drm/i915: Introduce drm_i915_gem_object_ops

In order to specialise functions depending upon the type of object, we
can attach vfuncs to each object via a new ->ops pointer.

For instance, this will be used in future patches to only bind pages from
a dma-buf for the duration that the object is used by the GPU - and so
prevent them from pinning those pages for the entire of the object.

v2: Bonus comments.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Ben Widawsky <ben@bwidawsk.net>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

1 files changed, 55 insertions, 23 deletions

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 87a64e5f28fb..4b2ee7ce8b15 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -1650,18 +1650,12 @@ i915_gem_object_is_purgeable(struct drm_i915_gem_object *obj)
         return obj->madv == I915_MADV_DONTNEED;
 }
 
-static int
+static void
 i915_gem_object_put_pages_gtt(struct drm_i915_gem_object *obj)
 {
         int page_count = obj->base.size / PAGE_SIZE;
         int ret, i;
 
-        BUG_ON(obj->gtt_space);
-
-        if (obj->pages == NULL)
-                return 0;
-
-        BUG_ON(obj->gtt_space);
         BUG_ON(obj->madv == __I915_MADV_PURGED);
 
         ret = i915_gem_object_set_to_cpu_domain(obj, true);
@@ -1693,9 +1687,21 @@ i915_gem_object_put_pages_gtt(struct drm_i915_gem_object *obj)
 
         drm_free_large(obj->pages);
         obj->pages = NULL;
+}
 
-        list_del(&obj->gtt_list);
+static int
+i915_gem_object_put_pages(struct drm_i915_gem_object *obj)
+{
+        const struct drm_i915_gem_object_ops *ops = obj->ops;
+
+        if (obj->sg_table || obj->pages == NULL)
+                return 0;
+
+        BUG_ON(obj->gtt_space);
 
+        ops->put_pages(obj);
+
+        list_del(&obj->gtt_list);
         if (i915_gem_object_is_purgeable(obj))
                 i915_gem_object_truncate(obj);
 
@@ -1712,7 +1718,7 @@ i915_gem_purge(struct drm_i915_private *dev_priv, long target)
                                  &dev_priv->mm.unbound_list,
                                  gtt_list) {
                 if (i915_gem_object_is_purgeable(obj) &&
-                    i915_gem_object_put_pages_gtt(obj) == 0) {
+                    i915_gem_object_put_pages(obj) == 0) {
                         count += obj->base.size >> PAGE_SHIFT;
                         if (count >= target)
                                 return count;
@@ -1724,7 +1730,7 @@ i915_gem_purge(struct drm_i915_private *dev_priv, long target)
                                  mm_list) {
                 if (i915_gem_object_is_purgeable(obj) &&
                     i915_gem_object_unbind(obj) == 0 &&
-                    i915_gem_object_put_pages_gtt(obj) == 0) {
+                    i915_gem_object_put_pages(obj) == 0) {
                         count += obj->base.size >> PAGE_SHIFT;
                         if (count >= target)
                                 return count;
@@ -1742,10 +1748,10 @@ i915_gem_shrink_all(struct drm_i915_private *dev_priv)
         i915_gem_evict_everything(dev_priv->dev);
 
         list_for_each_entry_safe(obj, next, &dev_priv->mm.unbound_list, gtt_list)
-                i915_gem_object_put_pages_gtt(obj);
+                i915_gem_object_put_pages(obj);
 }
 
-int
+static int
 i915_gem_object_get_pages_gtt(struct drm_i915_gem_object *obj)
 {
         struct drm_i915_private *dev_priv = obj->base.dev->dev_private;
@@ -1754,9 +1760,6 @@ i915_gem_object_get_pages_gtt(struct drm_i915_gem_object *obj)
         struct page *page;
         gfp_t gfp;
 
-        if (obj->pages || obj->sg_table)
-                return 0;
-
         /* Assert that the object is not currently in any GPU domain. As it
          * wasn't in the GTT, there shouldn't be any way it could have been in
          * a GPU cache
@@ -1806,7 +1809,6 @@ i915_gem_object_get_pages_gtt(struct drm_i915_gem_object *obj)
         if (i915_gem_object_needs_bit17_swizzle(obj))
                 i915_gem_object_do_bit_17_swizzle(obj);
 
