Merge branch 'llseek' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/bkl
[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/mmu_context.h>
14 #include <linux/miscdevice.h>
15 #include <linux/module.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
32 /* Max number of bytes transferred before requeueing the job.
33  * Using this limit prevents one virtqueue from starving others. */
34 #define VHOST_NET_WEIGHT 0x80000
35
36 enum {
37         VHOST_NET_VQ_RX = 0,
38         VHOST_NET_VQ_TX = 1,
39         VHOST_NET_VQ_MAX = 2,
40 };
41
42 enum vhost_net_poll_state {
43         VHOST_NET_POLL_DISABLED = 0,
44         VHOST_NET_POLL_STARTED = 1,
45         VHOST_NET_POLL_STOPPED = 2,
46 };
47
48 struct vhost_net {
49         struct vhost_dev dev;
50         struct vhost_virtqueue vqs[VHOST_NET_VQ_MAX];
51         struct vhost_poll poll[VHOST_NET_VQ_MAX];
52         /* Tells us whether we are polling a socket for TX.
53          * We only do this when socket buffer fills up.
54          * Protected by tx vq lock. */
55         enum vhost_net_poll_state tx_poll_state;
56 };
57
58 /* Pop first len bytes from iovec. Return number of segments used. */
59 static int move_iovec_hdr(struct iovec *from, struct iovec *to,
60                           size_t len, int iov_count)
61 {
62         int seg = 0;
63         size_t size;
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         while (len && seg < iovcount) {
84                 size = min(from->iov_len, len);
85                 to->iov_base = from->iov_base;
86                 to->iov_len = size;
87                 len -= size;
88                 ++from;
89                 ++to;
90                 ++seg;
91         }
92 }
93
94 /* Caller must have TX VQ lock */
95 static void tx_poll_stop(struct vhost_net *net)
96 {
97         if (likely(net->tx_poll_state != VHOST_NET_POLL_STARTED))
98                 return;
99         vhost_poll_stop(net->poll + VHOST_NET_VQ_TX);
100         net->tx_poll_state = VHOST_NET_POLL_STOPPED;
101 }
102
103 /* Caller must have TX VQ lock */
104 static void tx_poll_start(struct vhost_net *net, struct socket *sock)
105 {
106         if (unlikely(net->tx_poll_state != VHOST_NET_POLL_STOPPED))
107                 return;
108         vhost_poll_start(net->poll + VHOST_NET_VQ_TX, sock->file);
109         net->tx_poll_state = VHOST_NET_POLL_STARTED;
110 }
111
112 /* Expects to be always run from workqueue - which acts as
113  * read-size critical section for our kind of RCU. */
114 static void handle_tx(struct vhost_net *net)
115 {
116         struct vhost_virtqueue *vq = &net->dev.vqs[VHOST_NET_VQ_TX];
117         unsigned out, in, s;
118         int head;
119         struct msghdr msg = {
120                 .msg_name = NULL,
121                 .msg_namelen = 0,
122                 .msg_control = NULL,
123                 .msg_controllen = 0,
124                 .msg_iov = vq->iov,
125                 .msg_flags = MSG_DONTWAIT,
126         };
127         size_t len, total_len = 0;
128         int err, wmem;
129         size_t hdr_size;
130         struct socket *sock;
131
132         sock = rcu_dereference_check(vq->private_data,
133                                      lockdep_is_held(&vq->mutex));
134         if (!sock)
135                 return;
136
137         wmem = atomic_read(&sock->sk->sk_wmem_alloc);
138         if (wmem >= sock->sk->sk_sndbuf) {
139                 mutex_lock(&vq->mutex);
140                 tx_poll_start(net, sock);
141                 mutex_unlock(&vq->mutex);
142                 return;
143         }
144
145         use_mm(net->dev.mm);
146         mutex_lock(&vq->mutex);
147         vhost_disable_notify(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(vq))) {
