vhost: support event index
[linux-2.6.git] / drivers / vhost / net.c
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/mutex.h>
16 #include <linux/workqueue.h>
17 #include <linux/rcupdate.h>
18 #include <linux/file.h>
19 #include <linux/slab.h>
20
21 #include <linux/net.h>
22 #include <linux/if_packet.h>
23 #include <linux/if_arp.h>
24 #include <linux/if_tun.h>
25 #include <linux/if_macvlan.h>
26
27 #include <net/sock.h>
28
29 #include "vhost.h"
30
31 /* Max number of bytes transferred before requeueing the job.
32  * Using this limit prevents one virtqueue from starving others. */
33 #define VHOST_NET_WEIGHT 0x80000
34
35 enum {
36         VHOST_NET_VQ_RX = 0,
37         VHOST_NET_VQ_TX = 1,
38         VHOST_NET_VQ_MAX = 2,
39 };
40
41 enum vhost_net_poll_state {
42         VHOST_NET_POLL_DISABLED = 0,
43         VHOST_NET_POLL_STARTED = 1,
44         VHOST_NET_POLL_STOPPED = 2,
45 };
46
47 struct vhost_net {
48         struct vhost_dev dev;
49         struct vhost_virtqueue vqs[VHOST_NET_VQ_MAX];
50         struct vhost_poll poll[VHOST_NET_VQ_MAX];
51         /* Tells us whether we are polling a socket for TX.
52          * We only do this when socket buffer fills up.
53          * Protected by tx vq lock. */
54         enum vhost_net_poll_state tx_poll_state;
55 };
56
57 /* Pop first len bytes from iovec. Return number of segments used. */
58 static int move_iovec_hdr(struct iovec *from, struct iovec *to,
59                           size_t len, int iov_count)
60 {
61         int seg = 0;
62         size_t size;
63
64         while (len && seg < iov_count) {
65                 size = min(from->iov_len, len);
66                 to->iov_base = from->iov_base;
67                 to->iov_len = size;
68                 from->iov_len -= size;
69                 from->iov_base += size;
70                 len -= size;
71                 ++from;
72                 ++to;
73                 ++seg;
74         }
75         return seg;
76 }
77 /* Copy iovec entries for len bytes from iovec. */
78 static void copy_iovec_hdr(const struct iovec *from, struct iovec *to,
79                            size_t len, int iovcount)
80 {
81         int seg = 0;
82         size_t size;
83
84         while (len && seg < iovcount) {
85                 size = min(from->iov_len, len);
86                 to->iov_base = from->iov_base;
87                 to->iov_len = size;
88                 len -= size;
89                 ++from;
90                 ++to;
91                 ++seg;
92         }
93 }
94
95 /* Caller must have TX VQ lock */
96 static void tx_poll_stop(struct vhost_net *net)
97 {
98         if (likely(net->tx_poll_state != VHOST_NET_POLL_STARTED))
99                 return;
100         vhost_poll_stop(net->poll + VHOST_NET_VQ_TX);
101         net->tx_poll_state = VHOST_NET_POLL_STOPPED;
102 }
103
104 /* Caller must have TX VQ lock */
105 static void tx_poll_start(struct vhost_net *net, struct socket *sock)
106 {
107         if (unlikely(net->tx_poll_state != VHOST_NET_POLL_STOPPED))
108                 return;
109         vhost_poll_start(net->poll + VHOST_NET_VQ_TX, sock->file);
110         net->tx_poll_state = VHOST_NET_POLL_STARTED;
111 }
112
113 /* Expects to be always run from workqueue - which acts as
114  * read-size critical section for our kind of RCU. */
115 static void handle_tx(struct vhost_net *net)
116 {
117         struct vhost_virtqueue *vq = &net->dev.vqs[VHOST_NET_VQ_TX];
118         unsigned out, in, s;
119         int head;
120         struct msghdr msg = {
121                 .msg_name = NULL,
122                 .msg_namelen = 0,
123                 .msg_control = NULL,
124                 .msg_controllen = 0,
125                 .msg_iov = vq->iov,
126                 .msg_flags = MSG_DONTWAIT,
127         };
128         size_t len, total_len = 0;
129         int err, wmem;
130         size_t hdr_size;
131         struct socket *sock;
132
133         /* TODO: check that we are running from vhost_worker? */
