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1/* Copyright (C) 2009 Red Hat, Inc.
2 * Author: Michael S. Tsirkin <mst@redhat.com>
3 *
4 * This work is licensed under the terms of the GNU GPL, version 2.
5 *
6 * virtio-net server in host kernel.
7 */
8
9#include <linux/compat.h>
10#include <linux/eventfd.h>
11#include <linux/vhost.h>
12#include <linux/virtio_net.h>
13#include <linux/miscdevice.h>
14#include <linux/module.h>
15#include <linux/moduleparam.h>
16#include <linux/mutex.h>
17#include <linux/workqueue.h>
18#include <linux/rcupdate.h>
19#include <linux/file.h>
20#include <linux/slab.h>
21
22#include <linux/net.h>
23#include <linux/if_packet.h>
24#include <linux/if_arp.h>
25#include <linux/if_tun.h>
26#include <linux/if_macvlan.h>
27
28#include <net/sock.h>
29
30#include "vhost.h"
31
32static int experimental_zcopytx;
33module_param(experimental_zcopytx, int, 0444);
34MODULE_PARM_DESC(experimental_zcopytx, "Enable Experimental Zero Copy TX");
35
36/* Max number of bytes transferred before requeueing the job.
37 * Using this limit prevents one virtqueue from starving others. */
38#define VHOST_NET_WEIGHT 0x80000
39
40/* MAX number of TX used buffers for outstanding zerocopy */
41#define VHOST_MAX_PEND 128
42#define VHOST_GOODCOPY_LEN 256
43
44enum {
45 VHOST_NET_VQ_RX = 0,
46 VHOST_NET_VQ_TX = 1,
47 VHOST_NET_VQ_MAX = 2,
48};
49
50enum vhost_net_poll_state {
51 VHOST_NET_POLL_DISABLED = 0,
52 VHOST_NET_POLL_STARTED = 1,
53 VHOST_NET_POLL_STOPPED = 2,
54};
55
56struct vhost_net {
57 struct vhost_dev dev;
58 struct vhost_virtqueue vqs[VHOST_NET_VQ_MAX];
59 struct vhost_poll poll[VHOST_NET_VQ_MAX];
60 /* Tells us whether we are polling a socket for TX.
61 * We only do this when socket buffer fills up.
62 * Protected by tx vq lock. */
63 enum vhost_net_poll_state tx_poll_state;
64};
65
66static bool vhost_sock_zcopy(struct socket *sock)
67{
68 return unlikely(experimental_zcopytx) &&
69 sock_flag(sock->sk, SOCK_ZEROCOPY);
70}
71
72/* Pop first len bytes from iovec. Return number of segments used. */
73static int move_iovec_hdr(struct iovec *from, struct iovec *to,
74 size_t len, int iov_count)
75{
76 int seg = 0;
77 size_t size;
78
79 while (len && seg < iov_count) {
80 size = min(from->iov_len, len);
81 to->iov_base = from->iov_base;
82 to->iov_len = size;
83 from->iov_len -= size;
84 from->iov_base += size;
85 len -= size;
86 ++from;
87 ++to;
88 ++seg;
89 }
90 return seg;
91}
92/* Copy iovec entries for len bytes from iovec. */
93static void copy_iovec_hdr(const struct iovec *from, struct iovec *to,
94 size_t len, int iovcount)
95{
96 int seg = 0;
97 size_t size;
98
99 while (len && seg < iovcount) {
100 size = min(from->iov_len, len);
