[PATCH v19 27/30] drm/virtio: Pin display framebuffer BO

[Dmitry Osipenko <dmitry.osipenko@xxxxxxxxxxxxx>]

Prepare to addition of memory shrinker support by pinning display
framebuffer BO pages in memory while they are in use by display on host.
Shrinker is free to relocate framebuffer BO pages if it doesn't know that
pages are in use, thus pin the pages to disallow shrinker to move them.

Acked-by: Gerd Hoffmann <kraxel@xxxxxxxxxx>
Signed-off-by: Dmitry Osipenko <dmitry.osipenko@xxxxxxxxxxxxx>
---
 drivers/gpu/drm/virtio/virtgpu_drv.h   |  2 ++
 drivers/gpu/drm/virtio/virtgpu_gem.c   | 19 +++++++++++++++++++
 drivers/gpu/drm/virtio/virtgpu_plane.c | 17 +++++++++++++++--
 3 files changed, 36 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/virtio/virtgpu_drv.h b/drivers/gpu/drm/virtio/virtgpu_drv.h
index bb7d86a0c6a1..83d1e4622292 100644
--- a/drivers/gpu/drm/virtio/virtgpu_drv.h
+++ b/drivers/gpu/drm/virtio/virtgpu_drv.h
@@ -318,6 +318,8 @@ void virtio_gpu_array_put_free(struct virtio_gpu_object_array *objs);
 void virtio_gpu_array_put_free_delayed(struct virtio_gpu_device *vgdev,
 				       struct virtio_gpu_object_array *objs);
 void virtio_gpu_array_put_free_work(struct work_struct *work);
+int virtio_gpu_gem_pin(struct virtio_gpu_object *bo);
+void virtio_gpu_gem_unpin(struct virtio_gpu_object *bo);
 
 /* virtgpu_vq.c */
 int virtio_gpu_alloc_vbufs(struct virtio_gpu_device *vgdev);
diff --git a/drivers/gpu/drm/virtio/virtgpu_gem.c b/drivers/gpu/drm/virtio/virtgpu_gem.c
index 7db48d17ee3a..625c05d625bf 100644
--- a/drivers/gpu/drm/virtio/virtgpu_gem.c
+++ b/drivers/gpu/drm/virtio/virtgpu_gem.c
@@ -294,3 +294,22 @@ void virtio_gpu_array_put_free_work(struct work_struct *work)
 	}
 	spin_unlock(&vgdev->obj_free_lock);
 }
+
+int virtio_gpu_gem_pin(struct virtio_gpu_object *bo)
+{
+	int err;
+
+	if (virtio_gpu_is_shmem(bo)) {
+		err = drm_gem_shmem_pin(&bo->base);
+		if (err)
+			return err;
+	}
+
+	return 0;
+}
+
+void virtio_gpu_gem_unpin(struct virtio_gpu_object *bo)
+{
+	if (virtio_gpu_is_shmem(bo))
+		drm_gem_shmem_unpin(&bo->base);
+}
diff --git a/drivers/gpu/drm/virtio/virtgpu_plane.c b/drivers/gpu/drm/virtio/virtgpu_plane.c
index a72a2dbda031..162fb8a44d71 100644
--- a/drivers/gpu/drm/virtio/virtgpu_plane.c
+++ b/drivers/gpu/drm/virtio/virtgpu_plane.c
@@ -248,20 +248,28 @@ static int virtio_gpu_plane_prepare_fb(struct drm_plane *plane,
 	struct virtio_gpu_device *vgdev = dev->dev_private;
 	struct virtio_gpu_framebuffer *vgfb;
 	struct virtio_gpu_object *bo;
+	int err;
 
 	if (!new_state->fb)
 		return 0;
 
 	vgfb = to_virtio_gpu_framebuffer(new_state->fb);
 	bo = gem_to_virtio_gpu_obj(vgfb->base.obj[0]);
-	if (!bo || (plane->type == DRM_PLANE_TYPE_PRIMARY && !bo->guest_blob))
+
+	err = virtio_gpu_gem_pin(bo);
+	if (err)
+		return err;
+
+	if (plane->type == DRM_PLANE_TYPE_PRIMARY && !bo->guest_blob)
 		return 0;
 
 	if (bo->dumb && (plane->state->fb != new_state->fb)) {
 		vgfb->fence = virtio_gpu_fence_alloc(vgdev, vgdev->fence_drv.context,
 						     0);
-		if (!vgfb->fence)
+		if (!vgfb->fence) {
+			virtio_gpu_gem_unpin(bo);
 			return -ENOMEM;
+		}
 	}
 
 	return 0;
@@ -271,15 +279,20 @@ static void virtio_gpu_plane_cleanup_fb(struct drm_plane *plane,
 					struct drm_plane_state *state)
 {
 	struct virtio_gpu_framebuffer *vgfb;
+	struct virtio_gpu_object *bo;
 
 	if (!state->fb)
 		return;
 
 	vgfb = to_virtio_gpu_framebuffer(state->fb);
+	bo = gem_to_virtio_gpu_obj(vgfb->base.obj[0]);
+
 	if (vgfb->fence) {
 		dma_fence_put(&vgfb->fence->f);
 		vgfb->fence = NULL;
 	}
+
+	virtio_gpu_gem_unpin(bo);
 }
 
 static void virtio_gpu_cursor_plane_update(struct drm_plane *plane,
-- 
2.43.0