170                                 vhost_disable_notify(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         unuse_mm(net->dev.mm);
211 }
212
213 static int peek_head_len(struct sock *sk)
214 {
215         struct sk_buff *head;
216         int len = 0;
217
218         lock_sock(sk);
219         head = skb_peek(&sk->sk_receive_queue);
220         if (head)
221                 len = head->len;
222         release_sock(sk);
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  *      returns number of buffer heads allocated, negative on error
234  */
235 static int get_rx_bufs(struct vhost_virtqueue *vq,
236                        struct vring_used_elem *heads,
237                        int datalen,
238                        unsigned *iovcount,
239                        struct vhost_log *log,
240                        unsigned *log_num)
241 {
242         unsigned int out, in;
243         int seg = 0;
244         int headcount = 0;
245         unsigned d;
246         int r, nlogs = 0;
247
248         while (datalen > 0) {
249                 if (unlikely(seg >= VHOST_NET_MAX_SG)) {
250                         r = -ENOBUFS;
251                         goto err;
252                 }
253                 d = vhost_get_vq_desc(vq->dev, vq, vq->iov + seg,
254                                       ARRAY_SIZE(vq->iov) - seg, &out,
255                                       &in, log, log_num);
256                 if (d == vq->num) {
257                         r = 0;
258                         goto err;
259                 }
260                 if (unlikely(out || in <= 0)) {
261                         vq_err(vq, "unexpected descriptor format for RX: "
262                                 "out %d, in %d\n", out, in);
263                         r = -EINVAL;
264                         goto err;
265                 }
266                 if (unlikely(log)) {
267                         nlogs += *log_num;
268                         log += *log_num;
269                 }
270                 heads[headcount].id = d;
271                 heads[headcount].len = iov_length(vq->iov + seg, in);
272                 datalen -= heads[headcount].len;
273                 ++headcount;
274                 seg += in;
275         }
276         heads[headcount - 1].len += datalen;
277         *iovcount = seg;
278         if (unlikely(log))
279                 *log_num = nlogs;
280         return headcount;
281 err:
282         vhost_discard_vq_desc(vq, headcount);
283         return r;
284 }
285
286 /* Expects to be always run from workqueue - which acts as
287  * read-size critical section for our kind of RCU. */
288 static void handle_rx_big(struct vhost_net *net)
289 {
290         struct vhost_virtqueue *vq = &net->dev.vqs[VHOST_NET_VQ_RX];
291         unsigned out, in, log, s;
292         int head;
293         struct vhost_log *vq_log;
294         struct msghdr msg = {
295                 .msg_name = NULL,
296                 .msg_namelen = 0,
297                 .msg_control = NULL, /* FIXME: get and handle RX aux data. */
298                 .msg_controllen = 0,
299                 .msg_iov = vq->iov,
300                 .msg_flags = MSG_DONTWAIT,
301         };
302
303         struct virtio_net_hdr hdr = {
304                 .flags = 0,
305                 .gso_type = VIRTIO_NET_HDR_GSO_NONE
306         };
307
308         size_t len, total_len = 0;
309         int err;
310         size_t hdr_size;
311         struct socket *sock = rcu_dereference(vq->private_data);
312         if (!sock || skb_queue_empty(&sock->sk->sk_receive_queue))
313                 return;
314
315         use_mm(net->dev.mm);
316         mutex_lock(&vq->mutex);
317         vhost_disable_notify(vq);
318         hdr_size = vq->vhost_hlen;
319
320         vq_log = unlikely(vhost_has_feature(&net->dev, VHOST_F_LOG_ALL)) ?