101 to->iov_base = from->iov_base;
102 to->iov_len = size;
103 len -= size;
104 ++from;
105 ++to;
106 ++seg;
107 }
108}
109
110/* Caller must have TX VQ lock */
111static void tx_poll_stop(struct vhost_net *net)
112{
113 if (likely(net->tx_poll_state != VHOST_NET_POLL_STARTED))
114 return;
115 vhost_poll_stop(net->poll + VHOST_NET_VQ_TX);
116 net->tx_poll_state = VHOST_NET_POLL_STOPPED;
117}
118
119/* Caller must have TX VQ lock */
120static void tx_poll_start(struct vhost_net *net, struct socket *sock)
121{
122 if (unlikely(net->tx_poll_state != VHOST_NET_POLL_STOPPED))
123 return;
124 vhost_poll_start(net->poll + VHOST_NET_VQ_TX, sock->file);
125 net->tx_poll_state = VHOST_NET_POLL_STARTED;
126}
127
128/* Expects to be always run from workqueue - which acts as
129 * read-size critical section for our kind of RCU. */
130static void handle_tx(struct vhost_net *net)
131{
132 struct vhost_virtqueue *vq = &net->dev.vqs[VHOST_NET_VQ_TX];
133 unsigned out, in, s;
134 int head;
135 struct msghdr msg = {
136 .msg_name = NULL,
137 .msg_namelen = 0,
138 .msg_control = NULL,
139 .msg_controllen = 0,
140 .msg_iov = vq->iov,
141 .msg_flags = MSG_DONTWAIT,
142 };
143 size_t len, total_len = 0;
144 int err, wmem;
145 size_t hdr_size;
146 struct socket *sock;
147 struct vhost_ubuf_ref *uninitialized_var(ubufs);
148 bool zcopy;
149
150 /* TODO: check that we are running from vhost_worker? */
151 sock = rcu_dereference_check(vq->private_data, 1);
152 if (!sock)
153 return;
154
155 wmem = atomic_read(&sock->sk->sk_wmem_alloc);
156 if (wmem >= sock->sk->sk_sndbuf) {
157 mutex_lock(&vq->mutex);
158 tx_poll_start(net, sock);
159 mutex_unlock(&vq->mutex);
160 return;
161 }
162
163 mutex_lock(&vq->mutex);
164 vhost_disable_notify(&net->dev, vq);
165
166 if (wmem < sock->sk->sk_sndbuf / 2)
167 tx_poll_stop(net);
168 hdr_size = vq->vhost_hlen;
169 zcopy = vhost_sock_zcopy(sock);
170
171 for (;;) {
172 /* Release DMAs done buffers first */
173 if (zcopy)
174 vhost_zerocopy_signal_used(vq);
175
176 head = vhost_get_vq_desc(&net->dev, vq, vq->iov,
177 ARRAY_SIZE(vq->iov),
178 &out, &in,
179 NULL, NULL);
180 /* On error, stop handling until the next kick. */
181 if (unlikely(head < 0))
182 break;
183 /* Nothing new? Wait for eventfd to tell us they refilled. */
184 if (head == vq->num) {
185 int num_pends;
186
187 wmem = atomic_read(&sock->sk->sk_wmem_alloc);
188 if (wmem >= sock->sk->sk_sndbuf * 3 / 4) {
189 tx_poll_start(net, sock);
190 set_bit(SOCK_ASYNC_NOSPACE, &sock->flags);
191 break;
192 }
193 /* If more outstanding DMAs, queue the work.
194 * Handle upend_idx wrap around
195 */
196 num_pends = likely(vq->upend_idx >= vq->done_idx) ?
