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, 35 insertions, 2 deletions

diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c
index 6d2180c..c1e5c66 100644
--- a/drivers/gpu/drm/i915/i915_gem.c
+++ b/drivers/gpu/drm/i915/i915_gem.c
@@ -35,6 +35,7 @@
 #include <linux/slab.h>
 #include <linux/swap.h>
 #include <linux/pci.h>
+#include <linux/dma-buf.h>
 
 static __must_check int i915_gem_object_flush_gpu_write_domain(struct drm_i915_gem_object *obj);
 static void i915_gem_object_flush_gtt_write_domain(struct drm_i915_gem_object *obj);
@@ -538,6 +539,14 @@ i915_gem_pread_ioctl(struct drm_device *dev, void *data,
 		goto out;
 	}
 
+	/* prime objects have no backing filp to GEM pread/pwrite
+	 * pages from.
+	 */
+	if (!obj->base.filp) {
+		ret = -EINVAL;
+		goto out;
+	}
+
 	trace_i915_gem_object_pread(obj, args->offset, args->size);
 
 	ret = i915_gem_shmem_pread(dev, obj, args, file);
@@ -880,6 +889,14 @@ i915_gem_pwrite_ioctl(struct drm_device *dev, void *data,
 		goto out;
 	}
 
+	/* prime objects have no backing filp to GEM pread/pwrite
+	 * pages from.
+	 */
+	if (!obj->base.filp) {
+		ret = -EINVAL;
+		goto out;
+	}
+
 	trace_i915_gem_object_pwrite(obj, args->offset, args->size);
 
 	ret = -EFAULT;
@@ -1021,6 +1038,14 @@ i915_gem_mmap_ioctl(struct drm_device *dev, void *data,
 	if (obj == NULL)
 		return -ENOENT;
 
+	/* prime objects have no backing filp to GEM mmap
+	 * pages from.
+	 */
+	if (!obj->filp) {
+		drm_gem_object_unreference_unlocked(obj);
+		return -EINVAL;
+	}
+
 	addr = vm_mmap(obj->filp, 0, args->size,
 		       PROT_READ | PROT_WRITE, MAP_SHARED,
 		       args->offset);
@@ -1302,8 +1327,7 @@ i915_gem_mmap_gtt_ioctl(struct drm_device *dev, void *data,
 	return i915_gem_mmap_gtt(file, dev, args->handle, &args->offset);
 }
 
-
-static int
+int
 i915_gem_object_get_pages_gtt(struct drm_i915_gem_object *obj,
 			      gfp_t gfpmask)
 {
@@ -1312,6 +1336,9 @@ i915_gem_object_get_pages_gtt(struct drm_i915_gem_object *obj,
 	struct inode *inode;
 	struct page *page;
 
+	if (obj->pages || obj->sg_table)
+		return 0;
+
 	/* Get the list of pages out of our struct file.  They'll be pinned
 	 * at this point until we release them.
 	 */
@@ -1353,6 +1380,9 @@ i915_gem_object_put_pages_gtt(struct drm_i915_gem_object *obj)
 	int page_count = obj->base.size / PAGE_SIZE;
 	int i;
 
+	if (!obj->pages)
+		return;
+
 	BUG_ON(obj->madv == __I915_MADV_PURGED);
 
 	if (i915_gem_object_needs_bit17_swizzle(obj))
@@ -3327,6 +3357,9 @@ void i915_gem_free_object(struct drm_gem_object *gem_obj)
 
 	trace_i915_gem_object_destroy(obj);
 
+	if (gem_obj->import_attach)
+		drm_prime_gem_destroy(gem_obj, obj->sg_table);
+
 	if (obj->phys_obj)
 		i915_gem_detach_phys_object(dev, obj);