[PATCH v19 28/30] drm/virtio: Attach shmem BOs dynamically

[Dmitry Osipenko]

Prepare for addition of memory shrinker support by attaching shmem pages
to host dynamically on first use. Previously the attachment vq command
wasn't fenced and there was no vq kick made in the BO creation code path,
hence the attachment already was happening dynamically, but implicitly.
Making attachment explicitly dynamic will allow to simplify and reuse more
code when shrinker will be added. The virtio_gpu_object_shmem_init() now
works under the held reservation lock, which will be important to have for
shrinker to avoid moving pages while they are in active use by the driver.

Acked-by: Gerd Hoffmann <kraxel@xxxxxxxxxx>
Signed-off-by: Dmitry Osipenko <dmitry.osipenko@xxxxxxxxxxxxx>
---
 drivers/gpu/drm/virtio/virtgpu_drv.h    |  7 +++
 drivers/gpu/drm/virtio/virtgpu_gem.c    | 26 +++++++++
 drivers/gpu/drm/virtio/virtgpu_ioctl.c  | 32 +++++++----
 drivers/gpu/drm/virtio/virtgpu_object.c | 73 ++++++++++++++++++++-----
 drivers/gpu/drm/virtio/virtgpu_submit.c | 15 ++++-
 5 files changed, 125 insertions(+), 28 deletions(-)

diff --git a/drivers/gpu/drm/virtio/virtgpu_drv.h b/drivers/gpu/drm/virtio/virtgpu_drv.h
index 83d1e4622292..1837dc7ea9fb 100644
--- a/drivers/gpu/drm/virtio/virtgpu_drv.h
+++ b/drivers/gpu/drm/virtio/virtgpu_drv.h
@@ -92,6 +92,7 @@ struct virtio_gpu_object {
 	uint32_t hw_res_handle;
 	bool dumb;
 	bool created;
+	bool detached;
 	bool host3d_blob, guest_blob;
 	uint32_t blob_mem, blob_flags;
 
@@ -318,6 +319,8 @@ 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_array_prepare(struct virtio_gpu_device *vgdev,
+			     struct virtio_gpu_object_array *objs);
 int virtio_gpu_gem_pin(struct virtio_gpu_object *bo);
 void virtio_gpu_gem_unpin(struct virtio_gpu_object *bo);
 
@@ -458,6 +461,10 @@ int virtio_gpu_object_create(struct virtio_gpu_device *vgdev,
 
 bool virtio_gpu_is_shmem(struct virtio_gpu_object *bo);
 
+int virtio_gpu_reattach_shmem_object_locked(struct virtio_gpu_object *bo);
+
+int virtio_gpu_reattach_shmem_object(struct virtio_gpu_object *bo);
+
 int virtio_gpu_resource_id_get(struct virtio_gpu_device *vgdev,
 			       uint32_t *resid);
 /* virtgpu_prime.c */
diff --git a/drivers/gpu/drm/virtio/virtgpu_gem.c b/drivers/gpu/drm/virtio/virtgpu_gem.c
index 625c05d625bf..97e67064c97e 100644
--- a/drivers/gpu/drm/virtio/virtgpu_gem.c
+++ b/drivers/gpu/drm/virtio/virtgpu_gem.c
@@ -295,6 +295,26 @@ void virtio_gpu_array_put_free_work(struct work_struct *work)
 	spin_unlock(&vgdev->obj_free_lock);
 }
 
+int virtio_gpu_array_prepare(struct virtio_gpu_device *vgdev,
+			     struct virtio_gpu_object_array *objs)
+{
+	struct virtio_gpu_object *bo;
+	int ret = 0;
+	u32 i;
+
+	for (i = 0; i < objs->nents; i++) {
+		bo = gem_to_virtio_gpu_obj(objs->objs[i]);
+
+		if (virtio_gpu_is_shmem(bo) && bo->detached) {
+			ret = virtio_gpu_reattach_shmem_object_locked(bo);
+			if (ret)
+				break;
+		}
+	}
+
+	return ret;
+}
+
 int virtio_gpu_gem_pin(struct virtio_gpu_object *bo)
 {
 	int err;
@@ -303,6 +323,12 @@ int virtio_gpu_gem_pin(struct virtio_gpu_object *bo)
 		err = drm_gem_shmem_pin(&bo->base);
 		if (err)
 			return err;
+
+		err = virtio_gpu_reattach_shmem_object(bo);
+		if (err) {
+			drm_gem_shmem_unpin(&bo->base);
+			return err;
+		}
 	}
 
