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1 /* Copyright (C) 2009 Red Hat, Inc.
2  * Author: Michael S. Tsirkin <mst@redhat.com>
3  *
4  * This work is licensed under the terms of the GNU GPL, version 2.
5  *
6  * virtio-net server in host kernel.
7  */
8 
9 #include <linux/compat.h>
10 #include <linux/eventfd.h>
11 #include <linux/vhost.h>
12 #include <linux/virtio_net.h>
13 #include <linux/miscdevice.h>
14 #include <linux/module.h>
15 #include <linux/moduleparam.h>
16 #include <linux/mutex.h>
17 #include <linux/workqueue.h>
18 #include <linux/rcupdate.h>
19 #include <linux/file.h>
20 #include <linux/slab.h>
21 
22 #include <linux/net.h>
23 #include <linux/if_packet.h>
24 #include <linux/if_arp.h>
25 #include <linux/if_tun.h>
26 #include <linux/if_macvlan.h>
27 #include <linux/if_vlan.h>
28 
29 #include <net/sock.h>
30 
31 #include "vhost.h"
32 
33 static int experimental_zcopytx = 1;
34 module_param(experimental_zcopytx, int, 0444);
35 MODULE_PARM_DESC(experimental_zcopytx, "Enable Zero Copy TX;"
36 		                       " 1 -Enable; 0 - Disable");
37 
38 /* Max number of bytes transferred before requeueing the job.
39  * Using this limit prevents one virtqueue from starving others. */
40 #define VHOST_NET_WEIGHT 0x80000
41 
42 /* MAX number of TX used buffers for outstanding zerocopy */
43 #define VHOST_MAX_PEND 128
44 #define VHOST_GOODCOPY_LEN 256
45 
46 /*
47  * For transmit, used buffer len is unused; we override it to track buffer
48  * status internally; used for zerocopy tx only.
49  */
50 /* Lower device DMA failed */
51 #define VHOST_DMA_FAILED_LEN	3
52 /* Lower device DMA done */
53 #define VHOST_DMA_DONE_LEN	2
54 /* Lower device DMA in progress */
55 #define VHOST_DMA_IN_PROGRESS	1
56 /* Buffer unused */
57 #define VHOST_DMA_CLEAR_LEN	0
58 
59 #define VHOST_DMA_IS_DONE(len) ((len) >= VHOST_DMA_DONE_LEN)
60 
61 enum {
62 	VHOST_NET_FEATURES = VHOST_FEATURES |
63 			 (1ULL << VHOST_NET_F_VIRTIO_NET_HDR) |
64 			 (1ULL << VIRTIO_NET_F_MRG_RXBUF),
65 };
66 
67 enum {
68 	VHOST_NET_VQ_RX = 0,
69 	VHOST_NET_VQ_TX = 1,
70 	VHOST_NET_VQ_MAX = 2,
71 };
72 
73 struct vhost_net_ubuf_ref {
74 	struct kref kref;
75 	wait_queue_head_t wait;
76 	struct vhost_virtqueue *vq;
77 };
78 
79 struct vhost_net_virtqueue {
80 	struct vhost_virtqueue vq;
81 	/* hdr is used to store the virtio header.
82 	 * Since each iovec has >= 1 byte length, we never need more than
83 	 * header length entries to store the header. */
84 	struct iovec hdr[sizeof(struct virtio_net_hdr_mrg_rxbuf)];
85 	size_t vhost_hlen;
86 	size_t sock_hlen;
87 	/* vhost zerocopy support fields below: */
88 	/* last used idx for outstanding DMA zerocopy buffers */
89 	int upend_idx;
90 	/* first used idx for DMA done zerocopy buffers */
91 	int done_idx;
92 	/* an array of userspace buffers info */
93 	struct ubuf_info *ubuf_info;
94 	/* Reference counting for outstanding ubufs.
95 	 * Protected by vq mutex. Writers must also take device mutex. */
96 	struct vhost_net_ubuf_ref *ubufs;
97 };
98 
99 struct vhost_net {
100 	struct vhost_dev dev;
101 	struct vhost_net_virtqueue vqs[VHOST_NET_VQ_MAX];
102 	struct vhost_poll poll[VHOST_NET_VQ_MAX];
103 	/* Number of TX recently submitted.
104 	 * Protected by tx vq lock. */
105 	unsigned tx_packets;
106 	/* Number of times zerocopy TX recently failed.
