Loading...
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
28#include <net/sock.h>
29
30#include "vhost.h"
31
32static int experimental_zcopytx;
33module_param(experimental_zcopytx, int, 0444);
34MODULE_PARM_DESC(experimental_zcopytx, "Enable Experimental Zero Copy TX");
35
36/* Max number of bytes transferred before requeueing the job.
37 * Using this limit prevents one virtqueue from starving others. */
38#define VHOST_NET_WEIGHT 0x80000
39
40/* MAX number of TX used buffers for outstanding zerocopy */
41#define VHOST_MAX_PEND 128
42#define VHOST_GOODCOPY_LEN 256
43
44enum {
45 VHOST_NET_VQ_RX = 0,
46 VHOST_NET_VQ_TX = 1,
47 VHOST_NET_VQ_MAX = 2,
48};
49
50enum vhost_net_poll_state {
51 VHOST_NET_POLL_DISABLED = 0,
52 VHOST_NET_POLL_STARTED = 1,
53 VHOST_NET_POLL_STOPPED = 2,
54};
55
56struct vhost_net {
57 struct vhost_dev dev;
58 struct vhost_virtqueue vqs[VHOST_NET_VQ_MAX];
59 struct vhost_poll poll[VHOST_NET_VQ_MAX];
60 /* Tells us whether we are polling a socket for TX.
61 * We only do this when socket buffer fills up.
62 * Protected by tx vq lock. */
63 enum vhost_net_poll_state tx_poll_state;
64};
65
66static bool vhost_sock_zcopy(struct socket *sock)
67{
68 return unlikely(experimental_zcopytx) &&
69 sock_flag(sock->sk, SOCK_ZEROCOPY);
70}
71
72/* Pop first len bytes from iovec. Return number of segments used. */
73static int move_iovec_hdr(struct iovec *from, struct iovec *to,
74 size_t len, int iov_count)
75{
76 int seg = 0;
77 size_t size;
78
79 while (len && seg < iov_count) {
80 size = min(from->iov_len, len);
81 to->iov_base = from->iov_base;
82 to->iov_len = size;
83 from->iov_len -= size;
84 from->iov_base += size;
85 len -= size;
86 ++from;
87 ++to;
88 ++seg;
89 }
90 return seg;
91}
92/* Copy iovec entries for len bytes from iovec. */
93static void copy_iovec_hdr(const struct iovec *from, struct iovec *to,
94 size_t len, int iovcount)
95{
96 int seg = 0;
97 size_t size;
98
99 while (len && seg < iovcount) {
100 size = min(from->iov_len, len);
101 to->iov_base = from->iov_base;
102 to->iov_len = size;
103 len -= size;
104 ++from;
105 ++to;
106 ++seg;
107 }
108}
109
110/* Caller must have TX VQ lock */
111static void tx_poll_stop(struct vhost_net *net)
112{
113 if (likely(net->tx_poll_state != VHOST_NET_POLL_STARTED))
114 return;
115 vhost_poll_stop(net->poll + VHOST_NET_VQ_TX);
116 net->tx_poll_state = VHOST_NET_POLL_STOPPED;
117}
118
119/* Caller must have TX VQ lock */
120static void tx_poll_start(struct vhost_net *net, struct socket *sock)
121{
122 if (unlikely(net->tx_poll_state != VHOST_NET_POLL_STOPPED))
123 return;
124 vhost_poll_start(net->poll + VHOST_NET_VQ_TX, sock->file);
125 net->tx_poll_state = VHOST_NET_POLL_STARTED;
126}
127
128/* Expects to be always run from workqueue - which acts as
129 * read-size critical section for our kind of RCU. */
130static void handle_tx(struct vhost_net *net)
131{
132 struct vhost_virtqueue *vq = &net->dev.vqs[VHOST_NET_VQ_TX];
133 unsigned out, in, s;
134 int head;
135 struct msghdr msg = {
136 .msg_name = NULL,
137 .msg_namelen = 0,
138 .msg_control = NULL,
139 .msg_controllen = 0,
140 .msg_iov = vq->iov,
141 .msg_flags = MSG_DONTWAIT,
142 };
143 size_t len, total_len = 0;
144 int err, wmem;
145 size_t hdr_size;
146 struct socket *sock;
147 struct vhost_ubuf_ref *uninitialized_var(ubufs);
148 bool zcopy;
149
150 /* TODO: check that we are running from vhost_worker? */
151 sock = rcu_dereference_check(vq->private_data, 1);
152 if (!sock)
153 return;
154
155 wmem = atomic_read(&sock->sk->sk_wmem_alloc);
156 if (wmem >= sock->sk->sk_sndbuf) {
157 mutex_lock(&vq->mutex);
158 tx_poll_start(net, sock);
159 mutex_unlock(&vq->mutex);
160 return;
161 }
162
163 mutex_lock(&vq->mutex);
164 vhost_disable_notify(&net->dev, vq);
165
166 if (wmem < sock->sk->sk_sndbuf / 2)
167 tx_poll_stop(net);
168 hdr_size = vq->vhost_hlen;
169 zcopy = vhost_sock_zcopy(sock);
170
171 for (;;) {
172 /* Release DMAs done buffers first */
173 if (zcopy)
174 vhost_zerocopy_signal_used(vq);
175
176 head = vhost_get_vq_desc(&net->dev, vq, vq->iov,
177 ARRAY_SIZE(vq->iov),
178 &out, &in,
179 NULL, NULL);
180 /* On error, stop handling until the next kick. */
181 if (unlikely(head < 0))
182 break;
183 /* Nothing new? Wait for eventfd to tell us they refilled. */
184 if (head == vq->num) {
185 int num_pends;
186
187 wmem = atomic_read(&sock->sk->sk_wmem_alloc);
188 if (wmem >= sock->sk->sk_sndbuf * 3 / 4) {
189 tx_poll_start(net, sock);
190 set_bit(SOCK_ASYNC_NOSPACE, &sock->flags);
191 break;
192 }
193 /* If more outstanding DMAs, queue the work.
194 * Handle upend_idx wrap around
195 */
196 num_pends = likely(vq->upend_idx >= vq->done_idx) ?
197 (vq->upend_idx - vq->done_idx) :
198 (vq->upend_idx + UIO_MAXIOV - vq->done_idx);
199 if (unlikely(num_pends > VHOST_MAX_PEND)) {
200 tx_poll_start(net, sock);
201 set_bit(SOCK_ASYNC_NOSPACE, &sock->flags);
202 break;
203 }
204 if (unlikely(vhost_enable_notify(&net->dev, vq))) {
205 vhost_disable_notify(&net->dev, vq);
206 continue;
207 }
208 break;
209 }
210 if (in) {
211 vq_err(vq, "Unexpected descriptor format for TX: "
212 "out %d, int %d\n", out, in);
213 break;
214 }
215 /* Skip header. TODO: support TSO. */
216 s = move_iovec_hdr(vq->iov, vq->hdr, hdr_size, out);
217 msg.msg_iovlen = out;
218 len = iov_length(vq->iov, out);
219 /* Sanity check */
220 if (!len) {
221 vq_err(vq, "Unexpected header len for TX: "
222 "%zd expected %zd\n",
223 iov_length(vq->hdr, s), hdr_size);
224 break;
225 }
226 /* use msg_control to pass vhost zerocopy ubuf info to skb */
227 if (zcopy) {
228 vq->heads[vq->upend_idx].id = head;
229 if (len < VHOST_GOODCOPY_LEN) {
230 /* copy don't need to wait for DMA done */
231 vq->heads[vq->upend_idx].len =
232 VHOST_DMA_DONE_LEN;
233 msg.msg_control = NULL;
234 msg.msg_controllen = 0;
235 ubufs = NULL;
236 } else {
237 struct ubuf_info *ubuf = &vq->ubuf_info[head];
238
239 vq->heads[vq->upend_idx].len = len;
240 ubuf->callback = vhost_zerocopy_callback;
241 ubuf->arg = vq->ubufs;
242 ubuf->desc = vq->upend_idx;
243 msg.msg_control = ubuf;
244 msg.msg_controllen = sizeof(ubuf);
245 ubufs = vq->ubufs;
246 kref_get(&ubufs->kref);
247 }
248 vq->upend_idx = (vq->upend_idx + 1) % UIO_MAXIOV;
249 }
250 /* TODO: Check specific error and bomb out unless ENOBUFS? */
251 err = sock->ops->sendmsg(NULL, sock, &msg, len);
252 if (unlikely(err < 0)) {
253 if (zcopy) {
254 if (ubufs)
255 vhost_ubuf_put(ubufs);
256 vq->upend_idx = ((unsigned)vq->upend_idx - 1) %
257 UIO_MAXIOV;
258 }
259 vhost_discard_vq_desc(vq, 1);
260 tx_poll_start(net, sock);
261 break;
262 }
263 if (err != len)
264 pr_debug("Truncated TX packet: "
265 " len %d != %zd\n", err, len);
266 if (!zcopy)
267 vhost_add_used_and_signal(&net->dev, vq, head, 0);
268 total_len += len;
269 if (unlikely(total_len >= VHOST_NET_WEIGHT)) {
270 vhost_poll_queue(&vq->poll);
271 break;
272 }
273 }
274
275 mutex_unlock(&vq->mutex);
276}
277
278static int peek_head_len(struct sock *sk)
279{
280 struct sk_buff *head;
281 int len = 0;
282 unsigned long flags;
283
284 spin_lock_irqsave(&sk->sk_receive_queue.lock, flags);
285 head = skb_peek(&sk->sk_receive_queue);
286 if (likely(head))
287 len = head->len;
288 spin_unlock_irqrestore(&sk->sk_receive_queue.lock, flags);
289 return len;
290}
291
292/* This is a multi-buffer version of vhost_get_desc, that works if
293 * vq has read descriptors only.
