1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * virtio transport for vsock
4 *
5 * Copyright (C) 2013-2015 Red Hat, Inc.
6 * Author: Asias He <asias@redhat.com>
7 *         Stefan Hajnoczi <stefanha@redhat.com>
8 *
9 * Some of the code is take from Gerd Hoffmann <kraxel@redhat.com>'s
10 * early virtio-vsock proof-of-concept bits.
11 */
12#include <linux/spinlock.h>
13#include <linux/module.h>
14#include <linux/list.h>
15#include <linux/atomic.h>
16#include <linux/virtio.h>
17#include <linux/virtio_ids.h>
18#include <linux/virtio_config.h>
19#include <linux/virtio_vsock.h>
20#include <net/sock.h>
21#include <linux/mutex.h>
22#include <net/af_vsock.h>
23
24static struct workqueue_struct *virtio_vsock_workqueue;
25static struct virtio_vsock __rcu *the_virtio_vsock;
26static DEFINE_MUTEX(the_virtio_vsock_mutex); /* protects the_virtio_vsock */
27static struct virtio_transport virtio_transport; /* forward declaration */
28
29struct virtio_vsock {
30	struct virtio_device *vdev;
31	struct virtqueue *vqs[VSOCK_VQ_MAX];
32
33	/* Virtqueue processing is deferred to a workqueue */
34	struct work_struct tx_work;
35	struct work_struct rx_work;
36	struct work_struct event_work;
37
38	/* The following fields are protected by tx_lock.  vqs[VSOCK_VQ_TX]
39	 * must be accessed with tx_lock held.
40	 */
41	struct mutex tx_lock;
42	bool tx_run;
43
44	struct work_struct send_pkt_work;
45	struct sk_buff_head send_pkt_queue;
46
47	atomic_t queued_replies;
48
49	/* The following fields are protected by rx_lock.  vqs[VSOCK_VQ_RX]
50	 * must be accessed with rx_lock held.
51	 */
52	struct mutex rx_lock;
53	bool rx_run;
54	int rx_buf_nr;
55	int rx_buf_max_nr;
56
57	/* The following fields are protected by event_lock.
58	 * vqs[VSOCK_VQ_EVENT] must be accessed with event_lock held.
59	 */
60	struct mutex event_lock;
61	bool event_run;
62	struct virtio_vsock_event event_list[8];
63
64	u32 guest_cid;
65	bool seqpacket_allow;
66
67	/* These fields are used only in tx path in function
68	 * 'virtio_transport_send_pkt_work()', so to save
69	 * stack space in it, place both of them here. Each
70	 * pointer from 'out_sgs' points to the corresponding
71	 * element in 'out_bufs' - this is initialized in
72	 * 'virtio_vsock_probe()'. Both fields are protected
73	 * by 'tx_lock'. +1 is needed for packet header.
74	 */
75	struct scatterlist *out_sgs[MAX_SKB_FRAGS + 1];
76	struct scatterlist out_bufs[MAX_SKB_FRAGS + 1];
77};
78
79static u32 virtio_transport_get_local_cid(void)
80{
81	struct virtio_vsock *vsock;
82	u32 ret;
83
84	rcu_read_lock();
85	vsock = rcu_dereference(the_virtio_vsock);
86	if (!vsock) {
87		ret = VMADDR_CID_ANY;
88		goto out_rcu;
89	}
90
91	ret = vsock->guest_cid;
92out_rcu:
93	rcu_read_unlock();
94	return ret;
95}
96
97static void
98virtio_transport_send_pkt_work(struct work_struct *work)
99{
100	struct virtio_vsock *vsock =
101		container_of(work, struct virtio_vsock, send_pkt_work);
102	struct virtqueue *vq;
103	bool added = false;
104	bool restart_rx = false;
105
106	mutex_lock(&vsock->tx_lock);
107
108	if (!vsock->tx_run)
109		goto out;
110
111	vq = vsock->vqs[VSOCK_VQ_TX];
112
113	for (;;) {
114		int ret, in_sg = 0, out_sg = 0;
115		struct scatterlist **sgs;
116		struct sk_buff *skb;
117		bool reply;
118
119		skb = virtio_vsock_skb_dequeue(&vsock->send_pkt_queue);
120		if (!skb)
121			break;
122
123		reply = virtio_vsock_skb_reply(skb);
124		sgs = vsock->out_sgs;
125		sg_init_one(sgs[out_sg], virtio_vsock_hdr(skb),
126			    sizeof(*virtio_vsock_hdr(skb)));
127		out_sg++;
128
129		if (!skb_is_nonlinear(skb)) {
130			if (skb->len > 0) {
131				sg_init_one(sgs[out_sg], skb->data, skb->len);
132				out_sg++;
133			}
134		} else {
135			struct skb_shared_info *si;
136			int i;
137
138			/* If skb is nonlinear, then its buffer must contain
139			 * only header and nothing more. Data is stored in
140			 * the fragged part.
