# Re: \[PATCH v10 14/18\] virtio/vsock: enable SEQPACKET for transport

- From: Stefano Garzarella \<sgarzare@redhat.com\>
- Date: 2021-06-03 15:22:13 
- List: netdev
- Page: https://ratatoskr.run/netdev/2021/06/1401362
- Thread: https://ratatoskr.run/kvm/2021/05/1386559/t.md

```text
On Thu, May 20, 2021 at 10:18:57PM +0300, Arseny Krasnov wrote:
>To make transport work with SOCK_SEQPACKET two updates were
>added:

Present is better, and you can also mention that we enable it only if the feature is negotiated with the device.

>1) SOCK_SEQPACKET ops for virtio transport and 'seqpacket_allow()'
>   callback.
>2) Handling of SEQPACKET bit: guest tries to negotiate it with vhost.
>
>Signed-off-by: Arseny Krasnov <redacted>
>---
> v9 -> v10:
> 1) Use 'virtio_has_feature()' to check feature bit.
> 2) Move assignment to 'seqpacket_allow' before 'rcu_assign_pointer()'.
>
> net/vmw_vsock/virtio_transport.c | 24 ++++++++++++++++++++++++
> 1 file changed, 24 insertions(+)
>
>diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c
>index 2700a63ab095..bc5ee8df723a 100644
>--- a/net/vmw_vsock/virtio_transport.c
>+++ b/net/vmw_vsock/virtio_transport.c
>@@ -62,6 +62,7 @@ struct virtio_vsock {
> 	struct virtio_vsock_event event_list[8];
>
> 	u32 guest_cid;
>+	bool seqpacket_allow;
> };
>
> static u32 virtio_transport_get_local_cid(void)
>@@ -443,6 +444,8 @@ static void virtio_vsock_rx_done(struct virtqueue *vq)
> 	queue_work(virtio_vsock_workqueue, &vsock->rx_work);
> }
>
>+static bool virtio_transport_seqpacket_allow(u32 remote_cid);
>+
> static struct virtio_transport virtio_transport = {
> 	.transport = {
> 		.module                   = THIS_MODULE,
>@@ -469,6 +472,10 @@ static struct virtio_transport virtio_transport = {
> 		.stream_is_active         = virtio_transport_stream_is_active,
> 		.stream_allow             = virtio_transport_stream_allow,
>
>+		.seqpacket_dequeue        = virtio_transport_seqpacket_dequeue,
>+		.seqpacket_enqueue        = virtio_transport_seqpacket_enqueue,
>+		.seqpacket_allow          = virtio_transport_seqpacket_allow,
>+
> 		.notify_poll_in           = virtio_transport_notify_poll_in,
> 		.notify_poll_out          = virtio_transport_notify_poll_out,
> 		.notify_recv_init         = virtio_transport_notify_recv_init,
>@@ -485,6 +492,19 @@ static struct virtio_transport virtio_transport = {
> 	.send_pkt = virtio_transport_send_pkt,
> };
>
>+static bool virtio_transport_seqpacket_allow(u32 remote_cid)
>+{
>+	struct virtio_vsock *vsock;
>+	bool seqpacket_allow;
>+
>+	rcu_read_lock();
>+	vsock = rcu_dereference(the_virtio_vsock);
>+	seqpacket_allow = vsock->seqpacket_allow;
>+	rcu_read_unlock();
>+
>+	return seqpacket_allow;
>+}
>+
> static void virtio_transport_rx_work(struct work_struct *work)
> {
> 	struct virtio_vsock *vsock =
>@@ -608,6 +628,9 @@ static int virtio_vsock_probe(struct virtio_device *vdev)
> 	vsock->event_run = true;
> 	mutex_unlock(&vsock->event_lock);
>
>+	if (virtio_has_feature(vdev, VIRTIO_VSOCK_F_SEQPACKET))
>+		vsock->seqpacket_allow = true;
>+
> 	vdev->priv = vsock;
> 	rcu_assign_pointer(the_virtio_vsock, vsock);
>
>@@ -695,6 +718,7 @@ static struct virtio_device_id id_table[] = {
> };
>
> static unsigned int features[] = {
>+	VIRTIO_VSOCK_F_SEQPACKET
> };
>
> static struct virtio_driver virtio_vsock_driver = {
>-- 
>2.25.1
>

```