294 * @vq - the relevant virtqueue
295 * @datalen - data length we'll be reading
296 * @iovcount - returned count of io vectors we fill
297 * @log - vhost log
298 * @log_num - log offset
299 * @quota - headcount quota, 1 for big buffer
300 * returns number of buffer heads allocated, negative on error
301 */
302static int get_rx_bufs(struct vhost_virtqueue *vq,
303 struct vring_used_elem *heads,
304 int datalen,
305 unsigned *iovcount,
306 struct vhost_log *log,
307 unsigned *log_num,
308 unsigned int quota)
309{
310 unsigned int out, in;
311 int seg = 0;
312 int headcount = 0;
313 unsigned d;
314 int r, nlogs = 0;
315
316 while (datalen > 0 && headcount < quota) {
317 if (unlikely(seg >= UIO_MAXIOV)) {
318 r = -ENOBUFS;
319 goto err;
320 }
321 d = vhost_get_vq_desc(vq->dev, vq, vq->iov + seg,
322 ARRAY_SIZE(vq->iov) - seg, &out,
323 &in, log, log_num);
324 if (d == vq->num) {
325 r = 0;
326 goto err;
327 }
328 if (unlikely(out || in <= 0)) {
329 vq_err(vq, "unexpected descriptor format for RX: "
330 "out %d, in %d\n", out, in);
331 r = -EINVAL;
332 goto err;
333 }
334 if (unlikely(log)) {
335 nlogs += *log_num;
336 log += *log_num;
337 }
338 heads[headcount].id = d;
339 heads[headcount].len = iov_length(vq->iov + seg, in);
340 datalen -= heads[headcount].len;
341 ++headcount;
342 seg += in;
343 }
344 heads[headcount - 1].len += datalen;
345 *iovcount = seg;
346 if (unlikely(log))
347 *log_num = nlogs;
348 return headcount;
349err:
350 vhost_discard_vq_desc(vq, headcount);
351 return r;
352}
353
354/* Expects to be always run from workqueue - which acts as
355 * read-size critical section for our kind of RCU. */
356static void handle_rx(struct vhost_net *net)
357{
358 struct vhost_virtqueue *vq = &net->dev.vqs[VHOST_NET_VQ_RX];
359 unsigned uninitialized_var(in), log;
360 struct vhost_log *vq_log;
361 struct msghdr msg = {
362 .msg_name = NULL,
363 .msg_namelen = 0,
364 .msg_control = NULL, /* FIXME: get and handle RX aux data. */
365 .msg_controllen = 0,
366 .msg_iov = vq->iov,
367 .msg_flags = MSG_DONTWAIT,
368 };
369 struct virtio_net_hdr_mrg_rxbuf hdr = {
370 .hdr.flags = 0,
371 .hdr.gso_type = VIRTIO_NET_HDR_GSO_NONE
372 };
373 size_t total_len = 0;
374 int err, headcount, mergeable;
375 size_t vhost_hlen, sock_hlen;
376 size_t vhost_len, sock_len;
377 /* TODO: check that we are running from vhost_worker? */
378 struct socket *sock = rcu_dereference_check(vq->private_data, 1);
379
380 if (!sock)
381 return;
382
383 mutex_lock(&vq->mutex);
384 vhost_disable_notify(&net->dev, vq);
385 vhost_hlen = vq->vhost_hlen;
386 sock_hlen = vq->sock_hlen;
387
388 vq_log = unlikely(vhost_has_feature(&net->dev, VHOST_F_LOG_ALL)) ?
389 vq->log : NULL;
390 mergeable = vhost_has_feature(&net->dev, VIRTIO_NET_F_MRG_RXBUF);
391
392 while ((sock_len = peek_head_len(sock->sk))) {
393 sock_len += sock_hlen;
394 vhost_len = sock_len + vhost_hlen;
395 headcount = get_rx_bufs(vq, vq->heads, vhost_len,
396 &in, vq_log, &log,
397 likely(mergeable) ? UIO_MAXIOV : 1);
398 /* On error, stop handling until the next kick. */
399 if (unlikely(headcount < 0))
400 break;
401 /* OK, now we need to know about added descriptors. */
402 if (!headcount) {
403 if (unlikely(vhost_enable_notify(&net->dev, vq))) {
404 /* They have slipped one in as we were
405 * doing that: check again. */
406 vhost_disable_notify(&net->dev, vq);
407 continue;
408 }
409 /* Nothing new? Wait for eventfd to tell us
410 * they refilled. */
411 break;
412 }
413 /* We don't need to be notified again. */
414 if (unlikely((vhost_hlen)))
415 /* Skip header. TODO: support TSO. */
416 move_iovec_hdr(vq->iov, vq->hdr, vhost_hlen, in);
417 else
418 /* Copy the header for use in VIRTIO_NET_F_MRG_RXBUF:
419 * needed because recvmsg can modify msg_iov. */
420 copy_iovec_hdr(vq->iov, vq->hdr, sock_hlen, in);
421 msg.msg_iovlen = in;
422 err = sock->ops->recvmsg(NULL, sock, &msg,
423 sock_len, MSG_DONTWAIT | MSG_TRUNC);
424 /* Userspace might have consumed the packet meanwhile:
425 * it's not supposed to do this usually, but might be hard
426 * to prevent. Discard data we got (if any) and keep going. */
427 if (unlikely(err != sock_len)) {
428 pr_debug("Discarded rx packet: "
429 " len %d, expected %zd\n", err, sock_len);
430 vhost_discard_vq_desc(vq, headcount);
431 continue;
432 }
433 if (unlikely(vhost_hlen) &&
434 memcpy_toiovecend(vq->hdr, (unsigned char *)&hdr, 0,
435 vhost_hlen)) {
436 vq_err(vq, "Unable to write vnet_hdr at addr %p\n",
437 vq->iov->iov_base);
438 break;
439 }
440 /* TODO: Should check and handle checksum. */
441 if (likely(mergeable) &&
442 memcpy_toiovecend(vq->hdr, (unsigned char *)&headcount,
443 offsetof(typeof(hdr), num_buffers),
444 sizeof hdr.num_buffers)) {
445 vq_err(vq, "Failed num_buffers write");
446 vhost_discard_vq_desc(vq, headcount);
447 break;
448 }
449 vhost_add_used_and_signal_n(&net->dev, vq, vq->heads,
450 headcount);
451 if (unlikely(vq_log))
452 vhost_log_write(vq, vq_log, log, vhost_len);
453 total_len += vhost_len;
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
463static void handle_tx_kick(struct vhost_work *work)
464{
465 struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
466 poll.work);
467 struct vhost_net *net = container_of(vq->dev, struct vhost_net, dev);
468
469 handle_tx(net);
470}
471
472static void handle_rx_kick(struct vhost_work *work)
473{
474 struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
475 poll.work);
476 struct vhost_net *net = container_of(vq->dev, struct vhost_net, dev);
477
478 handle_rx(net);
479}
480
481static void handle_tx_net(struct vhost_work *work)
482{
483 struct vhost_net *net = container_of(work, struct vhost_net,
484 poll[VHOST_NET_VQ_TX].work);
485 handle_tx(net);
486}
487
488static void handle_rx_net(struct vhost_work *work)
489{
490 struct vhost_net *net = container_of(work, struct vhost_net,
491 poll[VHOST_NET_VQ_RX].work);
492 handle_rx(net);
493}
494
495static int vhost_net_open(struct inode *inode, struct file *f)
496{
497 struct vhost_net *n = kmalloc(sizeof *n, GFP_KERNEL);
498 struct vhost_dev *dev;
499 int r;
500
501 if (!n)
502 return -ENOMEM;
503
504 dev = &n->dev;
505 n->vqs[VHOST_NET_VQ_TX].handle_kick = handle_tx_kick;
506 n->vqs[VHOST_NET_VQ_RX].handle_kick = handle_rx_kick;
507 r = vhost_dev_init(dev, n->vqs, VHOST_NET_VQ_MAX);
