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

[Arseny Krasnov <arseny.krasnov@kaspersky.com>]

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@kaspersky.com>
---
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;
+
 	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