197 (vq->upend_idx - vq->done_idx) :
198 (vq->upend_idx + UIO_MAXIOV - vq->done_idx);
199 if (unlikely(num_pends > VHOST_MAX_PEND)) {
200 tx_poll_start(net, sock);
201 set_bit(SOCK_ASYNC_NOSPACE, &sock->flags);
202 break;
203 }
204 if (unlikely(vhost_enable_notify(&net->dev, vq))) {
205 vhost_disable_notify(&net->dev, vq);
206 continue;
207 }
208 break;
209 }
210 if (in) {
211 vq_err(vq, "Unexpected descriptor format for TX: "
212 "out %d, int %d\n", out, in);
213 break;
214 }
215 /* Skip header. TODO: support TSO. */
216 s = move_iovec_hdr(vq->iov, vq->hdr, hdr_size, out);
217 msg.msg_iovlen = out;
218 len = iov_length(vq->iov, out);
219 /* Sanity check */
220 if (!len) {
221 vq_err(vq, "Unexpected header len for TX: "
222 "%zd expected %zd\n",
223 iov_length(vq->hdr, s), hdr_size);
224 break;
225 }
226 /* use msg_control to pass vhost zerocopy ubuf info to skb */
227 if (zcopy) {
228 vq->heads[vq->upend_idx].id = head;
229 if (len < VHOST_GOODCOPY_LEN) {
230 /* copy don't need to wait for DMA done */
231 vq->heads[vq->upend_idx].len =
232 VHOST_DMA_DONE_LEN;
233 msg.msg_control = NULL;
234 msg.msg_controllen = 0;
235 ubufs = NULL;
236 } else {
237 struct ubuf_info *ubuf = &vq->ubuf_info[head];
238
239 vq->heads[vq->upend_idx].len = len;
240 ubuf->callback = vhost_zerocopy_callback;
241 ubuf->arg = vq->ubufs;
242 ubuf->desc = vq->upend_idx;
243 msg.msg_control = ubuf;
244 msg.msg_controllen = sizeof(ubuf);
245 ubufs = vq->ubufs;
246 kref_get(&ubufs->kref);
247 }
248 vq->upend_idx = (vq->upend_idx + 1) % UIO_MAXIOV;
249 }
250 /* TODO: Check specific error and bomb out unless ENOBUFS? */
251 err = sock->ops->sendmsg(NULL, sock, &msg, len);
252 if (unlikely(err < 0)) {
253 if (zcopy) {
254 if (ubufs)
255 vhost_ubuf_put(ubufs);
256 vq->upend_idx = ((unsigned)vq->upend_idx - 1) %
257 UIO_MAXIOV;
258 }
259 vhost_discard_vq_desc(vq, 1);
260 tx_poll_start(net, sock);
261 break;
262 }
263 if (err != len)
264 pr_debug("Truncated TX packet: "
265 " len %d != %zd\n", err, len);
266 if (!zcopy)
267 vhost_add_used_and_signal(&net->dev, vq, head, 0);
268 total_len += len;
269 if (unlikely(total_len >= VHOST_NET_WEIGHT)) {
270 vhost_poll_queue(&vq->poll);
271 break;
272 }
273 }
274
275 mutex_unlock(&vq->mutex);
276}
277
278static int peek_head_len(struct sock *sk)
279{
280 struct sk_buff *head;
281 int len = 0;
282 unsigned long flags;
283
284 spin_lock_irqsave(&sk->sk_receive_queue.lock, flags);
285 head = skb_peek(&sk->sk_receive_queue);
286 if (likely(head))
287 len = head->len;
288 spin_unlock_irqrestore(&sk->sk_receive_queue.lock, flags);
289 return len;
290}
291
292/* This is a multi-buffer version of vhost_get_desc, that works if
293 * vq has read descriptors only.
294 * @vq - the relevant virtqueue
295 * @datalen - data length we'll be reading
296 * @iovcount - returned count of io vectors we fill
297 * @log - vhost log
298 * @log_num - log offset
299 * @quota - headcount quota, 1 for big buffer
300 * returns number of buffer heads allocated, negative on error
301 */
302static int get_rx_bufs(struct vhost_virtqueue *vq,
303 struct vring_used_elem *heads,
304 int datalen,