508 if (r < 0) {
509 kfree(n);
510 return r;
511 }
512
513 vhost_poll_init(n->poll + VHOST_NET_VQ_TX, handle_tx_net, POLLOUT, dev);
514 vhost_poll_init(n->poll + VHOST_NET_VQ_RX, handle_rx_net, POLLIN, dev);
515 n->tx_poll_state = VHOST_NET_POLL_DISABLED;
516
517 f->private_data = n;
518
519 return 0;
520}
521
522static void vhost_net_disable_vq(struct vhost_net *n,
523 struct vhost_virtqueue *vq)
524{
525 if (!vq->private_data)
526 return;
527 if (vq == n->vqs + VHOST_NET_VQ_TX) {
528 tx_poll_stop(n);
529 n->tx_poll_state = VHOST_NET_POLL_DISABLED;
530 } else
531 vhost_poll_stop(n->poll + VHOST_NET_VQ_RX);
532}
533
534static void vhost_net_enable_vq(struct vhost_net *n,
535 struct vhost_virtqueue *vq)
536{
537 struct socket *sock;
538
539 sock = rcu_dereference_protected(vq->private_data,
540 lockdep_is_held(&vq->mutex));
541 if (!sock)
542 return;
543 if (vq == n->vqs + VHOST_NET_VQ_TX) {
544 n->tx_poll_state = VHOST_NET_POLL_STOPPED;
545 tx_poll_start(n, sock);
546 } else
547 vhost_poll_start(n->poll + VHOST_NET_VQ_RX, sock->file);
548}
549
550static struct socket *vhost_net_stop_vq(struct vhost_net *n,
551 struct vhost_virtqueue *vq)
552{
553 struct socket *sock;
554
555 mutex_lock(&vq->mutex);
556 sock = rcu_dereference_protected(vq->private_data,
557 lockdep_is_held(&vq->mutex));
558 vhost_net_disable_vq(n, vq);
559 rcu_assign_pointer(vq->private_data, NULL);
560 mutex_unlock(&vq->mutex);
561 return sock;
562}
563
564static void vhost_net_stop(struct vhost_net *n, struct socket **tx_sock,
565 struct socket **rx_sock)
566{
567 *tx_sock = vhost_net_stop_vq(n, n->vqs + VHOST_NET_VQ_TX);
568 *rx_sock = vhost_net_stop_vq(n, n->vqs + VHOST_NET_VQ_RX);
569}
570
571static void vhost_net_flush_vq(struct vhost_net *n, int index)
572{
573 vhost_poll_flush(n->poll + index);
574 vhost_poll_flush(&n->dev.vqs[index].poll);
575}
576
577static void vhost_net_flush(struct vhost_net *n)
578{
579 vhost_net_flush_vq(n, VHOST_NET_VQ_TX);
580 vhost_net_flush_vq(n, VHOST_NET_VQ_RX);
581}
582
583static int vhost_net_release(struct inode *inode, struct file *f)
584{
585 struct vhost_net *n = f->private_data;
586 struct socket *tx_sock;
587 struct socket *rx_sock;
588
589 vhost_net_stop(n, &tx_sock, &rx_sock);
590 vhost_net_flush(n);
591 vhost_dev_cleanup(&n->dev);
592 if (tx_sock)
593 fput(tx_sock->file);
594 if (rx_sock)
595 fput(rx_sock->file);
596 /* We do an extra flush before freeing memory,
597 * since jobs can re-queue themselves. */
598 vhost_net_flush(n);
599 kfree(n);
600 return 0;
601}
602
603static struct socket *get_raw_socket(int fd)
604{
605 struct {
606 struct sockaddr_ll sa;
607 char buf[MAX_ADDR_LEN];
608 } uaddr;
609 int uaddr_len = sizeof uaddr, r;
610 struct socket *sock = sockfd_lookup(fd, &r);
611
612 if (!sock)
613 return ERR_PTR(-ENOTSOCK);
614
615 /* Parameter checking */
616 if (sock->sk->sk_type != SOCK_RAW) {
617 r = -ESOCKTNOSUPPORT;
618 goto err;
619 }
620
621 r = sock->ops->getname(sock, (struct sockaddr *)&uaddr.sa,
622 &uaddr_len, 0);
623 if (r)
624 goto err;
625
626 if (uaddr.sa.sll_family != AF_PACKET) {
627 r = -EPFNOSUPPORT;
628 goto err;
629 }
630 return sock;
631err:
632 fput(sock->file);
633 return ERR_PTR(r);
634}
635
636static struct socket *get_tap_socket(int fd)
637{
638 struct file *file = fget(fd);
639 struct socket *sock;
640
641 if (!file)
642 return ERR_PTR(-EBADF);
643 sock = tun_get_socket(file);
644 if (!IS_ERR(sock))
645 return sock;
646 sock = macvtap_get_socket(file);
647 if (IS_ERR(sock))
648 fput(file);
649 return sock;
650}
651
652static struct socket *get_socket(int fd)
653{
654 struct socket *sock;
655
656 /* special case to disable backend */
657 if (fd == -1)
658 return NULL;
659 sock = get_raw_socket(fd);
660 if (!IS_ERR(sock))
661 return sock;
662 sock = get_tap_socket(fd);
663 if (!IS_ERR(sock))
664 return sock;
665 return ERR_PTR(-ENOTSOCK);
666}
667
668static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd)
669{
670 struct socket *sock, *oldsock;
671 struct vhost_virtqueue *vq;
672 struct vhost_ubuf_ref *ubufs, *oldubufs = NULL;
673 int r;
674
675 mutex_lock(&n->dev.mutex);
676 r = vhost_dev_check_owner(&n->dev);
677 if (r)
678 goto err;
679
680 if (index >= VHOST_NET_VQ_MAX) {
681 r = -ENOBUFS;
682 goto err;
683 }
684 vq = n->vqs + index;
685 mutex_lock(&vq->mutex);
686
687 /* Verify that ring has been setup correctly. */
688 if (!vhost_vq_access_ok(vq)) {
689 r = -EFAULT;
690 goto err_vq;
691 }
692 sock = get_socket(fd);
693 if (IS_ERR(sock)) {
694 r = PTR_ERR(sock);
695 goto err_vq;
696 }
697
698 /* start polling new socket */
699 oldsock = rcu_dereference_protected(vq->private_data,
700 lockdep_is_held(&vq->mutex));
701 if (sock != oldsock) {
702 ubufs = vhost_ubuf_alloc(vq, sock && vhost_sock_zcopy(sock));
703 if (IS_ERR(ubufs)) {
704 r = PTR_ERR(ubufs);
705 goto err_ubufs;
706 }
707 oldubufs = vq->ubufs;
708 vq->ubufs = ubufs;
709 vhost_net_disable_vq(n, vq);
710 rcu_assign_pointer(vq->private_data, sock);
711 vhost_net_enable_vq(n, vq);
712
713 r = vhost_init_used(vq);
714 if (r)
715 goto err_vq;
716 }
717
718 mutex_unlock(&vq->mutex);
719
720 if (oldubufs) {
721 vhost_ubuf_put_and_wait(oldubufs);
722 mutex_lock(&vq->mutex);
723 vhost_zerocopy_signal_used(vq);
724 mutex_unlock(&vq->mutex);
725 }
726
727 if (oldsock) {
728 vhost_net_flush_vq(n, index);
729 fput(oldsock->file);
730 }
731
732 mutex_unlock(&n->dev.mutex);
733 return 0;
734
735err_ubufs:
736 fput(sock->file);
737err_vq:
738 mutex_unlock(&vq->mutex);
739err:
740 mutex_unlock(&n->dev.mutex);
741 return r;
742}
743
744static long vhost_net_reset_owner(struct vhost_net *n)
745{
746 struct socket *tx_sock = NULL;
747 struct socket *rx_sock = NULL;
748 long err;
749
750 mutex_lock(&n->dev.mutex);
751 err = vhost_dev_check_owner(&n->dev);
752 if (err)
753 goto done;
754 vhost_net_stop(n, &tx_sock, &rx_sock);
755 vhost_net_flush(n);
756 err = vhost_dev_reset_owner(&n->dev);
757done:
758 mutex_unlock(&n->dev.mutex);
759 if (tx_sock)
760 fput(tx_sock->file);
761 if (rx_sock)
762 fput(rx_sock->file);
763 return err;
764}
765
766static int vhost_net_set_features(struct vhost_net *n, u64 features)
767{
768 size_t vhost_hlen, sock_hlen, hdr_len;
769 int i;
770
771 hdr_len = (features & (1 << VIRTIO_NET_F_MRG_RXBUF)) ?