141			 */
142			WARN_ON_ONCE(skb_headroom(skb) != sizeof(*virtio_vsock_hdr(skb)));
143
144			si = skb_shinfo(skb);
145
146			for (i = 0; i < si->nr_frags; i++) {
147				skb_frag_t *skb_frag = &si->frags[i];
148				void *va;
149
150				/* We will use 'page_to_virt()' for the userspace page
151				 * here, because virtio or dma-mapping layers will call
152				 * 'virt_to_phys()' later to fill the buffer descriptor.
153				 * We don't touch memory at "virtual" address of this page.
154				 */
155				va = page_to_virt(skb_frag_page(skb_frag));
156				sg_init_one(sgs[out_sg],
157					    va + skb_frag_off(skb_frag),
158					    skb_frag_size(skb_frag));
159				out_sg++;
160			}
161		}
162
163		ret = virtqueue_add_sgs(vq, sgs, out_sg, in_sg, skb, GFP_KERNEL);
164		/* Usually this means that there is no more space available in
165		 * the vq
166		 */
167		if (ret < 0) {
168			virtio_vsock_skb_queue_head(&vsock->send_pkt_queue, skb);
169			break;
170		}
171
172		virtio_transport_deliver_tap_pkt(skb);
173
174		if (reply) {
175			struct virtqueue *rx_vq = vsock->vqs[VSOCK_VQ_RX];
176			int val;
177
178			val = atomic_dec_return(&vsock->queued_replies);
179
180			/* Do we now have resources to resume rx processing? */
181			if (val + 1 == virtqueue_get_vring_size(rx_vq))
182				restart_rx = true;
183		}
184
185		added = true;
186	}
187
188	if (added)
189		virtqueue_kick(vq);
190
191out:
192	mutex_unlock(&vsock->tx_lock);
193
194	if (restart_rx)
195		queue_work(virtio_vsock_workqueue, &vsock->rx_work);
196}
197
198static int
199virtio_transport_send_pkt(struct sk_buff *skb)
200{
201	struct virtio_vsock_hdr *hdr;
202	struct virtio_vsock *vsock;
203	int len = skb->len;
204
205	hdr = virtio_vsock_hdr(skb);
206
207	rcu_read_lock();
208	vsock = rcu_dereference(the_virtio_vsock);
209	if (!vsock) {
210		kfree_skb(skb);
211		len = -ENODEV;
212		goto out_rcu;
213	}
214
215	if (le64_to_cpu(hdr->dst_cid) == vsock->guest_cid) {
216		kfree_skb(skb);
217		len = -ENODEV;
218		goto out_rcu;
219	}
220
221	if (virtio_vsock_skb_reply(skb))
222		atomic_inc(&vsock->queued_replies);
223
224	virtio_vsock_skb_queue_tail(&vsock->send_pkt_queue, skb);
225	queue_work(virtio_vsock_workqueue, &vsock->send_pkt_work);
226
227out_rcu:
228	rcu_read_unlock();
229	return len;
230}
231
232static int
233virtio_transport_cancel_pkt(struct vsock_sock *vsk)
234{
235	struct virtio_vsock *vsock;
236	int cnt = 0, ret;
237
238	rcu_read_lock();
239	vsock = rcu_dereference(the_virtio_vsock);
240	if (!vsock) {
241		ret = -ENODEV;
242		goto out_rcu;
243	}
244
245	cnt = virtio_transport_purge_skbs(vsk, &vsock->send_pkt_queue);
246
247	if (cnt) {
248		struct virtqueue *rx_vq = vsock->vqs[VSOCK_VQ_RX];
249		int new_cnt;
250
251		new_cnt = atomic_sub_return(cnt, &vsock->queued_replies);
252		if (new_cnt + cnt >= virtqueue_get_vring_size(rx_vq) &&
253		    new_cnt < virtqueue_get_vring_size(rx_vq))
254			queue_work(virtio_vsock_workqueue, &vsock->rx_work);
255	}