134         sock = rcu_dereference_check(vq->private_data, 1);
135         if (!sock)
136                 return;
137
138         wmem = atomic_read(&sock->sk->sk_wmem_alloc);
139         if (wmem >= sock->sk->sk_sndbuf) {
140                 mutex_lock(&vq->mutex);
141                 tx_poll_start(net, sock);
142                 mutex_unlock(&vq->mutex);
143                 return;
144         }
145
146         mutex_lock(&vq->mutex);
147         vhost_disable_notify(&net->dev, vq);
148
149         if (wmem < sock->sk->sk_sndbuf / 2)
150                 tx_poll_stop(net);
151         hdr_size = vq->vhost_hlen;
152
153         for (;;) {
154                 head = vhost_get_vq_desc(&net->dev, vq, vq->iov,
155                                          ARRAY_SIZE(vq->iov),
156                                          &out, &in,
157                                          NULL, NULL);
158                 /* On error, stop handling until the next kick. */
159                 if (unlikely(head < 0))
160                         break;
161                 /* Nothing new?  Wait for eventfd to tell us they refilled. */
162                 if (head == vq->num) {
163                         wmem = atomic_read(&sock->sk->sk_wmem_alloc);
164                         if (wmem >= sock->sk->sk_sndbuf * 3 / 4) {
165                                 tx_poll_start(net, sock);
166                                 set_bit(SOCK_ASYNC_NOSPACE, &sock->flags);
167                                 break;
168                         }
169                         if (unlikely(vhost_enable_notify(&net->dev, vq))) {
170                                 vhost_disable_notify(&net->dev, vq);
171                                 continue;
172                         }
173                         break;
174                 }
175                 if (in) {
176                         vq_err(vq, "Unexpected descriptor format for TX: "
177                                "out %d, int %d\n", out, in);
178                         break;
179                 }
180                 /* Skip header. TODO: support TSO. */
181                 s = move_iovec_hdr(vq->iov, vq->hdr, hdr_size, out);
182                 msg.msg_iovlen = out;
183                 len = iov_length(vq->iov, out);
184                 /* Sanity check */
185                 if (!len) {
186                         vq_err(vq, "Unexpected header len for TX: "
187                                "%zd expected %zd\n",
188                                iov_length(vq->hdr, s), hdr_size);
189                         break;
190                 }
191                 /* TODO: Check specific error and bomb out unless ENOBUFS? */
192                 err = sock->ops->sendmsg(NULL, sock, &msg, len);
193                 if (unlikely(err < 0)) {
194                         vhost_discard_vq_desc(vq, 1);
195                         tx_poll_start(net, sock);
196                         break;
197                 }
198                 if (err != len)
199                         pr_debug("Truncated TX packet: "
200                                  " len %d != %zd\n", err, len);
201                 vhost_add_used_and_signal(&net->dev, vq, head, 0);
202                 total_len += len;
203                 if (unlikely(total_len >= VHOST_NET_WEIGHT)) {
204                         vhost_poll_queue(&vq->poll);
205                         break;
206                 }
207         }
208
209         mutex_unlock(&vq->mutex);
210 }
211
212 static int peek_head_len(struct sock *sk)
213 {
214         struct sk_buff *head;
215         int len = 0;
216         unsigned long flags;
217
218         spin_lock_irqsave(&sk->sk_receive_queue.lock, flags);
219         head = skb_peek(&sk->sk_receive_queue);
220         if (likely(head))
221                 len = head->len;
222         spin_unlock_irqrestore(&sk->sk_receive_queue.lock, flags);
223         return len;
224 }
225
226 /* This is a multi-buffer version of vhost_get_desc, that works if
227  *      vq has read descriptors only.
