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// SPDX-License-Identifier: GPL-2.0-only
2/* Copyright (C) 2009 Red Hat, Inc.
3 * Author: Michael S. Tsirkin <mst@redhat.com>
4 *
5 * virtio-net server in host kernel.
6 */
7
8#include <linux/compat.h>
9#include <linux/eventfd.h>
10#include <linux/vhost.h>
11#include <linux/virtio_net.h>
12#include <linux/miscdevice.h>
13#include <linux/module.h>
14#include <linux/moduleparam.h>
15#include <linux/mutex.h>
16#include <linux/workqueue.h>
17#include <linux/file.h>
18#include <linux/slab.h>
19#include <linux/sched/clock.h>
20#include <linux/sched/signal.h>
21#include <linux/vmalloc.h>
22
23#include <linux/net.h>
24#include <linux/if_packet.h>
25#include <linux/if_arp.h>
26#include <linux/if_tun.h>
27#include <linux/if_macvlan.h>
28#include <linux/if_tap.h>
29#include <linux/if_vlan.h>
30#include <linux/skb_array.h>
31#include <linux/skbuff.h>
32
33#include <net/sock.h>
34#include <net/xdp.h>
35
36#include "vhost.h"
37
38static int experimental_zcopytx = 0;
39module_param(experimental_zcopytx, int, 0444);
40MODULE_PARM_DESC(experimental_zcopytx, "Enable Zero Copy TX;"
41 " 1 -Enable; 0 - Disable");
42
43/* Max number of bytes transferred before requeueing the job.
44 * Using this limit prevents one virtqueue from starving others. */
45#define VHOST_NET_WEIGHT 0x80000
46
47/* Max number of packets transferred before requeueing the job.
48 * Using this limit prevents one virtqueue from starving others with small
49 * pkts.
50 */
51#define VHOST_NET_PKT_WEIGHT 256
52
53/* MAX number of TX used buffers for outstanding zerocopy */
54#define VHOST_MAX_PEND 128
55#define VHOST_GOODCOPY_LEN 256
56
57/*
58 * For transmit, used buffer len is unused; we override it to track buffer
59 * status internally; used for zerocopy tx only.
60 */
61/* Lower device DMA failed */
62#define VHOST_DMA_FAILED_LEN ((__force __virtio32)3)
63/* Lower device DMA done */
64#define VHOST_DMA_DONE_LEN ((__force __virtio32)2)
65/* Lower device DMA in progress */
66#define VHOST_DMA_IN_PROGRESS ((__force __virtio32)1)
67/* Buffer unused */
68#define VHOST_DMA_CLEAR_LEN ((__force __virtio32)0)
69
70#define VHOST_DMA_IS_DONE(len) ((__force u32)(len) >= (__force u32)VHOST_DMA_DONE_LEN)
71
72enum {
73 VHOST_NET_FEATURES = VHOST_FEATURES |
74 (1ULL << VHOST_NET_F_VIRTIO_NET_HDR) |
75 (1ULL << VIRTIO_NET_F_MRG_RXBUF) |
76 (1ULL << VIRTIO_F_ACCESS_PLATFORM)
77};
78
79enum {
80 VHOST_NET_BACKEND_FEATURES = (1ULL << VHOST_BACKEND_F_IOTLB_MSG_V2)
81};
82
83enum {
84 VHOST_NET_VQ_RX = 0,
85 VHOST_NET_VQ_TX = 1,
86 VHOST_NET_VQ_MAX = 2,
87};
88
89struct vhost_net_ubuf_ref {
90 /* refcount follows semantics similar to kref:
91 * 0: object is released
92 * 1: no outstanding ubufs
93 * >1: outstanding ubufs
94 */
95 atomic_t refcount;
96 wait_queue_head_t wait;
97 struct vhost_virtqueue *vq;
98};
99
100#define VHOST_NET_BATCH 64
101struct vhost_net_buf {
102 void **queue;
103 int tail;
104 int head;
105};
106
107struct vhost_net_virtqueue {
108 struct vhost_virtqueue vq;
109 size_t vhost_hlen;
110 size_t sock_hlen;
111 /* vhost zerocopy support fields below: */
112 /* last used idx for outstanding DMA zerocopy buffers */
113 int upend_idx;
114 /* For TX, first used idx for DMA done zerocopy buffers
115 * For RX, number of batched heads
116 */
117 int done_idx;
118 /* Number of XDP frames batched */
119 int batched_xdp;
120 /* an array of userspace buffers info */
121 struct ubuf_info_msgzc *ubuf_info;
122 /* Reference counting for outstanding ubufs.
123 * Protected by vq mutex. Writers must also take device mutex. */
124 struct vhost_net_ubuf_ref *ubufs;
125 struct ptr_ring *rx_ring;
126 struct vhost_net_buf rxq;
127 /* Batched XDP buffs */
128 struct xdp_buff *xdp;
129};
130
131struct vhost_net {
132 struct vhost_dev dev;
133 struct vhost_net_virtqueue vqs[VHOST_NET_VQ_MAX];
134 struct vhost_poll poll[VHOST_NET_VQ_MAX];
135 /* Number of TX recently submitted.
136 * Protected by tx vq lock. */
137 unsigned tx_packets;
138 /* Number of times zerocopy TX recently failed.
139 * Protected by tx vq lock. */
140 unsigned tx_zcopy_err;
141 /* Flush in progress. Protected by tx vq lock. */
142 bool tx_flush;
143 /* Private page frag */
144 struct page_frag page_frag;
145 /* Refcount bias of page frag */
146 int refcnt_bias;
147};
148
149static unsigned vhost_net_zcopy_mask __read_mostly;
150
151static void *vhost_net_buf_get_ptr(struct vhost_net_buf *rxq)
152{
153 if (rxq->tail != rxq->head)
154 return rxq->queue[rxq->head];
155 else
156 return NULL;
157}
158
159static int vhost_net_buf_get_size(struct vhost_net_buf *rxq)
160{
161 return rxq->tail - rxq->head;
162}
163
164static int vhost_net_buf_is_empty(struct vhost_net_buf *rxq)
165{
166 return rxq->tail == rxq->head;
167}
168
169static void *vhost_net_buf_consume(struct vhost_net_buf *rxq)
170{
171 void *ret = vhost_net_buf_get_ptr(rxq);
172 ++rxq->head;
173 return ret;
174}
175
176static int vhost_net_buf_produce(struct vhost_net_virtqueue *nvq)
177{
178 struct vhost_net_buf *rxq = &nvq->rxq;
179
180 rxq->head = 0;
181 rxq->tail = ptr_ring_consume_batched(nvq->rx_ring, rxq->queue,
182 VHOST_NET_BATCH);
183 return rxq->tail;
184}
185
186static void vhost_net_buf_unproduce(struct vhost_net_virtqueue *nvq)
187{
188 struct vhost_net_buf *rxq = &nvq->rxq;
189
190 if (nvq->rx_ring && !vhost_net_buf_is_empty(rxq)) {
191 ptr_ring_unconsume(nvq->rx_ring, rxq->queue + rxq->head,
192 vhost_net_buf_get_size(rxq),
193 tun_ptr_free);
194 rxq->head = rxq->tail = 0;
195 }
196}
197
198static int vhost_net_buf_peek_len(void *ptr)
199{
200 if (tun_is_xdp_frame(ptr)) {
201 struct xdp_frame *xdpf = tun_ptr_to_xdp(ptr);
202
203 return xdpf->len;
204 }
205
206 return __skb_array_len_with_tag(ptr);
207}
208
209static int vhost_net_buf_peek(struct vhost_net_virtqueue *nvq)
210{
211 struct vhost_net_buf *rxq = &nvq->rxq;
212
213 if (!vhost_net_buf_is_empty(rxq))
214 goto out;
215
216 if (!vhost_net_buf_produce(nvq))
217 return 0;
218
219out:
220 return vhost_net_buf_peek_len(vhost_net_buf_get_ptr(rxq));
221}
222
223static void vhost_net_buf_init(struct vhost_net_buf *rxq)
224{
225 rxq->head = rxq->tail = 0;
226}
227
228static void vhost_net_enable_zcopy(int vq)
229{
230 vhost_net_zcopy_mask |= 0x1 << vq;
231}
232
233static struct vhost_net_ubuf_ref *
234vhost_net_ubuf_alloc(struct vhost_virtqueue *vq, bool zcopy)
235{
236 struct vhost_net_ubuf_ref *ubufs;
237 /* No zero copy backend? Nothing to count. */
238 if (!zcopy)
239 return NULL;
240 ubufs = kmalloc(sizeof(*ubufs), GFP_KERNEL);
241 if (!ubufs)
242 return ERR_PTR(-ENOMEM);
243 atomic_set(&ubufs->refcount, 1);
244 init_waitqueue_head(&ubufs->wait);
245 ubufs->vq = vq;
246 return ubufs;
247}
248
249static int vhost_net_ubuf_put(struct vhost_net_ubuf_ref *ubufs)
250{
251 int r = atomic_sub_return(1, &ubufs->refcount);
252 if (unlikely(!r))
253 wake_up(&ubufs->wait);
254 return r;
255}
256
257static void vhost_net_ubuf_put_and_wait(struct vhost_net_ubuf_ref *ubufs)
258{
259 vhost_net_ubuf_put(ubufs);
260 wait_event(ubufs->wait, !atomic_read(&ubufs->refcount));
261}
262
263static void vhost_net_ubuf_put_wait_and_free(struct vhost_net_ubuf_ref *ubufs)