256
257	ret = 0;
258
259out_rcu:
260	rcu_read_unlock();
261	return ret;
262}
263
264static void virtio_vsock_rx_fill(struct virtio_vsock *vsock)
265{
266	int total_len = VIRTIO_VSOCK_DEFAULT_RX_BUF_SIZE + VIRTIO_VSOCK_SKB_HEADROOM;
267	struct scatterlist pkt, *p;
268	struct virtqueue *vq;
269	struct sk_buff *skb;
270	int ret;
271
272	vq = vsock->vqs[VSOCK_VQ_RX];
273
274	do {
275		skb = virtio_vsock_alloc_skb(total_len, GFP_KERNEL);
276		if (!skb)
277			break;
278
279		memset(skb->head, 0, VIRTIO_VSOCK_SKB_HEADROOM);
280		sg_init_one(&pkt, virtio_vsock_hdr(skb), total_len);
281		p = &pkt;
282		ret = virtqueue_add_sgs(vq, &p, 0, 1, skb, GFP_KERNEL);
283		if (ret < 0) {
284			kfree_skb(skb);
285			break;
286		}
287
288		vsock->rx_buf_nr++;
289	} while (vq->num_free);
290	if (vsock->rx_buf_nr > vsock->rx_buf_max_nr)
291		vsock->rx_buf_max_nr = vsock->rx_buf_nr;
292	virtqueue_kick(vq);
293}
294
295static void virtio_transport_tx_work(struct work_struct *work)
296{
297	struct virtio_vsock *vsock =
298		container_of(work, struct virtio_vsock, tx_work);
299	struct virtqueue *vq;
300	bool added = false;
301
302	vq = vsock->vqs[VSOCK_VQ_TX];
303	mutex_lock(&vsock->tx_lock);
304
305	if (!vsock->tx_run)
306		goto out;
307
308	do {
309		struct sk_buff *skb;
310		unsigned int len;
311
312		virtqueue_disable_cb(vq);
313		while ((skb = virtqueue_get_buf(vq, &len)) != NULL) {
314			consume_skb(skb);
315			added = true;
316		}
317	} while (!virtqueue_enable_cb(vq));
318
319out:
320	mutex_unlock(&vsock->tx_lock);
321
322	if (added)
323		queue_work(virtio_vsock_workqueue, &vsock->send_pkt_work);
324}
325
326/* Is there space left for replies to rx packets? */
327static bool virtio_transport_more_replies(struct virtio_vsock *vsock)
328{
329	struct virtqueue *vq = vsock->vqs[VSOCK_VQ_RX];
330	int val;
331
332	smp_rmb(); /* paired with atomic_inc() and atomic_dec_return() */
333	val = atomic_read(&vsock->queued_replies);
334
335	return val < virtqueue_get_vring_size(vq);
336}
337
338/* event_lock must be held */
339static int virtio_vsock_event_fill_one(struct virtio_vsock *vsock,
340				       struct virtio_vsock_event *event)
341{
342	struct scatterlist sg;
343	struct virtqueue *vq;
344
345	vq = vsock->vqs[VSOCK_VQ_EVENT];
346
347	sg_init_one(&sg, event, sizeof(*event));
348
349	return virtqueue_add_inbuf(vq, &sg, 1, event, GFP_KERNEL);
350}
351
352/* event_lock must be held */
353static void virtio_vsock_event_fill(struct virtio_vsock *vsock)
354{
355	size_t i;
356
357	for (i = 0; i < ARRAY_SIZE(vsock->event_list); i++) {
358		struct virtio_vsock_event *event = &vsock->event_list[i];
359
360		virtio_vsock_event_fill_one(vsock, event);
361	}
362
363	virtqueue_kick(vsock->vqs[VSOCK_VQ_EVENT]);
364}
365
366static void virtio_vsock_reset_sock(struct sock *sk)
367{
368	/* vmci_transport.c doesn't take sk_lock here either.  At least we're
369	 * under vsock_table_lock so the sock cannot disappear while we're
370	 * executing.
