drivers/gpu/drm/i915/i915_ttm_buddy_manager.c - linux - Git at Google

 // SPDX-License-Identifier: MIT
 /*
  * Copyright © 2021 Intel Corporation
  */

 #include <linux/slab.h>

 #include <drm/ttm/ttm_placement.h>
 #include <drm/ttm/ttm_bo.h>

 #include <drm/drm_buddy.h>

 #include "i915_ttm_buddy_manager.h"

 #include "i915_gem.h"

 struct i915_ttm_buddy_manager {
 	struct ttm_resource_manager manager;
 	struct drm_buddy mm;
 	struct list_head reserved;
 	struct mutex lock;
 	unsigned long visible_size;
 	unsigned long visible_avail;
 	unsigned long visible_reserved;
 	u64 default_page_size;
 };

 static struct i915_ttm_buddy_manager *
 to_buddy_manager(struct ttm_resource_manager *man)
 {
 	return container_of(man, struct i915_ttm_buddy_manager, manager);
 }

 static int i915_ttm_buddy_man_alloc(struct ttm_resource_manager *man,
 				    struct ttm_buffer_object *bo,
 				    const struct ttm_place *place,
 				    struct ttm_resource **res)
 {
 	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, lpfn;
 	u64 min_page_size;
 	u64 size;
 	int err;

 	lpfn = place->lpfn;
 	if (!lpfn)
 		lpfn = man->size;

 	bman_res = kzalloc(sizeof(*bman_res), GFP_KERNEL);
 	if (!bman_res)
 		return -ENOMEM;

 	ttm_resource_init(bo, place, &bman_res->base);
 	INIT_LIST_HEAD(&bman_res->blocks);
 	bman_res->mm = mm;

 	if (place->flags & TTM_PL_FLAG_TOPDOWN)
 		bman_res->flags |= DRM_BUDDY_TOPDOWN_ALLOCATION;

 	if (place->flags & TTM_PL_FLAG_CONTIGUOUS)
 		bman_res->flags |= DRM_BUDDY_CONTIGUOUS_ALLOCATION;

 	if (place->fpfn || lpfn != man->size)
 		bman_res->flags |= DRM_BUDDY_RANGE_ALLOCATION;

 	GEM_BUG_ON(!bman_res->base.size);
 	size = bman_res->base.size;

 	min_page_size = bman->default_page_size;
 	if (bo->page_alignment)
 		min_page_size = bo->page_alignment << PAGE_SHIFT;

 	GEM_BUG_ON(min_page_size < mm->chunk_size);
 	GEM_BUG_ON(!IS_ALIGNED(size, min_page_size));

 	if (size > lpfn << PAGE_SHIFT) {
 		err = -E2BIG;
 		goto err_free_res;
 	}

 	n_pages = size >> ilog2(mm->chunk_size);

 	mutex_lock(&bman->lock);
 	if (lpfn <= bman->visible_size && n_pages > bman->visible_avail) {
 		mutex_unlock(&bman->lock);
 		err = -ENOSPC;
 		goto err_free_res;
 	}

 	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);
 	if (unlikely(err))
 		goto err_free_blocks;

 	if (lpfn <= bman->visible_size) {
 		bman_res->used_visible_size = PFN_UP(bman_res->base.size);
 	} else {
 		struct drm_buddy_block *block;

 		list_for_each_entry(block, &bman_res->blocks, link) {
 			unsigned long start =
 				drm_buddy_block_offset(block) >> PAGE_SHIFT;

 			if (start < bman->visible_size) {
 				unsigned long end = start +
 					(drm_buddy_block_size(mm, block) >> PAGE_SHIFT);

 				bman_res->used_visible_size +=
 					min(end, bman->visible_size) - start;
 			}
 		}
 	}

 	if (bman_res->used_visible_size)
 		bman->visible_avail -= bman_res->used_visible_size;

 	mutex_unlock(&bman->lock);

