drm/i915/buddy: track available visible size

Track the total amount of available visible memory, and also track
per-resource the amount of used visible memory. For now this is useful
for our debug output, and deciding if it is even worth calling into the
buddy allocator. In the future tracking the per-resource visible usage
will be useful for when deciding if we should attempt to evict certain
buffers.

v2:
 - s/place->lpfn/lpfn/, that way we can avoid scanning the list if the
   entire range is already mappable.
 - Move the end declaration inside the if block(Thomas).
 - Make sure to also account for reserved memory.

Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Acked-by: Nirmoy Das <nirmoy.das@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220225145502.331818-4-matthew.auld@intel.com

1 files changed, 67 insertions, 1 deletions

diff --git a/drivers/gpu/drm/i915/i915_ttm_buddy_manager.c b/drivers/gpu/drm/i915/i915_ttm_buddy_manager.c
index 76d5211c25eb..e47a3d46c6ff 100644
--- a/drivers/gpu/drm/i915/i915_ttm_buddy_manager.c
+++ b/drivers/gpu/drm/i915/i915_ttm_buddy_manager.c
@@ -19,6 +19,9 @@ struct i915_ttm_buddy_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;
 };
 
@@ -87,6 +90,12 @@ static int i915_ttm_buddy_man_alloc(struct ttm_resource_manager *man,
 	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,
@@ -107,6 +116,31 @@ static int i915_ttm_buddy_man_alloc(struct ttm_resource_manager *man,
 		mutex_unlock(&bman->lock);
 	}
 
+	if (lpfn <= bman->visible_size) {
+		bman_res->used_visible_size = bman_res->base.num_pages;
+	} 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) {
+		mutex_lock(&bman->lock);
+		bman->visible_avail -= bman_res->used_visible_size;
+		mutex_unlock(&bman->lock);
+	}
+
 	*res = &bman_res->base;
 	return 0;
 
@@ -128,6 +162,7 @@ static void i915_ttm_buddy_man_free(struct ttm_resource_manager *man,
 
 	mutex_lock(&bman->lock);
 	drm_buddy_free_list(&bman->mm, &bman_res->blocks);
+	bman->visible_avail += bman_res->used_visible_size;
 	mutex_unlock(&bman->lock);
 
 	ttm_resource_fini(man, res);
@@ -143,6 +178,12 @@ static void i915_ttm_buddy_man_debug(struct ttm_resource_manager *man,
 	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);
 
@@ -164,6 +205,7 @@ static const struct ttm_resource_manager_func i915_ttm_buddy_manager_func = {
  * @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.
@@ -187,7 +229,7 @@ static const struct ttm_resource_manager_func i915_ttm_buddy_manager_func = {
  */
 int i915_ttm_buddy_man_init(struct ttm_device *bdev,
 			    unsigned int type, bool use_tt,
-			    u64 size, u64 default_page_size,
+			    u64 size, u64 visible_size, u64 default_page_size,
 			    u64 chunk_size)
 {
 	struct ttm_resource_manager *man;
@@ -206,6 +248,8 @@ int i915_ttm_buddy_man_init(struct ttm_device *bdev,
 	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;
@@ -250,6 +294,8 @@ int i915_ttm_buddy_man_fini(struct ttm_device *bdev, unsigned int type)
 	mutex_lock(&bman->lock);
 	drm_buddy_free_list(mm, &bman->reserved);
 	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);
@@ -273,6 +319,7 @@ 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 fpfn = start >> PAGE_SHIFT;
 	unsigned long flags = 0;
 	int ret;
 
@@ -284,8 +331,27 @@ int i915_ttm_buddy_man_reserve(struct ttm_resource_manager *man,
 				     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;
+}