264{
265 vhost_net_ubuf_put_and_wait(ubufs);
266 kfree(ubufs);
267}
268
269static void vhost_net_clear_ubuf_info(struct vhost_net *n)
270{
271 int i;
272
273 for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
274 kfree(n->vqs[i].ubuf_info);
275 n->vqs[i].ubuf_info = NULL;
276 }
277}
278
279static int vhost_net_set_ubuf_info(struct vhost_net *n)
280{
281 bool zcopy;
282 int i;
283
284 for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
285 zcopy = vhost_net_zcopy_mask & (0x1 << i);
286 if (!zcopy)
287 continue;
288 n->vqs[i].ubuf_info =
289 kmalloc_array(UIO_MAXIOV,
290 sizeof(*n->vqs[i].ubuf_info),
291 GFP_KERNEL);
292 if (!n->vqs[i].ubuf_info)
293 goto err;
294 }
295 return 0;
296
297err:
298 vhost_net_clear_ubuf_info(n);
299 return -ENOMEM;
300}
301
302static void vhost_net_vq_reset(struct vhost_net *n)
303{
304 int i;
305
306 vhost_net_clear_ubuf_info(n);
307
308 for (i = 0; i < VHOST_NET_VQ_MAX; i++) {
309 n->vqs[i].done_idx = 0;
310 n->vqs[i].upend_idx = 0;
311 n->vqs[i].ubufs = NULL;
312 n->vqs[i].vhost_hlen = 0;
313 n->vqs[i].sock_hlen = 0;
314 vhost_net_buf_init(&n->vqs[i].rxq);
315 }
316
317}
318
319static void vhost_net_tx_packet(struct vhost_net *net)
320{
321 ++net->tx_packets;
322 if (net->tx_packets < 1024)
323 return;
324 net->tx_packets = 0;
325 net->tx_zcopy_err = 0;
326}
327
328static void vhost_net_tx_err(struct vhost_net *net)
329{
330 ++net->tx_zcopy_err;
331}
332
333static bool vhost_net_tx_select_zcopy(struct vhost_net *net)
334{
335 /* TX flush waits for outstanding DMAs to be done.
336 * Don't start new DMAs.
337 */
338 return !net->tx_flush &&
339 net->tx_packets / 64 >= net->tx_zcopy_err;
340}
341
342static bool vhost_sock_zcopy(struct socket *sock)
343{
344 return unlikely(experimental_zcopytx) &&
345 sock_flag(sock->sk, SOCK_ZEROCOPY);
346}
347
348static bool vhost_sock_xdp(struct socket *sock)
349{
350 return sock_flag(sock->sk, SOCK_XDP);
351}
352
353/* In case of DMA done not in order in lower device driver for some reason.
354 * upend_idx is used to track end of used idx, done_idx is used to track head
355 * of used idx. Once lower device DMA done contiguously, we will signal KVM
356 * guest used idx.
357 */
358static void vhost_zerocopy_signal_used(struct vhost_net *net,
359 struct vhost_virtqueue *vq)
360{
361 struct vhost_net_virtqueue *nvq =
362 container_of(vq, struct vhost_net_virtqueue, vq);
363 int i, add;
364 int j = 0;
365
366 for (i = nvq->done_idx; i != nvq->upend_idx; i = (i + 1) % UIO_MAXIOV) {
367 if (vq->heads[i].len == VHOST_DMA_FAILED_LEN)
368 vhost_net_tx_err(net);
369 if (VHOST_DMA_IS_DONE(vq->heads[i].len)) {
370 vq->heads[i].len = VHOST_DMA_CLEAR_LEN;
371 ++j;
372 } else
373 break;
374 }
375 while (j) {
376 add = min(UIO_MAXIOV - nvq->done_idx, j);
377 vhost_add_used_and_signal_n(vq->dev, vq,
378 &vq->heads[nvq->done_idx], add);
379 nvq->done_idx = (nvq->done_idx + add) % UIO_MAXIOV;
380 j -= add;
381 }
382}
383
384static void vhost_zerocopy_callback(struct sk_buff *skb,
385 struct ubuf_info *ubuf_base, bool success)
386{
387 struct ubuf_info_msgzc *ubuf = uarg_to_msgzc(ubuf_base);
388 struct vhost_net_ubuf_ref *ubufs = ubuf->ctx;
389 struct vhost_virtqueue *vq = ubufs->vq;
390 int cnt;
391
392 rcu_read_lock_bh();
393
394 /* set len to mark this desc buffers done DMA */
395 vq->heads[ubuf->desc].len = success ?
396 VHOST_DMA_DONE_LEN : VHOST_DMA_FAILED_LEN;
397 cnt = vhost_net_ubuf_put(ubufs);
398
399 /*
400 * Trigger polling thread if guest stopped submitting new buffers:
401 * in this case, the refcount after decrement will eventually reach 1.
402 * We also trigger polling periodically after each 16 packets
403 * (the value 16 here is more or less arbitrary, it's tuned to trigger
404 * less than 10% of times).
405 */
406 if (cnt <= 1 || !(cnt % 16))
407 vhost_poll_queue(&vq->poll);
408
409 rcu_read_unlock_bh();
410}
411
412static inline unsigned long busy_clock(void)
413{
414 return local_clock() >> 10;
415}
416
417static bool vhost_can_busy_poll(unsigned long endtime)
418{
419 return likely(!need_resched() && !time_after(busy_clock(), endtime) &&
420 !signal_pending(current));
421}
422
423static void vhost_net_disable_vq(struct vhost_net *n,
424 struct vhost_virtqueue *vq)
425{
426 struct vhost_net_virtqueue *nvq =
427 container_of(vq, struct vhost_net_virtqueue, vq);
428 struct vhost_poll *poll = n->poll + (nvq - n->vqs);
429 if (!vhost_vq_get_backend(vq))
430 return;
431 vhost_poll_stop(poll);
432}
433
434static int vhost_net_enable_vq(struct vhost_net *n,
435 struct vhost_virtqueue *vq)
436{
437 struct vhost_net_virtqueue *nvq =
438 container_of(vq, struct vhost_net_virtqueue, vq);
439 struct vhost_poll *poll = n->poll + (nvq - n->vqs);
440 struct socket *sock;
441
442 sock = vhost_vq_get_backend(vq);
443 if (!sock)
444 return 0;
445
446 return vhost_poll_start(poll, sock->file);
447}
448
449static void vhost_net_signal_used(struct vhost_net_virtqueue *nvq)
450{
451 struct vhost_virtqueue *vq = &nvq->vq;
452 struct vhost_dev *dev = vq->dev;
453
454 if (!nvq->done_idx)
455 return;
456
457 vhost_add_used_and_signal_n(dev, vq, vq->heads, nvq->done_idx);
458 nvq->done_idx = 0;
459}
460
461static void vhost_tx_batch(struct vhost_net *net,
462 struct vhost_net_virtqueue *nvq,
463 struct socket *sock,
464 struct msghdr *msghdr)
465{
466 struct tun_msg_ctl ctl = {
467 .type = TUN_MSG_PTR,
468 .num = nvq->batched_xdp,
469 .ptr = nvq->xdp,
470 };
471 int i, err;
472
473 if (nvq->batched_xdp == 0)
474 goto signal_used;
475
476 msghdr->msg_control = &ctl;
477 msghdr->msg_controllen = sizeof(ctl);
478 err = sock->ops->sendmsg(sock, msghdr, 0);
479 if (unlikely(err < 0)) {
480 vq_err(&nvq->vq, "Fail to batch sending packets\n");
481
482 /* free pages owned by XDP; since this is an unlikely error path,
483 * keep it simple and avoid more complex bulk update for the
484 * used pages
485 */
486 for (i = 0; i < nvq->batched_xdp; ++i)
487 put_page(virt_to_head_page(nvq->xdp[i].data));
488 nvq->batched_xdp = 0;
489 nvq->done_idx = 0;
490 return;
491 }
492
493signal_used:
494 vhost_net_signal_used(nvq);
495 nvq->batched_xdp = 0;
496}
497
498static int sock_has_rx_data(struct socket *sock)
499{
500 if (unlikely(!sock))
501 return 0;
502
503 if (sock->ops->peek_len)
504 return sock->ops->peek_len(sock);
505
506 return skb_queue_empty(&sock->sk->sk_receive_queue);
507}
508
509static void vhost_net_busy_poll_try_queue(struct vhost_net *net,
510 struct vhost_virtqueue *vq)
511{
512 if (!vhost_vq_avail_empty(&net->dev, vq)) {
513 vhost_poll_queue(&vq->poll);
514 } else if (unlikely(vhost_enable_notify(&net->dev, vq))) {
515 vhost_disable_notify(&net->dev, vq);
516 vhost_poll_queue(&vq->poll);
517 }
518}
519
520static void vhost_net_busy_poll(struct vhost_net *net,
521 struct vhost_virtqueue *rvq,
522 struct vhost_virtqueue *tvq,
523 bool *busyloop_intr,
524 bool poll_rx)
525{
526 unsigned long busyloop_timeout;
527 unsigned long endtime;
528 struct socket *sock;
529 struct vhost_virtqueue *vq = poll_rx ? tvq : rvq;
530
531 /* Try to hold the vq mutex of the paired virtqueue. We can't
532 * use mutex_lock() here since we could not guarantee a
533 * consistenet lock ordering.