305 unsigned *iovcount,
306 struct vhost_log *log,
307 unsigned *log_num,
308 unsigned int quota)
309{
310 unsigned int out, in;
311 int seg = 0;
312 int headcount = 0;
313 unsigned d;
314 int r, nlogs = 0;
315
316 while (datalen > 0 && headcount < quota) {
317 if (unlikely(seg >= UIO_MAXIOV)) {
318 r = -ENOBUFS;
319 goto err;
320 }
321 d = vhost_get_vq_desc(vq->dev, vq, vq->iov + seg,
322 ARRAY_SIZE(vq->iov) - seg, &out,
323 &in, log, log_num);
324 if (d == vq->num) {
325 r = 0;
326 goto err;
327 }
328 if (unlikely(out || in <= 0)) {
329 vq_err(vq, "unexpected descriptor format for RX: "
330 "out %d, in %d\n", out, in);
331 r = -EINVAL;
332 goto err;
333 }
334 if (unlikely(log)) {
335 nlogs += *log_num;
336 log += *log_num;
337 }
338 heads[headcount].id = d;
339 heads[headcount].len = iov_length(vq->iov + seg, in);
340 datalen -= heads[headcount].len;
341 ++headcount;
342 seg += in;
343 }
344 heads[headcount - 1].len += datalen;
345 *iovcount = seg;
346 if (unlikely(log))
347 *log_num = nlogs;
348 return headcount;
349err:
350 vhost_discard_vq_desc(vq, headcount);
351 return r;
352}
353
354/* Expects to be always run from workqueue - which acts as
355 * read-size critical section for our kind of RCU. */
356static void handle_rx(struct vhost_net *net)
357{
358 struct vhost_virtqueue *vq = &net->dev.vqs[VHOST_NET_VQ_RX];
359 unsigned uninitialized_var(in), log;
360 struct vhost_log *vq_log;
361 struct msghdr msg = {
362 .msg_name = NULL,
363 .msg_namelen = 0,
364 .msg_control = NULL, /* FIXME: get and handle RX aux data. */
365 .msg_controllen = 0,
366 .msg_iov = vq->iov,
367 .msg_flags = MSG_DONTWAIT,
368 };
369 struct virtio_net_hdr_mrg_rxbuf hdr = {
370 .hdr.flags = 0,
371 .hdr.gso_type = VIRTIO_NET_HDR_GSO_NONE
372 };
373 size_t total_len = 0;
374 int err, headcount, mergeable;
375 size_t vhost_hlen, sock_hlen;
376 size_t vhost_len, sock_len;
377 /* TODO: check that we are running from vhost_worker? */
378 struct socket *sock = rcu_dereference_check(vq->private_data, 1);
379
380 if (!sock)
381 return;
382
383 mutex_lock(&vq->mutex);
384 vhost_disable_notify(&net->dev, vq);
385 vhost_hlen = vq->vhost_hlen;
386 sock_hlen = vq->sock_hlen;
387
388 vq_log = unlikely(vhost_has_feature(&net->dev, VHOST_F_LOG_ALL)) ?
389 vq->log : NULL;
390 mergeable = vhost_has_feature(&net->dev, VIRTIO_NET_F_MRG_RXBUF);
391
392 while ((sock_len = peek_head_len(sock->sk))) {
393 sock_len += sock_hlen;
394 vhost_len = sock_len + vhost_hlen;
395 headcount = get_rx_bufs(vq, vq->heads, vhost_len,
396 &in, vq_log, &log,
397 likely(mergeable) ? UIO_MAXIOV : 1);
398 /* On error, stop handling until the next kick. */
399 if (unlikely(headcount < 0))
400 break;
401 /* OK, now we need to know about added descriptors. */
402 if (!headcount) {
403 if (unlikely(vhost_enable_notify(&net->dev, vq))) {
404 /* They have slipped one in as we were
405 * doing that: check again. */
406 vhost_disable_notify(&net->dev, vq);
407 continue;
408 }
409 /* Nothing new? Wait for eventfd to tell us
410 * they refilled. */
411 break;
412 }
413 /* We don't need to be notified again. */
414 if (unlikely((vhost_hlen)))