107 	 * Protected by tx vq lock. */
108 	unsigned tx_zcopy_err;
109 	/* Flush in progress. Protected by tx vq lock. */
110 	bool tx_flush;
111 };
112 
113 static unsigned vhost_net_zcopy_mask __read_mostly;
114 
vhost_net_enable_zcopy(int vq)115 static void vhost_net_enable_zcopy(int vq)
116 {
117 	vhost_net_zcopy_mask |= 0x1 << vq;
118 }
119 
vhost_net_zerocopy_done_signal(struct kref * kref)120 static void vhost_net_zerocopy_done_signal(struct kref *kref)
121 {
122 	struct vhost_net_ubuf_ref *ubufs;
123 
124 	ubufs = container_of(kref, struct vhost_net_ubuf_ref, kref);
125 	wake_up(&ubufs->wait);
126 }
127 
128 static struct vhost_net_ubuf_ref *
vhost_net_ubuf_alloc(struct vhost_virtqueue * vq,bool zcopy)129 vhost_net_ubuf_alloc(struct vhost_virtqueue *vq, bool zcopy)
130 {
131 	struct vhost_net_ubuf_ref *ubufs;
132 	/* No zero copy backend? Nothing to count. */
133 	if (!zcopy)
134 		return NULL;
135 	ubufs = kmalloc(sizeof(*ubufs), GFP_KERNEL);
136 	if (!ubufs)
137 		return ERR_PTR(-ENOMEM);
138 	kref_init(&ubufs->kref);
139 	init_waitqueue_head(&ubufs->wait);
140 	ubufs->vq = vq;
141 	return ubufs;
142 }
143 
vhost_net_ubuf_put(struct vhost_net_ubuf_ref * ubufs)144 static void vhost_net_ubuf_put(struct vhost_net_ubuf_ref *ubufs)
145 {
146 	kref_put(&ubufs->kref, vhost_net_zerocopy_done_signal);
147 }
148 
vhost_net_ubuf_put_and_wait(struct vhost_net_ubuf_ref * ubufs)149 static void vhost_net_ubuf_put_and_wait(struct vhost_net_ubuf_ref *ubufs)
150 {
151 	kref_put(&ubufs->kref, vhost_net_zerocopy_done_signal);
152 	wait_event(ubufs->wait, !atomic_read(&ubufs->kref.refcount));
153 	kfree(ubufs);
154 }
155 
vhost_net_clear_ubuf_info(struct vhost_net * n)156 static void vhost_net_clear_ubuf_info(struct vhost_net *n)
157 {
158 	int i;
159 
160 	for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
161 		kfree(n->vqs[i].ubuf_info);
162 		n->vqs[i].ubuf_info = NULL;
163 	}
164 }
165 
vhost_net_set_ubuf_info(struct vhost_net * n)166 int vhost_net_set_ubuf_info(struct vhost_net *n)
167 {
168 	bool zcopy;
169 	int i;
170 
171 	for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
172 		zcopy = vhost_net_zcopy_mask & (0x1 << i);
173 		if (!zcopy)
174 			continue;
175 		n->vqs[i].ubuf_info = kmalloc(sizeof(*n->vqs[i].ubuf_info) *
176 					      UIO_MAXIOV, GFP_KERNEL);
177 		if  (!n->vqs[i].ubuf_info)
178 			goto err;
179 	}
180 	return 0;
181 
182 err:
183 	vhost_net_clear_ubuf_info(n);
184 	return -ENOMEM;
185 }
186 
vhost_net_vq_reset(struct vhost_net * n)187 void vhost_net_vq_reset(struct vhost_net *n)
188 {
189 	int i;
190 
191 	vhost_net_clear_ubuf_info(n);
192 
193 	for (i = 0; i < VHOST_NET_VQ_MAX; i++) {
194 		n->vqs[i].done_idx = 0;
195 		n->vqs[i].upend_idx = 0;
196 		n->vqs[i].ubufs = NULL;
197 		n->vqs[i].vhost_hlen = 0;
198 		n->vqs[i].sock_hlen = 0;
199 	}
200 
201 }
202 
vhost_net_tx_packet(struct vhost_net * net)203 static void vhost_net_tx_packet(struct vhost_net *net)
204 {
205 	++net->tx_packets;
206 	if (net->tx_packets < 1024)
207 		return;
208 	net->tx_packets = 0;
209 	net->tx_zcopy_err = 0;
210 }
211 
vhost_net_tx_err(struct vhost_net * net)212 static void vhost_net_tx_err(struct vhost_net *net)
213 {
214 	++net->tx_zcopy_err;
215 }
216 
vhost_net_tx_select_zcopy(struct vhost_net * net)217 static bool vhost_net_tx_select_zcopy(struct vhost_net *net)
218 {
219 	/* TX flush waits for outstanding DMAs to be done.
220 	 * Don't start new DMAs.
221 	 */
222 	return !net->tx_flush &&
223 		net->tx_packets / 64 >= net->tx_zcopy_err;
224 }
225 
vhost_sock_zcopy(struct socket * sock)226 static bool vhost_sock_zcopy(struct socket *sock)
227 {
228 	return unlikely(experimental_zcopytx) &&
229 		sock_flag(sock->sk, SOCK_ZEROCOPY);
230 }
231 
232 /* Pop first len bytes from iovec. Return number of segments used. */
move_iovec_hdr(struct iovec * from,struct iovec * to,size_t len,int iov_count)233 static int move_iovec_hdr(struct iovec *from, struct iovec *to,
234 			  size_t len, int iov_count)
235 {
236 	int seg = 0;
237 	size_t size;
238 
239 	while (len && seg < iov_count) {
240 		size = min(from->iov_len, len);
241 		to->iov_base = from->iov_base;
242 		to->iov_len = size;
243 		from->iov_len -= size;
244 		from->iov_base += size;
245 		len -= size;
246 		++from;
247 		++to;
248 		++seg;
249 	}
250 	return seg;
251 }
252 /* Copy iovec entries for len bytes from iovec. */
copy_iovec_hdr(const struct iovec * from,struct iovec * to,size_t len,int iovcount)253 static void copy_iovec_hdr(const struct iovec *from, struct iovec *to,
254 			   size_t len, int iovcount)
255 {
256 	int seg = 0;
257 	size_t size;
258 
259 	while (len && seg < iovcount) {
260 		size = min(from->iov_len, len);
261 		to->iov_base = from->iov_base;
262 		to->iov_len = size;
263 		len -= size;
264 		++from;
265 		++to;
266 		++seg;
267 	}
268 }
269 
270 /* In case of DMA done not in order in lower device driver for some reason.
271  * upend_idx is used to track end of used idx, done_idx is used to track head
272  * of used idx. Once lower device DMA done contiguously, we will signal KVM
273  * guest used idx.
274  */
vhost_zerocopy_signal_used(struct vhost_net * net,struct vhost_virtqueue * vq)275 static int vhost_zerocopy_signal_used(struct vhost_net *net,
276 				      struct vhost_virtqueue *vq)
277 {
278 	struct vhost_net_virtqueue *nvq =
279 		container_of(vq, struct vhost_net_virtqueue, vq);
280 	int i;
281 	int j = 0;
282 
283 	for (i = nvq->done_idx; i != nvq->upend_idx; i = (i + 1) % UIO_MAXIOV) {
284 		if (vq->heads[i].len == VHOST_DMA_FAILED_LEN)
285 			vhost_net_tx_err(net);
286 		if (VHOST_DMA_IS_DONE(vq->heads[i].len)) {
287 			vq->heads[i].len = VHOST_DMA_CLEAR_LEN;
288 			vhost_add_used_and_signal(vq->dev, vq,
289 						  vq->heads[i].id, 0);
290 			++j;
291 		} else
292 			break;
293 	}
294 	if (j)
295 		nvq->done_idx = i;
296 	return j;
297 }
298 
vhost_zerocopy_callback(struct ubuf_info * ubuf,bool success)299 static void vhost_zerocopy_callback(struct ubuf_info *ubuf, bool success)
300 {
301 	struct vhost_net_ubuf_ref *ubufs = ubuf->ctx;
302 	struct vhost_virtqueue *vq = ubufs->vq;
303 	int cnt = atomic_read(&ubufs->kref.refcount);
304 
305 	/*
306 	 * Trigger polling thread if guest stopped submitting new buffers:
307 	 * in this case, the refcount after decrement will eventually reach 1
308 	 * so here it is 2.