772 sizeof(struct virtio_net_hdr_mrg_rxbuf) :
773 sizeof(struct virtio_net_hdr);
774 if (features & (1 << VHOST_NET_F_VIRTIO_NET_HDR)) {
775 /* vhost provides vnet_hdr */
776 vhost_hlen = hdr_len;
777 sock_hlen = 0;
778 } else {
779 /* socket provides vnet_hdr */
780 vhost_hlen = 0;
781 sock_hlen = hdr_len;
782 }
783 mutex_lock(&n->dev.mutex);
784 if ((features & (1 << VHOST_F_LOG_ALL)) &&
785 !vhost_log_access_ok(&n->dev)) {
786 mutex_unlock(&n->dev.mutex);
787 return -EFAULT;
788 }
789 n->dev.acked_features = features;
790 smp_wmb();
791 for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
792 mutex_lock(&n->vqs[i].mutex);
793 n->vqs[i].vhost_hlen = vhost_hlen;
794 n->vqs[i].sock_hlen = sock_hlen;
795 mutex_unlock(&n->vqs[i].mutex);
796 }
797 vhost_net_flush(n);
798 mutex_unlock(&n->dev.mutex);
799 return 0;
800}
801
802static long vhost_net_ioctl(struct file *f, unsigned int ioctl,
803 unsigned long arg)
804{
805 struct vhost_net *n = f->private_data;
806 void __user *argp = (void __user *)arg;
807 u64 __user *featurep = argp;
808 struct vhost_vring_file backend;
809 u64 features;
810 int r;
811
812 switch (ioctl) {
813 case VHOST_NET_SET_BACKEND:
814 if (copy_from_user(&backend, argp, sizeof backend))
815 return -EFAULT;
816 return vhost_net_set_backend(n, backend.index, backend.fd);
817 case VHOST_GET_FEATURES:
818 features = VHOST_FEATURES;
819 if (copy_to_user(featurep, &features, sizeof features))
820 return -EFAULT;
821 return 0;
822 case VHOST_SET_FEATURES:
823 if (copy_from_user(&features, featurep, sizeof features))
824 return -EFAULT;
825 if (features & ~VHOST_FEATURES)
826 return -EOPNOTSUPP;
827 return vhost_net_set_features(n, features);
828 case VHOST_RESET_OWNER:
829 return vhost_net_reset_owner(n);
830 default:
831 mutex_lock(&n->dev.mutex);
832 r = vhost_dev_ioctl(&n->dev, ioctl, arg);
833 vhost_net_flush(n);
834 mutex_unlock(&n->dev.mutex);
835 return r;
836 }
837}
838
839#ifdef CONFIG_COMPAT
840static long vhost_net_compat_ioctl(struct file *f, unsigned int ioctl,
841 unsigned long arg)
842{
843 return vhost_net_ioctl(f, ioctl, (unsigned long)compat_ptr(arg));
844}
845#endif
846
847static const struct file_operations vhost_net_fops = {
848 .owner = THIS_MODULE,
849 .release = vhost_net_release,
850 .unlocked_ioctl = vhost_net_ioctl,
851#ifdef CONFIG_COMPAT
852 .compat_ioctl = vhost_net_compat_ioctl,
853#endif
854 .open = vhost_net_open,
855 .llseek = noop_llseek,
856};
857
858static struct miscdevice vhost_net_misc = {
859 MISC_DYNAMIC_MINOR,
860 "vhost-net",
861 &vhost_net_fops,
862};
863
864static int vhost_net_init(void)
865{
866 if (experimental_zcopytx)
867 vhost_enable_zcopy(VHOST_NET_VQ_TX);
868 return misc_register(&vhost_net_misc);
869}
870module_init(vhost_net_init);
871
872static void vhost_net_exit(void)
873{
874 misc_deregister(&vhost_net_misc);
875}
876module_exit(vhost_net_exit);
877
878MODULE_VERSION("0.0.1");
879MODULE_LICENSE("GPL v2");
880MODULE_AUTHOR("Michael S. Tsirkin");
881MODULE_DESCRIPTION("Host kernel accelerator for virtio net");
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/file.h>
19#include <linux/slab.h>
20#include <linux/vmalloc.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
33static int experimental_zcopytx = 1;
34module_param(experimental_zcopytx, int, 0444);
35MODULE_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 ((__force __virtio32)3)
52/* Lower device DMA done */
53#define VHOST_DMA_DONE_LEN ((__force __virtio32)2)
54/* Lower device DMA in progress */
55#define VHOST_DMA_IN_PROGRESS ((__force __virtio32)1)
56/* Buffer unused */
57#define VHOST_DMA_CLEAR_LEN ((__force __virtio32)0)
58
59#define VHOST_DMA_IS_DONE(len) ((__force u32)(len) >= (__force u32)VHOST_DMA_DONE_LEN)
60
61enum {
62 VHOST_NET_FEATURES = VHOST_FEATURES |
63 (1ULL << VHOST_NET_F_VIRTIO_NET_HDR) |
64 (1ULL << VIRTIO_NET_F_MRG_RXBUF)
65};
66
67enum {
68 VHOST_NET_VQ_RX = 0,
69 VHOST_NET_VQ_TX = 1,
70 VHOST_NET_VQ_MAX = 2,
71};
72
73struct vhost_net_ubuf_ref {
74 /* refcount follows semantics similar to kref:
75 * 0: object is released
76 * 1: no outstanding ubufs
77 * >1: outstanding ubufs
78 */
79 atomic_t refcount;
80 wait_queue_head_t wait;
81 struct vhost_virtqueue *vq;
82};
83
84struct vhost_net_virtqueue {
85 struct vhost_virtqueue vq;
86 size_t vhost_hlen;
87 size_t sock_hlen;
88 /* vhost zerocopy support fields below: */
89 /* last used idx for outstanding DMA zerocopy buffers */
90 int upend_idx;
91 /* first used idx for DMA done zerocopy buffers */
92 int done_idx;
93 /* an array of userspace buffers info */
94 struct ubuf_info *ubuf_info;
95 /* Reference counting for outstanding ubufs.
96 * Protected by vq mutex. Writers must also take device mutex. */
97 struct vhost_net_ubuf_ref *ubufs;
98};
99
100struct vhost_net {
101 struct vhost_dev dev;
102 struct vhost_net_virtqueue vqs[VHOST_NET_VQ_MAX];
103 struct vhost_poll poll[VHOST_NET_VQ_MAX];
104 /* Number of TX recently submitted.
105 * Protected by tx vq lock. */
106 unsigned tx_packets;
107 /* Number of times zerocopy TX recently failed.
108 * Protected by tx vq lock. */
109 unsigned tx_zcopy_err;
110 /* Flush in progress. Protected by tx vq lock. */
111 bool tx_flush;
112};
113
114static unsigned vhost_net_zcopy_mask __read_mostly;
115
116static void vhost_net_enable_zcopy(int vq)
117{
118 vhost_net_zcopy_mask |= 0x1 << vq;
119}
120
121static struct vhost_net_ubuf_ref *
122vhost_net_ubuf_alloc(struct vhost_virtqueue *vq, bool zcopy)
123{
124 struct vhost_net_ubuf_ref *ubufs;
125 /* No zero copy backend? Nothing to count. */
126 if (!zcopy)
127 return NULL;
128 ubufs = kmalloc(sizeof(*ubufs), GFP_KERNEL);
129 if (!ubufs)
130 return ERR_PTR(-ENOMEM);
131 atomic_set(&ubufs->refcount, 1);
132 init_waitqueue_head(&ubufs->wait);
133 ubufs->vq = vq;
134 return ubufs;
135}
136
137static int vhost_net_ubuf_put(struct vhost_net_ubuf_ref *ubufs)
138{
139 int r = atomic_sub_return(1, &ubufs->refcount);
140 if (unlikely(!r))
141 wake_up(&ubufs->wait);
142 return r;
143}
144
145static void vhost_net_ubuf_put_and_wait(struct vhost_net_ubuf_ref *ubufs)
146{
147 vhost_net_ubuf_put(ubufs);
148 wait_event(ubufs->wait, !atomic_read(&ubufs->refcount));
149}
150
151static void vhost_net_ubuf_put_wait_and_free(struct vhost_net_ubuf_ref *ubufs)
152{
153 vhost_net_ubuf_put_and_wait(ubufs);
154 kfree(ubufs);
155}
156
157static void vhost_net_clear_ubuf_info(struct vhost_net *n)
158{
159 int i;
160
161 for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
162 kfree(n->vqs[i].ubuf_info);
163 n->vqs[i].ubuf_info = NULL;
164 }
165}
166
167static int vhost_net_set_ubuf_info(struct vhost_net *n)
168{
169 bool zcopy;
170 int i;
171
172 for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
173 zcopy = vhost_net_zcopy_mask & (0x1 << i);
174 if (!zcopy)
175 continue;
176 n->vqs[i].ubuf_info = kmalloc(sizeof(*n->vqs[i].ubuf_info) *
177 UIO_MAXIOV, GFP_KERNEL);
178 if (!n->vqs[i].ubuf_info)
179 goto err;
180 }
181 return 0;
182
183err:
184 vhost_net_clear_ubuf_info(n);
185 return -ENOMEM;
186}
187
188static void vhost_net_vq_reset(struct vhost_net *n)
189{
190 int i;
191
192 vhost_net_clear_ubuf_info(n);
193
194 for (i = 0; i < VHOST_NET_VQ_MAX; i++) {
195 n->vqs[i].done_idx = 0;
196 n->vqs[i].upend_idx = 0;
197 n->vqs[i].ubufs = NULL;
198 n->vqs[i].vhost_hlen = 0;
199 n->vqs[i].sock_hlen = 0;
200 }
201
202}
203
204static void vhost_net_tx_packet(struct vhost_net *net)
205{
206 ++net->tx_packets;
207 if (net->tx_packets < 1024)
208 return;
209 net->tx_packets = 0;
210 net->tx_zcopy_err = 0;
211}
212
213static void vhost_net_tx_err(struct vhost_net *net)
214{
215 ++net->tx_zcopy_err;
216}
217
218static bool vhost_net_tx_select_zcopy(struct vhost_net *net)
219{
220 /* TX flush waits for outstanding DMAs to be done.