534 */
535 if (!mutex_trylock(&vq->mutex))
536 return;
537
538 vhost_disable_notify(&net->dev, vq);
539 sock = vhost_vq_get_backend(rvq);
540
541 busyloop_timeout = poll_rx ? rvq->busyloop_timeout:
542 tvq->busyloop_timeout;
543
544 preempt_disable();
545 endtime = busy_clock() + busyloop_timeout;
546
547 while (vhost_can_busy_poll(endtime)) {
548 if (vhost_has_work(&net->dev)) {
549 *busyloop_intr = true;
550 break;
551 }
552
553 if ((sock_has_rx_data(sock) &&
554 !vhost_vq_avail_empty(&net->dev, rvq)) ||
555 !vhost_vq_avail_empty(&net->dev, tvq))
556 break;
557
558 cpu_relax();
559 }
560
561 preempt_enable();
562
563 if (poll_rx || sock_has_rx_data(sock))
564 vhost_net_busy_poll_try_queue(net, vq);
565 else if (!poll_rx) /* On tx here, sock has no rx data. */
566 vhost_enable_notify(&net->dev, rvq);
567
568 mutex_unlock(&vq->mutex);
569}
570
571static int vhost_net_tx_get_vq_desc(struct vhost_net *net,
572 struct vhost_net_virtqueue *tnvq,
573 unsigned int *out_num, unsigned int *in_num,
574 struct msghdr *msghdr, bool *busyloop_intr)
575{
576 struct vhost_net_virtqueue *rnvq = &net->vqs[VHOST_NET_VQ_RX];
577 struct vhost_virtqueue *rvq = &rnvq->vq;
578 struct vhost_virtqueue *tvq = &tnvq->vq;
579
580 int r = vhost_get_vq_desc(tvq, tvq->iov, ARRAY_SIZE(tvq->iov),
581 out_num, in_num, NULL, NULL);
582
583 if (r == tvq->num && tvq->busyloop_timeout) {
584 /* Flush batched packets first */
585 if (!vhost_sock_zcopy(vhost_vq_get_backend(tvq)))
586 vhost_tx_batch(net, tnvq,
587 vhost_vq_get_backend(tvq),
588 msghdr);
589
590 vhost_net_busy_poll(net, rvq, tvq, busyloop_intr, false);
591
592 r = vhost_get_vq_desc(tvq, tvq->iov, ARRAY_SIZE(tvq->iov),
593 out_num, in_num, NULL, NULL);
594 }
595
596 return r;
597}
598
599static bool vhost_exceeds_maxpend(struct vhost_net *net)
600{
601 struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_TX];
602 struct vhost_virtqueue *vq = &nvq->vq;
603
604 return (nvq->upend_idx + UIO_MAXIOV - nvq->done_idx) % UIO_MAXIOV >
605 min_t(unsigned int, VHOST_MAX_PEND, vq->num >> 2);
606}
607
608static size_t init_iov_iter(struct vhost_virtqueue *vq, struct iov_iter *iter,
609 size_t hdr_size, int out)
610{
611 /* Skip header. TODO: support TSO. */
612 size_t len = iov_length(vq->iov, out);
613
614 iov_iter_init(iter, ITER_SOURCE, vq->iov, out, len);
615 iov_iter_advance(iter, hdr_size);
616
617 return iov_iter_count(iter);
618}
619
620static int get_tx_bufs(struct vhost_net *net,
621 struct vhost_net_virtqueue *nvq,
622 struct msghdr *msg,
623 unsigned int *out, unsigned int *in,
624 size_t *len, bool *busyloop_intr)
625{
626 struct vhost_virtqueue *vq = &nvq->vq;
627 int ret;
628
629 ret = vhost_net_tx_get_vq_desc(net, nvq, out, in, msg, busyloop_intr);
630
631 if (ret < 0 || ret == vq->num)
632 return ret;
633
634 if (*in) {
635 vq_err(vq, "Unexpected descriptor format for TX: out %d, int %d\n",
636 *out, *in);
637 return -EFAULT;
638 }
639
640 /* Sanity check */
641 *len = init_iov_iter(vq, &msg->msg_iter, nvq->vhost_hlen, *out);
642 if (*len == 0) {
643 vq_err(vq, "Unexpected header len for TX: %zd expected %zd\n",
644 *len, nvq->vhost_hlen);
645 return -EFAULT;
646 }
647
648 return ret;
649}
650
651static bool tx_can_batch(struct vhost_virtqueue *vq, size_t total_len)
652{
653 return total_len < VHOST_NET_WEIGHT &&
654 !vhost_vq_avail_empty(vq->dev, vq);
655}
656
657static bool vhost_net_page_frag_refill(struct vhost_net *net, unsigned int sz,
658 struct page_frag *pfrag, gfp_t gfp)
659{
660 if (pfrag->page) {
661 if (pfrag->offset + sz <= pfrag->size)
662 return true;
663 __page_frag_cache_drain(pfrag->page, net->refcnt_bias);
664 }
665
666 pfrag->offset = 0;
667 net->refcnt_bias = 0;
668 if (SKB_FRAG_PAGE_ORDER) {
669 /* Avoid direct reclaim but allow kswapd to wake */
670 pfrag->page = alloc_pages((gfp & ~__GFP_DIRECT_RECLAIM) |
671 __GFP_COMP | __GFP_NOWARN |
672 __GFP_NORETRY,
673 SKB_FRAG_PAGE_ORDER);
674 if (likely(pfrag->page)) {
675 pfrag->size = PAGE_SIZE << SKB_FRAG_PAGE_ORDER;
676 goto done;
677 }
678 }
679 pfrag->page = alloc_page(gfp);
680 if (likely(pfrag->page)) {
681 pfrag->size = PAGE_SIZE;
682 goto done;
683 }
684 return false;
685
686done:
687 net->refcnt_bias = USHRT_MAX;
688 page_ref_add(pfrag->page, USHRT_MAX - 1);
689 return true;
690}
691
692#define VHOST_NET_RX_PAD (NET_IP_ALIGN + NET_SKB_PAD)
693
694static int vhost_net_build_xdp(struct vhost_net_virtqueue *nvq,
695 struct iov_iter *from)
696{
697 struct vhost_virtqueue *vq = &nvq->vq;
698 struct vhost_net *net = container_of(vq->dev, struct vhost_net,
699 dev);
700 struct socket *sock = vhost_vq_get_backend(vq);
701 struct page_frag *alloc_frag = &net->page_frag;
702 struct virtio_net_hdr *gso;
703 struct xdp_buff *xdp = &nvq->xdp[nvq->batched_xdp];
704 struct tun_xdp_hdr *hdr;
705 size_t len = iov_iter_count(from);
706 int headroom = vhost_sock_xdp(sock) ? XDP_PACKET_HEADROOM : 0;
707 int buflen = SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
708 int pad = SKB_DATA_ALIGN(VHOST_NET_RX_PAD + headroom + nvq->sock_hlen);
709 int sock_hlen = nvq->sock_hlen;
710 void *buf;
711 int copied;
712
713 if (unlikely(len < nvq->sock_hlen))
714 return -EFAULT;
715
716 if (SKB_DATA_ALIGN(len + pad) +
717 SKB_DATA_ALIGN(sizeof(struct skb_shared_info)) > PAGE_SIZE)
718 return -ENOSPC;
719
720 buflen += SKB_DATA_ALIGN(len + pad);
721 alloc_frag->offset = ALIGN((u64)alloc_frag->offset, SMP_CACHE_BYTES);
722 if (unlikely(!vhost_net_page_frag_refill(net, buflen,
723 alloc_frag, GFP_KERNEL)))
724 return -ENOMEM;
725
726 buf = (char *)page_address(alloc_frag->page) + alloc_frag->offset;
727 copied = copy_page_from_iter(alloc_frag->page,
728 alloc_frag->offset +
729 offsetof(struct tun_xdp_hdr, gso),
730 sock_hlen, from);
731 if (copied != sock_hlen)
732 return -EFAULT;
733
734 hdr = buf;
735 gso = &hdr->gso;
736