309 	 * We also trigger polling periodically after each 16 packets
310 	 * (the value 16 here is more or less arbitrary, it's tuned to trigger
311 	 * less than 10% of times).
312 	 */
313 	if (cnt <= 2 || !(cnt % 16))
314 		vhost_poll_queue(&vq->poll);
315 	/* set len to mark this desc buffers done DMA */
316 	vq->heads[ubuf->desc].len = success ?
317 		VHOST_DMA_DONE_LEN : VHOST_DMA_FAILED_LEN;
318 	vhost_net_ubuf_put(ubufs);
319 }
320 
321 /* Expects to be always run from workqueue - which acts as
322  * read-size critical section for our kind of RCU. */
handle_tx(struct vhost_net * net)323 static void handle_tx(struct vhost_net *net)
324 {
325 	struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_TX];
326 	struct vhost_virtqueue *vq = &nvq->vq;
327 	unsigned out, in, s;
328 	int head;
329 	struct msghdr msg = {
330 		.msg_name = NULL,
331 		.msg_namelen = 0,
332 		.msg_control = NULL,
333 		.msg_controllen = 0,
334 		.msg_iov = vq->iov,
335 		.msg_flags = MSG_DONTWAIT,
336 	};
337 	size_t len, total_len = 0;
338 	int err;
339 	size_t hdr_size;
340 	struct socket *sock;
341 	struct vhost_net_ubuf_ref *uninitialized_var(ubufs);
342 	bool zcopy, zcopy_used;
343 
344 	/* TODO: check that we are running from vhost_worker? */
345 	sock = rcu_dereference_check(vq->private_data, 1);
346 	if (!sock)
347 		return;
348 
349 	mutex_lock(&vq->mutex);
350 	vhost_disable_notify(&net->dev, vq);
351 
352 	hdr_size = nvq->vhost_hlen;
353 	zcopy = nvq->ubufs;
354 
355 	for (;;) {
356 		/* Release DMAs done buffers first */
357 		if (zcopy)
358 			vhost_zerocopy_signal_used(net, vq);
359 
360 		head = vhost_get_vq_desc(&net->dev, vq, vq->iov,
361 					 ARRAY_SIZE(vq->iov),
362 					 &out, &in,
363 					 NULL, NULL);
364 		/* On error, stop handling until the next kick. */
365 		if (unlikely(head < 0))
366 			break;
367 		/* Nothing new?  Wait for eventfd to tell us they refilled. */
368 		if (head == vq->num) {
369 			int num_pends;
370 
371 			/* If more outstanding DMAs, queue the work.
372 			 * Handle upend_idx wrap around
373 			 */
374 			num_pends = likely(nvq->upend_idx >= nvq->done_idx) ?
375 				    (nvq->upend_idx - nvq->done_idx) :
376 				    (nvq->upend_idx + UIO_MAXIOV -
377 				     nvq->done_idx);
378 			if (unlikely(num_pends > VHOST_MAX_PEND))
379 				break;
380 			if (unlikely(vhost_enable_notify(&net->dev, vq))) {
381 				vhost_disable_notify(&net->dev, vq);
382 				continue;
383 			}
384 			break;
385 		}
386 		if (in) {
387 			vq_err(vq, "Unexpected descriptor format for TX: "
388 			       "out %d, int %d\n", out, in);
389 			break;
390 		}
391 		/* Skip header. TODO: support TSO. */
392 		s = move_iovec_hdr(vq->iov, nvq->hdr, hdr_size, out);
393 		msg.msg_iovlen = out;
394 		len = iov_length(vq->iov, out);
395 		/* Sanity check */
396 		if (!len) {
397 			vq_err(vq, "Unexpected header len for TX: "
398 			       "%zd expected %zd\n",
399 			       iov_length(nvq->hdr, s), hdr_size);
400 			break;
401 		}
402 		zcopy_used = zcopy && (len >= VHOST_GOODCOPY_LEN ||
403 				       nvq->upend_idx != nvq->done_idx);
404 
405 		/* use msg_control to pass vhost zerocopy ubuf info to skb */
406 		if (zcopy_used) {
407 			vq->heads[nvq->upend_idx].id = head;
408 			if (!vhost_net_tx_select_zcopy(net) ||
409 			    len < VHOST_GOODCOPY_LEN) {
410 				/* copy don't need to wait for DMA done */
411 				vq->heads[nvq->upend_idx].len =
412 							VHOST_DMA_DONE_LEN;
413 				msg.msg_control = NULL;
414 				msg.msg_controllen = 0;
415 				ubufs = NULL;
416 			} else {
417 				struct ubuf_info *ubuf;
418 				ubuf = nvq->ubuf_info + nvq->upend_idx;
419 
420 				vq->heads[nvq->upend_idx].len =
421 					VHOST_DMA_IN_PROGRESS;
422 				ubuf->callback = vhost_zerocopy_callback;
423 				ubuf->ctx = nvq->ubufs;
424 				ubuf->desc = nvq->upend_idx;
425 				msg.msg_control = ubuf;
426 				msg.msg_controllen = sizeof(ubuf);
427 				ubufs = nvq->ubufs;
428 				kref_get(&ubufs->kref);
429 			}
430 			nvq->upend_idx = (nvq->upend_idx + 1) % UIO_MAXIOV;
431 		} else
432 			msg.msg_control = NULL;
433 		/* TODO: Check specific error and bomb out unless ENOBUFS? */
434 		err = sock->ops->sendmsg(NULL, sock, &msg, len);
435 		if (unlikely(err < 0)) {
436 			if (zcopy_used) {
437 				if (ubufs)
438 					vhost_net_ubuf_put(ubufs);