 	*res = &bman_res->base;
 	return 0;

 err_free_blocks:
 	drm_buddy_free_list(mm, &bman_res->blocks, 0);
 	mutex_unlock(&bman->lock);
 err_free_res:
 	ttm_resource_fini(man, &bman_res->base);
 	kfree(bman_res);
 	return err;
 }

 static void i915_ttm_buddy_man_free(struct ttm_resource_manager *man,
 				    struct ttm_resource *res)
 {
 	struct i915_ttm_buddy_resource *bman_res = to_ttm_buddy_resource(res);
 	struct i915_ttm_buddy_manager *bman = to_buddy_manager(man);

 	mutex_lock(&bman->lock);
 	drm_buddy_free_list(&bman->mm, &bman_res->blocks, 0);
 	bman->visible_avail += bman_res->used_visible_size;
 	mutex_unlock(&bman->lock);

 	ttm_resource_fini(man, res);
 	kfree(bman_res);
 }

 static bool i915_ttm_buddy_man_intersects(struct ttm_resource_manager *man,
 					  struct ttm_resource *res,
 					  const struct ttm_place *place,
 					  size_t size)
 {
 	struct i915_ttm_buddy_resource *bman_res = to_ttm_buddy_resource(res);
 	struct i915_ttm_buddy_manager *bman = to_buddy_manager(man);
 	struct drm_buddy *mm = &bman->mm;
 	struct drm_buddy_block *block;

 	if (!place->fpfn && !place->lpfn)
 		return true;

 	GEM_BUG_ON(!place->lpfn);

 	/*
 	 * If we just want something mappable then we can quickly check
 	 * if the current victim resource is using any of the CPU
 	 * visible portion.
 	 */
 	if (!place->fpfn &&
 	    place->lpfn == i915_ttm_buddy_man_visible_size(man))
 		return bman_res->used_visible_size > 0;

 	/* Check each drm buddy block individually */
 	list_for_each_entry(block, &bman_res->blocks, link) {
 		unsigned long fpfn =
 			drm_buddy_block_offset(block) >> PAGE_SHIFT;
 		unsigned long lpfn = fpfn +
 			(drm_buddy_block_size(mm, block) >> PAGE_SHIFT);

 		if (place->fpfn < lpfn && place->lpfn > fpfn)
 			return true;
 	}

 	return false;
 }

 static bool i915_ttm_buddy_man_compatible(struct ttm_resource_manager *man,
 					  struct ttm_resource *res,
 					  const struct ttm_place *place,
 					  size_t size)
 {
 	struct i915_ttm_buddy_resource *bman_res = to_ttm_buddy_resource(res);
 	struct i915_ttm_buddy_manager *bman = to_buddy_manager(man);
 	struct drm_buddy *mm = &bman->mm;
 	struct drm_buddy_block *block;

 	if (!place->fpfn && !place->lpfn)
 		return true;

 	GEM_BUG_ON(!place->lpfn);

 	if (!place->fpfn &&
 	    place->lpfn == i915_ttm_buddy_man_visible_size(man))
 		return bman_res->used_visible_size == PFN_UP(res->size);

 	/* Check each drm buddy block individually */
 	list_for_each_entry(block, &bman_res->blocks, link) {
 		unsigned long fpfn =
 			drm_buddy_block_offset(block) >> PAGE_SHIFT;
 		unsigned long lpfn = fpfn +
 			(drm_buddy_block_size(mm, block) >> PAGE_SHIFT);

 		if (fpfn < place->fpfn || lpfn > place->lpfn)
 			return false;
 	}

 	return true;
 }

 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 drm_buddy_block *block;

 	mutex_lock(&bman->lock);
 	drm_printf(printer, "default_page_size: %lluKiB\n",
 		   bman->default_page_size >> 10);
 	drm_printf(printer, "visible_avail: %lluMiB\n",
 		   (u64)bman->visible_avail << PAGE_SHIFT >> 20);
 	drm_printf(printer, "visible_size: %lluMiB\n",
 		   (u64)bman->visible_size << PAGE_SHIFT >> 20);
 	drm_printf(printer, "visible_reserved: %lluMiB\n",
 		   (u64)bman->visible_reserved << PAGE_SHIFT >> 20);

 	drm_buddy_print(&bman->mm, printer);

 	drm_printf(printer, "reserved:\n");
 	list_for_each_entry(block, &bman->reserved, link)
 		drm_buddy_block_print(&bman->mm, block, printer);
 	mutex_unlock(&bman->lock);
 }

 static const struct ttm_resource_manager_func i915_ttm_buddy_manager_func = {
 	.alloc = i915_ttm_buddy_man_alloc,
 	.free = i915_ttm_buddy_man_free,
 	.intersects = i915_ttm_buddy_man_intersects,
 	.compatible = i915_ttm_buddy_man_compatible,
 	.debug = i915_ttm_buddy_man_debug,
 };

