drm: move the buddy allocator from i915 into common drm

Move the base i915 buddy allocator code into drm
- Move i915_buddy.h to include/drm
- Move i915_buddy.c to drm root folder
- Rename "i915" string with "drm" string wherever applicable
- Rename "I915" string with "DRM" string wherever applicable
- Fix header file dependencies
- Fix alignment issues
- add Makefile support for drm buddy
- export functions and write kerneldoc description
- Remove i915 selftest config check condition as buddy selftest
  will be moved to drm selftest folder

cleanup i915 buddy references in i915 driver module
and replace with drm buddy

v2:
  - include header file in alphabetical order(Thomas)
  - merged changes listed in the body section into a single patch
    to keep the build intact(Christian, Jani)

v3:
  - make drm buddy a separate module(Thomas, Christian)

v4:
  - Fix build error reported by kernel test robot <lkp@intel.com>
  - removed i915 buddy selftest from i915_mock_selftests.h to
    avoid build error
  - removed selftests/i915_buddy.c file as we create a new set of
    buddy test cases in drm/selftests folder

v5:
  - Fix merge conflict issue

v6:
  - replace drm_buddy_mm structure name as drm_buddy(Thomas, Christian)
  - replace drm_buddy_alloc() function name as drm_buddy_alloc_blocks()
    (Thomas)
  - replace drm_buddy_free() function name as drm_buddy_free_block()
    (Thomas)
  - export drm_buddy_free_block() function
  - fix multiple instances of KMEM_CACHE() entry

v7:
  - fix warnings reported by kernel test robot <lkp@intel.com>
  - modify the license(Christian)

v8:
  - fix warnings reported by kernel test robot <lkp@intel.com>
Signed-off-by: Arunpravin <Arunpravin.PaneerSelvam@amd.com>
Acked-by: Christian König <christian.koenig@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220118104504.2349-1-Arunpravin.PaneerSelvam@amd.comSigned-off-by: Christian König <christian.koenig@amd.com>

drivers/gpu/drm/Kconfig

@@ -204,6 +204,12 @@ config DRM_TTM
 	  GPU memory types. Will be enabled automatically if a device driver
 	  uses it.
 
+config DRM_BUDDY
+	tristate
+	depends on DRM
+	help
+	  A page based buddy allocator
+
 config DRM_VRAM_HELPER
 	tristate
 	depends on DRM

drivers/gpu/drm/Makefile

@@ -40,6 +40,8 @@ obj-$(CONFIG_DRM_GEM_CMA_HELPER) += drm_cma_helper.o
 drm_shmem_helper-y := drm_gem_shmem_helper.o
 obj-$(CONFIG_DRM_GEM_SHMEM_HELPER) += drm_shmem_helper.o
 
+obj-$(CONFIG_DRM_BUDDY) += drm_buddy.o
+
 drm_vram_helper-y := drm_gem_vram_helper.o
 obj-$(CONFIG_DRM_VRAM_HELPER) += drm_vram_helper.o
 

drivers/gpu/drm/i915/Kconfig

@@ -28,6 +28,7 @@ config DRM_I915
 	select CEC_CORE if CEC_NOTIFIER
 	select VMAP_PFN
 	select DRM_TTM
+	select DRM_BUDDY
 	help
 	  Choose this option if you have a system that has "Intel Graphics
 	  Media Accelerator" or "HD Graphics" integrated graphics,

drivers/gpu/drm/i915/Makefile

@@ -161,7 +161,6 @@ gem-y += \
 i915-y += \
 	  $(gem-y) \
 	  i915_active.o \
-	  i915_buddy.o \
 	  i915_cmd_parser.o \
 	  i915_gem_evict.o \
 	  i915_gem_gtt.o \

drivers/gpu/drm/i915/i915_module.c

@@ -9,7 +9,6 @@
 #include "gem/i915_gem_context.h"
 #include "gem/i915_gem_object.h"
 #include "i915_active.h"
-#include "i915_buddy.h"
 #include "i915_params.h"
 #include "i915_pci.h"
 #include "i915_perf.h"
@@ -50,8 +49,6 @@ static const struct {
 	{ .init = i915_check_nomodeset },
 	{ .init = i915_active_module_init,
 	  .exit = i915_active_module_exit },
-	{ .init = i915_buddy_module_init,
-	  .exit = i915_buddy_module_exit },
 	{ .init = i915_context_module_init,
 	  .exit = i915_context_module_exit },
 	{ .init = i915_gem_context_module_init,

drivers/gpu/drm/i915/i915_scatterlist.c

@@ -5,10 +5,9 @@
  */
 
 #include "i915_scatterlist.h"
-
-#include "i915_buddy.h"
 #include "i915_ttm_buddy_manager.h"
 
