xref: /openbmc/linux/drivers/vhost/vsock.c (revision 30bd4593)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * vhost 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 #include <linux/miscdevice.h>
10 #include <linux/atomic.h>
11 #include <linux/module.h>
12 #include <linux/mutex.h>
13 #include <linux/vmalloc.h>
14 #include <net/sock.h>
15 #include <linux/virtio_vsock.h>
16 #include <linux/vhost.h>
17 #include <linux/hashtable.h>
18 
19 #include <net/af_vsock.h>
20 #include "vhost.h"
21 
22 #define VHOST_VSOCK_DEFAULT_HOST_CID	2
23 /* Max number of bytes transferred before requeueing the job.
24  * Using this limit prevents one virtqueue from starving others. */
25 #define VHOST_VSOCK_WEIGHT 0x80000
26 /* Max number of packets transferred before requeueing the job.
27  * Using this limit prevents one virtqueue from starving others with
28  * small pkts.
29  */
30 #define VHOST_VSOCK_PKT_WEIGHT 256
31 
32 enum {
33 	VHOST_VSOCK_FEATURES = VHOST_FEATURES |
34 			       (1ULL << VIRTIO_F_ACCESS_PLATFORM) |
35 			       (1ULL << VIRTIO_VSOCK_F_SEQPACKET)
36 };
37 
38 enum {
39 	VHOST_VSOCK_BACKEND_FEATURES = (1ULL << VHOST_BACKEND_F_IOTLB_MSG_V2)
40 };
41 
42 /* Used to track all the vhost_vsock instances on the system. */
43 static DEFINE_MUTEX(vhost_vsock_mutex);
44 static DEFINE_READ_MOSTLY_HASHTABLE(vhost_vsock_hash, 8);
45 
46 struct vhost_vsock {
47 	struct vhost_dev dev;
48 	struct vhost_virtqueue vqs[2];
49 
50 	/* Link to global vhost_vsock_hash, writes use vhost_vsock_mutex */
51 	struct hlist_node hash;
52 
53 	struct vhost_work send_pkt_work;
54 	struct sk_buff_head send_pkt_queue; /* host->guest pending packets */
55 
56 	atomic_t queued_replies;
57 
58 	u32 guest_cid;
59 	bool seqpacket_allow;
60 };
61 
vhost_transport_get_local_cid(void)62 static u32 vhost_transport_get_local_cid(void)
63 {
64 	return VHOST_VSOCK_DEFAULT_HOST_CID;
65 }
66 
67 /* Callers that dereference the return value must hold vhost_vsock_mutex or the
68  * RCU read lock.
69  */
vhost_vsock_get(u32 guest_cid)70 static struct vhost_vsock *vhost_vsock_get(u32 guest_cid)
71 {
72 	struct vhost_vsock *vsock;
73 
74 	hash_for_each_possible_rcu(vhost_vsock_hash, vsock, hash, guest_cid) {
75 		u32 other_cid = vsock->guest_cid;
76 
77 		/* Skip instances that have no CID yet */
78 		if (other_cid == 0)
79 			continue;
80 
81 		if (other_cid == guest_cid)
82 			return vsock;
83 
84 	}
85 
86 	return NULL;
87 }
88 
89 static void
vhost_transport_do_send_pkt(struct vhost_vsock * vsock,struct vhost_virtqueue * vq)90 vhost_transport_do_send_pkt(struct vhost_vsock *vsock,
91 			    struct vhost_virtqueue *vq)
92 {
93 	struct vhost_virtqueue *tx_vq = &vsock->vqs[VSOCK_VQ_TX];
94 	int pkts = 0, total_len = 0;
95 	bool added = false;
96 	bool restart_tx = false;
97 
98 	mutex_lock(&vq->mutex);
99 
100 	if (!vhost_vq_get_backend(vq))
101 		goto out;
102 
103 	if (!vq_meta_prefetch(vq))
104 		goto out;
105 
106 	/* Avoid further vmexits, we're already processing the virtqueue */
107 	vhost_disable_notify(&vsock->dev, vq);
108 
109 	do {
110 		struct virtio_vsock_hdr *hdr;
111 		size_t iov_len, payload_len;
112 		struct iov_iter iov_iter;
113 		u32 flags_to_restore = 0;
114 		struct sk_buff *skb;
115 		unsigned out, in;
116 		size_t nbytes;
117 		int head;
118 
119 		skb = virtio_vsock_skb_dequeue(&vsock->send_pkt_queue);
120 
121 		if (!skb) {
122 			vhost_enable_notify(&vsock->dev, vq);
123 			break;
124 		}
125 
126 		head = vhost_get_vq_desc(vq, vq->iov, ARRAY_SIZE(vq->iov),
127 					 &out, &in, NULL, NULL);
128 		if (head < 0) {
129 			virtio_vsock_skb_queue_head(&vsock->send_pkt_queue, skb);
130 			break;
131 		}
132 
133 		if (head == vq->num) {
134 			virtio_vsock_skb_queue_head(&vsock->send_pkt_queue, skb);
135 			/* We cannot finish yet if more buffers snuck in while
136 			 * re-enabling notify.