371	 */
372
373	sk->sk_state = TCP_CLOSE;
374	sk->sk_err = ECONNRESET;
375	sk_error_report(sk);
376}
377
378static void virtio_vsock_update_guest_cid(struct virtio_vsock *vsock)
379{
380	struct virtio_device *vdev = vsock->vdev;
381	__le64 guest_cid;
382
383	vdev->config->get(vdev, offsetof(struct virtio_vsock_config, guest_cid),
384			  &guest_cid, sizeof(guest_cid));
385	vsock->guest_cid = le64_to_cpu(guest_cid);
386}
387
388/* event_lock must be held */
389static void virtio_vsock_event_handle(struct virtio_vsock *vsock,
390				      struct virtio_vsock_event *event)
391{
392	switch (le32_to_cpu(event->id)) {
393	case VIRTIO_VSOCK_EVENT_TRANSPORT_RESET:
394		virtio_vsock_update_guest_cid(vsock);
395		vsock_for_each_connected_socket(&virtio_transport.transport,
396						virtio_vsock_reset_sock);
397		break;
398	}
399}
400
401static void virtio_transport_event_work(struct work_struct *work)
402{
403	struct virtio_vsock *vsock =
404		container_of(work, struct virtio_vsock, event_work);
405	struct virtqueue *vq;
406
407	vq = vsock->vqs[VSOCK_VQ_EVENT];
408
409	mutex_lock(&vsock->event_lock);
410
411	if (!vsock->event_run)
412		goto out;
413
414	do {
415		struct virtio_vsock_event *event;
416		unsigned int len;
417
418		virtqueue_disable_cb(vq);
419		while ((event = virtqueue_get_buf(vq, &len)) != NULL) {
420			if (len == sizeof(*event))
421				virtio_vsock_event_handle(vsock, event);
422
423			virtio_vsock_event_fill_one(vsock, event);
424		}
425	} while (!virtqueue_enable_cb(vq));
426
427	virtqueue_kick(vsock->vqs[VSOCK_VQ_EVENT]);
428out:
429	mutex_unlock(&vsock->event_lock);
430}
431
432static void virtio_vsock_event_done(struct virtqueue *vq)
433{
434	struct virtio_vsock *vsock = vq->vdev->priv;
435
436	if (!vsock)
437		return;
438	queue_work(virtio_vsock_workqueue, &vsock->event_work);
439}
440
441static void virtio_vsock_tx_done(struct virtqueue *vq)
442{
443	struct virtio_vsock *vsock = vq->vdev->priv;
444
445	if (!vsock)
446		return;
447	queue_work(virtio_vsock_workqueue, &vsock->tx_work);
448}
449
450static void virtio_vsock_rx_done(struct virtqueue *vq)
451{
452	struct virtio_vsock *vsock = vq->vdev->priv;
453
454	if (!vsock)
455		return;
456	queue_work(virtio_vsock_workqueue, &vsock->rx_work);
457}
458
459static bool virtio_transport_can_msgzerocopy(int bufs_num)
460{
461	struct virtio_vsock *vsock;
462	bool res = false;
463
464	rcu_read_lock();
465
466	vsock = rcu_dereference(the_virtio_vsock);
467	if (vsock) {
468		struct virtqueue *vq = vsock->vqs[VSOCK_VQ_TX];
469
470		/* Check that tx queue is large enough to keep whole
471		 * data to send. This is needed, because when there is
472		 * not enough free space in the queue, current skb to
473		 * send will be reinserted to the head of tx list of
474		 * the socket to retry transmission later, so if skb
475		 * is bigger than whole queue, it will be reinserted
476		 * again and again, thus blocking other skbs to be sent.
