Re: [PATCH v6 2/6] drm: improve drm_buddy_alloc function

On 26/12/2021 22:24, Arunpravin wrote:

• 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

Signed-off-by: Arunpravin Arunpravin.PaneerSelvam@amd.com

<snip>

@@ -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(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(mm, (u64)place->fpfn << PAGE_SHIFT,

• 	(u64)place->lpfn << PAGE_SHIFT,
  

place->lpfn will currently always be zero for i915, AFAIK. I assume here we want s/place->lpfn/lpfn/?

Also something in this series is preventing i915 from loading on discrete devices, according to CI. Hopefully that is just the lpfn issue...which might explain seeing -EINVAL here[1] when allocating some vram for the firmware.

[1] https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_21904/bat-dg1-6/boot0.txt

• 	(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;

@@ -266,10 +258,17 @@ 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 *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(mm, start,

• 	start + size,
  

• 	size, mm->chunk_size,
  

• 	&bman->reserved,
  

• 	flags);
  

  mutex_unlock(&bman->lock);

  return ret;

diff --git a/drivers/gpu/drm/i915/i915_ttm_buddy_manager.h b/drivers/gpu/drm/i915/i915_ttm_buddy_manager.h index fa644b512c2e..5ba490875f66 100644 --- a/drivers/gpu/drm/i915/i915_ttm_buddy_manager.h +++ b/drivers/gpu/drm/i915/i915_ttm_buddy_manager.h @@ -20,6 +20,7 @@ struct drm_buddy_mm;

• @base: struct ttm_resource base class we extend
• @blocks: the list of struct i915_buddy_block for this resource/allocation

• • @flags: DRM_BUDDY_*_ALLOCATION flags
  • @mm: the struct i915_buddy_mm for this resource
  • Extends the struct ttm_resource to manage an address space allocation with

@@ -28,6 +29,7 @@ struct drm_buddy_mm; struct i915_ttm_buddy_resource { struct ttm_resource base; struct list_head blocks;

• unsigned long flags; struct drm_buddy_mm *mm; };

diff --git a/include/drm/drm_buddy.h b/include/drm/drm_buddy.h index 09d73328c268..4368acaad222 100644 --- a/include/drm/drm_buddy.h +++ b/include/drm/drm_buddy.h @@ -13,15 +13,22 @@

#include <drm/drm_print.h>

-#define range_overflows(start, size, max) ({ \ +#define check_range_overflow(start, end, size, max) ({ \ typeof(start) start__ = (start); \

• typeof(end) end__ = (end);\ typeof(size) size__ = (size); \ typeof(max) max__ = (max); \ (void)(&start__ == &size__); \ (void)(&start__ == &max__); \

• start__ >= max__ || size__ > max__ - start__; \

• (void)(&start__ == &end__); \
• (void)(&end__ == &size__); \
• (void)(&end__ == &max__); \
• start__ >= max__ || end__ > max__ || \
• size__ > end__ - start__; \ })

+#define DRM_BUDDY_RANGE_ALLOCATION (1 << 0)

• struct drm_buddy_block { #define DRM_BUDDY_HEADER_OFFSET GENMASK_ULL(63, 12) #define DRM_BUDDY_HEADER_STATE GENMASK_ULL(11, 10)

@@ -132,12 +139,11 @@ int drm_buddy_init(struct drm_buddy_mm *mm, u64 size, u64 chunk_size);

void drm_buddy_fini(struct drm_buddy_mm *mm);

-struct drm_buddy_block * -drm_buddy_alloc(struct drm_buddy_mm *mm, unsigned int order);

-int drm_buddy_alloc_range(struct drm_buddy_mm *mm,

• 	  struct list_head *blocks,
  

• 	  u64 start, u64 size);
  

+int drm_buddy_alloc(struct drm_buddy_mm *mm,

•     u64 start, u64 end, u64 size,
  

•     u64 min_page_size,
  

•     struct list_head *blocks,
  

•     unsigned long flags);
  
  

  void drm_buddy_free(struct drm_buddy_mm *mm, struct drm_buddy_block *block);