137 			 */
138 			if (unlikely(vhost_enable_notify(&vsock->dev, vq))) {
139 				vhost_disable_notify(&vsock->dev, vq);
140 				continue;
141 			}
142 			break;
143 		}
144 
145 		if (out) {
146 			kfree_skb(skb);
147 			vq_err(vq, "Expected 0 output buffers, got %u\n", out);
148 			break;
149 		}
150 
151 		iov_len = iov_length(&vq->iov[out], in);
152 		if (iov_len < sizeof(*hdr)) {
153 			kfree_skb(skb);
154 			vq_err(vq, "Buffer len [%zu] too small\n", iov_len);
155 			break;
156 		}
157 
158 		iov_iter_init(&iov_iter, ITER_DEST, &vq->iov[out], in, iov_len);
159 		payload_len = skb->len;
160 		hdr = virtio_vsock_hdr(skb);
161 
162 		/* If the packet is greater than the space available in the
163 		 * buffer, we split it using multiple buffers.
164 		 */
165 		if (payload_len > iov_len - sizeof(*hdr)) {
166 			payload_len = iov_len - sizeof(*hdr);
167 
168 			/* As we are copying pieces of large packet's buffer to
169 			 * small rx buffers, headers of packets in rx queue are
170 			 * created dynamically and are initialized with header
171 			 * of current packet(except length). But in case of
172 			 * SOCK_SEQPACKET, we also must clear message delimeter
173 			 * bit (VIRTIO_VSOCK_SEQ_EOM) and MSG_EOR bit
174 			 * (VIRTIO_VSOCK_SEQ_EOR) if set. Otherwise,
175 			 * there will be sequence of packets with these
176 			 * bits set. After initialized header will be copied to
177 			 * rx buffer, these required bits will be restored.
178 			 */
179 			if (le32_to_cpu(hdr->flags) & VIRTIO_VSOCK_SEQ_EOM) {
180 				hdr->flags &= ~cpu_to_le32(VIRTIO_VSOCK_SEQ_EOM);
181 				flags_to_restore |= VIRTIO_VSOCK_SEQ_EOM;
182 
183 				if (le32_to_cpu(hdr->flags) & VIRTIO_VSOCK_SEQ_EOR) {
184 					hdr->flags &= ~cpu_to_le32(VIRTIO_VSOCK_SEQ_EOR);
185 					flags_to_restore |= VIRTIO_VSOCK_SEQ_EOR;
186 				}
187 			}
188 		}
189 
190 		/* Set the correct length in the header */
191 		hdr->len = cpu_to_le32(payload_len);
192 
193 		nbytes = copy_to_iter(hdr, sizeof(*hdr), &iov_iter);
194 		if (nbytes != sizeof(*hdr)) {
195 			kfree_skb(skb);
196 			vq_err(vq, "Faulted on copying pkt hdr\n");
197 			break;
198 		}
199 
200 		nbytes = copy_to_iter(skb->data, payload_len, &iov_iter);
201 		if (nbytes != payload_len) {
202 			kfree_skb(skb);
203 			vq_err(vq, "Faulted on copying pkt buf\n");
204 			break;
205 		}
206 
207 		/* Deliver to monitoring devices all packets that we
208 		 * will transmit.
209 		 */
210 		virtio_transport_deliver_tap_pkt(skb);
211 
212 		vhost_add_used(vq, head, sizeof(*hdr) + payload_len);
213 		added = true;
214 
215 		skb_pull(skb, payload_len);
216 		total_len += payload_len;
217 
218 		/* If we didn't send all the payload we can requeue the packet
219 		 * to send it with the next available buffer.
220 		 */
221 		if (skb->len > 0) {
222 			hdr->flags |= cpu_to_le32(flags_to_restore);
223 
224 			/* We are queueing the same skb to handle
225 			 * the remaining bytes, and we want to deliver it
226 			 * to monitoring devices in the next iteration.
227 			 */
228 			virtio_vsock_skb_clear_tap_delivered(skb);
229 			virtio_vsock_skb_queue_head(&vsock->send_pkt_queue, skb);
230 		} else {
231 			if (virtio_vsock_skb_reply(skb)) {
232 				int val;
233 
234 				val = atomic_dec_return(&vsock->queued_replies);
235 
236 				/* Do we have resources to resume tx
237 				 * processing?