221 * Don't start new DMAs.
222 */
223 return !net->tx_flush &&
224 net->tx_packets / 64 >= net->tx_zcopy_err;
225}
226
227static bool vhost_sock_zcopy(struct socket *sock)
228{
229 return unlikely(experimental_zcopytx) &&
230 sock_flag(sock->sk, SOCK_ZEROCOPY);
231}
232
233/* In case of DMA done not in order in lower device driver for some reason.
234 * upend_idx is used to track end of used idx, done_idx is used to track head
235 * of used idx. Once lower device DMA done contiguously, we will signal KVM
236 * guest used idx.
237 */
238static void vhost_zerocopy_signal_used(struct vhost_net *net,
239 struct vhost_virtqueue *vq)
240{
241 struct vhost_net_virtqueue *nvq =
242 container_of(vq, struct vhost_net_virtqueue, vq);
243 int i, add;
244 int j = 0;
245
246 for (i = nvq->done_idx; i != nvq->upend_idx; i = (i + 1) % UIO_MAXIOV) {
247 if (vq->heads[i].len == VHOST_DMA_FAILED_LEN)
248 vhost_net_tx_err(net);
249 if (VHOST_DMA_IS_DONE(vq->heads[i].len)) {
250 vq->heads[i].len = VHOST_DMA_CLEAR_LEN;
251 ++j;
252 } else
253 break;
254 }
255 while (j) {
256 add = min(UIO_MAXIOV - nvq->done_idx, j);
257 vhost_add_used_and_signal_n(vq->dev, vq,
258 &vq->heads[nvq->done_idx], add);
259 nvq->done_idx = (nvq->done_idx + add) % UIO_MAXIOV;
260 j -= add;
261 }
262}
263
264static void vhost_zerocopy_callback(struct ubuf_info *ubuf, bool success)
265{
266 struct vhost_net_ubuf_ref *ubufs = ubuf->ctx;
267 struct vhost_virtqueue *vq = ubufs->vq;
268 int cnt;
269
270 rcu_read_lock_bh();
271
272 /* set len to mark this desc buffers done DMA */
273 vq->heads[ubuf->desc].len = success ?
274 VHOST_DMA_DONE_LEN : VHOST_DMA_FAILED_LEN;
275 cnt = vhost_net_ubuf_put(ubufs);
276
277 /*
278 * Trigger polling thread if guest stopped submitting new buffers:
279 * in this case, the refcount after decrement will eventually reach 1.
280 * We also trigger polling periodically after each 16 packets
281 * (the value 16 here is more or less arbitrary, it's tuned to trigger
282 * less than 10% of times).
283 */
284 if (cnt <= 1 || !(cnt % 16))
285 vhost_poll_queue(&vq->poll);
286
287 rcu_read_unlock_bh();
288}
289
290static inline unsigned long busy_clock(void)
291{
292 return local_clock() >> 10;
293}
294
295static bool vhost_can_busy_poll(struct vhost_dev *dev,
296 unsigned long endtime)
297{
298 return likely(!need_resched()) &&
299 likely(!time_after(busy_clock(), endtime)) &&
300 likely(!signal_pending(current)) &&
301 !vhost_has_work(dev);
302}
303
304static int vhost_net_tx_get_vq_desc(struct vhost_net *net,
305 struct vhost_virtqueue *vq,
306 struct iovec iov[], unsigned int iov_size,
307 unsigned int *out_num, unsigned int *in_num)
308{
309 unsigned long uninitialized_var(endtime);
310 int r = vhost_get_vq_desc(vq, vq->iov, ARRAY_SIZE(vq->iov),
311 out_num, in_num, NULL, NULL);
312
313 if (r == vq->num && vq->busyloop_timeout) {
314 preempt_disable();
315 endtime = busy_clock() + vq->busyloop_timeout;
316 while (vhost_can_busy_poll(vq->dev, endtime) &&
317 vhost_vq_avail_empty(vq->dev, vq))
318 cpu_relax_lowlatency();
319 preempt_enable();
320 r = vhost_get_vq_desc(vq, vq->iov, ARRAY_SIZE(vq->iov),
321 out_num, in_num, NULL, NULL);
322 }
323
324 return r;
325}
326
327/* Expects to be always run from workqueue - which acts as
328 * read-size critical section for our kind of RCU. */
329static void handle_tx(struct vhost_net *net)
330{
331 struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_TX];
332 struct vhost_virtqueue *vq = &nvq->vq;
333 unsigned out, in;
334 int head;
335 struct msghdr msg = {
336 .msg_name = NULL,
337 .msg_namelen = 0,
338 .msg_control = NULL,
339 .msg_controllen = 0,
340 .msg_flags = MSG_DONTWAIT,
341 };
342 size_t len, total_len = 0;
343 int err;
344 size_t hdr_size;
345 struct socket *sock;
346 struct vhost_net_ubuf_ref *uninitialized_var(ubufs);
347 bool zcopy, zcopy_used;
348
349 mutex_lock(&vq->mutex);
350 sock = vq->private_data;
351 if (!sock)
352 goto out;
353
354 vhost_disable_notify(&net->dev, vq);
355
356 hdr_size = nvq->vhost_hlen;
357 zcopy = nvq->ubufs;
358
359 for (;;) {
360 /* Release DMAs done buffers first */
361 if (zcopy)
362 vhost_zerocopy_signal_used(net, vq);
363
364 /* If more outstanding DMAs, queue the work.
365 * Handle upend_idx wrap around
366 */
367 if (unlikely((nvq->upend_idx + vq->num - VHOST_MAX_PEND)
368 % UIO_MAXIOV == nvq->done_idx))
369 break;
370
371 head = vhost_net_tx_get_vq_desc(net, vq, vq->iov,
372 ARRAY_SIZE(vq->iov),
373 &out, &in);
374 /* On error, stop handling until the next kick. */
375 if (unlikely(head < 0))
376 break;
377 /* Nothing new? Wait for eventfd to tell us they refilled. */
378 if (head == vq->num) {
379 if (unlikely(vhost_enable_notify(&net->dev, vq))) {
380 vhost_disable_notify(&net->dev, vq);
381 continue;
382 }
383 break;
384 }
385 if (in) {
386 vq_err(vq, "Unexpected descriptor format for TX: "
387 "out %d, int %d\n", out, in);
388 break;
389 }
390 /* Skip header. TODO: support TSO. */
391 len = iov_length(vq->iov, out);
392 iov_iter_init(&msg.msg_iter, WRITE, vq->iov, out, len);
393 iov_iter_advance(&msg.msg_iter, hdr_size);
394 /* Sanity check */
395 if (!msg_data_left(&msg)) {
396 vq_err(vq, "Unexpected header len for TX: "
397 "%zd expected %zd\n",
398 len, hdr_size);
399 break;
400 }
401 len = msg_data_left(&msg);
402
403 zcopy_used = zcopy && len >= VHOST_GOODCOPY_LEN
404 && (nvq->upend_idx + 1) % UIO_MAXIOV !=
405 nvq->done_idx
406 && vhost_net_tx_select_zcopy(net);
407
408 /* use msg_control to pass vhost zerocopy ubuf info to skb */
409 if (zcopy_used) {
410 struct ubuf_info *ubuf;
411 ubuf = nvq->ubuf_info + nvq->upend_idx;
412
413 vq->heads[nvq->upend_idx].id = cpu_to_vhost32(vq, head);
414 vq->heads[nvq->upend_idx].len = VHOST_DMA_IN_PROGRESS;
415 ubuf->callback = vhost_zerocopy_callback;
416 ubuf->ctx = nvq->ubufs;
417 ubuf->desc = nvq->upend_idx;
418 msg.msg_control = ubuf;
419 msg.msg_controllen = sizeof(ubuf);
420 ubufs = nvq->ubufs;
421 atomic_inc(&ubufs->refcount);
422 nvq->upend_idx = (nvq->upend_idx + 1) % UIO_MAXIOV;
423 } else {
424 msg.msg_control = NULL;
425 ubufs = NULL;
426 }
427 /* TODO: Check specific error and bomb out unless ENOBUFS? */
428 err = sock->ops->sendmsg(sock, &msg, len);
429 if (unlikely(err < 0)) {
430 if (zcopy_used) {
431 vhost_net_ubuf_put(ubufs);
432 nvq->upend_idx = ((unsigned)nvq->upend_idx - 1)
433 % UIO_MAXIOV;
434 }
435 vhost_discard_vq_desc(vq, 1);
436 break;
437 }
438 if (err != len)
439 pr_debug("Truncated TX packet: "
440 " len %d != %zd\n", err, len);
441 if (!zcopy_used)
442 vhost_add_used_and_signal(&net->dev, vq, head, 0);
443 else
444 vhost_zerocopy_signal_used(net, vq);
445 total_len += len;
446 vhost_net_tx_packet(net);
447 if (unlikely(total_len >= VHOST_NET_WEIGHT)) {
448 vhost_poll_queue(&vq->poll);
449 break;
450 }
451 }
452out:
453 mutex_unlock(&vq->mutex);
454}
455
456static int peek_head_len(struct sock *sk)
457{
458 struct sk_buff *head;
459 int len = 0;
460 unsigned long flags;
461
462 spin_lock_irqsave(&sk->sk_receive_queue.lock, flags);
463 head = skb_peek(&sk->sk_receive_queue);
464 if (likely(head)) {
465 len = head->len;
466 if (skb_vlan_tag_present(head))
467 len += VLAN_HLEN;
468 }
469
470 spin_unlock_irqrestore(&sk->sk_receive_queue.lock, flags);
471 return len;
472}
473
474static int vhost_net_rx_peek_head_len(struct vhost_net *net, struct sock *sk)
475{
476 struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_TX];
477 struct vhost_virtqueue *vq = &nvq->vq;
478 unsigned long uninitialized_var(endtime);
479 int len = peek_head_len(sk);
480
481 if (!len && vq->busyloop_timeout) {
482 /* Both tx vq and rx socket were polled here */
483 mutex_lock(&vq->mutex);
484 vhost_disable_notify(&net->dev, vq);
485
486 preempt_disable();
487 endtime = busy_clock() + vq->busyloop_timeout;
488
489 while (vhost_can_busy_poll(&net->dev, endtime) &&
490 skb_queue_empty(&sk->sk_receive_queue) &&
491 vhost_vq_avail_empty(&net->dev, vq))
492 cpu_relax_lowlatency();
493
494 preempt_enable();
495
496 if (vhost_enable_notify(&net->dev, vq))
497 vhost_poll_queue(&vq->poll);
498 mutex_unlock(&vq->mutex);
499
500 len = peek_head_len(sk);
501 }
502
503 return len;
504}
505
506/* This is a multi-buffer version of vhost_get_desc, that works if
507 * vq has read descriptors only.
