vsock_loopback.c

  1// SPDX-License-Identifier: GPL-2.0-only
  2/* loopback transport for vsock using virtio_transport_common APIs
  3 *
  4 * Copyright (C) 2013-2019 Red Hat, Inc.
  5 * Authors: Asias He <asias@redhat.com>
  6 *          Stefan Hajnoczi <stefanha@redhat.com>
  7 *          Stefano Garzarella <sgarzare@redhat.com>
  8 *
  9 */
 10#include <linux/spinlock.h>
 11#include <linux/module.h>
 12#include <linux/list.h>
 13#include <linux/virtio_vsock.h>
 14
 15struct vsock_loopback {
 16	struct workqueue_struct *workqueue;
 17
 18	struct sk_buff_head pkt_queue;
 19	struct work_struct pkt_work;
 20};
 21
 22static struct vsock_loopback the_vsock_loopback;
 23
 24static u32 vsock_loopback_get_local_cid(void)
 25{
 26	return VMADDR_CID_LOCAL;
 27}
 28
 29static int vsock_loopback_send_pkt(struct sk_buff *skb)
 30{
 31	struct vsock_loopback *vsock = &the_vsock_loopback;
 32	int len = skb->len;
 33
 34	virtio_vsock_skb_queue_tail(&vsock->pkt_queue, skb);
 35	queue_work(vsock->workqueue, &vsock->pkt_work);
 36
 37	return len;
 38}
 39
 40static int vsock_loopback_cancel_pkt(struct vsock_sock *vsk)
 41{
 42	struct vsock_loopback *vsock = &the_vsock_loopback;
 43
 44	virtio_transport_purge_skbs(vsk, &vsock->pkt_queue);
 45
 46	return 0;
 47}
 48
 49static bool vsock_loopback_seqpacket_allow(u32 remote_cid);
 50static bool vsock_loopback_msgzerocopy_allow(void)
 51{
 52	return true;
 53}
 54
 55static struct virtio_transport loopback_transport = {
 56	.transport = {
 57		.module                   = THIS_MODULE,
 58
 59		.get_local_cid            = vsock_loopback_get_local_cid,
 60
 61		.init                     = virtio_transport_do_socket_init,
 62		.destruct                 = virtio_transport_destruct,
 63		.release                  = virtio_transport_release,
 64		.connect                  = virtio_transport_connect,
 65		.shutdown                 = virtio_transport_shutdown,
 66		.cancel_pkt               = vsock_loopback_cancel_pkt,
 67
 68		.dgram_bind               = virtio_transport_dgram_bind,
 69		.dgram_dequeue            = virtio_transport_dgram_dequeue,
 70		.dgram_enqueue            = virtio_transport_dgram_enqueue,
 71		.dgram_allow              = virtio_transport_dgram_allow,
 72
 73		.stream_dequeue           = virtio_transport_stream_dequeue,
 74		.stream_enqueue           = virtio_transport_stream_enqueue,
 75		.stream_has_data          = virtio_transport_stream_has_data,
 76		.stream_has_space         = virtio_transport_stream_has_space,
 77		.stream_rcvhiwat          = virtio_transport_stream_rcvhiwat,
 78		.stream_is_active         = virtio_transport_stream_is_active,
 79		.stream_allow             = virtio_transport_stream_allow,
 80
 81		.seqpacket_dequeue        = virtio_transport_seqpacket_dequeue,
 82		.seqpacket_enqueue        = virtio_transport_seqpacket_enqueue,
 83		.seqpacket_allow          = vsock_loopback_seqpacket_allow,
 84		.seqpacket_has_data       = virtio_transport_seqpacket_has_data,
 85
 86		.msgzerocopy_allow        = vsock_loopback_msgzerocopy_allow,
 87
 88		.notify_poll_in           = virtio_transport_notify_poll_in,
 89		.notify_poll_out          = virtio_transport_notify_poll_out,
 90		.notify_recv_init         = virtio_transport_notify_recv_init,
 91		.notify_recv_pre_block    = virtio_transport_notify_recv_pre_block,
 92		.notify_recv_pre_dequeue  = virtio_transport_notify_recv_pre_dequeue,
 93		.notify_recv_post_dequeue = virtio_transport_notify_recv_post_dequeue,
 94		.notify_send_init         = virtio_transport_notify_send_init,
 95		.notify_send_pre_block    = virtio_transport_notify_send_pre_block,
 96		.notify_send_pre_enqueue  = virtio_transport_notify_send_pre_enqueue,
 97		.notify_send_post_enqueue = virtio_transport_notify_send_post_enqueue,
 98		.notify_buffer_size       = virtio_transport_notify_buffer_size,
 99		.notify_set_rcvlowat      = virtio_transport_notify_set_rcvlowat,
100
101		.unsent_bytes             = virtio_transport_unsent_bytes,
102
103		.read_skb = virtio_transport_read_skb,
104	},
105
106	.send_pkt = vsock_loopback_send_pkt,
107};
108
109static bool vsock_loopback_seqpacket_allow(u32 remote_cid)
110{
111	return true;
112}
113
114static void vsock_loopback_work(struct work_struct *work)
115{
116	struct vsock_loopback *vsock =
117		container_of(work, struct vsock_loopback, pkt_work);
118	struct sk_buff_head pkts;
119	struct sk_buff *skb;
120
121	skb_queue_head_init(&pkts);
122
123	spin_lock_bh(&vsock->pkt_queue.lock);
124	skb_queue_splice_init(&vsock->pkt_queue, &pkts);
125	spin_unlock_bh(&vsock->pkt_queue.lock);
126
127	while ((skb = __skb_dequeue(&pkts))) {
128		/* Decrement the bytes_unsent counter without deallocating skb
129		 * It is freed by the receiver.
130		 */
131		virtio_transport_consume_skb_sent(skb, false);
132		virtio_transport_deliver_tap_pkt(skb);
133		virtio_transport_recv_pkt(&loopback_transport, skb);
134	}
135}
136
137static int __init vsock_loopback_init(void)
138{
139	struct vsock_loopback *vsock = &the_vsock_loopback;
140	int ret;
141
142	vsock->workqueue = alloc_workqueue("vsock-loopback", WQ_PERCPU, 0);
143	if (!vsock->workqueue)
144		return -ENOMEM;
145
146	skb_queue_head_init(&vsock->pkt_queue);
147	INIT_WORK(&vsock->pkt_work, vsock_loopback_work);
148
149	ret = vsock_core_register(&loopback_transport.transport,
150				  VSOCK_TRANSPORT_F_LOCAL);
151	if (ret)
152		goto out_wq;
153
154	return 0;
155
156out_wq:
157	destroy_workqueue(vsock->workqueue);
158	return ret;
159}
160
161static void __exit vsock_loopback_exit(void)
162{
163	struct vsock_loopback *vsock = &the_vsock_loopback;
164
165	vsock_core_unregister(&loopback_transport.transport);
166
167	flush_work(&vsock->pkt_work);
168
169	virtio_vsock_skb_queue_purge(&vsock->pkt_queue);
170
171	destroy_workqueue(vsock->workqueue);
172}
173
174module_init(vsock_loopback_init);
175module_exit(vsock_loopback_exit);
176MODULE_LICENSE("GPL v2");
177MODULE_AUTHOR("Stefano Garzarella <sgarzare@redhat.com>");
178MODULE_DESCRIPTION("loopback transport for vsock");
179MODULE_ALIAS_NETPROTO(PF_VSOCK);