477		 * Each page of the user provided buffer will be added
478		 * as a single buffer to the tx virtqueue, so compare
479		 * number of pages against maximum capacity of the queue.
480		 */
481		if (bufs_num <= vq->num_max)
482			res = true;
483	}
484
485	rcu_read_unlock();
486
487	return res;
488}
489
490static bool virtio_transport_msgzerocopy_allow(void)
491{
492	return true;
493}
494
495static bool virtio_transport_seqpacket_allow(u32 remote_cid);
496
497static struct virtio_transport virtio_transport = {
498	.transport = {
499		.module                   = THIS_MODULE,
500
501		.get_local_cid            = virtio_transport_get_local_cid,
502
503		.init                     = virtio_transport_do_socket_init,
504		.destruct                 = virtio_transport_destruct,
505		.release                  = virtio_transport_release,
506		.connect                  = virtio_transport_connect,
507		.shutdown                 = virtio_transport_shutdown,
508		.cancel_pkt               = virtio_transport_cancel_pkt,
509
510		.dgram_bind               = virtio_transport_dgram_bind,
511		.dgram_dequeue            = virtio_transport_dgram_dequeue,
512		.dgram_enqueue            = virtio_transport_dgram_enqueue,
513		.dgram_allow              = virtio_transport_dgram_allow,
514
515		.stream_dequeue           = virtio_transport_stream_dequeue,
516		.stream_enqueue           = virtio_transport_stream_enqueue,
517		.stream_has_data          = virtio_transport_stream_has_data,
518		.stream_has_space         = virtio_transport_stream_has_space,
519		.stream_rcvhiwat          = virtio_transport_stream_rcvhiwat,
520		.stream_is_active         = virtio_transport_stream_is_active,
521		.stream_allow             = virtio_transport_stream_allow,
522
523		.seqpacket_dequeue        = virtio_transport_seqpacket_dequeue,
524		.seqpacket_enqueue        = virtio_transport_seqpacket_enqueue,
525		.seqpacket_allow          = virtio_transport_seqpacket_allow,
526		.seqpacket_has_data       = virtio_transport_seqpacket_has_data,
527
528		.msgzerocopy_allow        = virtio_transport_msgzerocopy_allow,
529
530		.notify_poll_in           = virtio_transport_notify_poll_in,
531		.notify_poll_out          = virtio_transport_notify_poll_out,
532		.notify_recv_init         = virtio_transport_notify_recv_init,
533		.notify_recv_pre_block    = virtio_transport_notify_recv_pre_block,
534		.notify_recv_pre_dequeue  = virtio_transport_notify_recv_pre_dequeue,
535		.notify_recv_post_dequeue = virtio_transport_notify_recv_post_dequeue,
536		.notify_send_init         = virtio_transport_notify_send_init,
537		.notify_send_pre_block    = virtio_transport_notify_send_pre_block,
538		.notify_send_pre_enqueue  = virtio_transport_notify_send_pre_enqueue,
539		.notify_send_post_enqueue = virtio_transport_notify_send_post_enqueue,
540		.notify_buffer_size       = virtio_transport_notify_buffer_size,
541		.notify_set_rcvlowat      = virtio_transport_notify_set_rcvlowat,
542
543		.read_skb = virtio_transport_read_skb,
544	},
545
546	.send_pkt = virtio_transport_send_pkt,
547	.can_msgzerocopy = virtio_transport_can_msgzerocopy,
548};
549
550static bool virtio_transport_seqpacket_allow(u32 remote_cid)
551{
552	struct virtio_vsock *vsock;
553	bool seqpacket_allow;
554
555	seqpacket_allow = false;
556	rcu_read_lock();
557	vsock = rcu_dereference(the_virtio_vsock);
558	if (vsock)
559		seqpacket_allow = vsock->seqpacket_allow;
560	rcu_read_unlock();
561
562	return seqpacket_allow;
563}
564
565static void virtio_transport_rx_work(struct work_struct *work)
566{
567	struct virtio_vsock *vsock =
568		container_of(work, struct virtio_vsock, rx_work);
569	struct virtqueue *vq;
570
571	vq = vsock->vqs[VSOCK_VQ_RX];
572
573	mutex_lock(&vsock->rx_lock);
574
575	if (!vsock->rx_run)
576		goto out;
577
578	do {
579		virtqueue_disable_cb(vq);
580		for (;;) {
581			struct sk_buff *skb;
582			unsigned int len;
583
584			if (!virtio_transport_more_replies(vsock)) {
585				/* Stop rx until the device processes already
586				 * pending replies.  Leave rx virtqueue
587				 * callbacks disabled.