737 if ((gso->flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) &&
738 vhost16_to_cpu(vq, gso->csum_start) +
739 vhost16_to_cpu(vq, gso->csum_offset) + 2 >
740 vhost16_to_cpu(vq, gso->hdr_len)) {
741 gso->hdr_len = cpu_to_vhost16(vq,
742 vhost16_to_cpu(vq, gso->csum_start) +
743 vhost16_to_cpu(vq, gso->csum_offset) + 2);
744
745 if (vhost16_to_cpu(vq, gso->hdr_len) > len)
746 return -EINVAL;
747 }
748
749 len -= sock_hlen;
750 copied = copy_page_from_iter(alloc_frag->page,
751 alloc_frag->offset + pad,
752 len, from);
753 if (copied != len)
754 return -EFAULT;
755
756 xdp_init_buff(xdp, buflen, NULL);
757 xdp_prepare_buff(xdp, buf, pad, len, true);
758 hdr->buflen = buflen;
759
760 --net->refcnt_bias;
761 alloc_frag->offset += buflen;
762
763 ++nvq->batched_xdp;
764
765 return 0;
766}
767
768static void handle_tx_copy(struct vhost_net *net, struct socket *sock)
769{
770 struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_TX];
771 struct vhost_virtqueue *vq = &nvq->vq;
772 unsigned out, in;
773 int head;
774 struct msghdr msg = {
775 .msg_name = NULL,
776 .msg_namelen = 0,
777 .msg_control = NULL,
778 .msg_controllen = 0,
779 .msg_flags = MSG_DONTWAIT,
780 };
781 size_t len, total_len = 0;
782 int err;
783 int sent_pkts = 0;
784 bool sock_can_batch = (sock->sk->sk_sndbuf == INT_MAX);
785
786 do {
787 bool busyloop_intr = false;
788
789 if (nvq->done_idx == VHOST_NET_BATCH)
790 vhost_tx_batch(net, nvq, sock, &msg);
791
792 head = get_tx_bufs(net, nvq, &msg, &out, &in, &len,
793 &busyloop_intr);
794 /* On error, stop handling until the next kick. */
795 if (unlikely(head < 0))
796 break;
797 /* Nothing new? Wait for eventfd to tell us they refilled. */
798 if (head == vq->num) {
799 if (unlikely(busyloop_intr)) {
800 vhost_poll_queue(&vq->poll);
801 } else if (unlikely(vhost_enable_notify(&net->dev,
802 vq))) {
803 vhost_disable_notify(&net->dev, vq);
804 continue;
805 }
806 break;
807 }
808
809 total_len += len;
810
811 /* For simplicity, TX batching is only enabled if
812 * sndbuf is unlimited.
813 */
814 if (sock_can_batch) {
815 err = vhost_net_build_xdp(nvq, &msg.msg_iter);
816 if (!err) {
817 goto done;
818 } else if (unlikely(err != -ENOSPC)) {
819 vhost_tx_batch(net, nvq, sock, &msg);
820 vhost_discard_vq_desc(vq, 1);
821 vhost_net_enable_vq(net, vq);
822 break;
823 }
824
825 /* We can't build XDP buff, go for single
826 * packet path but let's flush batched
827 * packets.
828 */
829 vhost_tx_batch(net, nvq, sock, &msg);
830 msg.msg_control = NULL;
831 } else {
832 if (tx_can_batch(vq, total_len))
833 msg.msg_flags |= MSG_MORE;
834 else
835 msg.msg_flags &= ~MSG_MORE;
836 }
837
838 err = sock->ops->sendmsg(sock, &msg, len);
839 if (unlikely(err < 0)) {
840 if (err == -EAGAIN || err == -ENOMEM || err == -ENOBUFS) {
841 vhost_discard_vq_desc(vq, 1);
842 vhost_net_enable_vq(net, vq);
843 break;
844 }
845 pr_debug("Fail to send packet: err %d", err);
846 } else if (unlikely(err != len))
847 pr_debug("Truncated TX packet: len %d != %zd\n",
848 err, len);
849done:
850 vq->heads[nvq->done_idx].id = cpu_to_vhost32(vq, head);
851 vq->heads[nvq->done_idx].len = 0;
852 ++nvq->done_idx;
853 } while (likely(!vhost_exceeds_weight(vq, ++sent_pkts, total_len)));
854
855 vhost_tx_batch(net, nvq, sock, &msg);
856}
857
858static void handle_tx_zerocopy(struct vhost_net *net, struct socket *sock)
859{
860 struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_TX];
861 struct vhost_virtqueue *vq = &nvq->vq;
862 unsigned out, in;
863 int head;
864 struct msghdr msg = {
865 .msg_name = NULL,
866 .msg_namelen = 0,
867 .msg_control = NULL,
868 .msg_controllen = 0,
869 .msg_flags = MSG_DONTWAIT,
870 };
871 struct tun_msg_ctl ctl;
872 size_t len, total_len = 0;
873 int err;
874 struct vhost_net_ubuf_ref *ubufs;
875 struct ubuf_info_msgzc *ubuf;
876 bool zcopy_used;
877 int sent_pkts = 0;
878
879 do {
880 bool busyloop_intr;
881
882 /* Release DMAs done buffers first */
883 vhost_zerocopy_signal_used(net, vq);
884
885 busyloop_intr = false;
886 head = get_tx_bufs(net, nvq, &msg, &out, &in, &len,
887 &busyloop_intr);
888 /* On error, stop handling until the next kick. */
889 if (unlikely(head < 0))
890 break;
891 /* Nothing new? Wait for eventfd to tell us they refilled. */
892 if (head == vq->num) {
893 if (unlikely(busyloop_intr)) {
894 vhost_poll_queue(&vq->poll);
895 } else if (unlikely(vhost_enable_notify(&net->dev, vq))) {
896 vhost_disable_notify(&net->dev, vq);
897 continue;
898 }
899 break;
900 }
901
902 zcopy_used = len >= VHOST_GOODCOPY_LEN
903 && !vhost_exceeds_maxpend(net)
904 && vhost_net_tx_select_zcopy(net);
905
906 /* use msg_control to pass vhost zerocopy ubuf info to skb */
907 if (zcopy_used) {
908 ubuf = nvq->ubuf_info + nvq->upend_idx;
909 vq->heads[nvq->upend_idx].id = cpu_to_vhost32(vq, head);
910 vq->heads[nvq->upend_idx].len = VHOST_DMA_IN_PROGRESS;
911 ubuf->ctx = nvq->ubufs;
912 ubuf->desc = nvq->upend_idx;
913 ubuf->ubuf.callback = vhost_zerocopy_callback;
914 ubuf->ubuf.flags = SKBFL_ZEROCOPY_FRAG;
915 refcount_set(&ubuf->ubuf.refcnt, 1);
916 msg.msg_control = &ctl;
917 ctl.type = TUN_MSG_UBUF;
918 ctl.ptr = &ubuf->ubuf;
919 msg.msg_controllen = sizeof(ctl);
920 ubufs = nvq->ubufs;
921 atomic_inc(&ubufs->refcount);
922 nvq->upend_idx = (nvq->upend_idx + 1) % UIO_MAXIOV;
923 } else {
924 msg.msg_control = NULL;
925 ubufs = NULL;
926 }
927 total_len += len;
928 if (tx_can_batch(vq, total_len) &&
929 likely(!vhost_exceeds_maxpend(net))) {
930 msg.msg_flags |= MSG_MORE;
931 } else {
932 msg.msg_flags &= ~MSG_MORE;
933 }
934
935 err = sock->ops->sendmsg(sock, &msg, len);
936 if (unlikely(err < 0)) {
937 if (zcopy_used) {
938 if (vq->heads[ubuf->desc].len == VHOST_DMA_IN_PROGRESS)
939 vhost_net_ubuf_put(ubufs);
940 nvq->upend_idx = ((unsigned)nvq->upend_idx - 1)
941 % UIO_MAXIOV;
942 }
