Merge branch 'vsock-virtio-add-support-for-device-suspend-resume'

Stefano Garzarella says:

====================
vsock/virtio: add support for device suspend/resume

Vilas reported that virtio-vsock no longer worked properly after
suspend/resume (echo mem >/sys/power/state).
It was impossible to connect to the host and vice versa.

Indeed, the support has never been implemented.

This series implement .freeze and .restore callbacks of struct virtio_driver
to support device suspend/resume.

The first patch factors our the code to initialize and delete VQs.
The second patch uses that code to support device suspend/resume.
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
====================

Link: https://lore.kernel.org/r/20220428132241.152679-1-sgarzare@redhat.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

net/vmw_vsock/virtio_transport.c

@@ -566,67 +566,28 @@ static void virtio_transport_rx_work(struct work_struct *work)
 	mutex_unlock(&vsock->rx_lock);
 }
 
-static int virtio_vsock_probe(struct virtio_device *vdev)
+static int virtio_vsock_vqs_init(struct virtio_vsock *vsock)
 {
-	vq_callback_t *callbacks[] = {
-		virtio_vsock_rx_done,
-		virtio_vsock_tx_done,
-		virtio_vsock_event_done,
-	};
+	struct virtio_device *vdev = vsock->vdev;
 	static const char * const names[] = {
 		"rx",
 		"tx",
 		"event",
 	};
-	struct virtio_vsock *vsock = NULL;
+	vq_callback_t *callbacks[] = {
+		virtio_vsock_rx_done,
+		virtio_vsock_tx_done,
+		virtio_vsock_event_done,
+	};
 	int ret;
 
-	ret = mutex_lock_interruptible(&the_virtio_vsock_mutex);
-	if (ret)
-		return ret;
-
-	/* Only one virtio-vsock device per guest is supported */
-	if (rcu_dereference_protected(the_virtio_vsock,
-				lockdep_is_held(&the_virtio_vsock_mutex))) {
-		ret = -EBUSY;
-		goto out;
-	}
-
-	vsock = kzalloc(sizeof(*vsock), GFP_KERNEL);
-	if (!vsock) {
-		ret = -ENOMEM;
-		goto out;
-	}
-
-	vsock->vdev = vdev;
-
-	ret = virtio_find_vqs(vsock->vdev, VSOCK_VQ_MAX,
-			      vsock->vqs, callbacks, names,
+	ret = virtio_find_vqs(vdev, VSOCK_VQ_MAX, vsock->vqs, callbacks, names,
 			      NULL);
 	if (ret < 0)
-		goto out;
+		return ret;
 
 	virtio_vsock_update_guest_cid(vsock);
 
-	vsock->rx_buf_nr = 0;
-	vsock->rx_buf_max_nr = 0;
-	atomic_set(&vsock->queued_replies, 0);
-
-	mutex_init(&vsock->tx_lock);
-	mutex_init(&vsock->rx_lock);
-	mutex_init(&vsock->event_lock);
-	spin_lock_init(&vsock->send_pkt_list_lock);
-	INIT_LIST_HEAD(&vsock->send_pkt_list);
-	INIT_WORK(&vsock->rx_work, virtio_transport_rx_work);
-	INIT_WORK(&vsock->tx_work, virtio_transport_tx_work);
-	INIT_WORK(&vsock->event_work, virtio_transport_event_work);
-	INIT_WORK(&vsock->send_pkt_work, virtio_transport_send_pkt_work);
-
-	if (virtio_has_feature(vdev, VIRTIO_VSOCK_F_SEQPACKET))
-		vsock->seqpacket_allow = true;
-
-	vdev->priv = vsock;
-
 	virtio_device_ready(vdev);
 
 	mutex_lock(&vsock->tx_lock);
@@ -643,30 +604,15 @@ static int virtio_vsock_probe(struct virtio_device *vdev)
 	vsock->event_run = true;
 	mutex_unlock(&vsock->event_lock);
 
-	rcu_assign_pointer(the_virtio_vsock, vsock);
-
-	mutex_unlock(&the_virtio_vsock_mutex);
-
 	return 0;
-
-out:
-	kfree(vsock);
-	mutex_unlock(&the_virtio_vsock_mutex);
-	return ret;
 }
 
-static void virtio_vsock_remove(struct virtio_device *vdev)
+static void virtio_vsock_vqs_del(struct virtio_vsock *vsock)
 {
-	struct virtio_vsock *vsock = vdev->priv;
+	struct virtio_device *vdev = vsock->vdev;
 	struct virtio_vsock_pkt *pkt;
 
-	mutex_lock(&the_virtio_vsock_mutex);
-
-	vdev->priv = NULL;
-	rcu_assign_pointer(the_virtio_vsock, NULL);
-	synchronize_rcu();
-
-	/* Reset all connected sockets when the device disappear */
+	/* Reset all connected sockets when the VQs disappear */
 	vsock_for_each_connected_socket(&virtio_transport.transport,
 					virtio_vsock_reset_sock);
 
