[RFC PATCH 06/42] drm/i915/region: support continuous allocations

[Matthew Auld <matthew.auld@intel.com>]

Some objects may need to be allocated as a continuous block, thinking
ahead the various kernel io_mapping interfaces seem to expect it.

Signed-off-by: Matthew Auld <matthew.auld@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Abdiel Janulgue <abdiel.janulgue@linux.intel.com>
---
 drivers/gpu/drm/i915/i915_gem_object.h        |   2 +
 drivers/gpu/drm/i915/intel_memory_region.c    |   7 +-
 .../drm/i915/selftests/intel_memory_region.c  | 152 +++++++++++++++++-
 drivers/gpu/drm/i915/selftests/mock_region.c  |   3 +
 4 files changed, 158 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_gem_object.h b/drivers/gpu/drm/i915/i915_gem_object.h
index 76947a6f49f1..efc23fc2b1df 100644
--- a/drivers/gpu/drm/i915/i915_gem_object.h
+++ b/drivers/gpu/drm/i915/i915_gem_object.h
@@ -163,6 +163,8 @@ struct drm_i915_gem_object {
 	 * activity?
 	 */
 #define I915_BO_ACTIVE_REF 0
+#define I915_BO_ALLOC_CONTIGUOUS (1<<1)
+#define I915_BO_ALLOC_FLAGS (I915_BO_ALLOC_CONTIGUOUS)
 
 	/*
 	 * Is the object to be mapped as read-only to the GPU
diff --git a/drivers/gpu/drm/i915/intel_memory_region.c b/drivers/gpu/drm/i915/intel_memory_region.c
index f7fdc3e942e6..ed37599c7784 100644
--- a/drivers/gpu/drm/i915/intel_memory_region.c
+++ b/drivers/gpu/drm/i915/intel_memory_region.c
@@ -59,6 +59,7 @@ i915_memory_region_get_pages_buddy(struct drm_i915_gem_object *obj)
 {
 	struct intel_memory_region *mem = obj->memory_region;
 	resource_size_t size = obj->base.size;
+	unsigned int flags = obj->flags;
 	struct sg_table *st;
 	struct scatterlist *sg;
 	unsigned int sg_page_sizes;
@@ -99,7 +100,7 @@ i915_memory_region_get_pages_buddy(struct drm_i915_gem_object *obj)
 			if (!IS_ERR(block))
 				break;
 
-			if (!order--) {
+			if (flags & I915_BO_ALLOC_CONTIGUOUS || !order--) {
 				resource_size_t target;
 				int err;
 
@@ -185,6 +186,9 @@ i915_gem_object_create_region(struct intel_memory_region *mem,
 	if (!mem)
 		return ERR_PTR(-ENODEV);
 
+	if (flags & ~I915_BO_ALLOC_FLAGS)
+		return ERR_PTR(-EINVAL);
+
 	size = round_up(size, mem->min_page_size);
 
 	GEM_BUG_ON(!size);
@@ -202,6 +206,7 @@ i915_gem_object_create_region(struct intel_memory_region *mem,
 
 	INIT_LIST_HEAD(&obj->blocks);
 	obj->memory_region = mem;
+	obj->flags = flags;
 
 	mutex_lock(&mem->obj_lock);
 	list_add(&obj->region_link, &mem->objects);
diff --git a/drivers/gpu/drm/i915/selftests/intel_memory_region.c b/drivers/gpu/drm/i915/selftests/intel_memory_region.c
index 1cea381d2d5e..fbb1497d0f82 100644
--- a/drivers/gpu/drm/i915/selftests/intel_memory_region.c
+++ b/drivers/gpu/drm/i915/selftests/intel_memory_region.c
@@ -95,17 +95,17 @@ static int igt_mock_fill(void *arg)
 
 static void igt_mark_evictable(struct drm_i915_gem_object *obj)
 {
-	i915_gem_object_unpin_pages(obj);
+	if (i915_gem_object_has_pinned_pages(obj))
+		i915_gem_object_unpin_pages(obj);
 	obj->mm.madv = I915_MADV_DONTNEED;
 	list_move(&obj->region_link, &obj->memory_region->purgeable);
 }
 
-static int igt_mock_shrink(void *arg)
+static int igt_frag_region(struct intel_memory_region *mem,
+			   struct list_head *objects)
 {
-	struct intel_memory_region *mem = arg;
 	struct drm_i915_gem_object *obj;
 	unsigned long n_objects;
-	LIST_HEAD(objects);
 	resource_size_t target;
 	resource_size_t total;
 	int err = 0;
@@ -123,7 +123,7 @@ static int igt_mock_shrink(void *arg)
 			goto err_close_objects;
 		}
 
-		list_add(&obj->st_link, &objects);
+		list_add(&obj->st_link, objects);
 
 		err = i915_gem_object_pin_pages(obj);
 		if (err)
@@ -137,6 +137,39 @@ static int igt_mock_shrink(void *arg)
 			igt_mark_evictable(obj);
 	}
 