238 				 */
239 				if (val + 1 == tx_vq->num)
240 					restart_tx = true;
241 			}
242 
243 			consume_skb(skb);
244 		}
245 	} while(likely(!vhost_exceeds_weight(vq, ++pkts, total_len)));
246 	if (added)
247 		vhost_signal(&vsock->dev, vq);
248 
249 out:
250 	mutex_unlock(&vq->mutex);
251 
252 	if (restart_tx)
253 		vhost_poll_queue(&tx_vq->poll);
254 }
255 
vhost_transport_send_pkt_work(struct vhost_work * work)256 static void vhost_transport_send_pkt_work(struct vhost_work *work)
257 {
258 	struct vhost_virtqueue *vq;
259 	struct vhost_vsock *vsock;
260 
261 	vsock = container_of(work, struct vhost_vsock, send_pkt_work);
262 	vq = &vsock->vqs[VSOCK_VQ_RX];
263 
264 	vhost_transport_do_send_pkt(vsock, vq);
265 }
266 
267 static int
vhost_transport_send_pkt(struct sk_buff * skb)268 vhost_transport_send_pkt(struct sk_buff *skb)
269 {
270 	struct virtio_vsock_hdr *hdr = virtio_vsock_hdr(skb);
271 	struct vhost_vsock *vsock;
272 	int len = skb->len;
273 
274 	rcu_read_lock();
275 
276 	/* Find the vhost_vsock according to guest context id  */
277 	vsock = vhost_vsock_get(le64_to_cpu(hdr->dst_cid));
278 	if (!vsock) {
279 		rcu_read_unlock();
280 		kfree_skb(skb);
281 		return -ENODEV;
282 	}
283 
284 	if (virtio_vsock_skb_reply(skb))
285 		atomic_inc(&vsock->queued_replies);
286 
287 	virtio_vsock_skb_queue_tail(&vsock->send_pkt_queue, skb);
288 	vhost_vq_work_queue(&vsock->vqs[VSOCK_VQ_RX], &vsock->send_pkt_work);
289 
290 	rcu_read_unlock();
291 	return len;
292 }
293 
294 static int
vhost_transport_cancel_pkt(struct vsock_sock * vsk)295 vhost_transport_cancel_pkt(struct vsock_sock *vsk)
296 {
297 	struct vhost_vsock *vsock;
298 	int cnt = 0;
299 	int ret = -ENODEV;
300 
301 	rcu_read_lock();
302 
303 	/* Find the vhost_vsock according to guest context id  */
304 	vsock = vhost_vsock_get(vsk->remote_addr.svm_cid);
305 	if (!vsock)
306 		goto out;
307 
308 	cnt = virtio_transport_purge_skbs(vsk, &vsock->send_pkt_queue);
309 
310 	if (cnt) {
311 		struct vhost_virtqueue *tx_vq = &vsock->vqs[VSOCK_VQ_TX];
312 		int new_cnt;
313 
314 		new_cnt = atomic_sub_return(cnt, &vsock->queued_replies);
315 		if (new_cnt + cnt >= tx_vq->num && new_cnt < tx_vq->num)
316 			vhost_poll_queue(&tx_vq->poll);
317 	}
318 
319 	ret = 0;
320 out:
321 	rcu_read_unlock();
322 	return ret;
323 }
324 
325 static struct sk_buff *
vhost_vsock_alloc_skb(struct vhost_virtqueue * vq,unsigned int out,unsigned int in)326 vhost_vsock_alloc_skb(struct vhost_virtqueue *vq,
327 		      unsigned int out, unsigned int in)
328 {
329 	struct virtio_vsock_hdr *hdr;
330 	struct iov_iter iov_iter;
331 	struct sk_buff *skb;
332 	size_t payload_len;
333 	size_t nbytes;
334 	size_t len;
335 
336 	if (in != 0) {
337 		vq_err(vq, "Expected 0 input buffers, got %u\n", in);
338 		return NULL;
339 	}
340 
341 	len = iov_length(vq->iov, out);
342 
343 	/* len contains both payload and hdr */
344 	skb = virtio_vsock_alloc_skb(len, GFP_KERNEL);
345 	if (!skb)
346 		return NULL;
347 
348 	iov_iter_init(&iov_iter, ITER_SOURCE, vq->iov, out, len);
349 
350 	hdr = virtio_vsock_hdr(skb);
351 	nbytes = copy_from_iter(hdr, sizeof(*hdr), &iov_iter);
352 	if (nbytes != sizeof(*hdr)) {
353 		vq_err(vq, "Expected %zu bytes for pkt->hdr, got %zu bytes\n",
354 		       sizeof(*hdr), nbytes);
355 		kfree_skb(skb);
356 		return NULL;
357 	}
358 
359 	payload_len = le32_to_cpu(hdr->len);
360 
361 	/* No payload */
362 	if (!payload_len)
363 		return skb;
364 
365 	/* The pkt is too big or the length in the header is invalid */
366 	if (payload_len > VIRTIO_VSOCK_MAX_PKT_BUF_SIZE ||
367 	    payload_len + sizeof(*hdr) > len) {
368 		kfree_skb(skb);
369 		return NULL;
370 	}
371 
372 	virtio_vsock_skb_rx_put(skb);
373 
374 	nbytes = copy_from_iter(skb->data, payload_len, &iov_iter);
375 	if (nbytes != payload_len) {
376 		vq_err(vq, "Expected %zu byte payload, got %zu bytes\n",
377 		       payload_len, nbytes);
378 		kfree_skb(skb);
379 		return NULL;
380 	}
381 
382 	return skb;
383 }
384 
385 /* Is there space left for replies to rx packets? */
vhost_vsock_more_replies(struct vhost_vsock * vsock)386 static bool vhost_vsock_more_replies(struct vhost_vsock *vsock)
