drm/i915/gem: Migrate to system at dma-buf attach time

Until we support p2p dma or as a complement to that, migrate data
to system memory at dma-buf attach time if possible.

v2:
- Rebase on dynamic exporter. Update the igt_dmabuf_import_same_driver
  selftest to migrate if we are LMEM capable.
v3:
- Migrate also in the pin() callback.
v4:
- Migrate in attach

Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Signed-off-by: Michael J. Ruhl <michael.j.ruhl@intel.com>

drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c

@@ -170,9 +170,19 @@ static int i915_gem_dmabuf_attach(struct dma_buf *dmabuf,
 				  struct dma_buf_attachment *attach)
 {
 	struct drm_i915_gem_object *obj = dma_buf_to_obj(dmabuf);
+	int ret;
 
 	assert_object_held(obj);
-	return i915_gem_object_pin_pages(obj);
+
+	if (!i915_gem_object_can_migrate(obj, INTEL_REGION_SMEM))
+		return -EOPNOTSUPP;
+	ret = i915_gem_object_migrate(obj, NULL, INTEL_REGION_SMEM);
+	if (!ret)
+		ret = i915_gem_object_wait_migration(obj, 0);
+	if (!ret)
+		ret = i915_gem_object_pin_pages(obj);
+
+	return ret;
 }
 
 static void i915_gem_dmabuf_detach(struct dma_buf *dmabuf,

drivers/gpu/drm/i915/gem/selftests/i915_gem_dmabuf.c

@@ -106,7 +106,9 @@ static int igt_dmabuf_import_same_driver(void *arg)
 	int err;
 
 	force_different_devices = true;
-	obj = i915_gem_object_create_shmem(i915, PAGE_SIZE);
+	obj = i915_gem_object_create_lmem(i915, PAGE_SIZE, 0);
+	if (IS_ERR(obj))
+		obj = i915_gem_object_create_shmem(i915, PAGE_SIZE);
 	if (IS_ERR(obj))
 		goto out_ret;