i915: add dmabuf/prime buffer sharing support.

This adds handle->fd and fd->handle support to i915, this is to allow
for offloading of rendering in one direction and outputs in the other.

v2 from Daniel Vetter:
- fixup conflicts with the prepare/finish gtt prep work.
- implement ppgtt binding support.

Note that we have squat i-g-t testcoverage for any of the lifetime and
access rules dma_buf/prime support brings along. And there are quite a
few intricate situations here.

Also note that the integration with the existing code is a bit
hackish, especially around get_gtt_pages and put_gtt_pages. It imo
would be easier with the prep code from Chris Wilson's unbound series,
but that is for 3.6.

Also note that I didn't bother to put the new prepare/finish gtt hooks
to good use by moving the dma_buf_map/unmap_attachment calls in there
(like we've originally planned for).

Last but not least this patch is only compile-tested, but I've changed
very little compared to Dave Airlie's version. So there's a decent
chance v2 on drm-next works as well as v1 on 3.4-rc.

v3: Right when I've hit sent I've noticed that I've screwed up one
obj->sg_list (for dmar support) and obj->sg_table (for prime support)
disdinction. We should be able to merge these 2 paths, but that's
material for another patch.

v4: fix the error reporting bugs pointed out by ickle.

v5: fix another error, and stop non-gtt mmaps on shared objects
stop pread/pwrite on imported objects, add fake kmap

Signed-off-by: Dave Airlie <airlied@redhat.com>
Signed-Off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

1 files changed, 13 insertions, 2 deletions

diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.c b/drivers/gpu/drm/i915/i915_gem_gtt.c
index 29d573c27b3..9fd25a43553 100644
--- a/drivers/gpu/drm/i915/i915_gem_gtt.c
+++ b/drivers/gpu/drm/i915/i915_gem_gtt.c
@@ -267,7 +267,13 @@ void i915_ppgtt_bind_object(struct i915_hw_ppgtt *ppgtt,
                 BUG();
         }
 
-        if (dev_priv->mm.gtt->needs_dmar) {
+        if (obj->sg_table) {
+                i915_ppgtt_insert_sg_entries(ppgtt,
+                                             obj->sg_table->sgl,
+                                             obj->sg_table->nents,
+                                             obj->gtt_space->start >> PAGE_SHIFT,
+                                             pte_flags);
+        } else if (dev_priv->mm.gtt->needs_dmar) {
                 BUG_ON(!obj->sg_list);
 
                 i915_ppgtt_insert_sg_entries(ppgtt,
@@ -371,7 +377,12 @@ void i915_gem_gtt_bind_object(struct drm_i915_gem_object *obj,
         struct drm_i915_private *dev_priv = dev->dev_private;
         unsigned int agp_type = cache_level_to_agp_type(dev, cache_level);
 
-        if (dev_priv->mm.gtt->needs_dmar) {
+        if (obj->sg_table) {
+                intel_gtt_insert_sg_entries(obj->sg_table->sgl,
+                                            obj->sg_table->nents,
+                                            obj->gtt_space->start >> PAGE_SHIFT,
+                                            agp_type);
+        } else if (dev_priv->mm.gtt->needs_dmar) {
                 BUG_ON(!obj->sg_list);
 
                 intel_gtt_insert_sg_entries(obj->sg_list,