321                 vq->log : NULL;
322
323         for (;;) {
324                 head = vhost_get_vq_desc(&net->dev, vq, vq->iov,
325                                          ARRAY_SIZE(vq->iov),
326                                          &out, &in,
327                                          vq_log, &log);
328                 /* On error, stop handling until the next kick. */
329                 if (unlikely(head < 0))
330                         break;
331                 /* OK, now we need to know about added descriptors. */
332                 if (head == vq->num) {
333                         if (unlikely(vhost_enable_notify(vq))) {
334                                 /* They have slipped one in as we were
335                                  * doing that: check again. */
336                                 vhost_disable_notify(vq);
337                                 continue;
338                         }
339                         /* Nothing new?  Wait for eventfd to tell us
340                          * they refilled. */
341                         break;
342                 }
343                 /* We don't need to be notified again. */
344                 if (out) {
345                         vq_err(vq, "Unexpected descriptor format for RX: "
346                                "out %d, int %d\n",
347                                out, in);
348                         break;
349                 }
350                 /* Skip header. TODO: support TSO/mergeable rx buffers. */
351                 s = move_iovec_hdr(vq->iov, vq->hdr, hdr_size, in);
352                 msg.msg_iovlen = in;
353                 len = iov_length(vq->iov, in);
354                 /* Sanity check */
355                 if (!len) {
356                         vq_err(vq, "Unexpected header len for RX: "
357                                "%zd expected %zd\n",
358                                iov_length(vq->hdr, s), hdr_size);
359                         break;
360                 }
361                 err = sock->ops->recvmsg(NULL, sock, &msg,
362                                          len, MSG_DONTWAIT | MSG_TRUNC);
363                 /* TODO: Check specific error and bomb out unless EAGAIN? */
364                 if (err < 0) {
365                         vhost_discard_vq_desc(vq, 1);
366                         break;
367                 }
368                 /* TODO: Should check and handle checksum. */
369                 if (err > len) {
370                         pr_debug("Discarded truncated rx packet: "
371                                  " len %d > %zd\n", err, len);
372                         vhost_discard_vq_desc(vq, 1);
373                         continue;
374                 }
375                 len = err;
376                 err = memcpy_toiovec(vq->hdr, (unsigned char *)&hdr, hdr_size);
377                 if (err) {
378                         vq_err(vq, "Unable to write vnet_hdr at addr %p: %d\n",
379                                vq->iov->iov_base, err);
380                         break;
381                 }
382                 len += hdr_size;
383                 vhost_add_used_and_signal(&net->dev, vq, head, len);
384                 if (unlikely(vq_log))
385                         vhost_log_write(vq, vq_log, log, len);
386                 total_len += len;
387                 if (unlikely(total_len >= VHOST_NET_WEIGHT)) {
388                         vhost_poll_queue(&vq->poll);
389                         break;
390                 }
391         }
392
393         mutex_unlock(&vq->mutex);
394         unuse_mm(net->dev.mm);
395 }
396
397 /* Expects to be always run from workqueue - which acts as
398  * read-size critical section for our kind of RCU. */
399 static void handle_rx_mergeable(struct vhost_net *net)
400 {
401         struct vhost_virtqueue *vq = &net->dev.vqs[VHOST_NET_VQ_RX];
402         unsigned uninitialized_var(in), log;
403         struct vhost_log *vq_log;
404         struct msghdr msg = {
405                 .msg_name = NULL,
406                 .msg_namelen = 0,
407                 .msg_control = NULL, /* FIXME: get and handle RX aux data. */
408                 .msg_controllen = 0,
409                 .msg_iov = vq->iov,
410                 .msg_flags = MSG_DONTWAIT,
411         };
412
413         struct virtio_net_hdr_mrg_rxbuf hdr = {
414                 .hdr.flags = 0,
415                 .hdr.gso_type = VIRTIO_NET_HDR_GSO_NONE
416         };
417
418         size_t total_len = 0;
419         int err, headcount;
420         size_t vhost_hlen, sock_hlen;
421         size_t vhost_len, sock_len;
422         struct socket *sock = rcu_dereference(vq->private_data);
423         if (!sock || skb_queue_empty(&sock->sk->sk_receive_queue))
424                 return;
425
426         use_mm(net->dev.mm);
427         mutex_lock(&vq->mutex);
428         vhost_disable_notify(vq);
429         vhost_hlen = vq->vhost_hlen;
430         sock_hlen = vq->sock_hlen;
431
432         vq_log = unlikely(vhost_has_feature(&net->dev, VHOST_F_LOG_ALL)) ?