228  * @vq          - the relevant virtqueue
229  * @datalen     - data length we'll be reading
230  * @iovcount    - returned count of io vectors we fill
231  * @log         - vhost log
232  * @log_num     - log offset
233  * @quota       - headcount quota, 1 for big buffer
234  *      returns number of buffer heads allocated, negative on error
235  */
236 static int get_rx_bufs(struct vhost_virtqueue *vq,
237                        struct vring_used_elem *heads,
238                        int datalen,
239                        unsigned *iovcount,
240                        struct vhost_log *log,
241                        unsigned *log_num,
242                        unsigned int quota)
243 {
244         unsigned int out, in;
245         int seg = 0;
246         int headcount = 0;
247         unsigned d;
248         int r, nlogs = 0;
249
250         while (datalen > 0 && headcount < quota) {
251                 if (unlikely(seg >= UIO_MAXIOV)) {
252                         r = -ENOBUFS;
253                         goto err;
254                 }
255                 d = vhost_get_vq_desc(vq->dev, vq, vq->iov + seg,
256                                       ARRAY_SIZE(vq->iov) - seg, &out,
257                                       &in, log, log_num);
258                 if (d == vq->num) {
259                         r = 0;
260                         goto err;
261                 }
262                 if (unlikely(out || in <= 0)) {
263                         vq_err(vq, "unexpected descriptor format for RX: "
264                                 "out %d, in %d\n", out, in);
265                         r = -EINVAL;
266                         goto err;
267                 }
268                 if (unlikely(log)) {
269                         nlogs += *log_num;
270                         log += *log_num;
271                 }
272                 heads[headcount].id = d;
273                 heads[headcount].len = iov_length(vq->iov + seg, in);
274                 datalen -= heads[headcount].len;
275                 ++headcount;
276                 seg += in;
277         }
278         heads[headcount - 1].len += datalen;
279         *iovcount = seg;
280         if (unlikely(log))
281                 *log_num = nlogs;
282         return headcount;
283 err:
284         vhost_discard_vq_desc(vq, headcount);
285         return r;
286 }
287
288 /* Expects to be always run from workqueue - which acts as
289  * read-size critical section for our kind of RCU. */
290 static void handle_rx(struct vhost_net *net)
291 {
292         struct vhost_virtqueue *vq = &net->dev.vqs[VHOST_NET_VQ_RX];
293         unsigned uninitialized_var(in), log;
294         struct vhost_log *vq_log;
295         struct msghdr msg = {
296                 .msg_name = NULL,
297                 .msg_namelen = 0,
298                 .msg_control = NULL, /* FIXME: get and handle RX aux data. */
299                 .msg_controllen = 0,
300                 .msg_iov = vq->iov,
301                 .msg_flags = MSG_DONTWAIT,
302         };
303         struct virtio_net_hdr_mrg_rxbuf hdr = {
304                 .hdr.flags = 0,
305                 .hdr.gso_type = VIRTIO_NET_HDR_GSO_NONE
306         };
307         size_t total_len = 0;
308         int err, headcount, mergeable;
309         size_t vhost_hlen, sock_hlen;
310         size_t vhost_len, sock_len;
311         /* TODO: check that we are running from vhost_worker? */
312         struct socket *sock = rcu_dereference_check(vq->private_data, 1);
313
314         if (!sock)
315                 return;
316
317         mutex_lock(&vq->mutex);
318         vhost_disable_notify(&net->dev, vq);
319         vhost_hlen = vq->vhost_hlen;
320         sock_hlen = vq->sock_hlen;
321
322         vq_log = unlikely(vhost_has_feature(&net->dev, VHOST_F_LOG_ALL)) ?