943 if (err == -EAGAIN || err == -ENOMEM || err == -ENOBUFS) {
944 vhost_discard_vq_desc(vq, 1);
945 vhost_net_enable_vq(net, vq);
946 break;
947 }
948 pr_debug("Fail to send packet: err %d", err);
949 } else if (unlikely(err != len))
950 pr_debug("Truncated TX packet: "
951 " len %d != %zd\n", err, len);
952 if (!zcopy_used)
953 vhost_add_used_and_signal(&net->dev, vq, head, 0);
954 else
955 vhost_zerocopy_signal_used(net, vq);
956 vhost_net_tx_packet(net);
957 } while (likely(!vhost_exceeds_weight(vq, ++sent_pkts, total_len)));
958}
959
960/* Expects to be always run from workqueue - which acts as
961 * read-size critical section for our kind of RCU. */
962static void handle_tx(struct vhost_net *net)
963{
964 struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_TX];
965 struct vhost_virtqueue *vq = &nvq->vq;
966 struct socket *sock;
967
968 mutex_lock_nested(&vq->mutex, VHOST_NET_VQ_TX);
969 sock = vhost_vq_get_backend(vq);
970 if (!sock)
971 goto out;
972
973 if (!vq_meta_prefetch(vq))
974 goto out;
975
976 vhost_disable_notify(&net->dev, vq);
977 vhost_net_disable_vq(net, vq);
978
979 if (vhost_sock_zcopy(sock))
980 handle_tx_zerocopy(net, sock);
981 else
982 handle_tx_copy(net, sock);
983
984out:
985 mutex_unlock(&vq->mutex);
986}
987
988static int peek_head_len(struct vhost_net_virtqueue *rvq, struct sock *sk)
989{
990 struct sk_buff *head;
991 int len = 0;
992 unsigned long flags;
993
994 if (rvq->rx_ring)
995 return vhost_net_buf_peek(rvq);
996
997 spin_lock_irqsave(&sk->sk_receive_queue.lock, flags);
998 head = skb_peek(&sk->sk_receive_queue);
999 if (likely(head)) {
1000 len = head->len;
1001 if (skb_vlan_tag_present(head))
1002 len += VLAN_HLEN;
1003 }
1004
1005 spin_unlock_irqrestore(&sk->sk_receive_queue.lock, flags);
1006 return len;
1007}
1008
1009static int vhost_net_rx_peek_head_len(struct vhost_net *net, struct sock *sk,
1010 bool *busyloop_intr)
1011{
1012 struct vhost_net_virtqueue *rnvq = &net->vqs[VHOST_NET_VQ_RX];
1013 struct vhost_net_virtqueue *tnvq = &net->vqs[VHOST_NET_VQ_TX];
1014 struct vhost_virtqueue *rvq = &rnvq->vq;
1015 struct vhost_virtqueue *tvq = &tnvq->vq;
1016 int len = peek_head_len(rnvq, sk);
1017
1018 if (!len && rvq->busyloop_timeout) {
1019 /* Flush batched heads first */
1020 vhost_net_signal_used(rnvq);
1021 /* Both tx vq and rx socket were polled here */
1022 vhost_net_busy_poll(net, rvq, tvq, busyloop_intr, true);
1023
1024 len = peek_head_len(rnvq, sk);
1025 }
1026
1027 return len;
1028}
1029
1030/* This is a multi-buffer version of vhost_get_desc, that works if
1031 * vq has read descriptors only.
1032 * @vq - the relevant virtqueue
1033 * @datalen - data length we'll be reading
1034 * @iovcount - returned count of io vectors we fill
1035 * @log - vhost log
1036 * @log_num - log offset
1037 * @quota - headcount quota, 1 for big buffer
1038 * returns number of buffer heads allocated, negative on error
1039 */
1040static int get_rx_bufs(struct vhost_virtqueue *vq,
1041 struct vring_used_elem *heads,
1042 int datalen,
1043 unsigned *iovcount,
1044 struct vhost_log *log,
1045 unsigned *log_num,
1046 unsigned int quota)
1047{
1048 unsigned int out, in;
1049 int seg = 0;
1050 int headcount = 0;
1051 unsigned d;
1052 int r, nlogs = 0;
1053 /* len is always initialized before use since we are always called with
1054 * datalen > 0.
1055 */
1056 u32 len;
1057
1058 while (datalen > 0 && headcount < quota) {
1059 if (unlikely(seg >= UIO_MAXIOV)) {
1060 r = -ENOBUFS;
1061 goto err;
1062 }
1063 r = vhost_get_vq_desc(vq, vq->iov + seg,
1064 ARRAY_SIZE(vq->iov) - seg, &out,
1065 &in, log, log_num);
1066 if (unlikely(r < 0))
1067 goto err;
1068
1069 d = r;
1070 if (d == vq->num) {
1071 r = 0;
1072 goto err;
1073 }
1074 if (unlikely(out || in <= 0)) {
1075 vq_err(vq, "unexpected descriptor format for RX: "
1076 "out %d, in %d\n", out, in);
1077 r = -EINVAL;
1078 goto err;
1079 }
1080 if (unlikely(log)) {
1081 nlogs += *log_num;
1082 log += *log_num;
1083 }
1084 heads[headcount].id = cpu_to_vhost32(vq, d);
1085 len = iov_length(vq->iov + seg, in);
1086 heads[headcount].len = cpu_to_vhost32(vq, len);
1087 datalen -= len;
1088 ++headcount;
1089 seg += in;
1090 }
1091 heads[headcount - 1].len = cpu_to_vhost32(vq, len + datalen);
1092 *iovcount = seg;
1093 if (unlikely(log))
1094 *log_num = nlogs;
1095
1096 /* Detect overrun */
1097 if (unlikely(datalen > 0)) {
1098 r = UIO_MAXIOV + 1;
1099 goto err;
1100 }
1101 return headcount;
1102err:
1103 vhost_discard_vq_desc(vq, headcount);
1104 return r;
1105}
1106
1107/* Expects to be always run from workqueue - which acts as
1108 * read-size critical section for our kind of RCU. */
1109static void handle_rx(struct vhost_net *net)
1110{
1111 struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_RX];
1112 struct vhost_virtqueue *vq = &nvq->vq;
1113 unsigned in, log;
1114 struct vhost_log *vq_log;
1115 struct msghdr msg = {
1116 .msg_name = NULL,
1117 .msg_namelen = 0,
1118 .msg_control = NULL, /* FIXME: get and handle RX aux data. */
1119 .msg_controllen = 0,
1120 .msg_flags = MSG_DONTWAIT,
1121 };
1122 struct virtio_net_hdr hdr = {
1123 .flags = 0,
1124 .gso_type = VIRTIO_NET_HDR_GSO_NONE
1125 };
1126 size_t total_len = 0;
1127 int err, mergeable;
1128 s16 headcount;
1129 size_t vhost_hlen, sock_hlen;
1130 size_t vhost_len, sock_len;
1131 bool busyloop_intr = false;
1132 struct socket *sock;
1133 struct iov_iter fixup;
1134 __virtio16 num_buffers;
1135 int recv_pkts = 0;
1136
1137 mutex_lock_nested(&vq->mutex, VHOST_NET_VQ_RX);
1138 sock = vhost_vq_get_backend(vq);
1139 if (!sock)
1140 goto out;
1141
1142 if (!vq_meta_prefetch(vq))
1143 goto out;
1144
1145 vhost_disable_notify(&net->dev, vq);
1146 vhost_net_disable_vq(net, vq);
1147
1148 vhost_hlen = nvq->vhost_hlen;
1149 sock_hlen = nvq->sock_hlen;
1150
1151 vq_log = unlikely(vhost_has_feature(vq, VHOST_F_LOG_ALL)) ?