+#include <drm/drm_buddy.h>
 #include <drm/drm_mm.h>
 
 #include <linux/slab.h>
@@ -153,9 +152,9 @@ struct i915_refct_sgt *i915_rsgt_from_buddy_resource(struct ttm_resource *res,
 	struct i915_ttm_buddy_resource *bman_res = to_ttm_buddy_resource(res);
 	const u64 size = res->num_pages << PAGE_SHIFT;
 	const u64 max_segment = rounddown(UINT_MAX, PAGE_SIZE);
-	struct i915_buddy_mm *mm = bman_res->mm;
+	struct drm_buddy *mm = bman_res->mm;
 	struct list_head *blocks = &bman_res->blocks;
-	struct i915_buddy_block *block;
+	struct drm_buddy_block *block;
 	struct i915_refct_sgt *rsgt;
 	struct scatterlist *sg;
 	struct sg_table *st;
@@ -181,8 +180,8 @@ struct i915_refct_sgt *i915_rsgt_from_buddy_resource(struct ttm_resource *res,
 	list_for_each_entry(block, blocks, link) {
 		u64 block_size, offset;
 
-		block_size = min_t(u64, size, i915_buddy_block_size(mm, block));
-		offset = i915_buddy_block_offset(block);
+		block_size = min_t(u64, size, drm_buddy_block_size(mm, block));
+		offset = drm_buddy_block_offset(block);
 
 		while (block_size) {
 			u64 len;

drivers/gpu/drm/i915/i915_ttm_buddy_manager.c

@@ -8,14 +8,15 @@
 #include <drm/ttm/ttm_bo_driver.h>
 #include <drm/ttm/ttm_placement.h>
 
+#include <drm/drm_buddy.h>
+
 #include "i915_ttm_buddy_manager.h"
 
-#include "i915_buddy.h"
 #include "i915_gem.h"
 
 struct i915_ttm_buddy_manager {
 	struct ttm_resource_manager manager;
-	struct i915_buddy_mm mm;
+	struct drm_buddy mm;
 	struct list_head reserved;
 	struct mutex lock;
 	u64 default_page_size;
@@ -34,7 +35,7 @@ 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 i915_buddy_mm *mm = &bman->mm;
+	struct drm_buddy *mm = &bman->mm;
 	unsigned long n_pages;
 	unsigned int min_order;
 	u64 min_page_size;
@@ -73,7 +74,7 @@ static int i915_ttm_buddy_man_alloc(struct ttm_resource_manager *man,
 	n_pages = size >> ilog2(mm->chunk_size);
 
 	do {
-		struct i915_buddy_block *block;
+		struct drm_buddy_block *block;
 		unsigned int order;
 
 		order = fls(n_pages) - 1;
@@ -82,7 +83,7 @@ static int i915_ttm_buddy_man_alloc(struct ttm_resource_manager *man,
 
 		do {
 			mutex_lock(&bman->lock);
-			block = i915_buddy_alloc(mm, order);
+			block = drm_buddy_alloc_blocks(mm, order);
 			mutex_unlock(&bman->lock);
 			if (!IS_ERR(block))
 				break;
@@ -106,7 +107,7 @@ static int i915_ttm_buddy_man_alloc(struct ttm_resource_manager *man,
 
 err_free_blocks:
 	mutex_lock(&bman->lock);
-	i915_buddy_free_list(mm, &bman_res->blocks);
+	drm_buddy_free_list(mm, &bman_res->blocks);
 	mutex_unlock(&bman->lock);
 err_free_res:
 	kfree(bman_res);
@@ -120,7 +121,7 @@ static void i915_ttm_buddy_man_free(struct ttm_resource_manager *man,
 	struct i915_ttm_buddy_manager *bman = to_buddy_manager(man);
 
 	mutex_lock(&bman->lock);
-	i915_buddy_free_list(&bman->mm, &bman_res->blocks);
+	drm_buddy_free_list(&bman->mm, &bman_res->blocks);
 	mutex_unlock(&bman->lock);
 
 	kfree(bman_res);
@@ -130,17 +131,17 @@ static void i915_ttm_buddy_man_debug(struct ttm_resource_manager *man,
 				     struct drm_printer *printer)
 {
 	struct i915_ttm_buddy_manager *bman = to_buddy_manager(man);
-	struct i915_buddy_block *block;
+	struct drm_buddy_block *block;
 
 	mutex_lock(&bman->lock);
 	drm_printf(printer, "default_page_size: %lluKiB\n",
 		   bman->default_page_size >> 10);
 
