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	spinlock_t pkt_list_lock; /* protects pkt_list */
19	struct list_head pkt_list;
20	struct work_struct pkt_work;
21};
22
23static struct vsock_loopback the_vsock_loopback;
24
25static u32 vsock_loopback_get_local_cid(void)
26{
27	return VMADDR_CID_LOCAL;
28}
29
30static int vsock_loopback_send_pkt(struct virtio_vsock_pkt *pkt)
31{
32	struct vsock_loopback *vsock = &the_vsock_loopback;
33	int len = pkt->len;
34
35	spin_lock_bh(&vsock->pkt_list_lock);
36	list_add_tail(&pkt->list, &vsock->pkt_list);
37	spin_unlock_bh(&vsock->pkt_list_lock);
38
39	queue_work(vsock->workqueue, &vsock->pkt_work);
40
41	return len;
42}
43
44static int vsock_loopback_cancel_pkt(struct vsock_sock *vsk)
45{
46	struct vsock_loopback *vsock = &the_vsock_loopback;
47	struct virtio_vsock_pkt *pkt, *n;
48	LIST_HEAD(freeme);
49
50	spin_lock_bh(&vsock->pkt_list_lock);
51	list_for_each_entry_safe(pkt, n, &vsock->pkt_list, list) {
52		if (pkt->vsk != vsk)
53			continue;
54		list_move(&pkt->list, &freeme);
55	}
56	spin_unlock_bh(&vsock->pkt_list_lock);
57
58	list_for_each_entry_safe(pkt, n, &freeme, list) {
59		list_del(&pkt->list);
60		virtio_transport_free_pkt(pkt);
61	}
62
63	return 0;
64}
65
66static struct virtio_transport loopback_transport = {
67	.transport = {
68		.module                   = THIS_MODULE,
69
70		.get_local_cid            = vsock_loopback_get_local_cid,
71
72		.init                     = virtio_transport_do_socket_init,
73		.destruct                 = virtio_transport_destruct,
74		.release                  = virtio_transport_release,
75		.connect                  = virtio_transport_connect,
76		.shutdown                 = virtio_transport_shutdown,
77		.cancel_pkt               = vsock_loopback_cancel_pkt,
78
79		.dgram_bind               = virtio_transport_dgram_bind,
80		.dgram_dequeue            = virtio_transport_dgram_dequeue,
81		.dgram_enqueue            = virtio_transport_dgram_enqueue,
82		.dgram_allow              = virtio_transport_dgram_allow,
83
84		.stream_dequeue           = virtio_transport_stream_dequeue,
85		.stream_enqueue           = virtio_transport_stream_enqueue,
86		.stream_has_data          = virtio_transport_stream_has_data,
87		.stream_has_space         = virtio_transport_stream_has_space,
88		.stream_rcvhiwat          = virtio_transport_stream_rcvhiwat,
89		.stream_is_active         = virtio_transport_stream_is_active,
90		.stream_allow             = virtio_transport_stream_allow,
91
92		.notify_poll_in           = virtio_transport_notify_poll_in,
93		.notify_poll_out          = virtio_transport_notify_poll_out,
94		.notify_recv_init         = virtio_transport_notify_recv_init,
95		.notify_recv_pre_block    = virtio_transport_notify_recv_pre_block,
96		.notify_recv_pre_dequeue  = virtio_transport_notify_recv_pre_dequeue,
97		.notify_recv_post_dequeue = virtio_transport_notify_recv_post_dequeue,
98		.notify_send_init         = virtio_transport_notify_send_init,
99		.notify_send_pre_block    = virtio_transport_notify_send_pre_block,
100		.notify_send_pre_enqueue  = virtio_transport_notify_send_pre_enqueue,
101		.notify_send_post_enqueue = virtio_transport_notify_send_post_enqueue,
102		.notify_buffer_size       = virtio_transport_notify_buffer_size,
103	},
104
105	.send_pkt = vsock_loopback_send_pkt,
106};
107
108static void vsock_loopback_work(struct work_struct *work)
109{
110	struct vsock_loopback *vsock =
111		container_of(work, struct vsock_loopback, pkt_work);
112	LIST_HEAD(pkts);
113
114	spin_lock_bh(&vsock->pkt_list_lock);
115	list_splice_init(&vsock->pkt_list, &pkts);
116	spin_unlock_bh(&vsock->pkt_list_lock);
117
118	while (!list_empty(&pkts)) {
119		struct virtio_vsock_pkt *pkt;
120
121		pkt = list_first_entry(&pkts, struct virtio_vsock_pkt, list);
122		list_del_init(&pkt->list);
123
124		virtio_transport_deliver_tap_pkt(pkt);
125		virtio_transport_recv_pkt(&loopback_transport, pkt);
126	}
127}
128
129static int __init vsock_loopback_init(void)
130{
131	struct vsock_loopback *vsock = &the_vsock_loopback;
132	int ret;
133
134	vsock->workqueue = alloc_workqueue("vsock-loopback", 0, 0);
135	if (!vsock->workqueue)
136		return -ENOMEM;
137
138	spin_lock_init(&vsock->pkt_list_lock);
139	INIT_LIST_HEAD(&vsock->pkt_list);
140	INIT_WORK(&vsock->pkt_work, vsock_loopback_work);
141
142	ret = vsock_core_register(&loopback_transport.transport,
143				  VSOCK_TRANSPORT_F_LOCAL);
144	if (ret)
145		goto out_wq;
146
147	return 0;
148
149out_wq:
150	destroy_workqueue(vsock->workqueue);
151	return ret;
152}
153
154static void __exit vsock_loopback_exit(void)
155{
156	struct vsock_loopback *vsock = &the_vsock_loopback;
157	struct virtio_vsock_pkt *pkt;
158
159	vsock_core_unregister(&loopback_transport.transport);
160
161	flush_work(&vsock->pkt_work);
162
163	spin_lock_bh(&vsock->pkt_list_lock);
164	while (!list_empty(&vsock->pkt_list)) {
165		pkt = list_first_entry(&vsock->pkt_list,
166				       struct virtio_vsock_pkt, list);
167		list_del(&pkt->list);
168		virtio_transport_free_pkt(pkt);
169	}
170	spin_unlock_bh(&vsock->pkt_list_lock);
171
172	destroy_workqueue(vsock->workqueue);
173}
174
175module_init(vsock_loopback_init);
176module_exit(vsock_loopback_exit);
177MODULE_LICENSE("GPL v2");
178MODULE_AUTHOR("Stefano Garzarella <sgarzare@redhat.com>");
179MODULE_DESCRIPTION("loopback transport for vsock");
180MODULE_ALIAS_NETPROTO(PF_VSOCK);
181