikely(err))
+		goto err_free_blocks;
 
 	*res = &bman_res->base;
 	return 0;
@@ -268,10 +260,17 @@ int i915_ttm_buddy_man_reserve(struct ttm_resource_manager *man,
 {
 	struct i915_ttm_buddy_manager *bman = to_buddy_manager(man);
 	struct drm_buddy *mm = &bman->mm;
+	unsigned long flags = 0;
 	int ret;
 
+	flags |= DRM_BUDDY_RANGE_ALLOCATION;
+
 	mutex_lock(&bman->lock);
-	ret = drm_buddy_alloc_range(mm, &bman->reserved, start, size);
+	ret = drm_buddy_alloc_blocks(mm, start,
+				     start + size,
+				     size, mm->chunk_size,
+				     &bman->reserved,
+				     flags);
 	mutex_unlock(&bman->lock);
 
 	return ret;