415 /* Skip header. TODO: support TSO. */
416 move_iovec_hdr(vq->iov, vq->hdr, vhost_hlen, in);
417 else
418 /* Copy the header for use in VIRTIO_NET_F_MRG_RXBUF:
419 * needed because recvmsg can modify msg_iov. */
420 copy_iovec_hdr(vq->iov, vq->hdr, sock_hlen, in);
421 msg.msg_iovlen = in;
422 err = sock->ops->recvmsg(NULL, sock, &msg,
423 sock_len, MSG_DONTWAIT | MSG_TRUNC);
424 /* Userspace might have consumed the packet meanwhile:
425 * it's not supposed to do this usually, but might be hard
426 * to prevent. Discard data we got (if any) and keep going. */
427 if (unlikely(err != sock_len)) {
428 pr_debug("Discarded rx packet: "
429 " len %d, expected %zd\n", err, sock_len);
430 vhost_discard_vq_desc(vq, headcount);
431 continue;
432 }
433 if (unlikely(vhost_hlen) &&
434 memcpy_toiovecend(vq->hdr, (unsigned char *)&hdr, 0,
435 vhost_hlen)) {
436 vq_err(vq, "Unable to write vnet_hdr at addr %p\n",
437 vq->iov->iov_base);
438 break;
439 }
440 /* TODO: Should check and handle checksum. */
441 if (likely(mergeable) &&
442 memcpy_toiovecend(vq->hdr, (unsigned char *)&headcount,
443 offsetof(typeof(hdr), num_buffers),
444 sizeof hdr.num_buffers)) {
445 vq_err(vq, "Failed num_buffers write");
446 vhost_discard_vq_desc(vq, headcount);
447 break;
448 }
449 vhost_add_used_and_signal_n(&net->dev, vq, vq->heads,
450 headcount);
451 if (unlikely(vq_log))
452 vhost_log_write(vq, vq_log, log, vhost_len);
453 total_len += vhost_len;
454 if (unlikely(total_len >= VHOST_NET_WEIGHT)) {
455 vhost_poll_queue(&vq->poll);
456 break;
457 }
458 }
459
460 mutex_unlock(&vq->mutex);
461}
462
463static void handle_tx_kick(struct vhost_work *work)
464{
465 struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
466 poll.work);
467 struct vhost_net *net = container_of(vq->dev, struct vhost_net, dev);
468
469 handle_tx(net);
470}
471
472static void handle_rx_kick(struct vhost_work *work)
473{
474 struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
475 poll.work);
476 struct vhost_net *net = container_of(vq->dev, struct vhost_net, dev);
477
478 handle_rx(net);
479}
480
481static void handle_tx_net(struct vhost_work *work)
482{
483 struct vhost_net *net = container_of(work, struct vhost_net,
484 poll[VHOST_NET_VQ_TX].work);
485 handle_tx(net);
486}
487
488static void handle_rx_net(struct vhost_work *work)
489{
490 struct vhost_net *net = container_of(work, struct vhost_net,
491 poll[VHOST_NET_VQ_RX].work);
492 handle_rx(net);
493}
494
495static int vhost_net_open(struct inode *inode, struct file *f)
496{
497 struct vhost_net *n = kmalloc(sizeof *n, GFP_KERNEL);
498 struct vhost_dev *dev;
499 int r;
500
501 if (!n)
502 return -ENOMEM;
503
504 dev = &n->dev;
505 n->vqs[VHOST_NET_VQ_TX].handle_kick = handle_tx_kick;
506 n->vqs[VHOST_NET_VQ_RX].handle_kick = handle_rx_kick;
507 r = vhost_dev_init(dev, n->vqs, VHOST_NET_VQ_MAX);
508 if (r < 0) {
509 kfree(n);
510 return r;
511 }
512
513 vhost_poll_init(n->poll + VHOST_NET_VQ_TX, handle_tx_net, POLLOUT, dev);
514 vhost_poll_init(n->poll + VHOST_NET_VQ_RX, handle_rx_net, POLLIN, dev);
515 n->tx_poll_state = VHOST_NET_POLL_DISABLED;
516