-	i915_buddy_print(&bman->mm, printer);
+	drm_buddy_print(&bman->mm, printer);
 
 	drm_printf(printer, "reserved:\n");
 	list_for_each_entry(block, &bman->reserved, link)
-		i915_buddy_block_print(&bman->mm, block, printer);
+		drm_buddy_block_print(&bman->mm, block, printer);
 	mutex_unlock(&bman->lock);
 }
 
@@ -190,7 +191,7 @@ int i915_ttm_buddy_man_init(struct ttm_device *bdev,
 	if (!bman)
 		return -ENOMEM;
 
-	err = i915_buddy_init(&bman->mm, size, chunk_size);
+	err = drm_buddy_init(&bman->mm, size, chunk_size);
 	if (err)
 		goto err_free_bman;
 
@@ -228,7 +229,7 @@ int i915_ttm_buddy_man_fini(struct ttm_device *bdev, unsigned int type)
 {
 	struct ttm_resource_manager *man = ttm_manager_type(bdev, type);
 	struct i915_ttm_buddy_manager *bman = to_buddy_manager(man);
-	struct i915_buddy_mm *mm = &bman->mm;
+	struct drm_buddy *mm = &bman->mm;
 	int ret;
 
 	ttm_resource_manager_set_used(man, false);
@@ -240,8 +241,8 @@ int i915_ttm_buddy_man_fini(struct ttm_device *bdev, unsigned int type)
 	ttm_set_driver_manager(bdev, type, NULL);
 
 	mutex_lock(&bman->lock);
-	i915_buddy_free_list(mm, &bman->reserved);
-	i915_buddy_fini(mm);
+	drm_buddy_free_list(mm, &bman->reserved);
+	drm_buddy_fini(mm);
 	mutex_unlock(&bman->lock);
 
 	ttm_resource_manager_cleanup(man);
@@ -264,11 +265,11 @@ int i915_ttm_buddy_man_reserve(struct ttm_resource_manager *man,
 			       u64 start, u64 size)
 {
 	struct i915_ttm_buddy_manager *bman = to_buddy_manager(man);
-	struct i915_buddy_mm *mm = &bman->mm;
+	struct drm_buddy *mm = &bman->mm;
 	int ret;
 
 	mutex_lock(&bman->lock);
-	ret = i915_buddy_alloc_range(mm, &bman->reserved, start, size);
+	ret = drm_buddy_alloc_range(mm, &bman->reserved, start, size);
 	mutex_unlock(&bman->lock);
 
 	return ret;

drivers/gpu/drm/i915/i915_ttm_buddy_manager.h

@@ -13,7 +13,7 @@
 
 struct ttm_device;
 struct ttm_resource_manager;
-struct i915_buddy_mm;
+struct drm_buddy;
 
 /**
  * struct i915_ttm_buddy_resource
@@ -28,7 +28,7 @@ struct i915_buddy_mm;
 struct i915_ttm_buddy_resource {
 	struct ttm_resource base;
 	struct list_head blocks;
-	struct i915_buddy_mm *mm;
+	struct drm_buddy *mm;
 };
 
 /**

drivers/gpu/drm/i915/selftests/i915_mock_selftests.h

@@ -33,4 +33,3 @@ selftest(evict, i915_gem_evict_mock_selftests)
 selftest(gtt, i915_gem_gtt_mock_selftests)
 selftest(hugepages, i915_gem_huge_page_mock_selftests)
 selftest(memory_region, intel_memory_region_mock_selftests)
-selftest(buddy, i915_buddy_mock_selftests)

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

@@ -6,6 +6,8 @@
 #include <linux/prime_numbers.h>
 #include <linux/sort.h>
 
+#include <drm/drm_buddy.h>
+
 #include "../i915_selftest.h"
 