+	return 0;
+
+err_close_objects:
+	close_objects(objects);
+	return err;
+}
+
+static void igt_defrag_region(struct list_head *objects)
+{
+	struct drm_i915_gem_object *obj;
+
+	list_for_each_entry(obj, objects, st_link) {
+		if (obj->mm.madv == I915_MADV_WILLNEED)
+			igt_mark_evictable(obj);
+	}
+}
+
+static int igt_mock_shrink(void *arg)
+{
+	struct intel_memory_region *mem = arg;
+	struct drm_i915_gem_object *obj;
+	LIST_HEAD(objects);
+	resource_size_t target;
+	resource_size_t total;
+	int err;
+
+	err = igt_frag_region(mem, &objects);
+	if (err)
+		return err;
+
+	total = resource_size(&mem->region);
+	target = mem->mm.min_size;
+
 	while (target <= total / 2) {
 		obj = i915_gem_object_create_region(mem, target, 0);
 		if (IS_ERR(obj)) {
@@ -168,11 +201,120 @@ static int igt_mock_shrink(void *arg)
 	return err;
 }
 
+static int igt_mock_continuous(void *arg)
+{
+	struct intel_memory_region *mem = arg;
+	struct drm_i915_gem_object *obj;
+	LIST_HEAD(objects);
+	resource_size_t target;
+	resource_size_t total;
+	int err;
+
+	err = igt_frag_region(mem, &objects);
+	if (err)
+		return err;
+
+	total = resource_size(&mem->region);
+	target = total / 2;
+
+	/*
+	 * Sanity check that we can allocate all of the available fragmented
+	 * space.
+	 */
+	obj = i915_gem_object_create_region(mem, target, 0);
+	if (IS_ERR(obj)) {
+		err = PTR_ERR(obj);
+		goto err_close_objects;
+	}
+
+	list_add(&obj->st_link, &objects);
+
+	err = i915_gem_object_pin_pages(obj);
+	if (err) {
+		pr_err("failed to allocate available space\n");
+		goto err_close_objects;
+	}
+
+	igt_mark_evictable(obj);
+
+	/* Try the smallest possible size -- should succeed */
+	obj = i915_gem_object_create_region(mem, mem->mm.min_size,
+					    I915_BO_ALLOC_CONTIGUOUS);
+	if (IS_ERR(obj)) {
+		err = PTR_ERR(obj);
+		goto err_close_objects;
+	}
+
+	list_add(&obj->st_link, &objects);
+
+	err = i915_gem_object_pin_pages(obj);
+	if (err) {
+		pr_err("failed to allocate smallest possible size\n");
+		goto err_close_objects;
+	}
+
+	igt_mark_evictable(obj);
+
+	if (obj->mm.pages->nents != 1) {
+		pr_err("[1]object spans multiple sg entries\n");
+		err = -EINVAL;
+		goto err_close_objects;
+	}
+
+	/*
+	 * Even though there is enough free space for the allocation, we
+	 * shouldn't be able to allocate it, given that it is fragmented, and
+	 * non-continuous.
+	 */
+	obj = i915_gem_object_create_region(mem, target, I915_BO_ALLOC_CONTIGUOUS);
+	if (IS_ERR(obj)) {
+		err = PTR_ERR(obj);
+		goto err_close_objects;
+	}
+
+	list_add(&obj->st_link, &objects);
+
+	err = i915_gem_object_pin_pages(obj);
+	if (!err) {
+		pr_err("expected allocation to fail\n");
+		err = -EINVAL;
+		goto err_close_objects;
+	}
+
+	igt_defrag_region(&objects);
+
+	/* Should now succeed */
+	obj = i915_gem_object_create_region(mem, target, I915_BO_ALLOC_CONTIGUOUS);
+	if (IS_ERR(obj)) {
+		err = PTR_ERR(obj);
+		goto err_close_objects;
+	}
+
+	list_add(&obj->st_link, &objects);
+
+	err = i915_gem_object_pin_pages(obj);
+	if (err) {
+		pr_err("failed to allocate from defraged area\n");
+		goto err_close_objects;
+	}
+
+	if (obj->mm.pages->nents != 1) {
+		pr_err("object spans multiple sg entries\n");
+		err = -EINVAL;
+	}
+
+err_close_objects:
+	close_objects(&objects);
+
+	return err;
+}
+
 int intel_memory_region_mock_selftests(void)
 {
 	static const struct i915_subtest tests[] = {
 		SUBTEST(igt_mock_fill),
 		SUBTEST(igt_mock_shrink),
+		SUBTEST(igt_mock_continuous),
 	};
 	struct intel_memory_region *mem;
 	struct drm_i915_private *i915;
diff --git a/drivers/gpu/drm/i915/selftests/mock_region.c b/drivers/gpu/drm/i915/selftests/mock_region.c
index 11e9f379aaca..c1c09d0e4722 100644
--- a/drivers/gpu/drm/i915/selftests/mock_region.c
+++ b/drivers/gpu/drm/i915/selftests/mock_region.c
@@ -38,6 +38,9 @@ mock_object_create(struct intel_memory_region *mem,
 	struct drm_i915_private *i915 = mem->i915;
 	struct drm_i915_gem_object *obj;
 
+	if (flags & I915_BO_ALLOC_CONTIGUOUS)
+		size = roundup_pow_of_two(size);
+
 	if (size > BIT(mem->mm.max_order) * mem->mm.min_size)
 		return ERR_PTR(-E2BIG);
 
-- 
2.20.1

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