 /**
  * i915_ttm_buddy_man_init - Setup buddy allocator based ttm manager
  * @bdev: The ttm device
  * @type: Memory type we want to manage
  * @use_tt: Set use_tt for the manager
  * @size: The size in bytes to manage
  * @visible_size: The CPU visible size in bytes to manage
  * @default_page_size: The default minimum page size in bytes for allocations,
  * this must be at least as large as @chunk_size, and can be overridden by
  * setting the BO page_alignment, to be larger or smaller as needed.
  * @chunk_size: The minimum page size in bytes for our allocations i.e
  * order-zero
  *
  * Note that the starting address is assumed to be zero here, since this
  * simplifies keeping the property where allocated blocks having natural
  * power-of-two alignment. So long as the real starting address is some large
  * power-of-two, or naturally start from zero, then this should be fine.  Also
  * the &i915_ttm_buddy_man_reserve interface can be used to preserve alignment
  * if say there is some unusable range from the start of the region. We can
  * revisit this in the future and make the interface accept an actual starting
  * offset and let it take care of the rest.
  *
  * Note that if the @size is not aligned to the @chunk_size then we perform the
  * required rounding to get the usable size. The final size in pages can be
  * taken from &ttm_resource_manager.size.
  *
  * Return: 0 on success, negative error code on failure.
  */
 int i915_ttm_buddy_man_init(struct ttm_device *bdev,
 			    unsigned int type, bool use_tt,
 			    u64 size, u64 visible_size, u64 default_page_size,
 			    u64 chunk_size)
 {
 	struct ttm_resource_manager *man;
 	struct i915_ttm_buddy_manager *bman;
 	int err;

 	bman = kzalloc(sizeof(*bman), GFP_KERNEL);
 	if (!bman)
 		return -ENOMEM;

 	err = drm_buddy_init(&bman->mm, size, chunk_size);
 	if (err)
 		goto err_free_bman;

 	mutex_init(&bman->lock);
 	INIT_LIST_HEAD(&bman->reserved);
 	GEM_BUG_ON(default_page_size < chunk_size);
 	bman->default_page_size = default_page_size;
 	bman->visible_size = visible_size >> PAGE_SHIFT;
 	bman->visible_avail = bman->visible_size;

 	man = &bman->manager;
 	man->use_tt = use_tt;
 	man->func = &i915_ttm_buddy_manager_func;
 	ttm_resource_manager_init(man, bdev, bman->mm.size >> PAGE_SHIFT);

 	ttm_resource_manager_set_used(man, true);
 	ttm_set_driver_manager(bdev, type, man);

 	return 0;

 err_free_bman:
 	kfree(bman);
 	return err;
 }

 /**
  * i915_ttm_buddy_man_fini - Destroy the buddy allocator ttm manager
  * @bdev: The ttm device
  * @type: Memory type we want to manage
  *
  * Note that if we reserved anything with &i915_ttm_buddy_man_reserve, this will
  * also be freed for us here.
  *
  * Return: 0 on success, negative error code on failure.
  */
 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 drm_buddy *mm = &bman->mm;
 	int ret;

 	ttm_resource_manager_set_used(man, false);

 	ret = ttm_resource_manager_evict_all(bdev, man);
 	if (ret)
 		return ret;

 	ttm_set_driver_manager(bdev, type, NULL);

 	mutex_lock(&bman->lock);
 	drm_buddy_free_list(mm, &bman->reserved, 0);
 	drm_buddy_fini(mm);
 	bman->visible_avail += bman->visible_reserved;
 	WARN_ON_ONCE(bman->visible_avail != bman->visible_size);
 	mutex_unlock(&bman->lock);

 	ttm_resource_manager_cleanup(man);
 	kfree(bman);

