Re: [RFC PATCH v8 14/19] virtio/vsock: enable SEQPACKET for transport

[Stefano Garzarella]

On Tue, Apr 13, 2021 at 03:45:49PM +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 <arseny.krasnov@xxxxxxxxxxxxx>
> ---
> v7 -> v8:
> - This patch merged with patch which adds SEQPACKET feature bit to
>   virtio transport.
>
> net/vmw_vsock/virtio_transport.c | 17 +++++++++++++++++
> 1 file changed, 17 insertions(+)
>
> diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c
> index 2700a63ab095..ee99bd919a12 100644
> --- a/net/vmw_vsock/virtio_transport.c
> +++ b/net/vmw_vsock/virtio_transport.c
> @@ -443,6 +443,8 @@ static void virtio_vsock_rx_done(struct virtqueue 
> *vq)
> 	queue_work(virtio_vsock_workqueue, &vsock->rx_work);
> }
>
> +static bool virtio_transport_seqpacket_allow(void);
> +
> static struct virtio_transport virtio_transport = {
> 	.transport = {
> 		.module                   = THIS_MODULE,
> @@ -469,6 +471,10 @@ 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,
> @@ -483,8 +489,14 @@ static struct virtio_transport virtio_transport = {
> 	},
>
> 	.send_pkt = virtio_transport_send_pkt,
> +	.seqpacket_allow = false
> };
>
> +static bool virtio_transport_seqpacket_allow(void)
> +{
> +	return virtio_transport.seqpacket_allow;
> +}
> +
> static void virtio_transport_rx_work(struct work_struct *work)
> {
> 	struct virtio_vsock *vsock =
> @@ -612,6 +624,10 @@ 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))
> +		virtio_transport.seqpacket_allow = true;
> +

virtio-vsock devices can be hot-plugged and hot-unplugged, so we should 
reset virtio_transport.seqpacket_allow at every probe.

Now thinking about it more, would it be better to save this information 
in struct virtio_vsock instead of struct virtio_transport?

> 	return 0;
>
> out:
> @@ -695,6 +711,7 @@ 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