# Re: \[RFC PATCH v9 14/19\] virtio/vsock: enable SEQPACKET for transport

- From: Stefano Garzarella \<sgarzare@redhat.com\>
- Date: 2021-05-13 12:49:41 
- List: netdev
- Page: https://ratatoskr.run/netdev/2021/05/1376746
- Thread: https://ratatoskr.run/kvm/2021/05/6361587/t.md

```text
On Sat, May 08, 2021 at 07:36:14PM +0300, Arseny Krasnov wrote:
>This adds
>1) 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>
>---
> v8 -> v9:
> 1) Move 'seqpacket_allow' to 'struct virtio_vsock'.
>
> net/vmw_vsock/virtio_transport.c | 25 +++++++++++++++++++++++++
> 1 file changed, 25 insertions(+)
>
>diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c
>index 2700a63ab095..f714c16af65d 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 =
>@@ -612,6 +632,10 @@ static int virtio_vsock_probe(struct virtio_device *vdev)
> 	rcu_assign_pointer(the_virtio_vsock, vsock);
>
> 	mutex_unlock(&the_virtio_vsock_mutex);
>+
>+	if (vdev->features & (1ULL << VIRTIO_VSOCK_F_SEQPACKET))

We should use virtio_has_feature() to check the device features.

>+		vsock->seqpacket_allow = true;

When we assign the_virtio_vsock pointer, we should already set all the fields, so please move this code before the following block:

	# here

	vdev->priv = vsock;
	rcu_assign_pointer(the_virtio_vsock, vsock);

```