439 				nvq->upend_idx = ((unsigned)nvq->upend_idx - 1)
440 					% UIO_MAXIOV;
441 			}
442 			vhost_discard_vq_desc(vq, 1);
443 			break;
444 		}
445 		if (err != len)
446 			pr_debug("Truncated TX packet: "
447 				 " len %d != %zd\n", err, len);
448 		if (!zcopy_used)
449 			vhost_add_used_and_signal(&net->dev, vq, head, 0);
450 		else
451 			vhost_zerocopy_signal_used(net, vq);
452 		total_len += len;
453 		vhost_net_tx_packet(net);
454 		if (unlikely(total_len >= VHOST_NET_WEIGHT)) {
455 			vhost_poll_queue(&vq->poll);
456 			break;
457 		}
458 	}
459 
460 	mutex_unlock(&vq->mutex);
461 }
462 
peek_head_len(struct sock * sk)463 static int peek_head_len(struct sock *sk)
464 {
465 	struct sk_buff *head;
466 	int len = 0;
467 	unsigned long flags;
468 
469 	spin_lock_irqsave(&sk->sk_receive_queue.lock, flags);
470 	head = skb_peek(&sk->sk_receive_queue);
471 	if (likely(head)) {
472 		len = head->len;
473 		if (vlan_tx_tag_present(head))
474 			len += VLAN_HLEN;
475 	}
476 
477 	spin_unlock_irqrestore(&sk->sk_receive_queue.lock, flags);
478 	return len;
479 }
480 
481 /* This is a multi-buffer version of vhost_get_desc, that works if
482  *	vq has read descriptors only.
483  * @vq		- the relevant virtqueue
484  * @datalen	- data length we'll be reading
485  * @iovcount	- returned count of io vectors we fill
486  * @log		- vhost log
487  * @log_num	- log offset
488  * @quota       - headcount quota, 1 for big buffer
489  *	returns number of buffer heads allocated, negative on error
490  */
get_rx_bufs(struct vhost_virtqueue * vq,struct vring_used_elem * heads,int datalen,unsigned * iovcount,struct vhost_log * log,unsigned * log_num,unsigned int quota)491 static int get_rx_bufs(struct vhost_virtqueue *vq,
492 		       struct vring_used_elem *heads,
493 		       int datalen,
494 		       unsigned *iovcount,
495 		       struct vhost_log *log,
496 		       unsigned *log_num,
497 		       unsigned int quota)
498 {
499 	unsigned int out, in;
500 	int seg = 0;
501 	int headcount = 0;
502 	unsigned d;
503 	int r, nlogs = 0;
504 
505 	while (datalen > 0 && headcount < quota) {
506 		if (unlikely(seg >= UIO_MAXIOV)) {
507 			r = -ENOBUFS;
508 			goto err;
509 		}
510 		d = vhost_get_vq_desc(vq->dev, vq, vq->iov + seg,
511 				      ARRAY_SIZE(vq->iov) - seg, &out,
512 				      &in, log, log_num);
513 		if (d == vq->num) {
514 			r = 0;
515 			goto err;
516 		}
517 		if (unlikely(out || in <= 0)) {
518 			vq_err(vq, "unexpected descriptor format for RX: "
519 				"out %d, in %d\n", out, in);
520 			r = -EINVAL;
521 			goto err;
522 		}
523 		if (unlikely(log)) {
524 			nlogs += *log_num;
525 			log += *log_num;
526 		}
527 		heads[headcount].id = d;
528 		heads[headcount].len = iov_length(vq->iov + seg, in);
529 		datalen -= heads[headcount].len;
530 		++headcount;
531 		seg += in;
532 	}
533 	heads[headcount - 1].len += datalen;
534 	*iovcount = seg;
535 	if (unlikely(log))
536 		*log_num = nlogs;
537 	return headcount;
538 err:
539 	vhost_discard_vq_desc(vq, headcount);
540 	return r;
541 }
542 
543 /* Expects to be always run from workqueue - which acts as
544  * read-size critical section for our kind of RCU. */
handle_rx(struct vhost_net * net)545 static void handle_rx(struct vhost_net *net)
546 {
547 	struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_RX];
548 	struct vhost_virtqueue *vq = &nvq->vq;
549 	unsigned uninitialized_var(in), log;
550 	struct vhost_log *vq_log;
551 	struct msghdr msg = {
552 		.msg_name = NULL,
553 		.msg_namelen = 0,
554 		.msg_control = NULL, /* FIXME: get and handle RX aux data. */
555 		.msg_controllen = 0,
556 		.msg_iov = vq->iov,
557 		.msg_flags = MSG_DONTWAIT,
558 	};
559 	struct virtio_net_hdr_mrg_rxbuf hdr = {
560 		.hdr.flags = 0,
561 		.hdr.gso_type = VIRTIO_NET_HDR_GSO_NONE
562 	};
563 	size_t total_len = 0;
564 	int err, mergeable;
565 	s16 headcount;
566 	size_t vhost_hlen, sock_hlen;
567 	size_t vhost_len, sock_len;
568 	/* TODO: check that we are running from vhost_worker? */
569 	struct socket *sock = rcu_dereference_check(vq->private_data, 1);
570 
571 	if (!sock)
572 		return;
573 
574 	mutex_lock(&vq->mutex);
575 	vhost_disable_notify(&net->dev, vq);
576 	vhost_hlen = nvq->vhost_hlen;
577 	sock_hlen = nvq->sock_hlen;
578 
579 	vq_log = unlikely(vhost_has_feature(&net->dev, VHOST_F_LOG_ALL)) ?