387 {
388 	struct vhost_virtqueue *vq = &vsock->vqs[VSOCK_VQ_TX];
389 	int val;
390 
391 	smp_rmb(); /* paired with atomic_inc() and atomic_dec_return() */
392 	val = atomic_read(&vsock->queued_replies);
393 
394 	return val < vq->num;
395 }
396 
397 static bool vhost_transport_seqpacket_allow(u32 remote_cid);
398 
399 static struct virtio_transport vhost_transport = {
400 	.transport = {
401 		.module                   = THIS_MODULE,
402 
403 		.get_local_cid            = vhost_transport_get_local_cid,
404 
405 		.init                     = virtio_transport_do_socket_init,
406 		.destruct                 = virtio_transport_destruct,
407 		.release                  = virtio_transport_release,
408 		.connect                  = virtio_transport_connect,
409 		.shutdown                 = virtio_transport_shutdown,
410 		.cancel_pkt               = vhost_transport_cancel_pkt,
411 
412 		.dgram_enqueue            = virtio_transport_dgram_enqueue,
413 		.dgram_dequeue            = virtio_transport_dgram_dequeue,
414 		.dgram_bind               = virtio_transport_dgram_bind,
415 		.dgram_allow              = virtio_transport_dgram_allow,
416 
417 		.stream_enqueue           = virtio_transport_stream_enqueue,
418 		.stream_dequeue           = virtio_transport_stream_dequeue,
419 		.stream_has_data          = virtio_transport_stream_has_data,
420 		.stream_has_space         = virtio_transport_stream_has_space,
421 		.stream_rcvhiwat          = virtio_transport_stream_rcvhiwat,
422 		.stream_is_active         = virtio_transport_stream_is_active,
423 		.stream_allow             = virtio_transport_stream_allow,
424 
425 		.seqpacket_dequeue        = virtio_transport_seqpacket_dequeue,
426 		.seqpacket_enqueue        = virtio_transport_seqpacket_enqueue,
427 		.seqpacket_allow          = vhost_transport_seqpacket_allow,
428 		.seqpacket_has_data       = virtio_transport_seqpacket_has_data,
429 
430 		.notify_poll_in           = virtio_transport_notify_poll_in,
431 		.notify_poll_out          = virtio_transport_notify_poll_out,
432 		.notify_recv_init         = virtio_transport_notify_recv_init,
433 		.notify_recv_pre_block    = virtio_transport_notify_recv_pre_block,
434 		.notify_recv_pre_dequeue  = virtio_transport_notify_recv_pre_dequeue,
435 		.notify_recv_post_dequeue = virtio_transport_notify_recv_post_dequeue,
436 		.notify_send_init         = virtio_transport_notify_send_init,
437 		.notify_send_pre_block    = virtio_transport_notify_send_pre_block,
438 		.notify_send_pre_enqueue  = virtio_transport_notify_send_pre_enqueue,
439 		.notify_send_post_enqueue = virtio_transport_notify_send_post_enqueue,
440 		.notify_buffer_size       = virtio_transport_notify_buffer_size,
441 		.notify_set_rcvlowat      = virtio_transport_notify_set_rcvlowat,
442 
443 		.read_skb = virtio_transport_read_skb,
444 	},
445 
446 	.send_pkt = vhost_transport_send_pkt,
447 };
448 
vhost_transport_seqpacket_allow(u32 remote_cid)449 static bool vhost_transport_seqpacket_allow(u32 remote_cid)
450 {
451 	struct vhost_vsock *vsock;
452 	bool seqpacket_allow = false;
453 
454 	rcu_read_lock();
455 	vsock = vhost_vsock_get(remote_cid);
456 
457 	if (vsock)
458 		seqpacket_allow = vsock->seqpacket_allow;
459 
460 	rcu_read_unlock();
461 
462 	return seqpacket_allow;
463 }
464 
vhost_vsock_handle_tx_kick(struct vhost_work * work)465 static void vhost_vsock_handle_tx_kick(struct vhost_work *work)
466 {
467 	struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
468 						  poll.work);
469 	struct vhost_vsock *vsock = container_of(vq->dev, struct vhost_vsock,
470 						 dev);
471 	int head, pkts = 0, total_len = 0;
472 	unsigned int out, in;
473 	struct sk_buff *skb;
474 	bool added = false;
475 
476 	mutex_lock(&vq->mutex);
477 
478 	if (!vhost_vq_get_backend(vq))
479 		goto out;
480 
481 	if (!vq_meta_prefetch(vq))
482 		goto out;
483 
484 	vhost_disable_notify(&vsock->dev, vq);
485 	do {
486 		struct virtio_vsock_hdr *hdr;
487 
488 		if (!vhost_vsock_more_replies(vsock)) {
489 			/* Stop tx until the device processes already
490 			 * pending replies.  Leave tx virtqueue
491 			 * callbacks disabled.