588				 */
589				goto out;
590			}
591
592			skb = virtqueue_get_buf(vq, &len);
593			if (!skb)
594				break;
595
596			vsock->rx_buf_nr--;
597
598			/* Drop short/long packets */
599			if (unlikely(len < sizeof(struct virtio_vsock_hdr) ||
600				     len > virtio_vsock_skb_len(skb))) {
601				kfree_skb(skb);
602				continue;
603			}
604
605			virtio_vsock_skb_rx_put(skb);
606			virtio_transport_deliver_tap_pkt(skb);
607			virtio_transport_recv_pkt(&virtio_transport, skb);
608		}
609	} while (!virtqueue_enable_cb(vq));
610
611out:
612	if (vsock->rx_buf_nr < vsock->rx_buf_max_nr / 2)
613		virtio_vsock_rx_fill(vsock);
614	mutex_unlock(&vsock->rx_lock);
615}
616
617static int virtio_vsock_vqs_init(struct virtio_vsock *vsock)
618{
619	struct virtio_device *vdev = vsock->vdev;
620	static const char * const names[] = {
621		"rx",
622		"tx",
623		"event",
624	};
625	vq_callback_t *callbacks[] = {
626		virtio_vsock_rx_done,
627		virtio_vsock_tx_done,
628		virtio_vsock_event_done,
629	};
630	int ret;
631
632	ret = virtio_find_vqs(vdev, VSOCK_VQ_MAX, vsock->vqs, callbacks, names,
633			      NULL);
634	if (ret < 0)
635		return ret;
636
637	virtio_vsock_update_guest_cid(vsock);
638
639	virtio_device_ready(vdev);
640
641	return 0;
642}
643
644static void virtio_vsock_vqs_start(struct virtio_vsock *vsock)
645{
646	mutex_lock(&vsock->tx_lock);
647	vsock->tx_run = true;
648	mutex_unlock(&vsock->tx_lock);
649
650	mutex_lock(&vsock->rx_lock);
651	virtio_vsock_rx_fill(vsock);
652	vsock->rx_run = true;
653	mutex_unlock(&vsock->rx_lock);
654
655	mutex_lock(&vsock->event_lock);
656	virtio_vsock_event_fill(vsock);
657	vsock->event_run = true;
658	mutex_unlock(&vsock->event_lock);
659
660	/* virtio_transport_send_pkt() can queue packets once
661	 * the_virtio_vsock is set, but they won't be processed until
662	 * vsock->tx_run is set to true. We queue vsock->send_pkt_work
663	 * when initialization finishes to send those packets queued
664	 * earlier.
665	 * We don't need to queue the other workers (rx, event) because
666	 * as long as we don't fill the queues with empty buffers, the
667	 * host can't send us any notification.
668	 */
669	queue_work(virtio_vsock_workqueue, &vsock->send_pkt_work);
670}
671
672static void virtio_vsock_vqs_del(struct virtio_vsock *vsock)
673{
674	struct virtio_device *vdev = vsock->vdev;
675	struct sk_buff *skb;
676
677	/* Reset all connected sockets when the VQs disappear */
678	vsock_for_each_connected_socket(&virtio_transport.transport,
679					virtio_vsock_reset_sock);
680
681	/* Stop all work handlers to make sure no one is accessing the device,
682	 * so we can safely call virtio_reset_device().