580 		vq->log : NULL;
581 	mergeable = vhost_has_feature(&net->dev, VIRTIO_NET_F_MRG_RXBUF);
582 
583 	while ((sock_len = peek_head_len(sock->sk))) {
584 		sock_len += sock_hlen;
585 		vhost_len = sock_len + vhost_hlen;
586 		headcount = get_rx_bufs(vq, vq->heads, vhost_len,
587 					&in, vq_log, &log,
588 					likely(mergeable) ? UIO_MAXIOV : 1);
589 		/* On error, stop handling until the next kick. */
590 		if (unlikely(headcount < 0))
591 			break;
592 		/* OK, now we need to know about added descriptors. */
593 		if (!headcount) {
594 			if (unlikely(vhost_enable_notify(&net->dev, vq))) {
595 				/* They have slipped one in as we were
596 				 * doing that: check again. */
597 				vhost_disable_notify(&net->dev, vq);
598 				continue;
599 			}
600 			/* Nothing new?  Wait for eventfd to tell us
601 			 * they refilled. */
602 			break;
603 		}
604 		/* We don't need to be notified again. */
605 		if (unlikely((vhost_hlen)))
606 			/* Skip header. TODO: support TSO. */
607 			move_iovec_hdr(vq->iov, nvq->hdr, vhost_hlen, in);
608 		else
609 			/* Copy the header for use in VIRTIO_NET_F_MRG_RXBUF:
610 			 * needed because recvmsg can modify msg_iov. */
611 			copy_iovec_hdr(vq->iov, nvq->hdr, sock_hlen, in);
612 		msg.msg_iovlen = in;
613 		err = sock->ops->recvmsg(NULL, sock, &msg,
614 					 sock_len, MSG_DONTWAIT | MSG_TRUNC);
615 		/* Userspace might have consumed the packet meanwhile:
616 		 * it's not supposed to do this usually, but might be hard
617 		 * to prevent. Discard data we got (if any) and keep going. */
618 		if (unlikely(err != sock_len)) {
619 			pr_debug("Discarded rx packet: "
620 				 " len %d, expected %zd\n", err, sock_len);
621 			vhost_discard_vq_desc(vq, headcount);
622 			continue;
623 		}
624 		if (unlikely(vhost_hlen) &&
625 		    memcpy_toiovecend(nvq->hdr, (unsigned char *)&hdr, 0,
626 				      vhost_hlen)) {
627 			vq_err(vq, "Unable to write vnet_hdr at addr %p\n",
628 			       vq->iov->iov_base);
629 			break;
630 		}
631 		/* TODO: Should check and handle checksum. */
632 		if (likely(mergeable) &&
633 		    memcpy_toiovecend(nvq->hdr, (unsigned char *)&headcount,
634 				      offsetof(typeof(hdr), num_buffers),
635 				      sizeof hdr.num_buffers)) {
636 			vq_err(vq, "Failed num_buffers write");
637 			vhost_discard_vq_desc(vq, headcount);
638 			break;
639 		}
640 		vhost_add_used_and_signal_n(&net->dev, vq, vq->heads,
641 					    headcount);
642 		if (unlikely(vq_log))
643 			vhost_log_write(vq, vq_log, log, vhost_len);
644 		total_len += vhost_len;
645 		if (unlikely(total_len >= VHOST_NET_WEIGHT)) {
646 			vhost_poll_queue(&vq->poll);
647 			break;
648 		}
649 	}
650 
651 	mutex_unlock(&vq->mutex);
652 }
653 
handle_tx_kick(struct vhost_work * work)654 static void handle_tx_kick(struct vhost_work *work)
655 {
656 	struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
657 						  poll.work);
658 	struct vhost_net *net = container_of(vq->dev, struct vhost_net, dev);
659 
660 	handle_tx(net);
661 }
662 
handle_rx_kick(struct vhost_work * work)663 static void handle_rx_kick(struct vhost_work *work)
664 {
665 	struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
666 						  poll.work);
667 	struct vhost_net *net = container_of(vq->dev, struct vhost_net, dev);
668 
669 	handle_rx(net);
670 }
671 
handle_tx_net(struct vhost_work * work)672 static void handle_tx_net(struct vhost_work *work)
673 {
674 	struct vhost_net *net = container_of(work, struct vhost_net,
675 					     poll[VHOST_NET_VQ_TX].work);
676 	handle_tx(net);
677 }
678 
handle_rx_net(struct vhost_work * work)679 static void handle_rx_net(struct vhost_work *work)
680 {
681 	struct vhost_net *net = container_of(work, struct vhost_net,
682 					     poll[VHOST_NET_VQ_RX].work);
683 	handle_rx(net);
684 }
685 
vhost_net_open(struct inode * inode,struct file * f)686 static int vhost_net_open(struct inode *inode, struct file *f)
687 {
688 	struct vhost_net *n = kmalloc(sizeof *n, GFP_KERNEL);
689 	struct vhost_dev *dev;
690 	struct vhost_virtqueue **vqs;
691 	int r, i;
692 
693 	if (!n)
694 		return -ENOMEM;
695 	vqs = kmalloc(VHOST_NET_VQ_MAX * sizeof(*vqs), GFP_KERNEL);
696 	if (!vqs) {
697 		kfree(n);
698 		return -ENOMEM;
699 	}
700 
701 	dev = &n->dev;
702 	vqs[VHOST_NET_VQ_TX] = &n->vqs[VHOST_NET_VQ_TX].vq;
703 	vqs[VHOST_NET_VQ_RX] = &n->vqs[VHOST_NET_VQ_RX].vq;
704 	n->vqs[VHOST_NET_VQ_TX].vq.handle_kick = handle_tx_kick;
