i2c: tegra: Add stub runtime power management
[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/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
32 static int experimental_zcopytx;
33 module_param(experimental_zcopytx, int, 0444);
34 MODULE_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
44 enum {
45         VHOST_NET_VQ_RX = 0,
46         VHOST_NET_VQ_TX = 1,
47         VHOST_NET_VQ_MAX = 2,
48 };
49
50 enum vhost_net_poll_state {
51         VHOST_NET_POLL_DISABLED = 0,
52         VHOST_NET_POLL_STARTED = 1,
53         VHOST_NET_POLL_STOPPED = 2,
54 };
55
56 struct 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
66 static 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. */
73 static 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. */
93 static 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 */
111 static 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 */
120 static 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. */
130 static 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
278 static 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  */
302 static 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;
349 err:
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. */
356 static 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
463 static 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
472 static 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
481 static 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
488 static 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
495 static 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
522 static 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
534 static 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
550 static 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
564 static 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
571 static 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
577 static 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
583 static 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
603 static 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;
631 err:
632         fput(sock->file);
633         return ERR_PTR(r);
634 }
635
636 static 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
652 static 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
668 static 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
735 err_ubufs:
736         fput(sock->file);
737 err_vq:
738         mutex_unlock(&vq->mutex);
739 err:
740         mutex_unlock(&n->dev.mutex);
741         return r;
742 }
743
744 static 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);
757 done:
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
766 static 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
802 static 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
840 static 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
847 static 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
858 static struct miscdevice vhost_net_misc = {
859         MISC_DYNAMIC_MINOR,
860         "vhost-net",
861         &vhost_net_fops,
862 };
863
864 static 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 }
870 module_init(vhost_net_init);
871
872 static void vhost_net_exit(void)
873 {
874         misc_deregister(&vhost_net_misc);
875 }
876 module_exit(vhost_net_exit);
877
878 MODULE_VERSION("0.0.1");
879 MODULE_LICENSE("GPL v2");
880 MODULE_AUTHOR("Michael S. Tsirkin");
881 MODULE_DESCRIPTION("Host kernel accelerator for virtio net");