492 			 */
493 			goto no_more_replies;
494 		}
495 
496 		head = vhost_get_vq_desc(vq, vq->iov, ARRAY_SIZE(vq->iov),
497 					 &out, &in, NULL, NULL);
498 		if (head < 0)
499 			break;
500 
501 		if (head == vq->num) {
502 			if (unlikely(vhost_enable_notify(&vsock->dev, vq))) {
503 				vhost_disable_notify(&vsock->dev, vq);
504 				continue;
505 			}
506 			break;
507 		}
508 
509 		skb = vhost_vsock_alloc_skb(vq, out, in);
510 		if (!skb) {
511 			vq_err(vq, "Faulted on pkt\n");
512 			continue;
513 		}
514 
515 		total_len += sizeof(*hdr) + skb->len;
516 
517 		/* Deliver to monitoring devices all received packets */
518 		virtio_transport_deliver_tap_pkt(skb);
519 
520 		hdr = virtio_vsock_hdr(skb);
521 
522 		/* Only accept correctly addressed packets */
523 		if (le64_to_cpu(hdr->src_cid) == vsock->guest_cid &&
524 		    le64_to_cpu(hdr->dst_cid) ==
525 		    vhost_transport_get_local_cid())
526 			virtio_transport_recv_pkt(&vhost_transport, skb);
527 		else
528 			kfree_skb(skb);
529 
530 		vhost_add_used(vq, head, 0);
531 		added = true;
532 	} while(likely(!vhost_exceeds_weight(vq, ++pkts, total_len)));
533 
534 no_more_replies:
535 	if (added)
536 		vhost_signal(&vsock->dev, vq);
537 
538 out:
539 	mutex_unlock(&vq->mutex);
540 }
541 
vhost_vsock_handle_rx_kick(struct vhost_work * work)542 static void vhost_vsock_handle_rx_kick(struct vhost_work *work)
543 {
544 	struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
545 						poll.work);
546 	struct vhost_vsock *vsock = container_of(vq->dev, struct vhost_vsock,
547 						 dev);
548 
549 	vhost_transport_do_send_pkt(vsock, vq);
550 }
551 
vhost_vsock_start(struct vhost_vsock * vsock)552 static int vhost_vsock_start(struct vhost_vsock *vsock)
553 {
554 	struct vhost_virtqueue *vq;
555 	size_t i;
556 	int ret;
557 
558 	mutex_lock(&vsock->dev.mutex);
559 
560 	ret = vhost_dev_check_owner(&vsock->dev);
561 	if (ret)
562 		goto err;
563 
564 	for (i = 0; i < ARRAY_SIZE(vsock->vqs); i++) {
565 		vq = &vsock->vqs[i];
566 
567 		mutex_lock(&vq->mutex);
568 
569 		if (!vhost_vq_access_ok(vq)) {
570 			ret = -EFAULT;
571 			goto err_vq;
572 		}
573 
574 		if (!vhost_vq_get_backend(vq)) {
575 			vhost_vq_set_backend(vq, vsock);
576 			ret = vhost_vq_init_access(vq);
577 			if (ret)
578 				goto err_vq;
579 		}
580 
581 		mutex_unlock(&vq->mutex);
582 	}
583 
584 	/* Some packets may have been queued before the device was started,
585 	 * let's kick the send worker to send them.