323                 vq->log : NULL;
324         mergeable = vhost_has_feature(&net->dev, VIRTIO_NET_F_MRG_RXBUF);
325
326         while ((sock_len = peek_head_len(sock->sk))) {
327                 sock_len += sock_hlen;
328                 vhost_len = sock_len + vhost_hlen;
329                 headcount = get_rx_bufs(vq, vq->heads, vhost_len,
330                                         &in, vq_log, &log,
331                                         likely(mergeable) ? UIO_MAXIOV : 1);
332                 /* On error, stop handling until the next kick. */
333                 if (unlikely(headcount < 0))
334                         break;
335                 /* OK, now we need to know about added descriptors. */
336                 if (!headcount) {
337                         if (unlikely(vhost_enable_notify(&net->dev, vq))) {
338                                 /* They have slipped one in as we were
339                                  * doing that: check again. */
340                                 vhost_disable_notify(&net->dev, vq);
341                                 continue;
342                         }
343                         /* Nothing new?  Wait for eventfd to tell us
344                          * they refilled. */
345                         break;
346                 }
347                 /* We don't need to be notified again. */
348                 if (unlikely((vhost_hlen)))
349                         /* Skip header. TODO: support TSO. */
350                         move_iovec_hdr(vq->iov, vq->hdr, vhost_hlen, in);
351                 else
352                         /* Copy the header for use in VIRTIO_NET_F_MRG_RXBUF:
353                          * needed because recvmsg can modify msg_iov. */
354                         copy_iovec_hdr(vq->iov, vq->hdr, sock_hlen, in);
355                 msg.msg_iovlen = in;
356                 err = sock->ops->recvmsg(NULL, sock, &msg,
357                                          sock_len, MSG_DONTWAIT | MSG_TRUNC);
358                 /* Userspace might have consumed the packet meanwhile:
359                  * it's not supposed to do this usually, but might be hard
360                  * to prevent. Discard data we got (if any) and keep going. */
361                 if (unlikely(err != sock_len)) {
362                         pr_debug("Discarded rx packet: "
363                                  " len %d, expected %zd\n", err, sock_len);
364                         vhost_discard_vq_desc(vq, headcount);
365                         continue;
366                 }
367                 if (unlikely(vhost_hlen) &&
368                     memcpy_toiovecend(vq->hdr, (unsigned char *)&hdr, 0,
369                                       vhost_hlen)) {
370                         vq_err(vq, "Unable to write vnet_hdr at addr %p\n",
371                                vq->iov->iov_base);
372                         break;
373                 }
374                 /* TODO: Should check and handle checksum. */
375                 if (likely(mergeable) &&
376                     memcpy_toiovecend(vq->hdr, (unsigned char *)&headcount,
377                                       offsetof(typeof(hdr), num_buffers),
378                                       sizeof hdr.num_buffers)) {
379                         vq_err(vq, "Failed num_buffers write");
380                         vhost_discard_vq_desc(vq, headcount);
381                         break;
382                 }
383                 vhost_add_used_and_signal_n(&net->dev, vq, vq->heads,
384                                             headcount);
385                 if (unlikely(vq_log))
386                         vhost_log_write(vq, vq_log, log, vhost_len);
387                 total_len += vhost_len;
388                 if (unlikely(total_len >= VHOST_NET_WEIGHT)) {
389                         vhost_poll_queue(&vq->poll);
390                         break;
391                 }
392         }
393
394         mutex_unlock(&vq->mutex);
395 }
396
397 static void handle_tx_kick(struct vhost_work *work)
398 {
399         struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
400                                                   poll.work);
401         struct vhost_net *net = container_of(vq->dev, struct vhost_net, dev);
402
403         handle_tx(net);
404 }
405
406 static void handle_rx_kick(struct vhost_work *work)
407 {
408         struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