1152 vq->log : NULL;
1153 mergeable = vhost_has_feature(vq, VIRTIO_NET_F_MRG_RXBUF);
1154
1155 do {
1156 sock_len = vhost_net_rx_peek_head_len(net, sock->sk,
1157 &busyloop_intr);
1158 if (!sock_len)
1159 break;
1160 sock_len += sock_hlen;
1161 vhost_len = sock_len + vhost_hlen;
1162 headcount = get_rx_bufs(vq, vq->heads + nvq->done_idx,
1163 vhost_len, &in, vq_log, &log,
1164 likely(mergeable) ? UIO_MAXIOV : 1);
1165 /* On error, stop handling until the next kick. */
1166 if (unlikely(headcount < 0))
1167 goto out;
1168 /* OK, now we need to know about added descriptors. */
1169 if (!headcount) {
1170 if (unlikely(busyloop_intr)) {
1171 vhost_poll_queue(&vq->poll);
1172 } else if (unlikely(vhost_enable_notify(&net->dev, vq))) {
1173 /* They have slipped one in as we were
1174 * doing that: check again. */
1175 vhost_disable_notify(&net->dev, vq);
1176 continue;
1177 }
1178 /* Nothing new? Wait for eventfd to tell us
1179 * they refilled. */
1180 goto out;
1181 }
1182 busyloop_intr = false;
1183 if (nvq->rx_ring)
1184 msg.msg_control = vhost_net_buf_consume(&nvq->rxq);
1185 /* On overrun, truncate and discard */
1186 if (unlikely(headcount > UIO_MAXIOV)) {
1187 iov_iter_init(&msg.msg_iter, ITER_DEST, vq->iov, 1, 1);
1188 err = sock->ops->recvmsg(sock, &msg,
1189 1, MSG_DONTWAIT | MSG_TRUNC);
1190 pr_debug("Discarded rx packet: len %zd\n", sock_len);
1191 continue;
1192 }
1193 /* We don't need to be notified again. */
1194 iov_iter_init(&msg.msg_iter, ITER_DEST, vq->iov, in, vhost_len);
1195 fixup = msg.msg_iter;
1196 if (unlikely((vhost_hlen))) {
1197 /* We will supply the header ourselves
1198 * TODO: support TSO.
1199 */
1200 iov_iter_advance(&msg.msg_iter, vhost_hlen);
1201 }
1202 err = sock->ops->recvmsg(sock, &msg,
1203 sock_len, MSG_DONTWAIT | MSG_TRUNC);
1204 /* Userspace might have consumed the packet meanwhile:
1205 * it's not supposed to do this usually, but might be hard
1206 * to prevent. Discard data we got (if any) and keep going. */
1207 if (unlikely(err != sock_len)) {
1208 pr_debug("Discarded rx packet: "
1209 " len %d, expected %zd\n", err, sock_len);
1210 vhost_discard_vq_desc(vq, headcount);
1211 continue;
1212 }
1213 /* Supply virtio_net_hdr if VHOST_NET_F_VIRTIO_NET_HDR */
1214 if (unlikely(vhost_hlen)) {
1215 if (copy_to_iter(&hdr, sizeof(hdr),
1216 &fixup) != sizeof(hdr)) {
1217 vq_err(vq, "Unable to write vnet_hdr "
1218 "at addr %p\n", vq->iov->iov_base);
1219 goto out;
1220 }
1221 } else {
1222 /* Header came from socket; we'll need to patch
1223 * ->num_buffers over if VIRTIO_NET_F_MRG_RXBUF
1224 */
1225 iov_iter_advance(&fixup, sizeof(hdr));
1226 }
1227 /* TODO: Should check and handle checksum. */
1228
1229 num_buffers = cpu_to_vhost16(vq, headcount);
1230 if (likely(mergeable) &&
1231 copy_to_iter(&num_buffers, sizeof num_buffers,
1232 &fixup) != sizeof num_buffers) {
1233 vq_err(vq, "Failed num_buffers write");
1234 vhost_discard_vq_desc(vq, headcount);
1235 goto out;
1236 }
1237 nvq->done_idx += headcount;
1238 if (nvq->done_idx > VHOST_NET_BATCH)
1239 vhost_net_signal_used(nvq);
1240 if (unlikely(vq_log))
1241 vhost_log_write(vq, vq_log, log, vhost_len,
1242 vq->iov, in);
1243 total_len += vhost_len;
1244 } while (likely(!vhost_exceeds_weight(vq, ++recv_pkts, total_len)));
1245
1246 if (unlikely(busyloop_intr))
1247 vhost_poll_queue(&vq->poll);
1248 else if (!sock_len)
1249 vhost_net_enable_vq(net, vq);
1250out:
1251 vhost_net_signal_used(nvq);
1252 mutex_unlock(&vq->mutex);
1253}
1254
1255static void handle_tx_kick(struct vhost_work *work)
1256{
1257 struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
1258 poll.work);
1259 struct vhost_net *net = container_of(vq->dev, struct vhost_net, dev);
1260
1261 handle_tx(net);
1262}
1263
1264static void handle_rx_kick(struct vhost_work *work)
1265{
1266 struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
1267 poll.work);
1268 struct vhost_net *net = container_of(vq->dev, struct vhost_net, dev);
1269
1270 handle_rx(net);
1271}
1272
1273static void handle_tx_net(struct vhost_work *work)
1274{
1275 struct vhost_net *net = container_of(work, struct vhost_net,
1276 poll[VHOST_NET_VQ_TX].work);
1277 handle_tx(net);
1278}
1279
1280static void handle_rx_net(struct vhost_work *work)
1281{
1282 struct vhost_net *net = container_of(work, struct vhost_net,
1283 poll[VHOST_NET_VQ_RX].work);
1284 handle_rx(net);
1285}
1286
1287static int vhost_net_open(struct inode *inode, struct file *f)
1288{
1289 struct vhost_net *n;
1290 struct vhost_dev *dev;
1291 struct vhost_virtqueue **vqs;
1292 void **queue;
1293 struct xdp_buff *xdp;
1294 int i;
1295
1296 n = kvmalloc(sizeof *n, GFP_KERNEL | __GFP_RETRY_MAYFAIL);
1297 if (!n)
1298 return -ENOMEM;
1299 vqs = kmalloc_array(VHOST_NET_VQ_MAX, sizeof(*vqs), GFP_KERNEL);
1300 if (!vqs) {
1301 kvfree(n);
1302 return -ENOMEM;
1303 }
1304
1305 queue = kmalloc_array(VHOST_NET_BATCH, sizeof(void *),
1306 GFP_KERNEL);
1307 if (!queue) {
1308 kfree(vqs);
1309 kvfree(n);
1310 return -ENOMEM;
1311 }
1312 n->vqs[VHOST_NET_VQ_RX].rxq.queue = queue;
1313
1314 xdp = kmalloc_array(VHOST_NET_BATCH, sizeof(*xdp), GFP_KERNEL);
1315 if (!xdp) {
1316 kfree(vqs);
1317 kvfree(n);
1318 kfree(queue);
1319 return -ENOMEM;
1320 }
1321 n->vqs[VHOST_NET_VQ_TX].xdp = xdp;
1322
1323 dev = &n->dev;
1324 vqs[VHOST_NET_VQ_TX] = &n->vqs[VHOST_NET_VQ_TX].vq;
1325 vqs[VHOST_NET_VQ_RX] = &n->vqs[VHOST_NET_VQ_RX].vq;
1326 n->vqs[VHOST_NET_VQ_TX].vq.handle_kick = handle_tx_kick;
1327 n->vqs[VHOST_NET_VQ_RX].vq.handle_kick = handle_rx_kick;
1328 for (i = 0; i < VHOST_NET_VQ_MAX; i++) {
1329 n->vqs[i].ubufs = NULL;
1330 n->vqs[i].ubuf_info = NULL;
1331 n->vqs[i].upend_idx = 0;
1332 n->vqs[i].done_idx = 0;
1333 n->vqs[i].batched_xdp = 0;
1334 n->vqs[i].vhost_hlen = 0;
1335 n->vqs[i].sock_hlen = 0;
1336 n->vqs[i].rx_ring = NULL;
1337 vhost_net_buf_init(&n->vqs[i].rxq);
1338 }
1339 vhost_dev_init(dev, vqs, VHOST_NET_VQ_MAX,
1340 UIO_MAXIOV + VHOST_NET_BATCH,
1341 VHOST_NET_PKT_WEIGHT, VHOST_NET_WEIGHT, true,
1342 NULL);
1343
1344 vhost_poll_init(n->poll + VHOST_NET_VQ_TX, handle_tx_net, EPOLLOUT, dev);
1345 vhost_poll_init(n->poll + VHOST_NET_VQ_RX, handle_rx_net, EPOLLIN, dev);
1346
1347 f->private_data = n;
1348 n->page_frag.page = NULL;
1349 n->refcnt_bias = 0;
1350
1351 return 0;
1352}
1353
1354static struct socket *vhost_net_stop_vq(struct vhost_net *n,
1355 struct vhost_virtqueue *vq)
1356{
1357 struct socket *sock;
1358 struct vhost_net_virtqueue *nvq =
1359 container_of(vq, struct vhost_net_virtqueue, vq);
1360
1361 mutex_lock(&vq->mutex);
1362 sock = vhost_vq_get_backend(vq);
1363 vhost_net_disable_vq(n, vq);
1364 vhost_vq_set_backend(vq, NULL);