586 	 */
587 	vhost_vq_work_queue(&vsock->vqs[VSOCK_VQ_RX], &vsock->send_pkt_work);
588 
589 	mutex_unlock(&vsock->dev.mutex);
590 	return 0;
591 
592 err_vq:
593 	vhost_vq_set_backend(vq, NULL);
594 	mutex_unlock(&vq->mutex);
595 
596 	for (i = 0; i < ARRAY_SIZE(vsock->vqs); i++) {
597 		vq = &vsock->vqs[i];
598 
599 		mutex_lock(&vq->mutex);
600 		vhost_vq_set_backend(vq, NULL);
601 		mutex_unlock(&vq->mutex);
602 	}
603 err:
604 	mutex_unlock(&vsock->dev.mutex);
605 	return ret;
606 }
607 
vhost_vsock_stop(struct vhost_vsock * vsock,bool check_owner)608 static int vhost_vsock_stop(struct vhost_vsock *vsock, bool check_owner)
609 {
610 	size_t i;
611 	int ret = 0;
612 
613 	mutex_lock(&vsock->dev.mutex);
614 
615 	if (check_owner) {
616 		ret = vhost_dev_check_owner(&vsock->dev);
617 		if (ret)
618 			goto err;
619 	}
620 
621 	for (i = 0; i < ARRAY_SIZE(vsock->vqs); i++) {
622 		struct vhost_virtqueue *vq = &vsock->vqs[i];
623 
624 		mutex_lock(&vq->mutex);
625 		vhost_vq_set_backend(vq, NULL);
626 		mutex_unlock(&vq->mutex);
627 	}
628 
629 err:
630 	mutex_unlock(&vsock->dev.mutex);
631 	return ret;
632 }
633 
vhost_vsock_free(struct vhost_vsock * vsock)634 static void vhost_vsock_free(struct vhost_vsock *vsock)
635 {
636 	kvfree(vsock);
637 }
638 
vhost_vsock_dev_open(struct inode * inode,struct file * file)639 static int vhost_vsock_dev_open(struct inode *inode, struct file *file)
640 {
641 	struct vhost_virtqueue **vqs;
642 	struct vhost_vsock *vsock;
643 	int ret;
644 
645 	/* This struct is large and allocation could fail, fall back to vmalloc
646 	 * if there is no other way.
647 	 */
648 	vsock = kvmalloc(sizeof(*vsock), GFP_KERNEL | __GFP_RETRY_MAYFAIL);
649 	if (!vsock)
650 		return -ENOMEM;
651 
652 	vqs = kmalloc_array(ARRAY_SIZE(vsock->vqs), sizeof(*vqs), GFP_KERNEL);
653 	if (!vqs) {
654 		ret = -ENOMEM;
655 		goto out;
656 	}
657 
658 	vsock->guest_cid = 0; /* no CID assigned yet */
659 	vsock->seqpacket_allow = false;
660 
661 	atomic_set(&vsock->queued_replies, 0);
662 
663 	vqs[VSOCK_VQ_TX] = &vsock->vqs[VSOCK_VQ_TX];
664 	vqs[VSOCK_VQ_RX] = &vsock->vqs[VSOCK_VQ_RX];
665 	vsock->vqs[VSOCK_VQ_TX].handle_kick = vhost_vsock_handle_tx_kick;
666 	vsock->vqs[VSOCK_VQ_RX].handle_kick = vhost_vsock_handle_rx_kick;
667 
668 	vhost_dev_init(&vsock->dev, vqs, ARRAY_SIZE(vsock->vqs),
669 		       UIO_MAXIOV, VHOST_VSOCK_PKT_WEIGHT,
670 		       VHOST_VSOCK_WEIGHT, true, NULL);
671 
672 	file->private_data = vsock;
673 	skb_queue_head_init(&vsock->send_pkt_queue);
674 	vhost_work_init(&vsock->send_pkt_work, vhost_transport_send_pkt_work);
675 	return 0;
676 
677 out:
678 	vhost_vsock_free(vsock);
679 	return ret;
680 }
681 
vhost_vsock_flush(struct vhost_vsock * vsock)682 static void vhost_vsock_flush(struct vhost_vsock *vsock)
683 {
684 	vhost_dev_flush(&vsock->dev);
685 }
686 
vhost_vsock_reset_orphans(struct sock * sk)687 static void vhost_vsock_reset_orphans(struct sock *sk)
688 {
689 	struct vsock_sock *vsk = vsock_sk(sk);
690 
691 	/* vmci_transport.c doesn't take sk_lock here either.  At least we're
692 	 * under vsock_table_lock so the sock cannot disappear while we're
693 	 * executing.
694 	 */
695 
696 	/* If the peer is still valid, no need to reset connection */
697 	if (vhost_vsock_get(vsk->remote_addr.svm_cid))
698 		return;
699 
700 	/* If the close timeout is pending, let it expire.  This avoids races
701 	 * with the timeout callback.
702 	 */
703 	if (vsk->close_work_scheduled)
704 		return;
705 
706 	sock_set_flag(sk, SOCK_DONE);
707 	vsk->peer_shutdown = SHUTDOWN_MASK;
708 	sk->sk_state = SS_UNCONNECTED;
709 	sk->sk_err = ECONNRESET;
710 	sk_error_report(sk);
711 }
712 
vhost_vsock_dev_release(struct inode * inode,struct file * file)713 static int vhost_vsock_dev_release(struct inode *inode, struct file *file)
714 {
715 	struct vhost_vsock *vsock = file->private_data;
716 
717 	mutex_lock(&vhost_vsock_mutex);
718 	if (vsock->guest_cid)
719 		hash_del_rcu(&vsock->hash);
720 	mutex_unlock(&vhost_vsock_mutex);
721 
722 	/* Wait for other CPUs to finish using vsock */
723 	synchronize_rcu();
724 
725 	/* Iterating over all connections for all CIDs to find orphans is
726 	 * inefficient.  Room for improvement here. */
727 	vsock_for_each_connected_socket(&vhost_transport.transport,
728 					vhost_vsock_reset_orphans);
729 
730 	/* Don't check the owner, because we are in the release path, so we
731 	 * need to stop the vsock device in any case.