-        list_add_tail(&obj->gtt_list, &dev_priv->mm.unbound_list);
         return 0;
 
 err_pages:
@@ -1818,6 +1820,31 @@ err_pages:
         return PTR_ERR(page);
 }
 
+/* Ensure that the associated pages are gathered from the backing storage
+ * and pinned into our object. i915_gem_object_get_pages() may be called
+ * multiple times before they are released by a single call to
+ * i915_gem_object_put_pages() - once the pages are no longer referenced
+ * either as a result of memory pressure (reaping pages under the shrinker)
+ * or as the object is itself released.
+ */
+int
+i915_gem_object_get_pages(struct drm_i915_gem_object *obj)
+{
+        struct drm_i915_private *dev_priv = obj->base.dev->dev_private;
+        const struct drm_i915_gem_object_ops *ops = obj->ops;
+        int ret;
+
+        if (obj->sg_table || obj->pages)
+                return 0;
+
+        ret = ops->get_pages(obj);
+        if (ret)
+                return ret;
+
+        list_add_tail(&obj->gtt_list, &dev_priv->mm.unbound_list);
+        return 0;
+}
+
 void
 i915_gem_object_move_to_active(struct drm_i915_gem_object *obj,
                                struct intel_ring_buffer *ring,
@@ -2071,7 +2098,6 @@ void i915_gem_reset(struct drm_device *dev)
                 obj->base.read_domains &= ~I915_GEM_GPU_DOMAINS;
         }
 
-
         /* The fence registers are invalidated so clear them out */
         i915_gem_reset_fences(dev);
 }
@@ -2871,7 +2897,7 @@ i915_gem_object_bind_to_gtt(struct drm_i915_gem_object *obj,
                 return -E2BIG;
         }
 
-        ret = i915_gem_object_get_pages_gtt(obj);
+        ret = i915_gem_object_get_pages(obj);
         if (ret)
                 return ret;
 
@@ -3610,15 +3636,16 @@ unlock:
         return ret;
 }
 
-void i915_gem_object_init(struct drm_i915_gem_object *obj)
+void i915_gem_object_init(struct drm_i915_gem_object *obj,
+                          const struct drm_i915_gem_object_ops *ops)
 {
-        obj->base.driver_private = NULL;
-
         INIT_LIST_HEAD(&obj->mm_list);
         INIT_LIST_HEAD(&obj->gtt_list);
         INIT_LIST_HEAD(&obj->ring_list);
         INIT_LIST_HEAD(&obj->exec_list);
 
+        obj->ops = ops;
+
         obj->fence_reg = I915_FENCE_REG_NONE;
         obj->madv = I915_MADV_WILLNEED;
         /* Avoid an unnecessary call to unbind on the first bind. */
@@ -3627,6 +3654,11 @@ void i915_gem_object_init(struct drm_i915_gem_object *obj)
         i915_gem_info_add_obj(obj->base.dev->dev_private, obj->base.size);
 }
 
+static const struct drm_i915_gem_object_ops i915_gem_object_ops = {
+        .get_pages = i915_gem_object_get_pages_gtt,
+        .put_pages = i915_gem_object_put_pages_gtt,
+};
+
 struct drm_i915_gem_object *i915_gem_alloc_object(struct drm_device *dev,
                                                   size_t size)
 {
@@ -3653,7 +3685,7 @@ struct drm_i915_gem_object *i915_gem_alloc_object(struct drm_device *dev,
         mapping = obj->base.filp->f_path.dentry->d_inode->i_mapping;
         mapping_set_gfp_mask(mapping, mask);
 
-        i915_gem_object_init(obj);
+        i915_gem_object_init(obj, &i915_gem_object_ops);
 
         obj->base.write_domain = I915_GEM_DOMAIN_CPU;
         obj->base.read_domains = I915_GEM_DOMAIN_CPU;
@@ -3711,7 +3743,7 @@ void i915_gem_free_object(struct drm_gem_object *gem_obj)
                 dev_priv->mm.interruptible = was_interruptible;
         }
 
-        i915_gem_object_put_pages_gtt(obj);
+        i915_gem_object_put_pages(obj);
         i915_gem_object_free_mmap_offset(obj);
 
         drm_gem_object_release(&obj->base);