 	return 0;
 }

 /**
  * i915_ttm_buddy_man_reserve - Reserve address range
  * @man: The buddy allocator ttm manager
  * @start: The offset in bytes, where the region start is assumed to be zero
  * @size: The size in bytes
  *
  * Note that the starting address for the region is always assumed to be zero.
  *
  * Return: 0 on success, negative error code on failure.
  */
 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 drm_buddy *mm = &bman->mm;
 	unsigned long fpfn = start >> PAGE_SHIFT;
 	unsigned long flags = 0;
 	int ret;

 	flags |= DRM_BUDDY_RANGE_ALLOCATION;

 	mutex_lock(&bman->lock);
 	ret = drm_buddy_alloc_blocks(mm, start,
 				     start + size,
 				     size, mm->chunk_size,
 				     &bman->reserved,
 				     flags);

 	if (fpfn < bman->visible_size) {
 		unsigned long lpfn = fpfn + (size >> PAGE_SHIFT);
 		unsigned long visible = min(lpfn, bman->visible_size) - fpfn;

 		bman->visible_reserved += visible;
 		bman->visible_avail -= visible;
 	}
 	mutex_unlock(&bman->lock);

 	return ret;
 }

 /**
  * i915_ttm_buddy_man_visible_size - Return the size of the CPU visible portion
  * in pages.
  * @man: The buddy allocator ttm manager
  */
 u64 i915_ttm_buddy_man_visible_size(struct ttm_resource_manager *man)
 {
 	struct i915_ttm_buddy_manager *bman = to_buddy_manager(man);

 	return bman->visible_size;
 }

 /**
  * i915_ttm_buddy_man_avail - Query the avail tracking for the manager.
  *
  * @man: The buddy allocator ttm manager
  * @avail: The total available memory in pages for the entire manager.
  * @visible_avail: The total available memory in pages for the CPU visible
  * portion. Note that this will always give the same value as @avail on
  * configurations that don't have a small BAR.
  */
 void i915_ttm_buddy_man_avail(struct ttm_resource_manager *man,
 			      u64 *avail, u64 *visible_avail)
 {
 	struct i915_ttm_buddy_manager *bman = to_buddy_manager(man);

 	mutex_lock(&bman->lock);
 	*avail = bman->mm.avail >> PAGE_SHIFT;
 	*visible_avail = bman->visible_avail;
 	mutex_unlock(&bman->lock);
 }

 #if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
 void i915_ttm_buddy_man_force_visible_size(struct ttm_resource_manager *man,
 					   u64 size)
 {
 	struct i915_ttm_buddy_manager *bman = to_buddy_manager(man);

 	bman->visible_size = size;
 }
 #endif
	// SPDX-License-Identifier: MIT
	/*
	* Copyright © 2021 Intel Corporation
	*/

	#include <linux/slab.h>

	#include <drm/ttm/ttm_placement.h>
	#include <drm/ttm/ttm_bo.h>

	#include <drm/drm_buddy.h>

	#include "i915_ttm_buddy_manager.h"

	#include "i915_gem.h"

	struct i915_ttm_buddy_manager {
	struct ttm_resource_manager manager;
	struct drm_buddy mm;
	struct list_head reserved;
	struct mutex lock;
	unsigned long visible_size;
	unsigned long visible_avail;
	unsigned long visible_reserved;
	u64 default_page_size;
	};

	static struct i915_ttm_buddy_manager *
	to_buddy_manager(struct ttm_resource_manager *man)
	{
	return container_of(man, struct i915_ttm_buddy_manager, manager);
	}

	static int i915_ttm_buddy_man_alloc(struct ttm_resource_manager *man,
	struct ttm_buffer_object *bo,
	const struct ttm_place *place,
	struct ttm_resource **res)
	{
	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, lpfn;
	u64 min_page_size;
	u64 size;
	int err;

	lpfn = place->lpfn;
	if (!lpfn)
	lpfn = man->size;

	bman_res = kzalloc(sizeof(*bman_res), GFP_KERNEL);
	if (!bman_res)
	return -ENOMEM;

	ttm_resource_init(bo, place, &bman_res->base);
	INIT_LIST_HEAD(&bman_res->blocks);
	bman_res->mm = mm;

	if (place->flags & TTM_PL_FLAG_TOPDOWN)
	bman_res->flags \|= DRM_BUDDY_TOPDOWN_ALLOCATION;

	if (place->flags & TTM_PL_FLAG_CONTIGUOUS)
	bman_res->flags \|= DRM_BUDDY_CONTIGUOUS_ALLOCATION;

	if (place->fpfn \|\| lpfn != man->size)
	bman_res->flags \|= DRM_BUDDY_RANGE_ALLOCATION;