705 	n->vqs[VHOST_NET_VQ_RX].vq.handle_kick = handle_rx_kick;
706 	for (i = 0; i < VHOST_NET_VQ_MAX; i++) {
707 		n->vqs[i].ubufs = NULL;
708 		n->vqs[i].ubuf_info = NULL;
709 		n->vqs[i].upend_idx = 0;
710 		n->vqs[i].done_idx = 0;
711 		n->vqs[i].vhost_hlen = 0;
712 		n->vqs[i].sock_hlen = 0;
713 	}
714 	r = vhost_dev_init(dev, vqs, VHOST_NET_VQ_MAX);
715 	if (r < 0) {
716 		kfree(n);
717 		kfree(vqs);
718 		return r;
719 	}
720 
721 	vhost_poll_init(n->poll + VHOST_NET_VQ_TX, handle_tx_net, POLLOUT, dev);
722 	vhost_poll_init(n->poll + VHOST_NET_VQ_RX, handle_rx_net, POLLIN, dev);
723 
724 	f->private_data = n;
725 
726 	return 0;
727 }
728 
vhost_net_disable_vq(struct vhost_net * n,struct vhost_virtqueue * vq)729 static void vhost_net_disable_vq(struct vhost_net *n,
730 				 struct vhost_virtqueue *vq)
731 {
732 	struct vhost_net_virtqueue *nvq =
733 		container_of(vq, struct vhost_net_virtqueue, vq);
734 	struct vhost_poll *poll = n->poll + (nvq - n->vqs);
735 	if (!vq->private_data)
736 		return;
737 	vhost_poll_stop(poll);
738 }
739 
vhost_net_enable_vq(struct vhost_net * n,struct vhost_virtqueue * vq)740 static int vhost_net_enable_vq(struct vhost_net *n,
741 				struct vhost_virtqueue *vq)
742 {
743 	struct vhost_net_virtqueue *nvq =
744 		container_of(vq, struct vhost_net_virtqueue, vq);
745 	struct vhost_poll *poll = n->poll + (nvq - n->vqs);
746 	struct socket *sock;
747 
748 	sock = rcu_dereference_protected(vq->private_data,
749 					 lockdep_is_held(&vq->mutex));
750 	if (!sock)
751 		return 0;
752 
753 	return vhost_poll_start(poll, sock->file);
754 }
755 
vhost_net_stop_vq(struct vhost_net * n,struct vhost_virtqueue * vq)756 static struct socket *vhost_net_stop_vq(struct vhost_net *n,
757 					struct vhost_virtqueue *vq)
758 {
759 	struct socket *sock;
760 
761 	mutex_lock(&vq->mutex);
762 	sock = rcu_dereference_protected(vq->private_data,
763 					 lockdep_is_held(&vq->mutex));
764 	vhost_net_disable_vq(n, vq);
765 	rcu_assign_pointer(vq->private_data, NULL);
766 	mutex_unlock(&vq->mutex);
767 	return sock;
768 }
769 
vhost_net_stop(struct vhost_net * n,struct socket ** tx_sock,struct socket ** rx_sock)770 static void vhost_net_stop(struct vhost_net *n, struct socket **tx_sock,
771 			   struct socket **rx_sock)
772 {
773 	*tx_sock = vhost_net_stop_vq(n, &n->vqs[VHOST_NET_VQ_TX].vq);
774 	*rx_sock = vhost_net_stop_vq(n, &n->vqs[VHOST_NET_VQ_RX].vq);
775 }
776 
vhost_net_flush_vq(struct vhost_net * n,int index)777 static void vhost_net_flush_vq(struct vhost_net *n, int index)
778 {
779 	vhost_poll_flush(n->poll + index);
780 	vhost_poll_flush(&n->vqs[index].vq.poll);
781 }
782 
vhost_net_flush(struct vhost_net * n)783 static void vhost_net_flush(struct vhost_net *n)
784 {
785 	vhost_net_flush_vq(n, VHOST_NET_VQ_TX);
786 	vhost_net_flush_vq(n, VHOST_NET_VQ_RX);
787 	if (n->vqs[VHOST_NET_VQ_TX].ubufs) {
788 		mutex_lock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
789 		n->tx_flush = true;
790 		mutex_unlock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
791 		/* Wait for all lower device DMAs done. */
792 		vhost_net_ubuf_put_and_wait(n->vqs[VHOST_NET_VQ_TX].ubufs);
793 		mutex_lock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
794 		n->tx_flush = false;
795 		kref_init(&n->vqs[VHOST_NET_VQ_TX].ubufs->kref);
796 		mutex_unlock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
797 	}
798 }
799 
vhost_net_release(struct inode * inode,struct file * f)800 static int vhost_net_release(struct inode *inode, struct file *f)
801 {
802 	struct vhost_net *n = f->private_data;
803 	struct socket *tx_sock;
804 	struct socket *rx_sock;
805 
806 	vhost_net_stop(n, &tx_sock, &rx_sock);
807 	vhost_net_flush(n);
808 	vhost_dev_stop(&n->dev);
809 	vhost_dev_cleanup(&n->dev, false);
810 	vhost_net_vq_reset(n);
811 	if (tx_sock)
812 		fput(tx_sock->file);
813 	if (rx_sock)
814 		fput(rx_sock->file);
815 	/* We do an extra flush before freeing memory,
816 	 * since jobs can re-queue themselves. */
817 	vhost_net_flush(n);
818 	kfree(n->dev.vqs);
819 	kfree(n);
820 	return 0;
821 }
822 
get_raw_socket(int fd)823 static struct socket *get_raw_socket(int fd)
824 {
825 	struct {
826 		struct sockaddr_ll sa;
827 		char  buf[MAX_ADDR_LEN];
828 	} uaddr;
829 	int uaddr_len = sizeof uaddr, r;
830 	struct socket *sock = sockfd_lookup(fd, &r);
831 
832 	if (!sock)
833 		return ERR_PTR(-ENOTSOCK);
834 
835 	/* Parameter checking */