1365 vhost_net_buf_unproduce(nvq);
1366 nvq->rx_ring = NULL;
1367 mutex_unlock(&vq->mutex);
1368 return sock;
1369}
1370
1371static void vhost_net_stop(struct vhost_net *n, struct socket **tx_sock,
1372 struct socket **rx_sock)
1373{
1374 *tx_sock = vhost_net_stop_vq(n, &n->vqs[VHOST_NET_VQ_TX].vq);
1375 *rx_sock = vhost_net_stop_vq(n, &n->vqs[VHOST_NET_VQ_RX].vq);
1376}
1377
1378static void vhost_net_flush(struct vhost_net *n)
1379{
1380 vhost_dev_flush(&n->dev);
1381 if (n->vqs[VHOST_NET_VQ_TX].ubufs) {
1382 mutex_lock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
1383 n->tx_flush = true;
1384 mutex_unlock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
1385 /* Wait for all lower device DMAs done. */
1386 vhost_net_ubuf_put_and_wait(n->vqs[VHOST_NET_VQ_TX].ubufs);
1387 mutex_lock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
1388 n->tx_flush = false;
1389 atomic_set(&n->vqs[VHOST_NET_VQ_TX].ubufs->refcount, 1);
1390 mutex_unlock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
1391 }
1392}
1393
1394static int vhost_net_release(struct inode *inode, struct file *f)
1395{
1396 struct vhost_net *n = f->private_data;
1397 struct socket *tx_sock;
1398 struct socket *rx_sock;
1399
1400 vhost_net_stop(n, &tx_sock, &rx_sock);
1401 vhost_net_flush(n);
1402 vhost_dev_stop(&n->dev);
1403 vhost_dev_cleanup(&n->dev);
1404 vhost_net_vq_reset(n);
1405 if (tx_sock)
1406 sockfd_put(tx_sock);
1407 if (rx_sock)
1408 sockfd_put(rx_sock);
1409 /* Make sure no callbacks are outstanding */
1410 synchronize_rcu();
1411 /* We do an extra flush before freeing memory,
1412 * since jobs can re-queue themselves. */
1413 vhost_net_flush(n);
1414 kfree(n->vqs[VHOST_NET_VQ_RX].rxq.queue);
1415 kfree(n->vqs[VHOST_NET_VQ_TX].xdp);
1416 kfree(n->dev.vqs);
1417 if (n->page_frag.page)
1418 __page_frag_cache_drain(n->page_frag.page, n->refcnt_bias);
1419 kvfree(n);
1420 return 0;
1421}
1422
1423static struct socket *get_raw_socket(int fd)
1424{
1425 int r;
1426 struct socket *sock = sockfd_lookup(fd, &r);
1427
1428 if (!sock)
1429 return ERR_PTR(-ENOTSOCK);
1430
1431 /* Parameter checking */
1432 if (sock->sk->sk_type != SOCK_RAW) {
1433 r = -ESOCKTNOSUPPORT;
1434 goto err;
1435 }
1436
1437 if (sock->sk->sk_family != AF_PACKET) {
1438 r = -EPFNOSUPPORT;
1439 goto err;
1440 }
1441 return sock;
1442err:
1443 sockfd_put(sock);
1444 return ERR_PTR(r);
1445}
1446
1447static struct ptr_ring *get_tap_ptr_ring(struct file *file)
1448{
1449 struct ptr_ring *ring;
1450 ring = tun_get_tx_ring(file);
1451 if (!IS_ERR(ring))
1452 goto out;
1453 ring = tap_get_ptr_ring(file);
1454 if (!IS_ERR(ring))
1455 goto out;
1456 ring = NULL;
1457out:
1458 return ring;
1459}
1460
1461static struct socket *get_tap_socket(int fd)
1462{
1463 struct file *file = fget(fd);
1464 struct socket *sock;
1465
1466 if (!file)
1467 return ERR_PTR(-EBADF);
1468 sock = tun_get_socket(file);
1469 if (!IS_ERR(sock))
1470 return sock;
1471 sock = tap_get_socket(file);
1472 if (IS_ERR(sock))
1473 fput(file);
1474 return sock;
1475}
1476
1477static struct socket *get_socket(int fd)
1478{
1479 struct socket *sock;
1480
1481 /* special case to disable backend */
1482 if (fd == -1)
1483 return NULL;
1484 sock = get_raw_socket(fd);
1485 if (!IS_ERR(sock))
1486 return sock;
1487 sock = get_tap_socket(fd);
1488 if (!IS_ERR(sock))
1489 return sock;
1490 return ERR_PTR(-ENOTSOCK);
1491}
1492
1493static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd)
1494{
1495 struct socket *sock, *oldsock;
1496 struct vhost_virtqueue *vq;
1497 struct vhost_net_virtqueue *nvq;
1498 struct vhost_net_ubuf_ref *ubufs, *oldubufs = NULL;
1499 int r;
1500
1501 mutex_lock(&n->dev.mutex);
1502 r = vhost_dev_check_owner(&n->dev);
1503 if (r)
1504 goto err;
1505
1506 if (index >= VHOST_NET_VQ_MAX) {
1507 r = -ENOBUFS;
1508 goto err;
1509 }
1510 vq = &n->vqs[index].vq;
1511 nvq = &n->vqs[index];
1512 mutex_lock(&vq->mutex);
1513
1514 if (fd == -1)
1515 vhost_clear_msg(&n->dev);
1516
1517 /* Verify that ring has been setup correctly. */
1518 if (!vhost_vq_access_ok(vq)) {
1519 r = -EFAULT;
1520 goto err_vq;
1521 }
1522 sock = get_socket(fd);
1523 if (IS_ERR(sock)) {
1524 r = PTR_ERR(sock);
1525 goto err_vq;
1526 }
1527
1528 /* start polling new socket */
1529 oldsock = vhost_vq_get_backend(vq);
1530 if (sock != oldsock) {
1531 ubufs = vhost_net_ubuf_alloc(vq,
1532 sock && vhost_sock_zcopy(sock));
1533 if (IS_ERR(ubufs)) {
1534 r = PTR_ERR(ubufs);
1535 goto err_ubufs;
1536 }
1537
1538 vhost_net_disable_vq(n, vq);
1539 vhost_vq_set_backend(vq, sock);
1540 vhost_net_buf_unproduce(nvq);
1541 r = vhost_vq_init_access(vq);
1542 if (r)
1543 goto err_used;
1544 r = vhost_net_enable_vq(n, vq);
1545 if (r)
1546 goto err_used;
1547 if (index == VHOST_NET_VQ_RX) {
1548 if (sock)
1549 nvq->rx_ring = get_tap_ptr_ring(sock->file);
1550 else
1551 nvq->rx_ring = NULL;
1552 }
1553
1554 oldubufs = nvq->ubufs;
1555 nvq->ubufs = ubufs;
1556
1557 n->tx_packets = 0;
1558 n->tx_zcopy_err = 0;
1559 n->tx_flush = false;
1560 }
1561
1562 mutex_unlock(&vq->mutex);
1563
1564 if (oldubufs) {
1565 vhost_net_ubuf_put_wait_and_free(oldubufs);
1566 mutex_lock(&vq->mutex);
1567 vhost_zerocopy_signal_used(n, vq);
1568 mutex_unlock(&vq->mutex);
1569 }
1570
1571 if (oldsock) {
1572 vhost_dev_flush(&n->dev);
1573 sockfd_put(oldsock);
1574 }
1575
1576 mutex_unlock(&n->dev.mutex);
1577 return 0;
1578
1579err_used:
1580 vhost_vq_set_backend(vq, oldsock);
1581 vhost_net_enable_vq(n, vq);
1582 if (ubufs)
1583 vhost_net_ubuf_put_wait_and_free(ubufs);
1584err_ubufs:
1585 if (sock)
1586 sockfd_put(sock);
1587err_vq:
1588 mutex_unlock(&vq->mutex);
1589err:
1590 mutex_unlock(&n->dev.mutex);
1591 return r;
1592}
1593
1594static long vhost_net_reset_owner(struct vhost_net *n)
1595{
1596 struct socket *tx_sock = NULL;
1597 struct socket *rx_sock = NULL;
1598 long err;
1599 struct vhost_iotlb *umem;
1600
1601 mutex_lock(&n->dev.mutex);
1602 err = vhost_dev_check_owner(&n->dev);
1603 if (err)
1604 goto done;
1605 umem = vhost_dev_reset_owner_prepare();
1606 if (!umem) {
1607 err = -ENOMEM;
1608 goto done;
1609 }
1610 vhost_net_stop(n, &tx_sock, &rx_sock);
1611 vhost_net_flush(n);
1612 vhost_dev_stop(&n->dev);
1613 vhost_dev_reset_owner(&n->dev, umem);
1614 vhost_net_vq_reset(n);
1615done:
1616 mutex_unlock(&n->dev.mutex);
1617 if (tx_sock)
1618 sockfd_put(tx_sock);
1619 if (rx_sock)
1620 sockfd_put(rx_sock);
1621 return err;
1622}
1623
1624static int vhost_net_set_features(struct vhost_net *n, u64 features)
1625{
1626 size_t vhost_hlen, sock_hlen, hdr_len;
1627 int i;
1628
1629 hdr_len = (features & ((1ULL << VIRTIO_NET_F_MRG_RXBUF) |
1630 (1ULL << VIRTIO_F_VERSION_1))) ?