 	return 0;
diff --git a/drivers/gpu/drm/virtio/virtgpu_ioctl.c b/drivers/gpu/drm/virtio/virtgpu_ioctl.c
index e4f76f315550..c7da22006149 100644
--- a/drivers/gpu/drm/virtio/virtgpu_ioctl.c
+++ b/drivers/gpu/drm/virtio/virtgpu_ioctl.c
@@ -256,6 +256,10 @@ static int virtio_gpu_transfer_from_host_ioctl(struct drm_device *dev,
 	if (ret != 0)
 		goto err_put_free;
 
+	ret = virtio_gpu_array_prepare(vgdev, objs);
+	if (ret)
+		goto err_unlock;
+
 	fence = virtio_gpu_fence_alloc(vgdev, vgdev->fence_drv.context, 0);
 	if (!fence) {
 		ret = -ENOMEM;
@@ -298,11 +302,25 @@ static int virtio_gpu_transfer_to_host_ioctl(struct drm_device *dev, void *data,
 		goto err_put_free;
 	}
 
+	ret = virtio_gpu_array_lock_resv(objs);
+	if (ret != 0)
+		goto err_put_free;
+
+	ret = virtio_gpu_array_prepare(vgdev, objs);
+	if (ret)
+		goto err_unlock;
+
+	fence = virtio_gpu_fence_alloc(vgdev, vgdev->fence_drv.context, 0);
+	if (!fence) {
+		ret = -ENOMEM;
+		goto err_unlock;
+	}
+
 	if (!vgdev->has_virgl_3d) {
 		virtio_gpu_cmd_transfer_to_host_2d
 			(vgdev, offset,
 			 args->box.w, args->box.h, args->box.x, args->box.y,
-			 objs, NULL);
+			 objs, fence);
 	} else {
 		virtio_gpu_create_context(dev, file);
 
@@ -311,23 +329,13 @@ static int virtio_gpu_transfer_to_host_ioctl(struct drm_device *dev, void *data,
 			goto err_put_free;
 		}
 
-		ret = virtio_gpu_array_lock_resv(objs);
-		if (ret != 0)
-			goto err_put_free;
-
-		ret = -ENOMEM;
-		fence = virtio_gpu_fence_alloc(vgdev, vgdev->fence_drv.context,
-					       0);
-		if (!fence)
-			goto err_unlock;
-
 		virtio_gpu_cmd_transfer_to_host_3d
 			(vgdev,
 			 vfpriv ? vfpriv->ctx_id : 0, offset, args->level,
 			 args->stride, args->layer_stride, &args->box, objs,
 			 fence);
-		dma_fence_put(&fence->f);
 	}
+	dma_fence_put(&fence->f);
 	virtio_gpu_notify(vgdev);
 	return 0;
 
diff --git a/drivers/gpu/drm/virtio/virtgpu_object.c b/drivers/gpu/drm/virtio/virtgpu_object.c
index e58528c562ef..de347aa3b9a8 100644
--- a/drivers/gpu/drm/virtio/virtgpu_object.c
+++ b/drivers/gpu/drm/virtio/virtgpu_object.c
@@ -143,7 +143,7 @@ static int virtio_gpu_object_shmem_init(struct virtio_gpu_device *vgdev,
 	struct sg_table *pages;
 	int si;
 
-	pages = drm_gem_shmem_get_pages_sgt(&bo->base);
+	pages = drm_gem_shmem_get_pages_sgt_locked(&bo->base);
 	if (IS_ERR(pages))
 		return PTR_ERR(pages);
 
@@ -177,6 +177,40 @@ static int virtio_gpu_object_shmem_init(struct virtio_gpu_device *vgdev,
 	return 0;
 }
 