508 * @vq - the relevant virtqueue
509 * @datalen - data length we'll be reading
510 * @iovcount - returned count of io vectors we fill
511 * @log - vhost log
512 * @log_num - log offset
513 * @quota - headcount quota, 1 for big buffer
514 * returns number of buffer heads allocated, negative on error
515 */
516static int get_rx_bufs(struct vhost_virtqueue *vq,
517 struct vring_used_elem *heads,
518 int datalen,
519 unsigned *iovcount,
520 struct vhost_log *log,
521 unsigned *log_num,
522 unsigned int quota)
523{
524 unsigned int out, in;
525 int seg = 0;
526 int headcount = 0;
527 unsigned d;
528 int r, nlogs = 0;
529 /* len is always initialized before use since we are always called with
530 * datalen > 0.
531 */
532 u32 uninitialized_var(len);
533
534 while (datalen > 0 && headcount < quota) {
535 if (unlikely(seg >= UIO_MAXIOV)) {
536 r = -ENOBUFS;
537 goto err;
538 }
539 r = vhost_get_vq_desc(vq, vq->iov + seg,
540 ARRAY_SIZE(vq->iov) - seg, &out,
541 &in, log, log_num);
542 if (unlikely(r < 0))
543 goto err;
544
545 d = r;
546 if (d == vq->num) {
547 r = 0;
548 goto err;
549 }
550 if (unlikely(out || in <= 0)) {
551 vq_err(vq, "unexpected descriptor format for RX: "
552 "out %d, in %d\n", out, in);
553 r = -EINVAL;
554 goto err;
555 }
556 if (unlikely(log)) {
557 nlogs += *log_num;
558 log += *log_num;
559 }
560 heads[headcount].id = cpu_to_vhost32(vq, d);
561 len = iov_length(vq->iov + seg, in);
562 heads[headcount].len = cpu_to_vhost32(vq, len);
563 datalen -= len;
564 ++headcount;
565 seg += in;
566 }
567 heads[headcount - 1].len = cpu_to_vhost32(vq, len + datalen);
568 *iovcount = seg;
569 if (unlikely(log))
570 *log_num = nlogs;
571
572 /* Detect overrun */
573 if (unlikely(datalen > 0)) {
574 r = UIO_MAXIOV + 1;
575 goto err;
576 }
577 return headcount;
578err:
579 vhost_discard_vq_desc(vq, headcount);
580 return r;
581}
582
583/* Expects to be always run from workqueue - which acts as
584 * read-size critical section for our kind of RCU. */
585static void handle_rx(struct vhost_net *net)
586{
587 struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_RX];
588 struct vhost_virtqueue *vq = &nvq->vq;
589 unsigned uninitialized_var(in), log;
590 struct vhost_log *vq_log;
591 struct msghdr msg = {
592 .msg_name = NULL,
593 .msg_namelen = 0,
594 .msg_control = NULL, /* FIXME: get and handle RX aux data. */
595 .msg_controllen = 0,
596 .msg_flags = MSG_DONTWAIT,
597 };
598 struct virtio_net_hdr hdr = {
599 .flags = 0,
600 .gso_type = VIRTIO_NET_HDR_GSO_NONE
601 };
602 size_t total_len = 0;
603 int err, mergeable;
604 s16 headcount;
605 size_t vhost_hlen, sock_hlen;
606 size_t vhost_len, sock_len;
607 struct socket *sock;
608 struct iov_iter fixup;
609 __virtio16 num_buffers;
610
611 mutex_lock(&vq->mutex);
612 sock = vq->private_data;
613 if (!sock)
614 goto out;
615 vhost_disable_notify(&net->dev, vq);
616
617 vhost_hlen = nvq->vhost_hlen;
618 sock_hlen = nvq->sock_hlen;
619
620 vq_log = unlikely(vhost_has_feature(vq, VHOST_F_LOG_ALL)) ?
621 vq->log : NULL;
622 mergeable = vhost_has_feature(vq, VIRTIO_NET_F_MRG_RXBUF);
623
624 while ((sock_len = vhost_net_rx_peek_head_len(net, sock->sk))) {
625 sock_len += sock_hlen;
626 vhost_len = sock_len + vhost_hlen;
627 headcount = get_rx_bufs(vq, vq->heads, vhost_len,
628 &in, vq_log, &log,
629 likely(mergeable) ? UIO_MAXIOV : 1);
630 /* On error, stop handling until the next kick. */
631 if (unlikely(headcount < 0))
632 break;
633 /* On overrun, truncate and discard */
634 if (unlikely(headcount > UIO_MAXIOV)) {
635 iov_iter_init(&msg.msg_iter, READ, vq->iov, 1, 1);
636 err = sock->ops->recvmsg(sock, &msg,
637 1, MSG_DONTWAIT | MSG_TRUNC);
638 pr_debug("Discarded rx packet: len %zd\n", sock_len);
639 continue;
640 }
641 /* OK, now we need to know about added descriptors. */
642 if (!headcount) {
643 if (unlikely(vhost_enable_notify(&net->dev, vq))) {
644 /* They have slipped one in as we were
645 * doing that: check again. */
646 vhost_disable_notify(&net->dev, vq);
647 continue;
648 }
649 /* Nothing new? Wait for eventfd to tell us
650 * they refilled. */
651 break;
652 }
653 /* We don't need to be notified again. */
654 iov_iter_init(&msg.msg_iter, READ, vq->iov, in, vhost_len);
655 fixup = msg.msg_iter;
656 if (unlikely((vhost_hlen))) {
657 /* We will supply the header ourselves
658 * TODO: support TSO.