1631 sizeof(struct virtio_net_hdr_mrg_rxbuf) :
1632 sizeof(struct virtio_net_hdr);
1633 if (features & (1 << VHOST_NET_F_VIRTIO_NET_HDR)) {
1634 /* vhost provides vnet_hdr */
1635 vhost_hlen = hdr_len;
1636 sock_hlen = 0;
1637 } else {
1638 /* socket provides vnet_hdr */
1639 vhost_hlen = 0;
1640 sock_hlen = hdr_len;
1641 }
1642 mutex_lock(&n->dev.mutex);
1643 if ((features & (1 << VHOST_F_LOG_ALL)) &&
1644 !vhost_log_access_ok(&n->dev))
1645 goto out_unlock;
1646
1647 if ((features & (1ULL << VIRTIO_F_ACCESS_PLATFORM))) {
1648 if (vhost_init_device_iotlb(&n->dev, true))
1649 goto out_unlock;
1650 }
1651
1652 for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
1653 mutex_lock(&n->vqs[i].vq.mutex);
1654 n->vqs[i].vq.acked_features = features;
1655 n->vqs[i].vhost_hlen = vhost_hlen;
1656 n->vqs[i].sock_hlen = sock_hlen;
1657 mutex_unlock(&n->vqs[i].vq.mutex);
1658 }
1659 mutex_unlock(&n->dev.mutex);
1660 return 0;
1661
1662out_unlock:
1663 mutex_unlock(&n->dev.mutex);
1664 return -EFAULT;
1665}
1666
1667static long vhost_net_set_owner(struct vhost_net *n)
1668{
1669 int r;
1670
1671 mutex_lock(&n->dev.mutex);
1672 if (vhost_dev_has_owner(&n->dev)) {
1673 r = -EBUSY;
1674 goto out;
1675 }
1676 r = vhost_net_set_ubuf_info(n);
1677 if (r)
1678 goto out;
1679 r = vhost_dev_set_owner(&n->dev);
1680 if (r)
1681 vhost_net_clear_ubuf_info(n);
1682 vhost_net_flush(n);
1683out:
1684 mutex_unlock(&n->dev.mutex);
1685 return r;
1686}
1687
1688static long vhost_net_ioctl(struct file *f, unsigned int ioctl,
1689 unsigned long arg)
1690{
1691 struct vhost_net *n = f->private_data;
1692 void __user *argp = (void __user *)arg;
1693 u64 __user *featurep = argp;
1694 struct vhost_vring_file backend;
1695 u64 features;
1696 int r;
1697
1698 switch (ioctl) {
1699 case VHOST_NET_SET_BACKEND:
1700 if (copy_from_user(&backend, argp, sizeof backend))
1701 return -EFAULT;
1702 return vhost_net_set_backend(n, backend.index, backend.fd);
1703 case VHOST_GET_FEATURES:
1704 features = VHOST_NET_FEATURES;
1705 if (copy_to_user(featurep, &features, sizeof features))
1706 return -EFAULT;
1707 return 0;
1708 case VHOST_SET_FEATURES:
1709 if (copy_from_user(&features, featurep, sizeof features))
1710 return -EFAULT;
1711 if (features & ~VHOST_NET_FEATURES)
1712 return -EOPNOTSUPP;
1713 return vhost_net_set_features(n, features);
1714 case VHOST_GET_BACKEND_FEATURES:
1715 features = VHOST_NET_BACKEND_FEATURES;
1716 if (copy_to_user(featurep, &features, sizeof(features)))
1717 return -EFAULT;
1718 return 0;
1719 case VHOST_SET_BACKEND_FEATURES:
1720 if (copy_from_user(&features, featurep, sizeof(features)))
1721 return -EFAULT;
1722 if (features & ~VHOST_NET_BACKEND_FEATURES)
1723 return -EOPNOTSUPP;
1724 vhost_set_backend_features(&n->dev, features);
1725 return 0;
1726 case VHOST_RESET_OWNER:
1727 return vhost_net_reset_owner(n);
1728 case VHOST_SET_OWNER:
1729 return vhost_net_set_owner(n);
1730 default:
1731 mutex_lock(&n->dev.mutex);
1732 r = vhost_dev_ioctl(&n->dev, ioctl, argp);
1733 if (r == -ENOIOCTLCMD)
1734 r = vhost_vring_ioctl(&n->dev, ioctl, argp);
1735 else
1736 vhost_net_flush(n);
1737 mutex_unlock(&n->dev.mutex);
1738 return r;
1739 }
1740}
1741
1742static ssize_t vhost_net_chr_read_iter(struct kiocb *iocb, struct iov_iter *to)
1743{
1744 struct file *file = iocb->ki_filp;
1745 struct vhost_net *n = file->private_data;
1746 struct vhost_dev *dev = &n->dev;
1747 int noblock = file->f_flags & O_NONBLOCK;
1748
1749 return vhost_chr_read_iter(dev, to, noblock);
1750}
1751
1752static ssize_t vhost_net_chr_write_iter(struct kiocb *iocb,
1753 struct iov_iter *from)
1754{
1755 struct file *file = iocb->ki_filp;
1756 struct vhost_net *n = file->private_data;
1757 struct vhost_dev *dev = &n->dev;
1758
1759 return vhost_chr_write_iter(dev, from);
1760}
1761
1762static __poll_t vhost_net_chr_poll(struct file *file, poll_table *wait)
1763{
1764 struct vhost_net *n = file->private_data;
1765 struct vhost_dev *dev = &n->dev;
1766
1767 return vhost_chr_poll(file, dev, wait);
1768}
1769
1770static const struct file_operations vhost_net_fops = {
1771 .owner = THIS_MODULE,
1772 .release = vhost_net_release,
1773 .read_iter = vhost_net_chr_read_iter,
1774 .write_iter = vhost_net_chr_write_iter,
1775 .poll = vhost_net_chr_poll,
1776 .unlocked_ioctl = vhost_net_ioctl,
1777 .compat_ioctl = compat_ptr_ioctl,
1778 .open = vhost_net_open,
1779 .llseek = noop_llseek,
1780};
1781
1782static struct miscdevice vhost_net_misc = {
1783 .minor = VHOST_NET_MINOR,
1784 .name = "vhost-net",
1785 .fops = &vhost_net_fops,
1786};
1787
1788static int __init vhost_net_init(void)
1789{
1790 if (experimental_zcopytx)
1791 vhost_net_enable_zcopy(VHOST_NET_VQ_TX);
1792 return misc_register(&vhost_net_misc);
1793}
1794module_init(vhost_net_init);
1795
1796static void __exit vhost_net_exit(void)
1797{
1798 misc_deregister(&vhost_net_misc);
1799}
1800module_exit(vhost_net_exit);
1801
1802MODULE_VERSION("0.0.1");
1803MODULE_LICENSE("GPL v2");
1804MODULE_AUTHOR("Michael S. Tsirkin");
1805MODULE_DESCRIPTION("Host kernel accelerator for virtio net");
1806MODULE_ALIAS_MISCDEV(VHOST_NET_MINOR);
1807MODULE_ALIAS("devname:vhost-net");