 #include "mock_drm.h"
@@ -20,7 +22,6 @@
 #include "gt/intel_engine_pm.h"
 #include "gt/intel_engine_user.h"
 #include "gt/intel_gt.h"
-#include "i915_buddy.h"
 #include "gt/intel_migrate.h"
 #include "i915_memcpy.h"
 #include "i915_ttm_buddy_manager.h"
@@ -369,7 +370,7 @@ static int igt_mock_splintered_region(void *arg)
 	struct drm_i915_private *i915 = mem->i915;
 	struct i915_ttm_buddy_resource *res;
 	struct drm_i915_gem_object *obj;
-	struct i915_buddy_mm *mm;
+	struct drm_buddy *mm;
 	unsigned int expected_order;
 	LIST_HEAD(objects);
 	u64 size;
@@ -454,8 +455,8 @@ static int igt_mock_max_segment(void *arg)
 	struct drm_i915_private *i915 = mem->i915;
 	struct i915_ttm_buddy_resource *res;
 	struct drm_i915_gem_object *obj;
-	struct i915_buddy_block *block;
-	struct i915_buddy_mm *mm;
+	struct drm_buddy_block *block;
+	struct drm_buddy *mm;
 	struct list_head *blocks;
 	struct scatterlist *sg;
 	LIST_HEAD(objects);
@@ -485,8 +486,8 @@ static int igt_mock_max_segment(void *arg)
 	mm = res->mm;
 	size = 0;
 	list_for_each_entry(block, blocks, link) {
-		if (i915_buddy_block_size(mm, block) > size)
-			size = i915_buddy_block_size(mm, block);
+		if (drm_buddy_block_size(mm, block) > size)
+			size = drm_buddy_block_size(mm, block);
 	}
 	if (size < max_segment) {
 		pr_err("%s: Failed to create a huge contiguous block [> %u], largest block %lld\n",

drivers/gpu/drm/i915/i915_buddy.h → include/drm/drm_buddy.h

@@ -3,52 +3,62 @@
  * Copyright © 2021 Intel Corporation
  */
 
-#ifndef __I915_BUDDY_H__
-#define __I915_BUDDY_H__
+#ifndef __DRM_BUDDY_H__
+#define __DRM_BUDDY_H__
 
 #include <linux/bitops.h>
 #include <linux/list.h>
 #include <linux/slab.h>
+#include <linux/sched.h>
 
 #include <drm/drm_print.h>
 
-struct i915_buddy_block {
-#define I915_BUDDY_HEADER_OFFSET GENMASK_ULL(63, 12)
-#define I915_BUDDY_HEADER_STATE  GENMASK_ULL(11, 10)
-#define   I915_BUDDY_ALLOCATED	   (1 << 10)
-#define   I915_BUDDY_FREE	   (2 << 10)
-#define   I915_BUDDY_SPLIT	   (3 << 10)
+#define range_overflows(start, size, max) ({ \
+	typeof(start) start__ = (start); \
+	typeof(size) size__ = (size); \
+	typeof(max) max__ = (max); \
+	(void)(&start__ == &size__); \
+	(void)(&start__ == &max__); \
+	start__ >= max__ || size__ > max__ - start__; \
+})
+
+struct drm_buddy_block {
+#define DRM_BUDDY_HEADER_OFFSET GENMASK_ULL(63, 12)
+#define DRM_BUDDY_HEADER_STATE  GENMASK_ULL(11, 10)
+#define   DRM_BUDDY_ALLOCATED	   (1 << 10)
+#define   DRM_BUDDY_FREE	   (2 << 10)
+#define   DRM_BUDDY_SPLIT	   (3 << 10)
 /* Free to be used, if needed in the future */
-#define I915_BUDDY_HEADER_UNUSED GENMASK_ULL(9, 6)
-#define I915_BUDDY_HEADER_ORDER  GENMASK_ULL(5, 0)
+#define DRM_BUDDY_HEADER_UNUSED GENMASK_ULL(9, 6)
+#define DRM_BUDDY_HEADER_ORDER  GENMASK_ULL(5, 0)
 	u64 header;
 
-	struct i915_buddy_block *left;
-	struct i915_buddy_block *right;
-	struct i915_buddy_block *parent;
+	struct drm_buddy_block *left;
+	struct drm_buddy_block *right;
+	struct drm_buddy_block *parent;
 
 	void *private; /* owned by creator */
 
 	/*
-	 * While the block is allocated by the user through i915_buddy_alloc*,
+	 * While the block is allocated by the user through drm_buddy_alloc*,
 	 * the user has ownership of the link, for example to maintain within
 	 * a list, if so desired. As soon as the block is freed with
-	 * i915_buddy_free* ownership is given back to the mm.
+	 * drm_buddy_free* ownership is given back to the mm.
 	 */
 	struct list_head link;
 	struct list_head tmp_link;
 };
 
 /* Order-zero must be at least PAGE_SIZE */
-#define I915_BUDDY_MAX_ORDER (63 - PAGE_SHIFT)
+#define DRM_BUDDY_MAX_ORDER (63 - PAGE_SHIFT)
 
 /*
  * Binary Buddy System.
  *
  * Locking should be handled by the user, a simple mutex around
- * i915_buddy_alloc* and i915_buddy_free* should suffice.
+ * drm_buddy_alloc* and drm_buddy_free* should suffice.
  */
-struct i915_buddy_mm {
+struct drm_buddy {
 	/* Maintain a free list for each order. */
 	struct list_head *free_list;
 