517 f->private_data = n;
518
519 return 0;
520}
521
522static void vhost_net_disable_vq(struct vhost_net *n,
523 struct vhost_virtqueue *vq)
524{
525 if (!vq->private_data)
526 return;
527 if (vq == n->vqs + VHOST_NET_VQ_TX) {
528 tx_poll_stop(n);
529 n->tx_poll_state = VHOST_NET_POLL_DISABLED;
530 } else
531 vhost_poll_stop(n->poll + VHOST_NET_VQ_RX);
532}
533
534static void vhost_net_enable_vq(struct vhost_net *n,
535 struct vhost_virtqueue *vq)
536{
537 struct socket *sock;
538
539 sock = rcu_dereference_protected(vq->private_data,
540 lockdep_is_held(&vq->mutex));
541 if (!sock)
542 return;
543 if (vq == n->vqs + VHOST_NET_VQ_TX) {
544 n->tx_poll_state = VHOST_NET_POLL_STOPPED;
545 tx_poll_start(n, sock);
546 } else
547 vhost_poll_start(n->poll + VHOST_NET_VQ_RX, sock->file);
548}
549
550static struct socket *vhost_net_stop_vq(struct vhost_net *n,
551 struct vhost_virtqueue *vq)
552{
553 struct socket *sock;
554
555 mutex_lock(&vq->mutex);
556 sock = rcu_dereference_protected(vq->private_data,
557 lockdep_is_held(&vq->mutex));
558 vhost_net_disable_vq(n, vq);
559 rcu_assign_pointer(vq->private_data, NULL);
560 mutex_unlock(&vq->mutex);
561 return sock;
562}
563
564static void vhost_net_stop(struct vhost_net *n, struct socket **tx_sock,
565 struct socket **rx_sock)
566{
567 *tx_sock = vhost_net_stop_vq(n, n->vqs + VHOST_NET_VQ_TX);
568 *rx_sock = vhost_net_stop_vq(n, n->vqs + VHOST_NET_VQ_RX);
569}
570
571static void vhost_net_flush_vq(struct vhost_net *n, int index)
572{
573 vhost_poll_flush(n->poll + index);
574 vhost_poll_flush(&n->dev.vqs[index].poll);
575}
576
577static void vhost_net_flush(struct vhost_net *n)
578{
579 vhost_net_flush_vq(n, VHOST_NET_VQ_TX);
580 vhost_net_flush_vq(n, VHOST_NET_VQ_RX);
581}
582
583static int vhost_net_release(struct inode *inode, struct file *f)
584{
585 struct vhost_net *n = f->private_data;
586 struct socket *tx_sock;
587 struct socket *rx_sock;
588
589 vhost_net_stop(n, &tx_sock, &rx_sock);
590 vhost_net_flush(n);
591 vhost_dev_cleanup(&n->dev);
592 if (tx_sock)
593 fput(tx_sock->file);
594 if (rx_sock)
595 fput(rx_sock->file);
596 /* We do an extra flush before freeing memory,
597 * since jobs can re-queue themselves. */
598 vhost_net_flush(n);
599 kfree(n);
600 return 0;
601}
602
603static struct socket *get_raw_socket(int fd)
604{
605 struct {
606 struct sockaddr_ll sa;
607 char buf[MAX_ADDR_LEN];
608 } uaddr;
609 int uaddr_len = sizeof uaddr, r;
610 struct socket *sock = sockfd_lookup(fd, &r);
611
612 if (!sock)
613 return ERR_PTR(-ENOTSOCK);
614
615 /* Parameter checking */
616 if (sock->sk->sk_type != SOCK_RAW) {
617 r = -ESOCKTNOSUPPORT;
618 goto err;
619 }
620
621 r = sock->ops->getname(sock, (struct sockaddr *)&uaddr.sa,
622 &uaddr_len, 0);
623 if (r)
624 goto err;
625
626 if (uaddr.sa.sll_family != AF_PACKET) {
627 r = -EPFNOSUPPORT;
628 goto err;
629 }
630 return sock;
631err:
632 fput(sock->file);
633 return ERR_PTR(r);
634}
635
636static struct socket *get_tap_socket(int fd)
637{
638 struct file *file = fget(fd);
639 struct socket *sock;
640
641 if (!file)
642 return ERR_PTR(-EBADF);
643 sock = tun_get_socket(file);