409                                                   poll.work);
410         struct vhost_net *net = container_of(vq->dev, struct vhost_net, dev);
411
412         handle_rx(net);
413 }
414
415 static void handle_tx_net(struct vhost_work *work)
416 {
417         struct vhost_net *net = container_of(work, struct vhost_net,
418                                              poll[VHOST_NET_VQ_TX].work);
419         handle_tx(net);
420 }
421
422 static void handle_rx_net(struct vhost_work *work)
423 {
424         struct vhost_net *net = container_of(work, struct vhost_net,
425                                              poll[VHOST_NET_VQ_RX].work);
426         handle_rx(net);
427 }
428
429 static int vhost_net_open(struct inode *inode, struct file *f)
430 {
431         struct vhost_net *n = kmalloc(sizeof *n, GFP_KERNEL);
432         struct vhost_dev *dev;
433         int r;
434
435         if (!n)
436                 return -ENOMEM;
437
438         dev = &n->dev;
439         n->vqs[VHOST_NET_VQ_TX].handle_kick = handle_tx_kick;
440         n->vqs[VHOST_NET_VQ_RX].handle_kick = handle_rx_kick;
441         r = vhost_dev_init(dev, n->vqs, VHOST_NET_VQ_MAX);
442         if (r < 0) {
443                 kfree(n);
444                 return r;
445         }
446
447         vhost_poll_init(n->poll + VHOST_NET_VQ_TX, handle_tx_net, POLLOUT, dev);
448         vhost_poll_init(n->poll + VHOST_NET_VQ_RX, handle_rx_net, POLLIN, dev);
449         n->tx_poll_state = VHOST_NET_POLL_DISABLED;
450
451         f->private_data = n;
452
453         return 0;
454 }
455
456 static void vhost_net_disable_vq(struct vhost_net *n,
457                                  struct vhost_virtqueue *vq)
458 {
459         if (!vq->private_data)
460                 return;
461         if (vq == n->vqs + VHOST_NET_VQ_TX) {
462                 tx_poll_stop(n);
463                 n->tx_poll_state = VHOST_NET_POLL_DISABLED;
464         } else
465                 vhost_poll_stop(n->poll + VHOST_NET_VQ_RX);
466 }
467
468 static void vhost_net_enable_vq(struct vhost_net *n,
469                                 struct vhost_virtqueue *vq)
470 {
471         struct socket *sock;
472
473         sock = rcu_dereference_protected(vq->private_data,
474                                          lockdep_is_held(&vq->mutex));
475         if (!sock)
476                 return;
477         if (vq == n->vqs + VHOST_NET_VQ_TX) {
478                 n->tx_poll_state = VHOST_NET_POLL_STOPPED;
479                 tx_poll_start(n, sock);
480         } else
481                 vhost_poll_start(n->poll + VHOST_NET_VQ_RX, sock->file);
482 }
483
484 static struct socket *vhost_net_stop_vq(struct vhost_net *n,
485                                         struct vhost_virtqueue *vq)
486 {
487         struct socket *sock;
488
489         mutex_lock(&vq->mutex);
490         sock = rcu_dereference_protected(vq->private_data,
491                                          lockdep_is_held(&vq->mutex));
492         vhost_net_disable_vq(n, vq);
493         rcu_assign_pointer(vq->private_data, NULL);
494         mutex_unlock(&vq->mutex);
495         return sock;
496 }
497
498 static void vhost_net_stop(struct vhost_net *n, struct socket **tx_sock,
499                            struct socket **rx_sock)
500 {
501         *tx_sock = vhost_net_stop_vq(n, n->vqs + VHOST_NET_VQ_TX);
502         *rx_sock = vhost_net_stop_vq(n, n->vqs + VHOST_NET_VQ_RX);
503 }
504
505 static void vhost_net_flush_vq(struct vhost_net *n, int index)
506 {
507         vhost_poll_flush(n->poll + index);
508         vhost_poll_flush(&n->dev.vqs[index].poll);
509 }
510
511 static void vhost_net_flush(struct vhost_net *n)
512 {
513         vhost_net_flush_vq(n, VHOST_NET_VQ_TX);
514         vhost_net_flush_vq(n, VHOST_NET_VQ_RX);
515 }
516
517 static int vhost_net_release(struct inode *inode, struct file *f)
518 {
519         struct vhost_net *n = f->private_data;
520         struct socket *tx_sock;
521         struct socket *rx_sock;
522
523         vhost_net_stop(n, &tx_sock, &rx_sock);
524         vhost_net_flush(n);
525         vhost_dev_cleanup(&n->dev);
526         if (tx_sock)
527                 fput(tx_sock->file);
528         if (rx_sock)
529                 fput(rx_sock->file);
530         /* We do an extra flush before freeing memory,
531          * since jobs can re-queue themselves. */
532         vhost_net_flush(n);