	GEM_BUG_ON(!bman_res->base.size);
	size = bman_res->base.size;

	min_page_size = bman->default_page_size;
	if (bo->page_alignment)
	min_page_size = bo->page_alignment << PAGE_SHIFT;

	GEM_BUG_ON(min_page_size < mm->chunk_size);
	GEM_BUG_ON(!IS_ALIGNED(size, min_page_size));

	if (size > lpfn << PAGE_SHIFT) {
	err = -E2BIG;
	goto err_free_res;
	}

	n_pages = size >> ilog2(mm->chunk_size);

	mutex_lock(&bman->lock);
	if (lpfn <= bman->visible_size && n_pages > bman->visible_avail) {
	mutex_unlock(&bman->lock);
	err = -ENOSPC;
	goto err_free_res;
	}

	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);
	if (unlikely(err))
	goto err_free_blocks;

	if (lpfn <= bman->visible_size) {
	bman_res->used_visible_size = PFN_UP(bman_res->base.size);
	} else {
	struct drm_buddy_block *block;

	list_for_each_entry(block, &bman_res->blocks, link) {
	unsigned long start =
	drm_buddy_block_offset(block) >> PAGE_SHIFT;

	if (start < bman->visible_size) {
	unsigned long end = start +
	(drm_buddy_block_size(mm, block) >> PAGE_SHIFT);

	bman_res->used_visible_size +=
	min(end, bman->visible_size) - start;
	}
	}
	}

	if (bman_res->used_visible_size)
	bman->visible_avail -= bman_res->used_visible_size;

	mutex_unlock(&bman->lock);

	*res = &bman_res->base;
	return 0;

	err_free_blocks:
	drm_buddy_free_list(mm, &bman_res->blocks, 0);
	mutex_unlock(&bman->lock);
	err_free_res:
	ttm_resource_fini(man, &bman_res->base);
	kfree(bman_res);
	return err;
	}

	static void i915_ttm_buddy_man_free(struct ttm_resource_manager *man,
	struct ttm_resource *res)
	{
	struct i915_ttm_buddy_resource *bman_res = to_ttm_buddy_resource(res);
	struct i915_ttm_buddy_manager *bman = to_buddy_manager(man);

	mutex_lock(&bman->lock);
	drm_buddy_free_list(&bman->mm, &bman_res->blocks, 0);
	bman->visible_avail += bman_res->used_visible_size;
	mutex_unlock(&bman->lock);

	ttm_resource_fini(man, res);
	kfree(bman_res);
	}

	static bool i915_ttm_buddy_man_intersects(struct ttm_resource_manager *man,
	struct ttm_resource *res,
	const struct ttm_place *place,
	size_t size)
	{
	struct i915_ttm_buddy_resource *bman_res = to_ttm_buddy_resource(res);
	struct i915_ttm_buddy_manager *bman = to_buddy_manager(man);
	struct drm_buddy *mm = &bman->mm;
	struct drm_buddy_block *block;

	if (!place->fpfn && !place->lpfn)
	return true;

	GEM_BUG_ON(!place->lpfn);

	/*
	* If we just want something mappable then we can quickly check
	* if the current victim resource is using any of the CPU
	* visible portion.
	*/
	if (!place->fpfn &&
	place->lpfn == i915_ttm_buddy_man_visible_size(man))
	return bman_res->used_visible_size > 0;

	/* Check each drm buddy block individually */
	list_for_each_entry(block, &bman_res->blocks, link) {
	unsigned long fpfn =
	drm_buddy_block_offset(block) >> PAGE_SHIFT;
	unsigned long lpfn = fpfn +
	(drm_buddy_block_size(mm, block) >> PAGE_SHIFT);

	if (place->fpfn < lpfn && place->lpfn > fpfn)
	return true;
	}

	return false;
	}

	static bool i915_ttm_buddy_man_compatible(struct ttm_resource_manager *man,
	struct ttm_resource *res,
	const struct ttm_place *place,
	size_t size)
	{
	struct i915_ttm_buddy_resource *bman_res = to_ttm_buddy_resource(res);
	struct i915_ttm_buddy_manager *bman = to_buddy_manager(man);
	struct drm_buddy *mm = &bman->mm;
	struct drm_buddy_block *block;

	if (!place->fpfn && !place->lpfn)
	return true;

