drm/i915: Refactor common list iteration over GGTT vma

In quite a few places, we have a list iteration over the vma on an
object that only want to inspect GGTT vma. By construction, these are
placed at the start of the list, so we have copied that knowledge into
many callsites. Pull that knowledge back to i915_vma.h and provide a
for_each_ggtt_vma() to tidy up the code.

v2: Add a backreference from vma_create() to remind ourselves why we put
ggtt vma at the head of the obj->vma_list (and ppgtt vma at the tail).
v3: Fixup s/vma/V/

Suggested-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20171207211407.31549-1-chris@chris-wilson.co.uk

6 files changed, 30 insertions, 29 deletions

diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index 28294470ae31..7b41a1799a03 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -111,8 +111,8 @@ static u64 i915_gem_obj_total_ggtt_size(struct drm_i915_gem_object *obj)
 	u64 size = 0;
 	struct i915_vma *vma;
 
-	list_for_each_entry(vma, &obj->vma_list, obj_link) {
-		if (i915_vma_is_ggtt(vma) && drm_mm_node_allocated(&vma->node))
+	for_each_ggtt_vma(vma, obj) {
+		if (drm_mm_node_allocated(&vma->node))
 			size += vma->node.size;
 	}
 
diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 67dc11effc8e..c7b5db78fbb4 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -714,10 +714,7 @@ flush_write_domain(struct drm_i915_gem_object *obj, unsigned int flush_domains)
 		intel_fb_obj_flush(obj,
 				   fb_write_origin(obj, I915_GEM_DOMAIN_GTT));
 
-		list_for_each_entry(vma, &obj->vma_list, obj_link) {
-			if (!i915_vma_is_ggtt(vma))
-				break;
-
+		for_each_ggtt_vma(vma, obj) {
 			if (vma->iomap)
 				continue;
 
@@ -1569,10 +1566,7 @@ static void i915_gem_object_bump_inactive_ggtt(struct drm_i915_gem_object *obj)
 
 	GEM_BUG_ON(!i915_gem_object_has_pinned_pages(obj));
 
-	list_for_each_entry(vma, &obj->vma_list, obj_link) {
-		if (!i915_vma_is_ggtt(vma))
-			break;
-
+	for_each_ggtt_vma(vma, obj) {
 		if (i915_vma_is_active(vma))
 			continue;
 
@@ -2051,12 +2045,8 @@ static void __i915_gem_object_release_mmap(struct drm_i915_gem_object *obj)
 	drm_vma_node_unmap(&obj->base.vma_node,
 			   obj->base.dev->anon_inode->i_mapping);
 
-	list_for_each_entry(vma, &obj->vma_list, obj_link) {
-		if (!i915_vma_is_ggtt(vma))
-			break;
-
+	for_each_ggtt_vma(vma, obj)
 		i915_vma_unset_userfault(vma);
-	}
 }
 
 /**
@@ -3822,7 +3812,7 @@ restart:
 			 * dropped the fence as all snoopable access is
 			 * supposed to be linear.
 			 */
-			list_for_each_entry(vma, &obj->vma_list, obj_link) {
+			for_each_ggtt_vma(vma, obj) {
 				ret = i915_vma_put_fence(vma);
 				if (ret)
 					return ret;
diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
index 86fbd67388f3..c4bb02ecd217 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.c
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
@@ -3620,10 +3620,7 @@ void i915_gem_restore_gtt_mappings(struct drm_i915_private *dev_priv)
 		bool ggtt_bound = false;
 		struct i915_vma *vma;
 
-		list_for_each_entry(vma, &obj->vma_list, obj_link) {
-			if (vma->vm != &ggtt->base)
-				continue;
-
+		for_each_ggtt_vma(vma, obj) {
 			if (!i915_vma_unbind(vma))
 				continue;
 
diff --git a/drivers/gpu/drm/i915/i915_gem_tiling.c b/drivers/gpu/drm/i915/i915_gem_tiling.c
index b85d7ebd9bee..d9dc9df523b5 100644
--- a/drivers/gpu/drm/i915/i915_gem_tiling.c
+++ b/drivers/gpu/drm/i915/i915_gem_tiling.c
@@ -205,10 +205,7 @@ i915_gem_object_fence_prepare(struct drm_i915_gem_object *obj,
 	if (tiling_mode == I915_TILING_NONE)
 		return 0;
 
-	list_for_each_entry(vma, &obj->vma_list, obj_link) {
-		if (!i915_vma_is_ggtt(vma))
-			break;
-
+	for_each_ggtt_vma(vma, obj) {
 		if (i915_vma_fence_prepare(vma, tiling_mode, stride))
 			continue;
 
@@ -285,10 +282,7 @@ i915_gem_object_set_tiling(struct drm_i915_gem_object *obj,
 	}
 	mutex_unlock(&obj->mm.lock);
 
-	list_for_each_entry(vma, &obj->vma_list, obj_link) {
-		if (!i915_vma_is_ggtt(vma))
-			break;
-
+	for_each_ggtt_vma(vma, obj) {
 		vma->fence_size =
 			i915_gem_fence_size(i915, vma->size, tiling, stride);
 		vma->fence_alignment =
diff --git a/drivers/gpu/drm/i915/i915_vma.c b/drivers/gpu/drm/i915/i915_vma.c
index 0ebd75693505..92c11e70fea4 100644
--- a/drivers/gpu/drm/i915/i915_vma.c
+++ b/drivers/gpu/drm/i915/i915_vma.c
@@ -142,6 +142,12 @@ vma_create(struct drm_i915_gem_object *obj,
 								i915_gem_object_get_stride(obj));
 		GEM_BUG_ON(!is_power_of_2(vma->fence_alignment));
 
+		/*
+		 * We put the GGTT vma at the start of the vma-list, followed
+		 * by the ppGGTT vma. This allows us to break early when
+		 * iterating over only the GGTT vma for an object, see
+		 * for_each_ggtt_vma()
+		 */
 		vma->flags |= I915_VMA_GGTT;
 		list_add(&vma->obj_link, &obj->vma_list);
 	} else {
diff --git a/drivers/gpu/drm/i915/i915_vma.h b/drivers/gpu/drm/i915/i915_vma.h
index f636243eb8f7..fd5b84904f7c 100644
--- a/drivers/gpu/drm/i915/i915_vma.h
+++ b/drivers/gpu/drm/i915/i915_vma.h
@@ -408,5 +408,19 @@ i915_vma_unpin_fence(struct i915_vma *vma)
 		__i915_vma_unpin_fence(vma);
 }
 
-#endif
+#define for_each_until(cond) if (cond) break; else
+
+/**
+ * for_each_ggtt_vma - Iterate over the GGTT VMA belonging to an object.
+ * @V: the #i915_vma iterator
+ * @OBJ: the #drm_i915_gem_object
+ *
+ * GGTT VMA are placed at the being of the object's vma_list, see
+ * vma_create(), so we can stop our walk as soon as we see a ppgtt VMA,
+ * or the list is empty ofc.
+ */
+#define for_each_ggtt_vma(V, OBJ) \
+	list_for_each_entry(V, &(OBJ)->vma_list, obj_link)		\
+		for_each_until(!i915_vma_is_ggtt(V))
 
+#endif