533         kfree(n);
534         return 0;
535 }
536
537 static struct socket *get_raw_socket(int fd)
538 {
539         struct {
540                 struct sockaddr_ll sa;
541                 char  buf[MAX_ADDR_LEN];
542         } uaddr;
543         int uaddr_len = sizeof uaddr, r;
544         struct socket *sock = sockfd_lookup(fd, &r);
545
546         if (!sock)
547                 return ERR_PTR(-ENOTSOCK);
548
549         /* Parameter checking */
550         if (sock->sk->sk_type != SOCK_RAW) {
551                 r = -ESOCKTNOSUPPORT;
552                 goto err;
553         }
554
555         r = sock->ops->getname(sock, (struct sockaddr *)&uaddr.sa,
556                                &uaddr_len, 0);
557         if (r)
558                 goto err;
559
560         if (uaddr.sa.sll_family != AF_PACKET) {
561                 r = -EPFNOSUPPORT;
562                 goto err;
563         }
564         return sock;
565 err:
566         fput(sock->file);
567         return ERR_PTR(r);
568 }
569
570 static struct socket *get_tap_socket(int fd)
571 {
572         struct file *file = fget(fd);
573         struct socket *sock;
574
575         if (!file)
576                 return ERR_PTR(-EBADF);
577         sock = tun_get_socket(file);
578         if (!IS_ERR(sock))
579                 return sock;
580         sock = macvtap_get_socket(file);
581         if (IS_ERR(sock))
582                 fput(file);
583         return sock;
584 }
585
586 static struct socket *get_socket(int fd)
587 {
588         struct socket *sock;
589
590         /* special case to disable backend */
591         if (fd == -1)
592                 return NULL;
593         sock = get_raw_socket(fd);
594         if (!IS_ERR(sock))
595                 return sock;
596         sock = get_tap_socket(fd);
597         if (!IS_ERR(sock))
598                 return sock;
599         return ERR_PTR(-ENOTSOCK);
600 }
601
602 static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd)
603 {
604         struct socket *sock, *oldsock;
605         struct vhost_virtqueue *vq;
606         int r;
607
608         mutex_lock(&n->dev.mutex);
609         r = vhost_dev_check_owner(&n->dev);
610         if (r)
611                 goto err;
612
613         if (index >= VHOST_NET_VQ_MAX) {
614                 r = -ENOBUFS;
615                 goto err;
616         }
617         vq = n->vqs + index;
618         mutex_lock(&vq->mutex);
619
620         /* Verify that ring has been setup correctly. */
621         if (!vhost_vq_access_ok(vq)) {
622                 r = -EFAULT;
623                 goto err_vq;
624         }
625         sock = get_socket(fd);
626         if (IS_ERR(sock)) {
627                 r = PTR_ERR(sock);
628                 goto err_vq;
629         }
630
631         /* start polling new socket */
632         oldsock = rcu_dereference_protected(vq->private_data,
633                                             lockdep_is_held(&vq->mutex));
634         if (sock != oldsock) {
635                 vhost_net_disable_vq(n, vq);
636                 rcu_assign_pointer(vq->private_data, sock);
637                 vhost_net_enable_vq(n, vq);
638         }
639
640         mutex_unlock(&vq->mutex);
641
642         if (oldsock) {
643                 vhost_net_flush_vq(n, index);
644                 fput(oldsock->file);
645         }
646
647         mutex_unlock(&n->dev.mutex);
648         return 0;
649
650 err_vq:
651         mutex_unlock(&vq->mutex);
652 err:
653         mutex_unlock(&n->dev.mutex);
654         return r;
655 }
656
657 static long vhost_net_reset_owner(struct vhost_net *n)
658 {
659         struct socket *tx_sock = NULL;
660         struct socket *rx_sock = NULL;
661         long err;
662
663         mutex_lock(&n->dev.mutex);
664         err = vhost_dev_check_owner(&n->dev);
665         if (err)
666                 goto done;
667         vhost_net_stop(n, &tx_sock, &rx_sock);
668         vhost_net_flush(n);
669         err = vhost_dev_reset_owner(&n->dev);
670 done:
671         mutex_unlock(&n->dev.mutex);
672         if (tx_sock)
673                 fput(tx_sock->file);
674         if (rx_sock)
675                 fput(rx_sock->file);
676         return err;
677 }
678
679 static int vhost_net_set_features(struct vhost_net *n, u64 features)
680 {
681         size_t vhost_hlen, sock_hlen, hdr_len;
682         int i;
683
684         hdr_len = (features & (1 << VIRTIO_NET_F_MRG_RXBUF)) ?