	GEM_BUG_ON(!place->lpfn);

	if (!place->fpfn &&
	place->lpfn == i915_ttm_buddy_man_visible_size(man))
	return bman_res->used_visible_size == PFN_UP(res->size);

	/* Check each drm buddy block individually */
	list_for_each_entry(block, &bman_res->blocks, link) {
	unsigned long fpfn =
	drm_buddy_block_offset(block) >> PAGE_SHIFT;
	unsigned long lpfn = fpfn +
	(drm_buddy_block_size(mm, block) >> PAGE_SHIFT);

	if (fpfn < place->fpfn \|\| lpfn > place->lpfn)
	return false;
	}

	return true;
	}

	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 drm_buddy_block *block;

	mutex_lock(&bman->lock);
	drm_printf(printer, "default_page_size: %lluKiB\n",
	bman->default_page_size >> 10);
	drm_printf(printer, "visible_avail: %lluMiB\n",
	(u64)bman->visible_avail << PAGE_SHIFT >> 20);
	drm_printf(printer, "visible_size: %lluMiB\n",
	(u64)bman->visible_size << PAGE_SHIFT >> 20);
	drm_printf(printer, "visible_reserved: %lluMiB\n",
	(u64)bman->visible_reserved << PAGE_SHIFT >> 20);

	drm_buddy_print(&bman->mm, printer);

	drm_printf(printer, "reserved:\n");
	list_for_each_entry(block, &bman->reserved, link)
	drm_buddy_block_print(&bman->mm, block, printer);
	mutex_unlock(&bman->lock);
	}

	static const struct ttm_resource_manager_func i915_ttm_buddy_manager_func = {
	.alloc = i915_ttm_buddy_man_alloc,
	.free = i915_ttm_buddy_man_free,
	.intersects = i915_ttm_buddy_man_intersects,
	.compatible = i915_ttm_buddy_man_compatible,
	.debug = i915_ttm_buddy_man_debug,
	};

	/**
	* i915_ttm_buddy_man_init - Setup buddy allocator based ttm manager
	* @bdev: The ttm device
	* @type: Memory type we want to manage
	* @use_tt: Set use_tt for the manager
	* @size: The size in bytes to manage
	* @visible_size: The CPU visible size in bytes to manage
	* @default_page_size: The default minimum page size in bytes for allocations,
	* this must be at least as large as @chunk_size, and can be overridden by
	* setting the BO page_alignment, to be larger or smaller as needed.
	* @chunk_size: The minimum page size in bytes for our allocations i.e
	* order-zero
	*
	* Note that the starting address is assumed to be zero here, since this
	* simplifies keeping the property where allocated blocks having natural
	* power-of-two alignment. So long as the real starting address is some large
	* power-of-two, or naturally start from zero, then this should be fine. Also
	* the &i915_ttm_buddy_man_reserve interface can be used to preserve alignment
	* if say there is some unusable range from the start of the region. We can
	* revisit this in the future and make the interface accept an actual starting
	* offset and let it take care of the rest.
	*
	* Note that if the @size is not aligned to the @chunk_size then we perform the
	* required rounding to get the usable size. The final size in pages can be
	* taken from &ttm_resource_manager.size.
	*
	* Return: 0 on success, negative error code on failure.
	*/
	int i915_ttm_buddy_man_init(struct ttm_device *bdev,
	unsigned int type, bool use_tt,
	u64 size, u64 visible_size, u64 default_page_size,
	u64 chunk_size)
	{
	struct ttm_resource_manager *man;
	struct i915_ttm_buddy_manager *bman;
	int err;

	bman = kzalloc(sizeof(*bman), GFP_KERNEL);
	if (!bman)
	return -ENOMEM;

	err = drm_buddy_init(&bman->mm, size, chunk_size);
	if (err)
	goto err_free_bman;