433                 vq->log : NULL;
434
435         while ((sock_len = peek_head_len(sock->sk))) {
436                 sock_len += sock_hlen;
437                 vhost_len = sock_len + vhost_hlen;
438                 headcount = get_rx_bufs(vq, vq->heads, vhost_len,
439                                         &in, vq_log, &log);
440                 /* On error, stop handling until the next kick. */
441                 if (unlikely(headcount < 0))
442                         break;
443                 /* OK, now we need to know about added descriptors. */
444                 if (!headcount) {
445                         if (unlikely(vhost_enable_notify(vq))) {
446                                 /* They have slipped one in as we were
447                                  * doing that: check again. */
448                                 vhost_disable_notify(vq);
449                                 continue;
450                         }
451                         /* Nothing new?  Wait for eventfd to tell us
452                          * they refilled. */
453                         break;
454                 }
455                 /* We don't need to be notified again. */
456                 if (unlikely((vhost_hlen)))
457                         /* Skip header. TODO: support TSO. */
458                         move_iovec_hdr(vq->iov, vq->hdr, vhost_hlen, in);
459                 else
460                         /* Copy the header for use in VIRTIO_NET_F_MRG_RXBUF:
461                          * needed because sendmsg can modify msg_iov. */
462                         copy_iovec_hdr(vq->iov, vq->hdr, sock_hlen, in);
463                 msg.msg_iovlen = in;
464                 err = sock->ops->recvmsg(NULL, sock, &msg,
465                                          sock_len, MSG_DONTWAIT | MSG_TRUNC);
466                 /* Userspace might have consumed the packet meanwhile:
467                  * it's not supposed to do this usually, but might be hard
468                  * to prevent. Discard data we got (if any) and keep going. */
469                 if (unlikely(err != sock_len)) {
470                         pr_debug("Discarded rx packet: "
471                                  " len %d, expected %zd\n", err, sock_len);
472                         vhost_discard_vq_desc(vq, headcount);
473                         continue;
474                 }
475                 if (unlikely(vhost_hlen) &&
476                     memcpy_toiovecend(vq->hdr, (unsigned char *)&hdr, 0,
477                                       vhost_hlen)) {
478                         vq_err(vq, "Unable to write vnet_hdr at addr %p\n",
479                                vq->iov->iov_base);
480                         break;
481                 }
482                 /* TODO: Should check and handle checksum. */
483                 if (vhost_has_feature(&net->dev, VIRTIO_NET_F_MRG_RXBUF) &&
484                     memcpy_toiovecend(vq->hdr, (unsigned char *)&headcount,
485                                       offsetof(typeof(hdr), num_buffers),
486                                       sizeof hdr.num_buffers)) {
487                         vq_err(vq, "Failed num_buffers write");
488                         vhost_discard_vq_desc(vq, headcount);
489                         break;
490                 }
491                 vhost_add_used_and_signal_n(&net->dev, vq, vq->heads,
492                                             headcount);
493                 if (unlikely(vq_log))
494                         vhost_log_write(vq, vq_log, log, vhost_len);
495                 total_len += vhost_len;
496                 if (unlikely(total_len >= VHOST_NET_WEIGHT)) {
497                         vhost_poll_queue(&vq->poll);
498                         break;
499                 }
500         }
501
502         mutex_unlock(&vq->mutex);
503         unuse_mm(net->dev.mm);
504 }
505
506 static void handle_rx(struct vhost_net *net)
507 {
508         if (vhost_has_feature(&net->dev, VIRTIO_NET_F_MRG_RXBUF))
509                 handle_rx_mergeable(net);
510         else
511                 handle_rx_big(net);
512 }
513
514 static void handle_tx_kick(struct vhost_work *work)
515 {
516         struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
517                                                   poll.work);
518         struct vhost_net *net = container_of(vq->dev, struct vhost_net, dev);
519
520         handle_tx(net);
521 }
522