683	 */
684	mutex_lock(&vsock->rx_lock);
685	vsock->rx_run = false;
686	mutex_unlock(&vsock->rx_lock);
687
688	mutex_lock(&vsock->tx_lock);
689	vsock->tx_run = false;
690	mutex_unlock(&vsock->tx_lock);
691
692	mutex_lock(&vsock->event_lock);
693	vsock->event_run = false;
694	mutex_unlock(&vsock->event_lock);
695
696	/* Flush all device writes and interrupts, device will not use any
697	 * more buffers.
698	 */
699	virtio_reset_device(vdev);
700
701	mutex_lock(&vsock->rx_lock);
702	while ((skb = virtqueue_detach_unused_buf(vsock->vqs[VSOCK_VQ_RX])))
703		kfree_skb(skb);
704	mutex_unlock(&vsock->rx_lock);
705
706	mutex_lock(&vsock->tx_lock);
707	while ((skb = virtqueue_detach_unused_buf(vsock->vqs[VSOCK_VQ_TX])))
708		kfree_skb(skb);
709	mutex_unlock(&vsock->tx_lock);
710
711	virtio_vsock_skb_queue_purge(&vsock->send_pkt_queue);
712
713	/* Delete virtqueues and flush outstanding callbacks if any */
714	vdev->config->del_vqs(vdev);
715}
716
717static int virtio_vsock_probe(struct virtio_device *vdev)
718{
719	struct virtio_vsock *vsock = NULL;
720	int ret;
721	int i;
722
723	ret = mutex_lock_interruptible(&the_virtio_vsock_mutex);
724	if (ret)
725		return ret;
726
727	/* Only one virtio-vsock device per guest is supported */
728	if (rcu_dereference_protected(the_virtio_vsock,
729				lockdep_is_held(&the_virtio_vsock_mutex))) {
730		ret = -EBUSY;
731		goto out;
732	}
733
734	vsock = kzalloc(sizeof(*vsock), GFP_KERNEL);
735	if (!vsock) {
736		ret = -ENOMEM;
737		goto out;
738	}
739
740	vsock->vdev = vdev;
741
742	vsock->rx_buf_nr = 0;
743	vsock->rx_buf_max_nr = 0;
744	atomic_set(&vsock->queued_replies, 0);
745
746	mutex_init(&vsock->tx_lock);
747	mutex_init(&vsock->rx_lock);
748	mutex_init(&vsock->event_lock);
749	skb_queue_head_init(&vsock->send_pkt_queue);
750	INIT_WORK(&vsock->rx_work, virtio_transport_rx_work);
751	INIT_WORK(&vsock->tx_work, virtio_transport_tx_work);
752	INIT_WORK(&vsock->event_work, virtio_transport_event_work);
753	INIT_WORK(&vsock->send_pkt_work, virtio_transport_send_pkt_work);
754
755	if (virtio_has_feature(vdev, VIRTIO_VSOCK_F_SEQPACKET))
756		vsock->seqpacket_allow = true;
757
758	vdev->priv = vsock;
759
760	ret = virtio_vsock_vqs_init(vsock);
761	if (ret < 0)
762		goto out;
763
764	for (i = 0; i < ARRAY_SIZE(vsock->out_sgs); i++)
765		vsock->out_sgs[i] = &vsock->out_bufs[i];
766
767	rcu_assign_pointer(the_virtio_vsock, vsock);
768	virtio_vsock_vqs_start(vsock);
769
770	mutex_unlock(&the_virtio_vsock_mutex);
771
772	return 0;
773
774out:
775	kfree(vsock);
776	mutex_unlock(&the_virtio_vsock_mutex);
777	return ret;
778}
779
780static void virtio_vsock_remove(struct virtio_device *vdev)
781{
782	struct virtio_vsock *vsock = vdev->priv;
783
784	mutex_lock(&the_virtio_vsock_mutex);
785
786	vdev->priv = NULL;
787	rcu_assign_pointer(the_virtio_vsock, NULL);
788	synchronize_rcu();
789
790	virtio_vsock_vqs_del(vsock);
791
792	/* Other works can be queued before 'config->del_vqs()', so we flush
793	 * all works before to free the vsock object to avoid use after free.