+int virtio_gpu_reattach_shmem_object_locked(struct virtio_gpu_object *bo)
+{
+	struct virtio_gpu_device *vgdev = bo->base.base.dev->dev_private;
+	struct virtio_gpu_mem_entry *ents;
+	unsigned int nents;
+	int err;
+
+	if (!bo->detached)
+		return 0;
+
+	err = virtio_gpu_object_shmem_init(vgdev, bo, &ents, &nents);
+	if (err)
+		return err;
+
+	virtio_gpu_object_attach(vgdev, bo, ents, nents);
+
+	bo->detached = false;
+
+	return 0;
+}
+
+int virtio_gpu_reattach_shmem_object(struct virtio_gpu_object *bo)
+{
+	int ret;
+
+	ret = dma_resv_lock_interruptible(bo->base.base.resv, NULL);
+	if (ret)
+		return ret;
+	ret = virtio_gpu_reattach_shmem_object_locked(bo);
+	dma_resv_unlock(bo->base.base.resv);
+
+	return ret;
+}
+
 int virtio_gpu_object_create(struct virtio_gpu_device *vgdev,
 			     struct virtio_gpu_object_params *params,
 			     struct virtio_gpu_object **bo_ptr,
@@ -207,45 +241,56 @@ int virtio_gpu_object_create(struct virtio_gpu_device *vgdev,
 
 	bo->dumb = params->dumb;
 
-	ret = virtio_gpu_object_shmem_init(vgdev, bo, &ents, &nents);
-	if (ret != 0)
-		goto err_put_id;
+	if (bo->blob_mem == VIRTGPU_BLOB_MEM_GUEST)
+		bo->guest_blob = true;
 
 	if (fence) {
 		ret = -ENOMEM;
 		objs = virtio_gpu_array_alloc(1);
 		if (!objs)
-			goto err_free_entry;
+			goto err_put_id;
 		virtio_gpu_array_add_obj(objs, &bo->base.base);
 
 		ret = virtio_gpu_array_lock_resv(objs);
 		if (ret != 0)
 			goto err_put_objs;
+	} else {
+		ret = dma_resv_lock(bo->base.base.resv, NULL);
+		if (ret)
+			goto err_put_id;
 	}
 
 	if (params->blob) {
-		if (params->blob_mem == VIRTGPU_BLOB_MEM_GUEST)
-			bo->guest_blob = true;
+		ret = virtio_gpu_object_shmem_init(vgdev, bo, &ents, &nents);
+		if (ret)
+			goto err_unlock_objs;
+	} else {
+		bo->detached = true;
+	}
 
+	if (params->blob)
 		virtio_gpu_cmd_resource_create_blob(vgdev, bo, params,
 						    ents, nents);
-	} else if (params->virgl) {
+	else if (params->virgl)
 		virtio_gpu_cmd_resource_create_3d(vgdev, bo, params,
 						  objs, fence);
-		virtio_gpu_object_attach(vgdev, bo, ents, nents);
-	} else {
+	else
 		virtio_gpu_cmd_create_resource(vgdev, bo, params,
 					       objs, fence);
-		virtio_gpu_object_attach(vgdev, bo, ents, nents);
-	}
+
+	if (!fence)
+		dma_resv_unlock(bo->base.base.resv);
 
 	*bo_ptr = bo;
 	return 0;
 
+err_unlock_objs:
+	if (fence)
+		virtio_gpu_array_unlock_resv(objs);
+	else
+		dma_resv_unlock(bo->base.base.resv);
 err_put_objs:
 	virtio_gpu_array_put_free(objs);
-err_free_entry:
-	kvfree(ents);
 err_put_id:
 	virtio_gpu_resource_id_put(vgdev, bo->hw_res_handle);
 err_put_pages:
diff --git a/drivers/gpu/drm/virtio/virtgpu_submit.c b/drivers/gpu/drm/virtio/virtgpu_submit.c
index 5c514946bbad..6e4ef2593e8f 100644
--- a/drivers/gpu/drm/virtio/virtgpu_submit.c
+++ b/drivers/gpu/drm/virtio/virtgpu_submit.c
@@ -464,8 +464,19 @@ static void virtio_gpu_install_out_fence_fd(struct virtio_gpu_submit *submit)
 
 static int virtio_gpu_lock_buflist(struct virtio_gpu_submit *submit)
 {
-	if (submit->buflist)
-		return virtio_gpu_array_lock_resv(submit->buflist);
+	int err;
+
+	if (submit->buflist) {
+		err = virtio_gpu_array_lock_resv(submit->buflist);
+		if (err)
+			return err;
+
+		err = virtio_gpu_array_prepare(submit->vgdev, submit->buflist);
+		if (err) {
+			virtio_gpu_array_unlock_resv(submit->buflist);
+			return err;
+		}
+	}
 
 	return 0;
 }
-- 
2.43.0