523 static void handle_rx_kick(struct vhost_work *work)
524 {
525         struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
526                                                   poll.work);
527         struct vhost_net *net = container_of(vq->dev, struct vhost_net, dev);
528
529         handle_rx(net);
530 }
531
532 static void handle_tx_net(struct vhost_work *work)
533 {
534         struct vhost_net *net = container_of(work, struct vhost_net,
535                                              poll[VHOST_NET_VQ_TX].work);
536         handle_tx(net);
537 }
538
539 static void handle_rx_net(struct vhost_work *work)
540 {
541         struct vhost_net *net = container_of(work, struct vhost_net,
542                                              poll[VHOST_NET_VQ_RX].work);
543         handle_rx(net);
544 }
545
546 static int vhost_net_open(struct inode *inode, struct file *f)
547 {
548         struct vhost_net *n = kmalloc(sizeof *n, GFP_KERNEL);
549         struct vhost_dev *dev;
550         int r;
551
552         if (!n)
553                 return -ENOMEM;
554
555         dev = &n->dev;
556         n->vqs[VHOST_NET_VQ_TX].handle_kick = handle_tx_kick;
557         n->vqs[VHOST_NET_VQ_RX].handle_kick = handle_rx_kick;
558         r = vhost_dev_init(dev, n->vqs, VHOST_NET_VQ_MAX);
559         if (r < 0) {
560                 kfree(n);
561                 return r;
562         }
563
564         vhost_poll_init(n->poll + VHOST_NET_VQ_TX, handle_tx_net, POLLOUT, dev);
565         vhost_poll_init(n->poll + VHOST_NET_VQ_RX, handle_rx_net, POLLIN, dev);
566         n->tx_poll_state = VHOST_NET_POLL_DISABLED;
567
568         f->private_data = n;
569
570         return 0;
571 }
572
573 static void vhost_net_disable_vq(struct vhost_net *n,
574                                  struct vhost_virtqueue *vq)
575 {
576         if (!vq->private_data)
577                 return;
578         if (vq == n->vqs + VHOST_NET_VQ_TX) {
579                 tx_poll_stop(n);
580                 n->tx_poll_state = VHOST_NET_POLL_DISABLED;
581         } else
582                 vhost_poll_stop(n->poll + VHOST_NET_VQ_RX);
583 }
584
585 static void vhost_net_enable_vq(struct vhost_net *n,
586                                 struct vhost_virtqueue *vq)
587 {
588         struct socket *sock;
589
590         sock = rcu_dereference_protected(vq->private_data,
591                                          lockdep_is_held(&vq->mutex));
592         if (!sock)
593                 return;
594         if (vq == n->vqs + VHOST_NET_VQ_TX) {
595                 n->tx_poll_state = VHOST_NET_POLL_STOPPED;
596                 tx_poll_start(n, sock);
597         } else
598                 vhost_poll_start(n->poll + VHOST_NET_VQ_RX, sock->file);
599 }
600
601 static struct socket *vhost_net_stop_vq(struct vhost_net *n,
602                                         struct vhost_virtqueue *vq)
603 {
604         struct socket *sock;
605
606         mutex_lock(&vq->mutex);
607         sock = rcu_dereference_protected(vq->private_data,
608                                          lockdep_is_held(&vq->mutex));
609         vhost_net_disable_vq(n, vq);
610         rcu_assign_pointer(vq->private_data, NULL);
611         mutex_unlock(&vq->mutex);
612         return sock;
613 }
614
615 static void vhost_net_stop(struct vhost_net *n, struct socket **tx_sock,
616                            struct socket **rx_sock)
617 {
618         *tx_sock = vhost_net_stop_vq(n, n->vqs + VHOST_NET_VQ_TX);
619         *rx_sock = vhost_net_stop_vq(n, n->vqs + VHOST_NET_VQ_RX);
620 }
621
622 static void vhost_net_flush_vq(struct vhost_net *n, int index)
623 {
624         vhost_poll_flush(n->poll + index);
625         vhost_poll_flush(&n->dev.vqs[index].poll);
626 }
627
628 static void vhost_net_flush(struct vhost_net *n)
629 {
630         vhost_net_flush_vq(n, VHOST_NET_VQ_TX);
631         vhost_net_flush_vq(n, VHOST_NET_VQ_RX);
632 }
633
634 static int vhost_net_release(struct inode *inode, struct file *f)
635 {
636         struct vhost_net *n = f->private_data;
637         struct socket *tx_sock;
638         struct socket *rx_sock;
639
640         vhost_net_stop(n, &tx_sock, &rx_sock);
641         vhost_net_flush(n);
642         vhost_dev_cleanup(&n->dev);
643         if (tx_sock)
644                 fput(tx_sock->file);
645         if (rx_sock)
646                 fput(rx_sock->file);
647         /* We do an extra flush before freeing memory,
648          * since jobs can re-queue themselves. */
