drm/i915: prepare bind_to_vm for preallocated vma

In the new execbuf code we want to track buffers using the vmas even
before they're all properly mapped. Which means that bind_to_vm needs
to deal with buffers which have preallocated vmas which aren't yet
bound.

This patch implements this prep work and adjusts our WARN/BUG checks.

Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
[danvet: Split out from Ben's big execbuf patch. Also move one BUG
back to its original place to deflate the diff a notch.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

1 files changed, 17 insertions, 6 deletions

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index ca29055ae206..449575b85b31 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -3124,9 +3124,6 @@ i915_gem_object_bind_to_vm(struct drm_i915_gem_object *obj,
         struct i915_vma *vma;
         int ret;
 
-        if (WARN_ON(!list_empty(&obj->vma_list)))
-                return -EBUSY;
-
         fence_size = i915_gem_get_gtt_size(dev,
                                            obj->base.size,
                                            obj->tiling_mode);
@@ -3165,16 +3162,17 @@ i915_gem_object_bind_to_vm(struct drm_i915_gem_object *obj,
 
         i915_gem_object_pin_pages(obj);
 
-        /* FIXME: For now we only ever use 1 VMA per object */
         BUG_ON(!i915_is_ggtt(vm));
-        WARN_ON(!list_empty(&obj->vma_list));
 
-        vma = i915_gem_vma_create(obj, vm);
+        vma = i915_gem_obj_lookup_or_create_vma(obj, vm);
         if (IS_ERR(vma)) {
                 ret = PTR_ERR(vma);
                 goto err_unpin;
         }
 
+        /* For now we only ever use 1 vma per object */
+        WARN_ON(!list_is_singular(&obj->vma_list));
+
 search_free:
         ret = drm_mm_insert_node_in_range_generic(&vm->mm, &vma->node,
                                                   size, alignment,
@@ -4882,3 +4880,16 @@ struct i915_vma *i915_gem_obj_to_vma(struct drm_i915_gem_object *obj,
 
         return NULL;
 }
+
+struct i915_vma *
+i915_gem_obj_lookup_or_create_vma(struct drm_i915_gem_object *obj,
+                                  struct i915_address_space *vm)
+{
+        struct i915_vma *vma;
+
+        vma = i915_gem_obj_to_vma(obj, vm);
+        if (!vma)
+                vma = i915_gem_vma_create(obj, vm);
+
+        return vma;
+}