@@ -711,6 +657,78 @@ static void virtio_vsock_remove(struct virtio_device *vdev)
 
 	/* Delete virtqueues and flush outstanding callbacks if any */
 	vdev->config->del_vqs(vdev);
+}
+
+static int virtio_vsock_probe(struct virtio_device *vdev)
+{
+	struct virtio_vsock *vsock = NULL;
+	int ret;
+
+	ret = mutex_lock_interruptible(&the_virtio_vsock_mutex);
+	if (ret)
+		return ret;
+
+	/* Only one virtio-vsock device per guest is supported */
+	if (rcu_dereference_protected(the_virtio_vsock,
+				lockdep_is_held(&the_virtio_vsock_mutex))) {
+		ret = -EBUSY;
+		goto out;
+	}
+
+	vsock = kzalloc(sizeof(*vsock), GFP_KERNEL);
+	if (!vsock) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	vsock->vdev = vdev;
+
+	vsock->rx_buf_nr = 0;
+	vsock->rx_buf_max_nr = 0;
+	atomic_set(&vsock->queued_replies, 0);
+
+	mutex_init(&vsock->tx_lock);
+	mutex_init(&vsock->rx_lock);
+	mutex_init(&vsock->event_lock);
+	spin_lock_init(&vsock->send_pkt_list_lock);
+	INIT_LIST_HEAD(&vsock->send_pkt_list);
+	INIT_WORK(&vsock->rx_work, virtio_transport_rx_work);
+	INIT_WORK(&vsock->tx_work, virtio_transport_tx_work);
+	INIT_WORK(&vsock->event_work, virtio_transport_event_work);
+	INIT_WORK(&vsock->send_pkt_work, virtio_transport_send_pkt_work);
+
+	if (virtio_has_feature(vdev, VIRTIO_VSOCK_F_SEQPACKET))
+		vsock->seqpacket_allow = true;
+
+	vdev->priv = vsock;
+
+	ret = virtio_vsock_vqs_init(vsock);
+	if (ret < 0)
+		goto out;
+
+	rcu_assign_pointer(the_virtio_vsock, vsock);
+
+	mutex_unlock(&the_virtio_vsock_mutex);
+
+	return 0;
+
+out:
+	kfree(vsock);
+	mutex_unlock(&the_virtio_vsock_mutex);
+	return ret;
+}
+
+static void virtio_vsock_remove(struct virtio_device *vdev)
+{
+	struct virtio_vsock *vsock = vdev->priv;
+
+	mutex_lock(&the_virtio_vsock_mutex);
+
+	vdev->priv = NULL;
+	rcu_assign_pointer(the_virtio_vsock, NULL);
+	synchronize_rcu();
+
+	virtio_vsock_vqs_del(vsock);
 
 	/* Other works can be queued before 'config->del_vqs()', so we flush
 	 * all works before to free the vsock object to avoid use after free.
@@ -725,6 +743,49 @@ static void virtio_vsock_remove(struct virtio_device *vdev)
 	kfree(vsock);
 }
 
+#ifdef CONFIG_PM_SLEEP
+static int virtio_vsock_freeze(struct virtio_device *vdev)
+{
+	struct virtio_vsock *vsock = vdev->priv;
+
+	mutex_lock(&the_virtio_vsock_mutex);
+
+	rcu_assign_pointer(the_virtio_vsock, NULL);
+	synchronize_rcu();
+
+	virtio_vsock_vqs_del(vsock);
+
+	mutex_unlock(&the_virtio_vsock_mutex);
+
+	return 0;
+}
+
+static int virtio_vsock_restore(struct virtio_device *vdev)
+{
+	struct virtio_vsock *vsock = vdev->priv;
+	int ret;
+
+	mutex_lock(&the_virtio_vsock_mutex);
+
+	/* Only one virtio-vsock device per guest is supported */
+	if (rcu_dereference_protected(the_virtio_vsock,
+				lockdep_is_held(&the_virtio_vsock_mutex))) {
+		ret = -EBUSY;
+		goto out;
+	}
+
+	ret = virtio_vsock_vqs_init(vsock);
+	if (ret < 0)
+		goto out;
+
+	rcu_assign_pointer(the_virtio_vsock, vsock);
+
+out:
+	mutex_unlock(&the_virtio_vsock_mutex);
+	return ret;
+}
+#endif /* CONFIG_PM_SLEEP */
+
 static struct virtio_device_id id_table[] = {
 	{ VIRTIO_ID_VSOCK, VIRTIO_DEV_ANY_ID },
 	{ 0 },
@@ -742,6 +803,10 @@ static struct virtio_driver virtio_vsock_driver = {
 	.id_table = id_table,
 	.probe = virtio_vsock_probe,
 	.remove = virtio_vsock_remove,
+#ifdef CONFIG_PM_SLEEP
+	.freeze = virtio_vsock_freeze,
+	.restore = virtio_vsock_restore,
+#endif
 };
 
 static int __init virtio_vsock_init(void)