649         vhost_net_flush(n);
650         kfree(n);
651         return 0;
652 }
653
654 static struct socket *get_raw_socket(int fd)
655 {
656         struct {
657                 struct sockaddr_ll sa;
658                 char  buf[MAX_ADDR_LEN];
659         } uaddr;
660         int uaddr_len = sizeof uaddr, r;
661         struct socket *sock = sockfd_lookup(fd, &r);
662         if (!sock)
663                 return ERR_PTR(-ENOTSOCK);
664
665         /* Parameter checking */
666         if (sock->sk->sk_type != SOCK_RAW) {
667                 r = -ESOCKTNOSUPPORT;
668                 goto err;
669         }
670
671         r = sock->ops->getname(sock, (struct sockaddr *)&uaddr.sa,
672                                &uaddr_len, 0);
673         if (r)
674                 goto err;
675
676         if (uaddr.sa.sll_family != AF_PACKET) {
677                 r = -EPFNOSUPPORT;
678                 goto err;
679         }
680         return sock;
681 err:
682         fput(sock->file);
683         return ERR_PTR(r);
684 }
685
686 static struct socket *get_tap_socket(int fd)
687 {
688         struct file *file = fget(fd);
689         struct socket *sock;
690         if (!file)
691                 return ERR_PTR(-EBADF);
692         sock = tun_get_socket(file);
693         if (!IS_ERR(sock))
694                 return sock;
695         sock = macvtap_get_socket(file);
696         if (IS_ERR(sock))
697                 fput(file);
698         return sock;
699 }
700
701 static struct socket *get_socket(int fd)
702 {
703         struct socket *sock;
704         /* special case to disable backend */
705         if (fd == -1)
706                 return NULL;
707         sock = get_raw_socket(fd);
708         if (!IS_ERR(sock))
709                 return sock;
710         sock = get_tap_socket(fd);
711         if (!IS_ERR(sock))
712                 return sock;
713         return ERR_PTR(-ENOTSOCK);
714 }
715
716 static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd)
717 {
718         struct socket *sock, *oldsock;
719         struct vhost_virtqueue *vq;
720         int r;
721
722         mutex_lock(&n->dev.mutex);
723         r = vhost_dev_check_owner(&n->dev);
724         if (r)
725                 goto err;
726
727         if (index >= VHOST_NET_VQ_MAX) {
728                 r = -ENOBUFS;
729                 goto err;
730         }
731         vq = n->vqs + index;
732         mutex_lock(&vq->mutex);
733
734         /* Verify that ring has been setup correctly. */
735         if (!vhost_vq_access_ok(vq)) {
736                 r = -EFAULT;
737                 goto err_vq;
738         }
739         sock = get_socket(fd);
740         if (IS_ERR(sock)) {
741                 r = PTR_ERR(sock);
742                 goto err_vq;
743         }
744
745         /* start polling new socket */
746         oldsock = rcu_dereference_protected(vq->private_data,
747                                             lockdep_is_held(&vq->mutex));
748         if (sock != oldsock) {
749                 vhost_net_disable_vq(n, vq);
750                 rcu_assign_pointer(vq->private_data, sock);
751                 vhost_net_enable_vq(n, vq);
752         }
753
754         mutex_unlock(&vq->mutex);
755
756         if (oldsock) {
757                 vhost_net_flush_vq(n, index);
758                 fput(oldsock->file);
759         }
760
761         mutex_unlock(&n->dev.mutex);
762         return 0;
763
764 err_vq:
765         mutex_unlock(&vq->mutex);
766 err:
767         mutex_unlock(&n->dev.mutex);
768         return r;
769 }
770
771 static long vhost_net_reset_owner(struct vhost_net *n)
772 {
773         struct socket *tx_sock = NULL;
774         struct socket *rx_sock = NULL;
775         long err;
776         mutex_lock(&n->dev.mutex);
777         err = vhost_dev_check_owner(&n->dev);
778         if (err)
779                 goto done;
780         vhost_net_stop(n, &tx_sock, &rx_sock);
781         vhost_net_flush(n);
782         err = vhost_dev_reset_owner(&n->dev);
783 done:
784         mutex_unlock(&n->dev.mutex);
785         if (tx_sock)
786                 fput(tx_sock->file);
787         if (rx_sock)
788                 fput(rx_sock->file);
789         return err;
790 }
791
792 static int vhost_net_set_features(struct vhost_net *n, u64 features)
793 {
794         size_t vhost_hlen, sock_hlen, hdr_len;
795         int i;
796
797         hdr_len = (features & (1 << VIRTIO_NET_F_MRG_RXBUF)) ?