794	 */
795	flush_work(&vsock->rx_work);
796	flush_work(&vsock->tx_work);
797	flush_work(&vsock->event_work);
798	flush_work(&vsock->send_pkt_work);
799
800	mutex_unlock(&the_virtio_vsock_mutex);
801
802	kfree(vsock);
803}
804
805#ifdef CONFIG_PM_SLEEP
806static int virtio_vsock_freeze(struct virtio_device *vdev)
807{
808	struct virtio_vsock *vsock = vdev->priv;
809
810	mutex_lock(&the_virtio_vsock_mutex);
811
812	rcu_assign_pointer(the_virtio_vsock, NULL);
813	synchronize_rcu();
814
815	virtio_vsock_vqs_del(vsock);
816
817	mutex_unlock(&the_virtio_vsock_mutex);
818
819	return 0;
820}
821
822static int virtio_vsock_restore(struct virtio_device *vdev)
823{
824	struct virtio_vsock *vsock = vdev->priv;
825	int ret;
826
827	mutex_lock(&the_virtio_vsock_mutex);
828
829	/* Only one virtio-vsock device per guest is supported */
830	if (rcu_dereference_protected(the_virtio_vsock,
831				lockdep_is_held(&the_virtio_vsock_mutex))) {
832		ret = -EBUSY;
833		goto out;
834	}
835
836	ret = virtio_vsock_vqs_init(vsock);
837	if (ret < 0)
838		goto out;
839
840	rcu_assign_pointer(the_virtio_vsock, vsock);
841	virtio_vsock_vqs_start(vsock);
842
843out:
844	mutex_unlock(&the_virtio_vsock_mutex);
845	return ret;
846}
847#endif /* CONFIG_PM_SLEEP */
848
849static struct virtio_device_id id_table[] = {
850	{ VIRTIO_ID_VSOCK, VIRTIO_DEV_ANY_ID },
851	{ 0 },
852};
853
854static unsigned int features[] = {
855	VIRTIO_VSOCK_F_SEQPACKET
856};
857
858static struct virtio_driver virtio_vsock_driver = {
859	.feature_table = features,
860	.feature_table_size = ARRAY_SIZE(features),
861	.driver.name = KBUILD_MODNAME,
862	.driver.owner = THIS_MODULE,
863	.id_table = id_table,
864	.probe = virtio_vsock_probe,
865	.remove = virtio_vsock_remove,
866#ifdef CONFIG_PM_SLEEP
867	.freeze = virtio_vsock_freeze,
868	.restore = virtio_vsock_restore,
869#endif
870};
871
872static int __init virtio_vsock_init(void)
873{
874	int ret;
875
876	virtio_vsock_workqueue = alloc_workqueue("virtio_vsock", 0, 0);
877	if (!virtio_vsock_workqueue)
878		return -ENOMEM;
879
880	ret = vsock_core_register(&virtio_transport.transport,
881				  VSOCK_TRANSPORT_F_G2H);
882	if (ret)
883		goto out_wq;
884
885	ret = register_virtio_driver(&virtio_vsock_driver);
886	if (ret)
887		goto out_vci;
888
889	return 0;
890
891out_vci:
892	vsock_core_unregister(&virtio_transport.transport);
893out_wq:
894	destroy_workqueue(virtio_vsock_workqueue);
895	return ret;
896}
897
898static void __exit virtio_vsock_exit(void)
899{
900	unregister_virtio_driver(&virtio_vsock_driver);
901	vsock_core_unregister(&virtio_transport.transport);
902	destroy_workqueue(virtio_vsock_workqueue);
903}
904
905module_init(virtio_vsock_init);
906module_exit(virtio_vsock_exit);
907MODULE_LICENSE("GPL v2");
908MODULE_AUTHOR("Asias He");
909MODULE_DESCRIPTION("virtio transport for vsock");
910MODULE_DEVICE_TABLE(virtio, id_table);
911