659 */
660 iov_iter_advance(&msg.msg_iter, vhost_hlen);
661 }
662 err = sock->ops->recvmsg(sock, &msg,
663 sock_len, MSG_DONTWAIT | MSG_TRUNC);
664 /* Userspace might have consumed the packet meanwhile:
665 * it's not supposed to do this usually, but might be hard
666 * to prevent. Discard data we got (if any) and keep going. */
667 if (unlikely(err != sock_len)) {
668 pr_debug("Discarded rx packet: "
669 " len %d, expected %zd\n", err, sock_len);
670 vhost_discard_vq_desc(vq, headcount);
671 continue;
672 }
673 /* Supply virtio_net_hdr if VHOST_NET_F_VIRTIO_NET_HDR */
674 if (unlikely(vhost_hlen)) {
675 if (copy_to_iter(&hdr, sizeof(hdr),
676 &fixup) != sizeof(hdr)) {
677 vq_err(vq, "Unable to write vnet_hdr "
678 "at addr %p\n", vq->iov->iov_base);
679 break;
680 }
681 } else {
682 /* Header came from socket; we'll need to patch
683 * ->num_buffers over if VIRTIO_NET_F_MRG_RXBUF
684 */
685 iov_iter_advance(&fixup, sizeof(hdr));
686 }
687 /* TODO: Should check and handle checksum. */
688
689 num_buffers = cpu_to_vhost16(vq, headcount);
690 if (likely(mergeable) &&
691 copy_to_iter(&num_buffers, sizeof num_buffers,
692 &fixup) != sizeof num_buffers) {
693 vq_err(vq, "Failed num_buffers write");
694 vhost_discard_vq_desc(vq, headcount);
695 break;
696 }
697 vhost_add_used_and_signal_n(&net->dev, vq, vq->heads,
698 headcount);
699 if (unlikely(vq_log))
700 vhost_log_write(vq, vq_log, log, vhost_len);
701 total_len += vhost_len;
702 if (unlikely(total_len >= VHOST_NET_WEIGHT)) {
703 vhost_poll_queue(&vq->poll);
704 break;
705 }
706 }
707out:
708 mutex_unlock(&vq->mutex);
709}
710
711static void handle_tx_kick(struct vhost_work *work)
712{
713 struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
714 poll.work);
715 struct vhost_net *net = container_of(vq->dev, struct vhost_net, dev);
716
717 handle_tx(net);
718}
719
720static void handle_rx_kick(struct vhost_work *work)
721{
722 struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
723 poll.work);
724 struct vhost_net *net = container_of(vq->dev, struct vhost_net, dev);
725
726 handle_rx(net);
727}
728
729static void handle_tx_net(struct vhost_work *work)
730{
731 struct vhost_net *net = container_of(work, struct vhost_net,
732 poll[VHOST_NET_VQ_TX].work);
733 handle_tx(net);
734}
735
736static void handle_rx_net(struct vhost_work *work)
737{
738 struct vhost_net *net = container_of(work, struct vhost_net,
739 poll[VHOST_NET_VQ_RX].work);
740 handle_rx(net);
741}
742
743static int vhost_net_open(struct inode *inode, struct file *f)
744{
745 struct vhost_net *n;
746 struct vhost_dev *dev;
747 struct vhost_virtqueue **vqs;
748 int i;
749
750 n = kmalloc(sizeof *n, GFP_KERNEL | __GFP_NOWARN | __GFP_REPEAT);
751 if (!n) {
752 n = vmalloc(sizeof *n);
753 if (!n)
754 return -ENOMEM;
755 }
756 vqs = kmalloc(VHOST_NET_VQ_MAX * sizeof(*vqs), GFP_KERNEL);
757 if (!vqs) {
758 kvfree(n);
759 return -ENOMEM;
760 }
761
762 dev = &n->dev;
763 vqs[VHOST_NET_VQ_TX] = &n->vqs[VHOST_NET_VQ_TX].vq;
764 vqs[VHOST_NET_VQ_RX] = &n->vqs[VHOST_NET_VQ_RX].vq;
765 n->vqs[VHOST_NET_VQ_TX].vq.handle_kick = handle_tx_kick;
766 n->vqs[VHOST_NET_VQ_RX].vq.handle_kick = handle_rx_kick;
767 for (i = 0; i < VHOST_NET_VQ_MAX; i++) {
768 n->vqs[i].ubufs = NULL;
769 n->vqs[i].ubuf_info = NULL;
770 n->vqs[i].upend_idx = 0;
771 n->vqs[i].done_idx = 0;
772 n->vqs[i].vhost_hlen = 0;
773 n->vqs[i].sock_hlen = 0;
774 }
775 vhost_dev_init(dev, vqs, VHOST_NET_VQ_MAX);
776
777 vhost_poll_init(n->poll + VHOST_NET_VQ_TX, handle_tx_net, POLLOUT, dev);
778 vhost_poll_init(n->poll + VHOST_NET_VQ_RX, handle_rx_net, POLLIN, dev);
779
780 f->private_data = n;
781
782 return 0;
783}
784
785static void vhost_net_disable_vq(struct vhost_net *n,
786 struct vhost_virtqueue *vq)
787{
788 struct vhost_net_virtqueue *nvq =
789 container_of(vq, struct vhost_net_virtqueue, vq);
790 struct vhost_poll *poll = n->poll + (nvq - n->vqs);
791 if (!vq->private_data)
792 return;
793 vhost_poll_stop(poll);
794}
795
796static int vhost_net_enable_vq(struct vhost_net *n,
797 struct vhost_virtqueue *vq)
798{
799 struct vhost_net_virtqueue *nvq =
800 container_of(vq, struct vhost_net_virtqueue, vq);
801 struct vhost_poll *poll = n->poll + (nvq - n->vqs);
802 struct socket *sock;
803
804 sock = vq->private_data;
805 if (!sock)
806 return 0;
807
808 return vhost_poll_start(poll, sock->file);
809}
810
811static struct socket *vhost_net_stop_vq(struct vhost_net *n,
812 struct vhost_virtqueue *vq)
813{
814 struct socket *sock;
815
816 mutex_lock(&vq->mutex);
817 sock = vq->private_data;
818 vhost_net_disable_vq(n, vq);
819 vq->private_data = NULL;
820 mutex_unlock(&vq->mutex);
821 return sock;
822}
823
824static void vhost_net_stop(struct vhost_net *n, struct socket **tx_sock,
825 struct socket **rx_sock)
826{
827 *tx_sock = vhost_net_stop_vq(n, &n->vqs[VHOST_NET_VQ_TX].vq);
828 *rx_sock = vhost_net_stop_vq(n, &n->vqs[VHOST_NET_VQ_RX].vq);
829}
830
831static void vhost_net_flush_vq(struct vhost_net *n, int index)
832{
833 vhost_poll_flush(n->poll + index);
834 vhost_poll_flush(&n->vqs[index].vq.poll);
835}
836
837static void vhost_net_flush(struct vhost_net *n)
838{
839 vhost_net_flush_vq(n, VHOST_NET_VQ_TX);
840 vhost_net_flush_vq(n, VHOST_NET_VQ_RX);
841 if (n->vqs[VHOST_NET_VQ_TX].ubufs) {
842 mutex_lock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
843 n->tx_flush = true;
844 mutex_unlock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
845 /* Wait for all lower device DMAs done. */
846 vhost_net_ubuf_put_and_wait(n->vqs[VHOST_NET_VQ_TX].ubufs);
847 mutex_lock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
848 n->tx_flush = false;
849 atomic_set(&n->vqs[VHOST_NET_VQ_TX].ubufs->refcount, 1);
850 mutex_unlock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
851 }
852}
853
854static int vhost_net_release(struct inode *inode, struct file *f)
855{
856 struct vhost_net *n = f->private_data;
857 struct socket *tx_sock;
858 struct socket *rx_sock;
859
860 vhost_net_stop(n, &tx_sock, &rx_sock);
861 vhost_net_flush(n);
862 vhost_dev_stop(&n->dev);
863 vhost_dev_cleanup(&n->dev, false);
864 vhost_net_vq_reset(n);
865 if (tx_sock)
866 sockfd_put(tx_sock);
867 if (rx_sock)
868 sockfd_put(rx_sock);
869 /* Make sure no callbacks are outstanding */
870 synchronize_rcu_bh();
871 /* We do an extra flush before freeing memory,
872 * since jobs can re-queue themselves. */
873 vhost_net_flush(n);
874 kfree(n->dev.vqs);
875 kvfree(n);
876 return 0;
877}
878
879static struct socket *get_raw_socket(int fd)
880{
881 struct {
882 struct sockaddr_ll sa;
883 char buf[MAX_ADDR_LEN];
884 } uaddr;
885 int uaddr_len = sizeof uaddr, r;
886 struct socket *sock = sockfd_lookup(fd, &r);
887
888 if (!sock)
889 return ERR_PTR(-ENOTSOCK);
890
891 /* Parameter checking */
892 if (sock->sk->sk_type != SOCK_RAW) {
893 r = -ESOCKTNOSUPPORT;
894 goto err;
895 }
896
897 r = sock->ops->getname(sock, (struct sockaddr *)&uaddr.sa,
898 &uaddr_len, 0);
899 if (r)
900 goto err;
901
902 if (uaddr.sa.sll_family != AF_PACKET) {
903 r = -EPFNOSUPPORT;
904 goto err;
905 }
906 return sock;
907err:
908 sockfd_put(sock);
909 return ERR_PTR(r);
910}
911
912static struct socket *get_tap_socket(int fd)
913{
914 struct file *file = fget(fd);
915 struct socket *sock;
916
917 if (!file)