732 	 * vhost_vsock_stop() can not fail in this case, so we don't need to
733 	 * check the return code.
734 	 */
735 	vhost_vsock_stop(vsock, false);
736 	vhost_vsock_flush(vsock);
737 	vhost_dev_stop(&vsock->dev);
738 
739 	virtio_vsock_skb_queue_purge(&vsock->send_pkt_queue);
740 
741 	vhost_dev_cleanup(&vsock->dev);
742 	kfree(vsock->dev.vqs);
743 	vhost_vsock_free(vsock);
744 	return 0;
745 }
746 
vhost_vsock_set_cid(struct vhost_vsock * vsock,u64 guest_cid)747 static int vhost_vsock_set_cid(struct vhost_vsock *vsock, u64 guest_cid)
748 {
749 	struct vhost_vsock *other;
750 
751 	/* Refuse reserved CIDs */
752 	if (guest_cid <= VMADDR_CID_HOST ||
753 	    guest_cid == U32_MAX)
754 		return -EINVAL;
755 
756 	/* 64-bit CIDs are not yet supported */
757 	if (guest_cid > U32_MAX)
758 		return -EINVAL;
759 
760 	/* Refuse if CID is assigned to the guest->host transport (i.e. nested
761 	 * VM), to make the loopback work.
762 	 */
763 	if (vsock_find_cid(guest_cid))
764 		return -EADDRINUSE;
765 
766 	/* Refuse if CID is already in use */
767 	mutex_lock(&vhost_vsock_mutex);
768 	other = vhost_vsock_get(guest_cid);
769 	if (other && other != vsock) {
770 		mutex_unlock(&vhost_vsock_mutex);
771 		return -EADDRINUSE;
772 	}
773 
774 	if (vsock->guest_cid)
775 		hash_del_rcu(&vsock->hash);
776 
777 	vsock->guest_cid = guest_cid;
778 	hash_add_rcu(vhost_vsock_hash, &vsock->hash, vsock->guest_cid);
779 	mutex_unlock(&vhost_vsock_mutex);
780 
781 	return 0;
782 }
783 
vhost_vsock_set_features(struct vhost_vsock * vsock,u64 features)784 static int vhost_vsock_set_features(struct vhost_vsock *vsock, u64 features)
785 {
786 	struct vhost_virtqueue *vq;
787 	int i;
788 
789 	if (features & ~VHOST_VSOCK_FEATURES)
790 		return -EOPNOTSUPP;
791 
792 	mutex_lock(&vsock->dev.mutex);
793 	if ((features & (1 << VHOST_F_LOG_ALL)) &&
794 	    !vhost_log_access_ok(&vsock->dev)) {
795 		goto err;
796 	}
797 
798 	if ((features & (1ULL << VIRTIO_F_ACCESS_PLATFORM))) {
799 		if (vhost_init_device_iotlb(&vsock->dev))
800 			goto err;
801 	}
802 
803 	vsock->seqpacket_allow = features & (1ULL << VIRTIO_VSOCK_F_SEQPACKET);
804 
805 	for (i = 0; i < ARRAY_SIZE(vsock->vqs); i++) {
806 		vq = &vsock->vqs[i];
807 		mutex_lock(&vq->mutex);
808 		vq->acked_features = features;
809 		mutex_unlock(&vq->mutex);
810 	}
811 	mutex_unlock(&vsock->dev.mutex);
812 	return 0;
813 
814 err:
815 	mutex_unlock(&vsock->dev.mutex);
816 	return -EFAULT;
817 }
818 
vhost_vsock_dev_ioctl(struct file * f,unsigned int ioctl,unsigned long arg)819 static long vhost_vsock_dev_ioctl(struct file *f, unsigned int ioctl,
820 				  unsigned long arg)
821 {
822 	struct vhost_vsock *vsock = f->private_data;
823 	void __user *argp = (void __user *)arg;
824 	u64 guest_cid;
825 	u64 features;
826 	int start;
827 	int r;
828 
829 	switch (ioctl) {
830 	case VHOST_VSOCK_SET_GUEST_CID:
831 		if (copy_from_user(&guest_cid, argp, sizeof(guest_cid)))
832 			return -EFAULT;
833 		return vhost_vsock_set_cid(vsock, guest_cid);
834 	case VHOST_VSOCK_SET_RUNNING:
835 		if (copy_from_user(&start, argp, sizeof(start)))
836 			return -EFAULT;
837 		if (start)
838 			return vhost_vsock_start(vsock);
839 		else
840 			return vhost_vsock_stop(vsock, true);
841 	case VHOST_GET_FEATURES:
842 		features = VHOST_VSOCK_FEATURES;
843 		if (copy_to_user(argp, &features, sizeof(features)))
844 			return -EFAULT;
845 		return 0;
846 	case VHOST_SET_FEATURES:
847 		if (copy_from_user(&features, argp, sizeof(features)))
848 			return -EFAULT;
849 		return vhost_vsock_set_features(vsock, features);
850 	case VHOST_GET_BACKEND_FEATURES:
851 		features = VHOST_VSOCK_BACKEND_FEATURES;
852 		if (copy_to_user(argp, &features, sizeof(features)))
853 			return -EFAULT;
854 		return 0;
855 	case VHOST_SET_BACKEND_FEATURES:
856 		if (copy_from_user(&features, argp, sizeof(features)))
857 			return -EFAULT;
858 		if (features & ~VHOST_VSOCK_BACKEND_FEATURES)
859 			return -EOPNOTSUPP;
860 		vhost_set_backend_features(&vsock->dev, features);
861 		return 0;
862 	default:
863 		mutex_lock(&vsock->dev.mutex);
864 		r = vhost_dev_ioctl(&vsock->dev, ioctl, argp);
865 		if (r == -ENOIOCTLCMD)
866 			r = vhost_vring_ioctl(&vsock->dev, ioctl, argp);
867 		else
868 			vhost_vsock_flush(vsock);
869 		mutex_unlock(&vsock->dev.mutex);
870 		return r;
871 	}
872 }
873 
vhost_vsock_chr_read_iter(struct kiocb * iocb,struct iov_iter * to)874 static ssize_t vhost_vsock_chr_read_iter(struct kiocb *iocb, struct iov_iter *to)
875 {
876 	struct file *file = iocb->ki_filp;
877 	struct vhost_vsock *vsock = file->private_data;
878 	struct vhost_dev *dev = &vsock->dev;
879 	int noblock = file->f_flags & O_NONBLOCK;
880 
881 	return vhost_chr_read_iter(dev, to, noblock);
882 }
883 
vhost_vsock_chr_write_iter(struct kiocb * iocb,struct iov_iter * from)884 static ssize_t vhost_vsock_chr_write_iter(struct kiocb *iocb,
885 					struct iov_iter *from)
886 {
887 	struct file *file = iocb->ki_filp;
888 	struct vhost_vsock *vsock = file->private_data;
889 	struct vhost_dev *dev = &vsock->dev;
890 
891 	return vhost_chr_write_iter(dev, from);
892 }
893 
vhost_vsock_chr_poll(struct file * file,poll_table * wait)894 static __poll_t vhost_vsock_chr_poll(struct file *file, poll_table *wait)
895 {
896 	struct vhost_vsock *vsock = file->private_data;
897 	struct vhost_dev *dev = &vsock->dev;
898 
899 	return vhost_chr_poll(file, dev, wait);
900 }
901 
902 static const struct file_operations vhost_vsock_fops = {
903 	.owner          = THIS_MODULE,
904 	.open           = vhost_vsock_dev_open,
905 	.release        = vhost_vsock_dev_release,
906 	.llseek		= noop_llseek,
907 	.unlocked_ioctl = vhost_vsock_dev_ioctl,
908 	.compat_ioctl   = compat_ptr_ioctl,
909 	.read_iter      = vhost_vsock_chr_read_iter,
910 	.write_iter     = vhost_vsock_chr_write_iter,
911 	.poll           = vhost_vsock_chr_poll,
912 };
913 
914 static struct miscdevice vhost_vsock_misc = {
915 	.minor = VHOST_VSOCK_MINOR,
916 	.name = "vhost-vsock",
917 	.fops = &vhost_vsock_fops,
918 };
919 
vhost_vsock_init(void)920 static int __init vhost_vsock_init(void)
921 {
922 	int ret;
923 
924 	ret = vsock_core_register(&vhost_transport.transport,
925 				  VSOCK_TRANSPORT_F_H2G);
926 	if (ret < 0)
927 		return ret;
928 
929 	ret = misc_register(&vhost_vsock_misc);
930 	if (ret) {
931 		vsock_core_unregister(&vhost_transport.transport);
932 		return ret;
933 	}
934 
935 	return 0;
936 };
937 
vhost_vsock_exit(void)938 static void __exit vhost_vsock_exit(void)
939 {
940 	misc_deregister(&vhost_vsock_misc);
941 	vsock_core_unregister(&vhost_transport.transport);
942 };
943 
944 module_init(vhost_vsock_init);
945 module_exit(vhost_vsock_exit);
946 MODULE_LICENSE("GPL v2");
947 MODULE_AUTHOR("Asias He");
948 MODULE_DESCRIPTION("vhost transport for vsock ");
949 MODULE_ALIAS_MISCDEV(VHOST_VSOCK_MINOR);
950 MODULE_ALIAS("devname:vhost-vsock");
951