685                         sizeof(struct virtio_net_hdr_mrg_rxbuf) :
686                         sizeof(struct virtio_net_hdr);
687         if (features & (1 << VHOST_NET_F_VIRTIO_NET_HDR)) {
688                 /* vhost provides vnet_hdr */
689                 vhost_hlen = hdr_len;
690                 sock_hlen = 0;
691         } else {
692                 /* socket provides vnet_hdr */
693                 vhost_hlen = 0;
694                 sock_hlen = hdr_len;
695         }
696         mutex_lock(&n->dev.mutex);
697         if ((features & (1 << VHOST_F_LOG_ALL)) &&
698             !vhost_log_access_ok(&n->dev)) {
699                 mutex_unlock(&n->dev.mutex);
700                 return -EFAULT;
701         }
702         n->dev.acked_features = features;
703         smp_wmb();
704         for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
705                 mutex_lock(&n->vqs[i].mutex);
706                 n->vqs[i].vhost_hlen = vhost_hlen;
707                 n->vqs[i].sock_hlen = sock_hlen;
708                 mutex_unlock(&n->vqs[i].mutex);
709         }
710         vhost_net_flush(n);
711         mutex_unlock(&n->dev.mutex);
712         return 0;
713 }
714
715 static long vhost_net_ioctl(struct file *f, unsigned int ioctl,
716                             unsigned long arg)
717 {
718         struct vhost_net *n = f->private_data;
719         void __user *argp = (void __user *)arg;
720         u64 __user *featurep = argp;
721         struct vhost_vring_file backend;
722         u64 features;
723         int r;
724
725         switch (ioctl) {
726         case VHOST_NET_SET_BACKEND:
727                 if (copy_from_user(&backend, argp, sizeof backend))
728                         return -EFAULT;
729                 return vhost_net_set_backend(n, backend.index, backend.fd);
730         case VHOST_GET_FEATURES:
731                 features = VHOST_FEATURES;
732                 if (copy_to_user(featurep, &features, sizeof features))
733                         return -EFAULT;
734                 return 0;
735         case VHOST_SET_FEATURES:
736                 if (copy_from_user(&features, featurep, sizeof features))
737                         return -EFAULT;
738                 if (features & ~VHOST_FEATURES)
739                         return -EOPNOTSUPP;
740                 return vhost_net_set_features(n, features);
741         case VHOST_RESET_OWNER:
742                 return vhost_net_reset_owner(n);
743         default:
744                 mutex_lock(&n->dev.mutex);
745                 r = vhost_dev_ioctl(&n->dev, ioctl, arg);
746                 vhost_net_flush(n);
747                 mutex_unlock(&n->dev.mutex);
748                 return r;
749         }
750 }
751
752 #ifdef CONFIG_COMPAT
753 static long vhost_net_compat_ioctl(struct file *f, unsigned int ioctl,
754                                    unsigned long arg)
755 {
756         return vhost_net_ioctl(f, ioctl, (unsigned long)compat_ptr(arg));
757 }
758 #endif
759
760 static const struct file_operations vhost_net_fops = {
761         .owner          = THIS_MODULE,
762         .release        = vhost_net_release,
763         .unlocked_ioctl = vhost_net_ioctl,
764 #ifdef CONFIG_COMPAT
765         .compat_ioctl   = vhost_net_compat_ioctl,
766 #endif
767         .open           = vhost_net_open,
768         .llseek         = noop_llseek,
769 };
770
771 static struct miscdevice vhost_net_misc = {
772         MISC_DYNAMIC_MINOR,
773         "vhost-net",
774         &vhost_net_fops,
775 };
776
777 static int vhost_net_init(void)
778 {
779         return misc_register(&vhost_net_misc);
780 }
781 module_init(vhost_net_init);
782
783 static void vhost_net_exit(void)
784 {
785         misc_deregister(&vhost_net_misc);
786 }
787 module_exit(vhost_net_exit);
788
789 MODULE_VERSION("0.0.1");
790 MODULE_LICENSE("GPL v2");
791 MODULE_AUTHOR("Michael S. Tsirkin");
792 MODULE_DESCRIPTION("Host kernel accelerator for virtio net");