@@ -59,7 +69,7 @@ struct i915_buddy_mm {
 	 * block.  Nodes are either allocated or free, in which case they will
 	 * also exist on the respective free list.
 	 */
-	struct i915_buddy_block **roots;
+	struct drm_buddy_block **roots;
 
 	/*
 	 * Anything from here is public, and remains static for the lifetime of
@@ -75,69 +85,66 @@ struct i915_buddy_mm {
 };
 
 static inline u64
-i915_buddy_block_offset(struct i915_buddy_block *block)
+drm_buddy_block_offset(struct drm_buddy_block *block)
 {
-	return block->header & I915_BUDDY_HEADER_OFFSET;
+	return block->header & DRM_BUDDY_HEADER_OFFSET;
 }
 
 static inline unsigned int
-i915_buddy_block_order(struct i915_buddy_block *block)
+drm_buddy_block_order(struct drm_buddy_block *block)
 {
-	return block->header & I915_BUDDY_HEADER_ORDER;
+	return block->header & DRM_BUDDY_HEADER_ORDER;
 }
 
 static inline unsigned int
-i915_buddy_block_state(struct i915_buddy_block *block)
+drm_buddy_block_state(struct drm_buddy_block *block)
 {
-	return block->header & I915_BUDDY_HEADER_STATE;
+	return block->header & DRM_BUDDY_HEADER_STATE;
 }
 
 static inline bool
-i915_buddy_block_is_allocated(struct i915_buddy_block *block)
+drm_buddy_block_is_allocated(struct drm_buddy_block *block)
 {
-	return i915_buddy_block_state(block) == I915_BUDDY_ALLOCATED;
+	return drm_buddy_block_state(block) == DRM_BUDDY_ALLOCATED;
 }
 
 static inline bool
-i915_buddy_block_is_free(struct i915_buddy_block *block)
+drm_buddy_block_is_free(struct drm_buddy_block *block)
 {
-	return i915_buddy_block_state(block) == I915_BUDDY_FREE;
+	return drm_buddy_block_state(block) == DRM_BUDDY_FREE;
 }
 
 static inline bool
-i915_buddy_block_is_split(struct i915_buddy_block *block)
+drm_buddy_block_is_split(struct drm_buddy_block *block)
 {
-	return i915_buddy_block_state(block) == I915_BUDDY_SPLIT;
+	return drm_buddy_block_state(block) == DRM_BUDDY_SPLIT;
 }
 
 static inline u64
-i915_buddy_block_size(struct i915_buddy_mm *mm,
-		      struct i915_buddy_block *block)
+drm_buddy_block_size(struct drm_buddy *mm,
+		     struct drm_buddy_block *block)
 {
-	return mm->chunk_size << i915_buddy_block_order(block);
+	return mm->chunk_size << drm_buddy_block_order(block);
 }
 
-int i915_buddy_init(struct i915_buddy_mm *mm, u64 size, u64 chunk_size);
+int drm_buddy_init(struct drm_buddy *mm, u64 size, u64 chunk_size);
 
-void i915_buddy_fini(struct i915_buddy_mm *mm);
+void drm_buddy_fini(struct drm_buddy *mm);
 
-struct i915_buddy_block *
-i915_buddy_alloc(struct i915_buddy_mm *mm, unsigned int order);
+struct drm_buddy_block *
+drm_buddy_alloc_blocks(struct drm_buddy *mm, unsigned int order);
 
-int i915_buddy_alloc_range(struct i915_buddy_mm *mm,
+int drm_buddy_alloc_range(struct drm_buddy *mm,
 			  struct list_head *blocks,
 			  u64 start, u64 size);
 
-void i915_buddy_free(struct i915_buddy_mm *mm, struct i915_buddy_block *block);
+void drm_buddy_free_block(struct drm_buddy *mm, struct drm_buddy_block *block);
 
-void i915_buddy_free_list(struct i915_buddy_mm *mm, struct list_head *objects);
+void drm_buddy_free_list(struct drm_buddy *mm, struct list_head *objects);
 
-void i915_buddy_print(struct i915_buddy_mm *mm, struct drm_printer *p);
-void i915_buddy_block_print(struct i915_buddy_mm *mm,
-			    struct i915_buddy_block *block,
+void drm_buddy_print(struct drm_buddy *mm, struct drm_printer *p);
+void drm_buddy_block_print(struct drm_buddy *mm,
+			   struct drm_buddy_block *block,
 			   struct drm_printer *p);
 
-void i915_buddy_module_exit(void);
-int i915_buddy_module_init(void);
-
 #endif