	mutex_init(&bman->lock);
	INIT_LIST_HEAD(&bman->reserved);
	GEM_BUG_ON(default_page_size < chunk_size);
	bman->default_page_size = default_page_size;
	bman->visible_size = visible_size >> PAGE_SHIFT;
	bman->visible_avail = bman->visible_size;

	man = &bman->manager;
	man->use_tt = use_tt;
	man->func = &i915_ttm_buddy_manager_func;
	ttm_resource_manager_init(man, bdev, bman->mm.size >> PAGE_SHIFT);

	ttm_resource_manager_set_used(man, true);
	ttm_set_driver_manager(bdev, type, man);

	return 0;

	err_free_bman:
	kfree(bman);
	return err;
	}

	/**
	* i915_ttm_buddy_man_fini - Destroy the buddy allocator ttm manager
	* @bdev: The ttm device
	* @type: Memory type we want to manage
	*
	* Note that if we reserved anything with &i915_ttm_buddy_man_reserve, this will
	* also be freed for us here.
	*
	* Return: 0 on success, negative error code on failure.
	*/
	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 drm_buddy *mm = &bman->mm;
	int ret;

	ttm_resource_manager_set_used(man, false);

	ret = ttm_resource_manager_evict_all(bdev, man);
	if (ret)
	return ret;

	ttm_set_driver_manager(bdev, type, NULL);

	mutex_lock(&bman->lock);
	drm_buddy_free_list(mm, &bman->reserved, 0);
	drm_buddy_fini(mm);
	bman->visible_avail += bman->visible_reserved;
	WARN_ON_ONCE(bman->visible_avail != bman->visible_size);
	mutex_unlock(&bman->lock);

	ttm_resource_manager_cleanup(man);
	kfree(bman);

	return 0;
	}

	/**
	* i915_ttm_buddy_man_reserve - Reserve address range
	* @man: The buddy allocator ttm manager
	* @start: The offset in bytes, where the region start is assumed to be zero
	* @size: The size in bytes
	*
	* Note that the starting address for the region is always assumed to be zero.
	*
	* Return: 0 on success, negative error code on failure.
	*/
	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 drm_buddy *mm = &bman->mm;
	unsigned long fpfn = start >> PAGE_SHIFT;
	unsigned long flags = 0;
	int ret;

	flags \|= DRM_BUDDY_RANGE_ALLOCATION;

	mutex_lock(&bman->lock);
	ret = drm_buddy_alloc_blocks(mm, start,
	start + size,
	size, mm->chunk_size,
	&bman->reserved,
	flags);

	if (fpfn < bman->visible_size) {
	unsigned long lpfn = fpfn + (size >> PAGE_SHIFT);
	unsigned long visible = min(lpfn, bman->visible_size) - fpfn;

	bman->visible_reserved += visible;
	bman->visible_avail -= visible;
	}
	mutex_unlock(&bman->lock);

	return ret;
	}

	/**
	* i915_ttm_buddy_man_visible_size - Return the size of the CPU visible portion
	* in pages.
	* @man: The buddy allocator ttm manager
	*/
	u64 i915_ttm_buddy_man_visible_size(struct ttm_resource_manager *man)
	{
	struct i915_ttm_buddy_manager *bman = to_buddy_manager(man);

	return bman->visible_size;
	}

	/**
	* i915_ttm_buddy_man_avail - Query the avail tracking for the manager.
	*
	* @man: The buddy allocator ttm manager
	* @avail: The total available memory in pages for the entire manager.
	* @visible_avail: The total available memory in pages for the CPU visible
	* portion. Note that this will always give the same value as @avail on
	* configurations that don't have a small BAR.
	*/
	void i915_ttm_buddy_man_avail(struct ttm_resource_manager *man,
	u64 avail, u64 visible_avail)
	{
	struct i915_ttm_buddy_manager *bman = to_buddy_manager(man);

	mutex_lock(&bman->lock);
	*avail = bman->mm.avail >> PAGE_SHIFT;
	*visible_avail = bman->visible_avail;
	mutex_unlock(&bman->lock);
	}

	#if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
	void i915_ttm_buddy_man_force_visible_size(struct ttm_resource_manager *man,
	u64 size)
	{
	struct i915_ttm_buddy_manager *bman = to_buddy_manager(man);

	bman->visible_size = size;
	}
	#endif