798                         sizeof(struct virtio_net_hdr_mrg_rxbuf) :
799                         sizeof(struct virtio_net_hdr);
800         if (features & (1 << VHOST_NET_F_VIRTIO_NET_HDR)) {
801                 /* vhost provides vnet_hdr */
802                 vhost_hlen = hdr_len;
803                 sock_hlen = 0;
804         } else {
805                 /* socket provides vnet_hdr */
806                 vhost_hlen = 0;
807                 sock_hlen = hdr_len;
808         }
809         mutex_lock(&n->dev.mutex);
810         if ((features & (1 << VHOST_F_LOG_ALL)) &&
811             !vhost_log_access_ok(&n->dev)) {
812                 mutex_unlock(&n->dev.mutex);
813                 return -EFAULT;
814         }
815         n->dev.acked_features = features;
816         smp_wmb();
817         for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
818                 mutex_lock(&n->vqs[i].mutex);
819                 n->vqs[i].vhost_hlen = vhost_hlen;
820                 n->vqs[i].sock_hlen = sock_hlen;
821                 mutex_unlock(&n->vqs[i].mutex);
822         }
823         vhost_net_flush(n);
824         mutex_unlock(&n->dev.mutex);
825         return 0;
826 }
827
828 static long vhost_net_ioctl(struct file *f, unsigned int ioctl,
829                             unsigned long arg)
830 {
831         struct vhost_net *n = f->private_data;
832         void __user *argp = (void __user *)arg;
833         u64 __user *featurep = argp;
834         struct vhost_vring_file backend;
835         u64 features;
836         int r;
837         switch (ioctl) {
838         case VHOST_NET_SET_BACKEND:
839                 if (copy_from_user(&backend, argp, sizeof backend))
840                         return -EFAULT;
841                 return vhost_net_set_backend(n, backend.index, backend.fd);
842         case VHOST_GET_FEATURES:
843                 features = VHOST_FEATURES;
844                 if (copy_to_user(featurep, &features, sizeof features))
845                         return -EFAULT;
846                 return 0;
847         case VHOST_SET_FEATURES:
848                 if (copy_from_user(&features, featurep, sizeof features))
849                         return -EFAULT;
850                 if (features & ~VHOST_FEATURES)
851                         return -EOPNOTSUPP;
852                 return vhost_net_set_features(n, features);
853         case VHOST_RESET_OWNER:
854                 return vhost_net_reset_owner(n);
855         default:
856                 mutex_lock(&n->dev.mutex);
857                 r = vhost_dev_ioctl(&n->dev, ioctl, arg);
858                 vhost_net_flush(n);
859                 mutex_unlock(&n->dev.mutex);
860                 return r;
861         }
862 }
863
864 #ifdef CONFIG_COMPAT
865 static long vhost_net_compat_ioctl(struct file *f, unsigned int ioctl,
866                                    unsigned long arg)
867 {
868         return vhost_net_ioctl(f, ioctl, (unsigned long)compat_ptr(arg));
869 }
870 #endif
871
872 static const struct file_operations vhost_net_fops = {
873         .owner          = THIS_MODULE,
874         .release        = vhost_net_release,
875         .unlocked_ioctl = vhost_net_ioctl,
876 #ifdef CONFIG_COMPAT
877         .compat_ioctl   = vhost_net_compat_ioctl,
878 #endif
879         .open           = vhost_net_open,
880         .llseek         = noop_llseek,
881 };
882
883 static struct miscdevice vhost_net_misc = {
884         MISC_DYNAMIC_MINOR,
885         "vhost-net",
886         &vhost_net_fops,
887 };
888
889 static int vhost_net_init(void)
890 {
891         return misc_register(&vhost_net_misc);
892 }
893 module_init(vhost_net_init);
894
895 static void vhost_net_exit(void)
896 {
897         misc_deregister(&vhost_net_misc);
898 }
899 module_exit(vhost_net_exit);
900
901 MODULE_VERSION("0.0.1");
902 MODULE_LICENSE("GPL v2");
903 MODULE_AUTHOR("Michael S. Tsirkin");
904 MODULE_DESCRIPTION("Host kernel accelerator for virtio net");