drm/i915/ttm: add ttm_buddy_man

Add back our standalone i915_buddy allocator and integrate it into a
ttm_resource_manager. This will plug into our ttm backend for managing
device local-memory in the next couple of patches.

v2(Thomas):
    - Return -ENOSPC from the buddy; ttm expects this in order to
      trigger eviction
    - Drop the unnecessary inline
    - bo->page_alignment is in page units

Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Acked-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210616152501.394518-1-matthew.auld@intel.com

1 files changed, 248 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/i915_ttm_buddy_manager.c b/drivers/gpu/drm/i915/i915_ttm_buddy_manager.c
new file mode 100644
index 000000000000..fc7ad5c035b8
--- /dev/null
+++ b/drivers/gpu/drm/i915/i915_ttm_buddy_manager.c
@@ -0,0 +1,248 @@
+// SPDX-License-Identifier: MIT
+/*
+ * Copyright © 2021 Intel Corporation
+ */
+
+#include <linux/slab.h>
+
+#include <drm/ttm/ttm_bo_driver.h>
+#include <drm/ttm/ttm_placement.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 list_head reserved;
+	struct mutex lock;
+};
+
+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 i915_buddy_mm *mm = &bman->mm;
+	unsigned long n_pages;
+	unsigned int min_order;
+	u64 min_page_size;
+	u64 size;
+	int err;
+
+	GEM_BUG_ON(place->fpfn || place->lpfn);
+
+	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;
+
+	GEM_BUG_ON(!bman_res->base.num_pages);
+	size = bman_res->base.num_pages << PAGE_SHIFT;
+
+	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) {
+		size = roundup_pow_of_two(size);
+		min_order = ilog2(size) - ilog2(mm->chunk_size);
+	}
+
+	if (size > mm->size) {
+		err = -E2BIG;
+		goto err_free_res;
+	}
+
+	n_pages = size >> ilog2(mm->chunk_size);
+
+	do {
+		struct i915_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 = i915_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);
+
+	*res = &bman_res->base;
+	return 0;
+
+err_free_blocks:
+	mutex_lock(&bman->lock);
+	i915_buddy_free_list(mm, &bman_res->blocks);
+	mutex_unlock(&bman->lock);
+err_free_res:
+	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);
+	i915_buddy_free_list(&bman->mm, &bman_res->blocks);
+	mutex_unlock(&bman->lock);
+
+	kfree(bman_res);
+}
+
+static const struct ttm_resource_manager_func i915_ttm_buddy_manager_func = {
+	.alloc = i915_ttm_buddy_man_alloc,
+	.free = i915_ttm_buddy_man_free,
+};
+
+
+/**
+ * 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
+ * @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 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 = i915_buddy_init(&bman->mm, size, chunk_size);
+	if (err)
+		goto err_free_bman;
+
+	mutex_init(&bman->lock);
+	INIT_LIST_HEAD(&bman->reserved);
+
+	man = &bman->manager;
+	man->use_tt = use_tt;
+	man->func = &i915_ttm_buddy_manager_func;
+	ttm_resource_manager_init(man, 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 i915_buddy_mm *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);
+	i915_buddy_free_list(mm, &bman->reserved);
+	i915_buddy_fini(mm);
+	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 i915_buddy_mm *mm = &bman->mm;
+	int ret;
+
+	mutex_lock(&bman->lock);
+	ret = i915_buddy_alloc_range(mm, &bman->reserved, start, size);
+	mutex_unlock(&bman->lock);
+
+	return ret;
+}
+