836 	if (sock->sk->sk_type != SOCK_RAW) {
837 		r = -ESOCKTNOSUPPORT;
838 		goto err;
839 	}
840 
841 	r = sock->ops->getname(sock, (struct sockaddr *)&uaddr.sa,
842 			       &uaddr_len, 0);
843 	if (r)
844 		goto err;
845 
846 	if (uaddr.sa.sll_family != AF_PACKET) {
847 		r = -EPFNOSUPPORT;
848 		goto err;
849 	}
850 	return sock;
851 err:
852 	fput(sock->file);
853 	return ERR_PTR(r);
854 }
855 
get_tap_socket(int fd)856 static struct socket *get_tap_socket(int fd)
857 {
858 	struct file *file = fget(fd);
859 	struct socket *sock;
860 
861 	if (!file)
862 		return ERR_PTR(-EBADF);
863 	sock = tun_get_socket(file);
864 	if (!IS_ERR(sock))
865 		return sock;
866 	sock = macvtap_get_socket(file);
867 	if (IS_ERR(sock))
868 		fput(file);
869 	return sock;
870 }
871 
get_socket(int fd)872 static struct socket *get_socket(int fd)
873 {
874 	struct socket *sock;
875 
876 	/* special case to disable backend */
877 	if (fd == -1)
878 		return NULL;
879 	sock = get_raw_socket(fd);
880 	if (!IS_ERR(sock))
881 		return sock;
882 	sock = get_tap_socket(fd);
883 	if (!IS_ERR(sock))
884 		return sock;
885 	return ERR_PTR(-ENOTSOCK);
886 }
887 
vhost_net_set_backend(struct vhost_net * n,unsigned index,int fd)888 static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd)
889 {
890 	struct socket *sock, *oldsock;
891 	struct vhost_virtqueue *vq;
892 	struct vhost_net_virtqueue *nvq;
893 	struct vhost_net_ubuf_ref *ubufs, *oldubufs = NULL;
894 	int r;
895 
896 	mutex_lock(&n->dev.mutex);
897 	r = vhost_dev_check_owner(&n->dev);
898 	if (r)
899 		goto err;
900 
901 	if (index >= VHOST_NET_VQ_MAX) {
902 		r = -ENOBUFS;
903 		goto err;
904 	}
905 	vq = &n->vqs[index].vq;
906 	nvq = &n->vqs[index];
907 	mutex_lock(&vq->mutex);
908 
909 	/* Verify that ring has been setup correctly. */
910 	if (!vhost_vq_access_ok(vq)) {
911 		r = -EFAULT;
912 		goto err_vq;
913 	}
914 	sock = get_socket(fd);
915 	if (IS_ERR(sock)) {
916 		r = PTR_ERR(sock);
917 		goto err_vq;
918 	}
919 
920 	/* start polling new socket */
921 	oldsock = rcu_dereference_protected(vq->private_data,
922 					    lockdep_is_held(&vq->mutex));
923 	if (sock != oldsock) {
924 		ubufs = vhost_net_ubuf_alloc(vq,
925 					     sock && vhost_sock_zcopy(sock));
926 		if (IS_ERR(ubufs)) {
927 			r = PTR_ERR(ubufs);
928 			goto err_ubufs;
929 		}
930 
931 		vhost_net_disable_vq(n, vq);
932 		rcu_assign_pointer(vq->private_data, sock);
933 		r = vhost_init_used(vq);
934 		if (r)
935 			goto err_used;
936 		r = vhost_net_enable_vq(n, vq);
937 		if (r)
938 			goto err_used;
939 
940 		oldubufs = nvq->ubufs;
941 		nvq->ubufs = ubufs;
942 
943 		n->tx_packets = 0;
944 		n->tx_zcopy_err = 0;
945 		n->tx_flush = false;
946 	}
947 
948 	mutex_unlock(&vq->mutex);
949 
950 	if (oldubufs) {
951 		vhost_net_ubuf_put_and_wait(oldubufs);
952 		mutex_lock(&vq->mutex);
953 		vhost_zerocopy_signal_used(n, vq);
954 		mutex_unlock(&vq->mutex);
955 	}
956 
957 	if (oldsock) {
958 		vhost_net_flush_vq(n, index);
959 		fput(oldsock->file);
960 	}
961 
962 	mutex_unlock(&n->dev.mutex);
963 	return 0;
964 
965 err_used:
966 	rcu_assign_pointer(vq->private_data, oldsock);
967 	vhost_net_enable_vq(n, vq);
968 	if (ubufs)
969 		vhost_net_ubuf_put_and_wait(ubufs);
970 err_ubufs:
971 	fput(sock->file);
972 err_vq:
973 	mutex_unlock(&vq->mutex);
974 err:
975 	mutex_unlock(&n->dev.mutex);
976 	return r;
977 }
978 
vhost_net_reset_owner(struct vhost_net * n)979 static long vhost_net_reset_owner(struct vhost_net *n)
980 {
981 	struct socket *tx_sock = NULL;
982 	struct socket *rx_sock = NULL;
983 	long err;
984 	struct vhost_memory *memory;
985 
986 	mutex_lock(&n->dev.mutex);
987 	err = vhost_dev_check_owner(&n->dev);
988 	if (err)
989 		goto done;
990 	memory = vhost_dev_reset_owner_prepare();
991 	if (!memory) {
992 		err = -ENOMEM;
993 		goto done;
994 	}
995 	vhost_net_stop(n, &tx_sock, &rx_sock);
996 	vhost_net_flush(n);
997 	vhost_dev_reset_owner(&n->dev, memory);
998 	vhost_net_vq_reset(n);
999 done:
1000 	mutex_unlock(&n->dev.mutex);
1001 	if (tx_sock)
1002 		fput(tx_sock->file);
1003 	if (rx_sock)
1004 		fput(rx_sock->file);
1005 	return err;
1006 }
1007 
vhost_net_set_features(struct vhost_net * n,u64 features)1008 static int vhost_net_set_features(struct vhost_net *n, u64 features)
1009 {
1010 	size_t vhost_hlen, sock_hlen, hdr_len;
1011 	int i;
1012 
1013 	hdr_len = (features & (1 << VIRTIO_NET_F_MRG_RXBUF)) ?
