[LINUX KERNEL PATCH v5 2/2] virtgpu: Add freeze and restore func to reinit vqs

[Jiqian Chen]

When we suspended guest VM, it called into Qemu to call
virtio_reset->__virtio_queue_reset, this cleared all virtqueue information
of virtgpu on Qemu end, but guest kernel still keep the virtqueus. As a
result, after guest resumed, if guest sent ctrl/cursor requests to Qemu
through virtqueue, but now Qemu can't get requests from the virtqueue.
(Failed in function virtio_queue_notify, vq->vring.desc is NULL)

So, this patch add freeze and restore function for virtgpu driver. In
freeze function, it flushes all virtqueue works and deletes virtqueues. In
restore function, it re-initializes virtqueues. And then, Qemu and guest
can communicate normally.

Signed-off-by: Jiqian Chen <Jiqian.Chen@xxxxxxx>
---
 drivers/gpu/drm/virtio/virtgpu_drv.c | 23 +++++++++++++++++++++
 drivers/gpu/drm/virtio/virtgpu_drv.h |  1 +
 drivers/gpu/drm/virtio/virtgpu_kms.c | 30 +++++++++++++++++++---------
 3 files changed, 45 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/virtio/virtgpu_drv.c b/drivers/gpu/drm/virtio/virtgpu_drv.c
index 644b8ee51009..8e751db129e4 100644
--- a/drivers/gpu/drm/virtio/virtgpu_drv.c
+++ b/drivers/gpu/drm/virtio/virtgpu_drv.c
@@ -130,6 +130,25 @@ static void virtio_gpu_config_changed(struct virtio_device *vdev)
 	schedule_work(&vgdev->config_changed_work);
 }
 
+#ifdef CONFIG_PM
+static int virtio_gpu_freeze(struct virtio_device *dev)
+{
+	struct drm_device *ddev = dev->priv;
+	struct virtio_gpu_device *vgdev = ddev->dev_private;
+
+	flush_work(&vgdev->ctrlq.dequeue_work);
+	flush_work(&vgdev->cursorq.dequeue_work);
+	vgdev->vdev->config->del_vqs(vgdev->vdev);
+
+	return 0;
+}
+
+static int virtio_gpu_restore(struct virtio_device *dev)
+{
+	return virtio_gpu_init_vqs(dev);
+}
+#endif
+
 static struct virtio_device_id id_table[] = {
 	{ VIRTIO_ID_GPU, VIRTIO_DEV_ANY_ID },
 	{ 0 },
@@ -156,6 +175,10 @@ static struct virtio_driver virtio_gpu_driver = {
 	.driver.owner = THIS_MODULE,
 	.id_table = id_table,
 	.probe = virtio_gpu_probe,
+#ifdef CONFIG_PM
+	.freeze = virtio_gpu_freeze,
+	.restore = virtio_gpu_restore,
+#endif
 	.remove = virtio_gpu_remove,
 	.config_changed = virtio_gpu_config_changed
 };
diff --git a/drivers/gpu/drm/virtio/virtgpu_drv.h b/drivers/gpu/drm/virtio/virtgpu_drv.h
index 4126c384286b..d93dd53a947d 100644
--- a/drivers/gpu/drm/virtio/virtgpu_drv.h
+++ b/drivers/gpu/drm/virtio/virtgpu_drv.h
@@ -282,6 +282,7 @@ extern struct drm_ioctl_desc virtio_gpu_ioctls[DRM_VIRTIO_NUM_IOCTLS];
 void virtio_gpu_create_context(struct drm_device *dev, struct drm_file *file);
 
 /* virtgpu_kms.c */
+int virtio_gpu_init_vqs(struct virtio_device *vdev);
 int virtio_gpu_init(struct virtio_device *vdev, struct drm_device *dev);
 void virtio_gpu_deinit(struct drm_device *dev);
 void virtio_gpu_release(struct drm_device *dev);
diff --git a/drivers/gpu/drm/virtio/virtgpu_kms.c b/drivers/gpu/drm/virtio/virtgpu_kms.c
index 5a3b5aaed1f3..871b7ba98257 100644
--- a/drivers/gpu/drm/virtio/virtgpu_kms.c
+++ b/drivers/gpu/drm/virtio/virtgpu_kms.c
@@ -114,16 +114,33 @@ static void virtio_gpu_get_capsets(struct virtio_gpu_device *vgdev,
 	vgdev->num_capsets = num_capsets;
 }
 
-int virtio_gpu_init(struct virtio_device *vdev, struct drm_device *dev)
+int virtio_gpu_init_vqs(struct virtio_device *vdev)
 {
 	static vq_callback_t *callbacks[] = {
 		virtio_gpu_ctrl_ack, virtio_gpu_cursor_ack
 	};
 	static const char * const names[] = { "control", "cursor" };
+	struct drm_device *dev = vdev->priv;
+	struct virtio_gpu_device *vgdev = dev->dev_private;
+	struct virtqueue *vqs[2];
+	int ret;
+
+	virtio_gpu_init_vq(&vgdev->ctrlq, virtio_gpu_dequeue_ctrl_func);
+	virtio_gpu_init_vq(&vgdev->cursorq, virtio_gpu_dequeue_cursor_func);
+
+	ret = virtio_find_vqs(vgdev->vdev, 2, vqs, callbacks, names, NULL);
+	if (ret) {
+		DRM_ERROR("failed to find virt queues\n");
+		return ret;
+	}
+	vgdev->ctrlq.vq = vqs[0];
+	vgdev->cursorq.vq = vqs[1];
+	return 0;
+}
 
+int virtio_gpu_init(struct virtio_device *vdev, struct drm_device *dev)
+{
 	struct virtio_gpu_device *vgdev;
-	/* this will expand later */
-	struct virtqueue *vqs[2];
 	u32 num_scanouts, num_capsets;
 	int ret = 0;
 
@@ -144,8 +161,6 @@ int virtio_gpu_init(struct virtio_device *vdev, struct drm_device *dev)
 	ida_init(&vgdev->ctx_id_ida);
 	ida_init(&vgdev->resource_ida);
 	init_waitqueue_head(&vgdev->resp_wq);
-	virtio_gpu_init_vq(&vgdev->ctrlq, virtio_gpu_dequeue_ctrl_func);
-	virtio_gpu_init_vq(&vgdev->cursorq, virtio_gpu_dequeue_cursor_func);
 
 	vgdev->fence_drv.context = dma_fence_context_alloc(1);
 	spin_lock_init(&vgdev->fence_drv.lock);
@@ -207,13 +222,10 @@ int virtio_gpu_init(struct virtio_device *vdev, struct drm_device *dev)
 	DRM_INFO("features: %ccontext_init\n",
 		 vgdev->has_context_init ? '+' : '-');
 
-	ret = virtio_find_vqs(vgdev->vdev, 2, vqs, callbacks, names, NULL);
+	ret = virtio_gpu_init_vqs(vdev);
 	if (ret) {
-		DRM_ERROR("failed to find virt queues\n");
 		goto err_vqs;
 	}
-	vgdev->ctrlq.vq = vqs[0];
-	vgdev->cursorq.vq = vqs[1];
 	ret = virtio_gpu_alloc_vbufs(vgdev);
 	if (ret) {
 		DRM_ERROR("failed to alloc vbufs\n");
-- 
2.34.1