[PATCH 2/2] drm/i915/gem: Migrate to system at dma-buf attach time (v5)

[Jason Ekstrand <jason@xxxxxxxxxxxxxx>]

From: Thomas Hellström <thomas.hellstrom@xxxxxxxxxxxxxxx>

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
v5: (jason)
- Lock around the migration

Signed-off-by: Thomas Hellström <thomas.hellstrom@xxxxxxxxxxxxxxx>
Signed-off-by: Michael J. Ruhl <michael.j.ruhl@xxxxxxxxx>
Reported-by: kernel test robot <lkp@xxxxxxxxx>
Signed-off-by: Jason Ekstrand <jason@xxxxxxxxxxxxxx>
Reviewed-by: Jason Ekstrand <jason@xxxxxxxxxxxxxx>
---
 drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c    | 25 ++++++++++++++++++-
 .../drm/i915/gem/selftests/i915_gem_dmabuf.c  |  4 ++-
 2 files changed, 27 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c b/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c
index 9a655f69a0671..3163f00554476 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c
@@ -170,8 +170,31 @@ 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);
+	struct i915_gem_ww_ctx ww;
+	int err;
+
+	for_i915_gem_ww(&ww, err, true) {
+		err = i915_gem_object_lock(obj, &ww);
+		if (err)
+			continue;
+
+		if (!i915_gem_object_can_migrate(obj, INTEL_REGION_SMEM)) {
+			err = -EOPNOTSUPP;
+			continue;
+		}
+
+		err = i915_gem_object_migrate(obj, &ww, INTEL_REGION_SMEM);
+		if (err)
+			continue;
 
-	return i915_gem_object_pin_pages_unlocked(obj);
+		err = i915_gem_object_wait_migration(obj, 0);
+		if (err)
+			continue;
+
+		err = i915_gem_object_pin_pages(obj);
+	}
+
+	return err;
 }
 
 static void i915_gem_dmabuf_detach(struct dma_buf *dmabuf,
diff --git a/drivers/gpu/drm/i915/gem/selftests/i915_gem_dmabuf.c b/drivers/gpu/drm/i915/gem/selftests/i915_gem_dmabuf.c
index 3dc0f8b3cdab0..4f7e77b1c0152 100644
--- a/drivers/gpu/drm/i915/gem/selftests/i915_gem_dmabuf.c
+++ b/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;
 
-- 
2.31.1