1014 			sizeof(struct virtio_net_hdr_mrg_rxbuf) :
1015 			sizeof(struct virtio_net_hdr);
1016 	if (features & (1 << VHOST_NET_F_VIRTIO_NET_HDR)) {
1017 		/* vhost provides vnet_hdr */
1018 		vhost_hlen = hdr_len;
1019 		sock_hlen = 0;
1020 	} else {
1021 		/* socket provides vnet_hdr */
1022 		vhost_hlen = 0;
1023 		sock_hlen = hdr_len;
1024 	}
1025 	mutex_lock(&n->dev.mutex);
1026 	if ((features & (1 << VHOST_F_LOG_ALL)) &&
1027 	    !vhost_log_access_ok(&n->dev)) {
1028 		mutex_unlock(&n->dev.mutex);
1029 		return -EFAULT;
1030 	}
1031 	n->dev.acked_features = features;
1032 	smp_wmb();
1033 	for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
1034 		mutex_lock(&n->vqs[i].vq.mutex);
1035 		n->vqs[i].vhost_hlen = vhost_hlen;
1036 		n->vqs[i].sock_hlen = sock_hlen;
1037 		mutex_unlock(&n->vqs[i].vq.mutex);
1038 	}
1039 	vhost_net_flush(n);
1040 	mutex_unlock(&n->dev.mutex);
1041 	return 0;
1042 }
1043 
vhost_net_set_owner(struct vhost_net * n)1044 static long vhost_net_set_owner(struct vhost_net *n)
1045 {
1046 	int r;
1047 
1048 	mutex_lock(&n->dev.mutex);
1049 	if (vhost_dev_has_owner(&n->dev)) {
1050 		r = -EBUSY;
1051 		goto out;
1052 	}
1053 	r = vhost_net_set_ubuf_info(n);
1054 	if (r)
1055 		goto out;
1056 	r = vhost_dev_set_owner(&n->dev);
1057 	if (r)
1058 		vhost_net_clear_ubuf_info(n);
1059 	vhost_net_flush(n);
1060 out:
1061 	mutex_unlock(&n->dev.mutex);
1062 	return r;
1063 }
1064 
vhost_net_ioctl(struct file * f,unsigned int ioctl,unsigned long arg)1065 static long vhost_net_ioctl(struct file *f, unsigned int ioctl,
1066 			    unsigned long arg)
1067 {
1068 	struct vhost_net *n = f->private_data;
1069 	void __user *argp = (void __user *)arg;
1070 	u64 __user *featurep = argp;
1071 	struct vhost_vring_file backend;
1072 	u64 features;
1073 	int r;
1074 
1075 	switch (ioctl) {
1076 	case VHOST_NET_SET_BACKEND:
1077 		if (copy_from_user(&backend, argp, sizeof backend))
1078 			return -EFAULT;
1079 		return vhost_net_set_backend(n, backend.index, backend.fd);
1080 	case VHOST_GET_FEATURES:
1081 		features = VHOST_NET_FEATURES;
1082 		if (copy_to_user(featurep, &features, sizeof features))
1083 			return -EFAULT;
1084 		return 0;
1085 	case VHOST_SET_FEATURES:
1086 		if (copy_from_user(&features, featurep, sizeof features))
1087 			return -EFAULT;
1088 		if (features & ~VHOST_NET_FEATURES)
1089 			return -EOPNOTSUPP;
1090 		return vhost_net_set_features(n, features);
1091 	case VHOST_RESET_OWNER:
1092 		return vhost_net_reset_owner(n);
1093 	case VHOST_SET_OWNER:
1094 		return vhost_net_set_owner(n);
1095 	default:
1096 		mutex_lock(&n->dev.mutex);
1097 		r = vhost_dev_ioctl(&n->dev, ioctl, argp);
1098 		if (r == -ENOIOCTLCMD)
1099 			r = vhost_vring_ioctl(&n->dev, ioctl, argp);
1100 		else
1101 			vhost_net_flush(n);
1102 		mutex_unlock(&n->dev.mutex);
1103 		return r;
1104 	}
1105 }
1106 
1107 #ifdef CONFIG_COMPAT
vhost_net_compat_ioctl(struct file * f,unsigned int ioctl,unsigned long arg)1108 static long vhost_net_compat_ioctl(struct file *f, unsigned int ioctl,
1109 				   unsigned long arg)
1110 {
1111 	return vhost_net_ioctl(f, ioctl, (unsigned long)compat_ptr(arg));
1112 }
1113 #endif
1114 
1115 static const struct file_operations vhost_net_fops = {
1116 	.owner          = THIS_MODULE,
1117 	.release        = vhost_net_release,
1118 	.unlocked_ioctl = vhost_net_ioctl,
1119 #ifdef CONFIG_COMPAT
1120 	.compat_ioctl   = vhost_net_compat_ioctl,
1121 #endif
1122 	.open           = vhost_net_open,
1123 	.llseek		= noop_llseek,
1124 };
1125 
1126 static struct miscdevice vhost_net_misc = {
1127 	.minor = VHOST_NET_MINOR,
1128 	.name = "vhost-net",
1129 	.fops = &vhost_net_fops,
1130 };
1131 
vhost_net_init(void)1132 static int vhost_net_init(void)
1133 {
1134 	if (experimental_zcopytx)
1135 		vhost_net_enable_zcopy(VHOST_NET_VQ_TX);
1136 	return misc_register(&vhost_net_misc);
1137 }
1138 module_init(vhost_net_init);
1139 
vhost_net_exit(void)1140 static void vhost_net_exit(void)
1141 {
1142 	misc_deregister(&vhost_net_misc);
1143 }
1144 module_exit(vhost_net_exit);
1145 
1146 MODULE_VERSION("0.0.1");
1147 MODULE_LICENSE("GPL v2");
1148 MODULE_AUTHOR("Michael S. Tsirkin");
1149 MODULE_DESCRIPTION("Host kernel accelerator for virtio net");
1150 MODULE_ALIAS_MISCDEV(VHOST_NET_MINOR);
1151 MODULE_ALIAS("devname:vhost-net");
1152