[RFC 09/10] drm/i915/vm_bind: Skip vma_lookup for persistent vmas

[Niranjana Vishwanathapura <niranjana.vishwanathapura@intel.com>]

vma_lookup is tied to segment of the object instead of section
of VA space. Hence, it do not support aliasing (ie., multiple
bindings to the same section of the object).
Skip vma_lookup for persistent vmas as it supports aliasing.

Signed-off-by: Niranjana Vishwanathapura <niranjana.vishwanathapura@intel.com>
---
 drivers/gpu/drm/i915/i915_vma.c | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_vma.c b/drivers/gpu/drm/i915/i915_vma.c
index 6adb013579be..9aa38b772b5b 100644
--- a/drivers/gpu/drm/i915/i915_vma.c
+++ b/drivers/gpu/drm/i915/i915_vma.c
@@ -197,6 +197,10 @@ vma_create(struct drm_i915_gem_object *obj,
 		__set_bit(I915_VMA_GGTT_BIT, __i915_vma_flags(vma));
 	}
 
+	if (!i915_vma_is_ggtt(vma) &&
+	    (view && view->type == I915_GGTT_VIEW_PARTIAL))
+		goto skip_rb_insert;
+
 	rb = NULL;
 	p = &obj->vma.tree.rb_node;
 	while (*p) {
@@ -221,6 +225,7 @@ vma_create(struct drm_i915_gem_object *obj,
 	rb_link_node(&vma->obj_node, rb, p);
 	rb_insert_color(&vma->obj_node, &obj->vma.tree);
 
+skip_rb_insert:
 	if (i915_vma_is_ggtt(vma))
 		/*
 		 * We put the GGTT vma at the start of the vma-list, followed
@@ -292,13 +297,16 @@ i915_vma_instance(struct drm_i915_gem_object *obj,
 		  struct i915_address_space *vm,
 		  const struct i915_ggtt_view *view)
 {
-	struct i915_vma *vma;
+	struct i915_vma *vma = NULL;
 
 	GEM_BUG_ON(!kref_read(&vm->ref));
 
-	spin_lock(&obj->vma.lock);
-	vma = i915_vma_lookup(obj, vm, view);
-	spin_unlock(&obj->vma.lock);
+	if (i915_is_ggtt(vm) || !view ||
+	    view->type != I915_GGTT_VIEW_PARTIAL) {
+		spin_lock(&obj->vma.lock);
+		vma = i915_vma_lookup(obj, vm, view);
+		spin_unlock(&obj->vma.lock);
+	}
 
 	/* vma_create() will resolve the race if another creates the vma */
 	if (unlikely(!vma))
@@ -1670,7 +1678,8 @@ static void release_references(struct i915_vma *vma, bool vm_ddestroy)
 
 	spin_lock(&obj->vma.lock);
 	list_del(&vma->obj_link);
-	if (!RB_EMPTY_NODE(&vma->obj_node))
+	if (!i915_vma_is_persistent(vma) &&
+	    !RB_EMPTY_NODE(&vma->obj_node))
 		rb_erase(&vma->obj_node, &obj->vma.tree);
 
 	spin_unlock(&obj->vma.lock);
-- 
2.21.0.rc0.32.g243a4c7e27