918 return ERR_PTR(-EBADF);
919 sock = tun_get_socket(file);
920 if (!IS_ERR(sock))
921 return sock;
922 sock = macvtap_get_socket(file);
923 if (IS_ERR(sock))
924 fput(file);
925 return sock;
926}
927
928static struct socket *get_socket(int fd)
929{
930 struct socket *sock;
931
932 /* special case to disable backend */
933 if (fd == -1)
934 return NULL;
935 sock = get_raw_socket(fd);
936 if (!IS_ERR(sock))
937 return sock;
938 sock = get_tap_socket(fd);
939 if (!IS_ERR(sock))
940 return sock;
941 return ERR_PTR(-ENOTSOCK);
942}
943
944static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd)
945{
946 struct socket *sock, *oldsock;
947 struct vhost_virtqueue *vq;
948 struct vhost_net_virtqueue *nvq;
949 struct vhost_net_ubuf_ref *ubufs, *oldubufs = NULL;
950 int r;
951
952 mutex_lock(&n->dev.mutex);
953 r = vhost_dev_check_owner(&n->dev);
954 if (r)
955 goto err;
956
957 if (index >= VHOST_NET_VQ_MAX) {
958 r = -ENOBUFS;
959 goto err;
960 }
961 vq = &n->vqs[index].vq;
962 nvq = &n->vqs[index];
963 mutex_lock(&vq->mutex);
964
965 /* Verify that ring has been setup correctly. */
966 if (!vhost_vq_access_ok(vq)) {
967 r = -EFAULT;
968 goto err_vq;
969 }
970 sock = get_socket(fd);
971 if (IS_ERR(sock)) {
972 r = PTR_ERR(sock);
973 goto err_vq;
974 }
975
976 /* start polling new socket */
977 oldsock = vq->private_data;
978 if (sock != oldsock) {
979 ubufs = vhost_net_ubuf_alloc(vq,
980 sock && vhost_sock_zcopy(sock));
981 if (IS_ERR(ubufs)) {
982 r = PTR_ERR(ubufs);
983 goto err_ubufs;
984 }
985
986 vhost_net_disable_vq(n, vq);
987 vq->private_data = sock;
988 r = vhost_vq_init_access(vq);
989 if (r)
990 goto err_used;
991 r = vhost_net_enable_vq(n, vq);
992 if (r)
993 goto err_used;
994
995 oldubufs = nvq->ubufs;
996 nvq->ubufs = ubufs;
997
998 n->tx_packets = 0;
999 n->tx_zcopy_err = 0;
1000 n->tx_flush = false;
1001 }
1002
1003 mutex_unlock(&vq->mutex);
1004
1005 if (oldubufs) {
1006 vhost_net_ubuf_put_wait_and_free(oldubufs);
1007 mutex_lock(&vq->mutex);
1008 vhost_zerocopy_signal_used(n, vq);
1009 mutex_unlock(&vq->mutex);
1010 }
1011
1012 if (oldsock) {
1013 vhost_net_flush_vq(n, index);
1014 sockfd_put(oldsock);
1015 }
1016
1017 mutex_unlock(&n->dev.mutex);
1018 return 0;
1019
1020err_used:
1021 vq->private_data = oldsock;
1022 vhost_net_enable_vq(n, vq);
1023 if (ubufs)
1024 vhost_net_ubuf_put_wait_and_free(ubufs);
1025err_ubufs:
1026 sockfd_put(sock);
1027err_vq:
1028 mutex_unlock(&vq->mutex);
1029err:
1030 mutex_unlock(&n->dev.mutex);
1031 return r;
1032}
1033
1034static long vhost_net_reset_owner(struct vhost_net *n)
1035{
1036 struct socket *tx_sock = NULL;
1037 struct socket *rx_sock = NULL;
1038 long err;
1039 struct vhost_memory *memory;
1040
1041 mutex_lock(&n->dev.mutex);
1042 err = vhost_dev_check_owner(&n->dev);
1043 if (err)
1044 goto done;
1045 memory = vhost_dev_reset_owner_prepare();
1046 if (!memory) {
1047 err = -ENOMEM;
1048 goto done;
1049 }
1050 vhost_net_stop(n, &tx_sock, &rx_sock);
1051 vhost_net_flush(n);
1052 vhost_dev_reset_owner(&n->dev, memory);
1053 vhost_net_vq_reset(n);
1054done:
1055 mutex_unlock(&n->dev.mutex);
1056 if (tx_sock)
1057 sockfd_put(tx_sock);
1058 if (rx_sock)
1059 sockfd_put(rx_sock);
1060 return err;
1061}
1062
1063static int vhost_net_set_features(struct vhost_net *n, u64 features)
1064{
1065 size_t vhost_hlen, sock_hlen, hdr_len;
1066 int i;
1067
1068 hdr_len = (features & ((1ULL << VIRTIO_NET_F_MRG_RXBUF) |
1069 (1ULL << VIRTIO_F_VERSION_1))) ?
1070 sizeof(struct virtio_net_hdr_mrg_rxbuf) :
1071 sizeof(struct virtio_net_hdr);
1072 if (features & (1 << VHOST_NET_F_VIRTIO_NET_HDR)) {
1073 /* vhost provides vnet_hdr */
1074 vhost_hlen = hdr_len;
1075 sock_hlen = 0;
1076 } else {
1077 /* socket provides vnet_hdr */
1078 vhost_hlen = 0;
1079 sock_hlen = hdr_len;
1080 }
1081 mutex_lock(&n->dev.mutex);
1082 if ((features & (1 << VHOST_F_LOG_ALL)) &&
1083 !vhost_log_access_ok(&n->dev)) {
1084 mutex_unlock(&n->dev.mutex);
1085 return -EFAULT;
1086 }
1087 for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
1088 mutex_lock(&n->vqs[i].vq.mutex);
1089 n->vqs[i].vq.acked_features = features;
1090 n->vqs[i].vhost_hlen = vhost_hlen;
1091 n->vqs[i].sock_hlen = sock_hlen;
1092 mutex_unlock(&n->vqs[i].vq.mutex);
1093 }
1094 mutex_unlock(&n->dev.mutex);
1095 return 0;
1096}
1097
1098static long vhost_net_set_owner(struct vhost_net *n)
1099{
1100 int r;
1101
1102 mutex_lock(&n->dev.mutex);
1103 if (vhost_dev_has_owner(&n->dev)) {
1104 r = -EBUSY;
1105 goto out;
1106 }
1107 r = vhost_net_set_ubuf_info(n);
1108 if (r)
1109 goto out;
1110 r = vhost_dev_set_owner(&n->dev);
1111 if (r)
1112 vhost_net_clear_ubuf_info(n);
1113 vhost_net_flush(n);
1114out:
1115 mutex_unlock(&n->dev.mutex);
1116 return r;
1117}
1118
1119static long vhost_net_ioctl(struct file *f, unsigned int ioctl,
1120 unsigned long arg)
1121{
1122 struct vhost_net *n = f->private_data;
1123 void __user *argp = (void __user *)arg;
1124 u64 __user *featurep = argp;
1125 struct vhost_vring_file backend;
1126 u64 features;
1127 int r;
1128
1129 switch (ioctl) {
1130 case VHOST_NET_SET_BACKEND:
1131 if (copy_from_user(&backend, argp, sizeof backend))
1132 return -EFAULT;
1133 return vhost_net_set_backend(n, backend.index, backend.fd);
1134 case VHOST_GET_FEATURES:
1135 features = VHOST_NET_FEATURES;
1136 if (copy_to_user(featurep, &features, sizeof features))
1137 return -EFAULT;
1138 return 0;
1139 case VHOST_SET_FEATURES:
1140 if (copy_from_user(&features, featurep, sizeof features))
1141 return -EFAULT;
1142 if (features & ~VHOST_NET_FEATURES)
1143 return -EOPNOTSUPP;
1144 return vhost_net_set_features(n, features);
1145 case VHOST_RESET_OWNER:
1146 return vhost_net_reset_owner(n);
1147 case VHOST_SET_OWNER:
1148 return vhost_net_set_owner(n);
1149 default:
1150 mutex_lock(&n->dev.mutex);
1151 r = vhost_dev_ioctl(&n->dev, ioctl, argp);
1152 if (r == -ENOIOCTLCMD)
1153 r = vhost_vring_ioctl(&n->dev, ioctl, argp);
1154 else
1155 vhost_net_flush(n);
1156 mutex_unlock(&n->dev.mutex);
1157 return r;
1158 }
1159}
1160
1161#ifdef CONFIG_COMPAT
1162static long vhost_net_compat_ioctl(struct file *f, unsigned int ioctl,
1163 unsigned long arg)
1164{
1165 return vhost_net_ioctl(f, ioctl, (unsigned long)compat_ptr(arg));
1166}
1167#endif
1168
1169static const struct file_operations vhost_net_fops = {
1170 .owner = THIS_MODULE,
1171 .release = vhost_net_release,
1172 .unlocked_ioctl = vhost_net_ioctl,
1173#ifdef CONFIG_COMPAT
1174 .compat_ioctl = vhost_net_compat_ioctl,
1175#endif
1176 .open = vhost_net_open,
1177 .llseek = noop_llseek,
1178};
1179
1180static struct miscdevice vhost_net_misc = {
1181 .minor = VHOST_NET_MINOR,
1182 .name = "vhost-net",
1183 .fops = &vhost_net_fops,
1184};
1185
1186static int vhost_net_init(void)
1187{
1188 if (experimental_zcopytx)
1189 vhost_net_enable_zcopy(VHOST_NET_VQ_TX);
1190 return misc_register(&vhost_net_misc);
1191}
1192module_init(vhost_net_init);
1193
1194static void vhost_net_exit(void)
1195{
1196 misc_deregister(&vhost_net_misc);
1197}
1198module_exit(vhost_net_exit);
1199
1200MODULE_VERSION("0.0.1");
1201MODULE_LICENSE("GPL v2");
1202MODULE_AUTHOR("Michael S. Tsirkin");
1203MODULE_DESCRIPTION("Host kernel accelerator for virtio net");
1204MODULE_ALIAS_MISCDEV(VHOST_NET_MINOR);
1205MODULE_ALIAS("devname:vhost-net");