644 if (!IS_ERR(sock))
645 return sock;
646 sock = macvtap_get_socket(file);
647 if (IS_ERR(sock))
648 fput(file);
649 return sock;
650}
651
652static struct socket *get_socket(int fd)
653{
654 struct socket *sock;
655
656 /* special case to disable backend */
657 if (fd == -1)
658 return NULL;
659 sock = get_raw_socket(fd);
660 if (!IS_ERR(sock))
661 return sock;
662 sock = get_tap_socket(fd);
663 if (!IS_ERR(sock))
664 return sock;
665 return ERR_PTR(-ENOTSOCK);
666}
667
668static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd)
669{
670 struct socket *sock, *oldsock;
671 struct vhost_virtqueue *vq;
672 struct vhost_ubuf_ref *ubufs, *oldubufs = NULL;
673 int r;
674
675 mutex_lock(&n->dev.mutex);
676 r = vhost_dev_check_owner(&n->dev);
677 if (r)
678 goto err;
679
680 if (index >= VHOST_NET_VQ_MAX) {
681 r = -ENOBUFS;
682 goto err;
683 }
684 vq = n->vqs + index;
685 mutex_lock(&vq->mutex);
686
687 /* Verify that ring has been setup correctly. */
688 if (!vhost_vq_access_ok(vq)) {
689 r = -EFAULT;
690 goto err_vq;
691 }
692 sock = get_socket(fd);
693 if (IS_ERR(sock)) {
694 r = PTR_ERR(sock);
695 goto err_vq;
696 }
697
698 /* start polling new socket */
699 oldsock = rcu_dereference_protected(vq->private_data,
700 lockdep_is_held(&vq->mutex));
701 if (sock != oldsock) {
702 ubufs = vhost_ubuf_alloc(vq, sock && vhost_sock_zcopy(sock));
703 if (IS_ERR(ubufs)) {
704 r = PTR_ERR(ubufs);
705 goto err_ubufs;
706 }
707 oldubufs = vq->ubufs;
708 vq->ubufs = ubufs;
709 vhost_net_disable_vq(n, vq);
710 rcu_assign_pointer(vq->private_data, sock);
711 vhost_net_enable_vq(n, vq);
712
713 r = vhost_init_used(vq);
714 if (r)
715 goto err_vq;
716 }
717
718 mutex_unlock(&vq->mutex);
719
720 if (oldubufs) {
721 vhost_ubuf_put_and_wait(oldubufs);
722 mutex_lock(&vq->mutex);
723 vhost_zerocopy_signal_used(vq);
724 mutex_unlock(&vq->mutex);
725 }
726
727 if (oldsock) {
728 vhost_net_flush_vq(n, index);
729 fput(oldsock->file);
730 }
731
732 mutex_unlock(&n->dev.mutex);
733 return 0;
734
735err_ubufs:
736 fput(sock->file);
737err_vq:
738 mutex_unlock(&vq->mutex);
739err:
740 mutex_unlock(&n->dev.mutex);
741 return r;
742}
743
744static long vhost_net_reset_owner(struct vhost_net *n)
745{
746 struct socket *tx_sock = NULL;
747 struct socket *rx_sock = NULL;
748 long err;
749
750 mutex_lock(&n->dev.mutex);
751 err = vhost_dev_check_owner(&n->dev);
752 if (err)
753 goto done;
754 vhost_net_stop(n, &tx_sock, &rx_sock);
755 vhost_net_flush(n);
756 err = vhost_dev_reset_owner(&n->dev);
757done:
758 mutex_unlock(&n->dev.mutex);
759 if (tx_sock)
760 fput(tx_sock->file);
761 if (rx_sock)
762 fput(rx_sock->file);
763 return err;
764}
765
766static int vhost_net_set_features(struct vhost_net *n, u64 features)
767{
768 size_t vhost_hlen, sock_hlen, hdr_len;
769 int i;
770
771 hdr_len = (features & (1 << VIRTIO_NET_F_MRG_RXBUF)) ?
772 sizeof(struct virtio_net_hdr_mrg_rxbuf) :
773 sizeof(struct virtio_net_hdr);
774 if (features & (1 << VHOST_NET_F_VIRTIO_NET_HDR)) {
775 /* vhost provides vnet_hdr */
776 vhost_hlen = hdr_len;
777 sock_hlen = 0;
778 } else {
779 /* socket provides vnet_hdr */
780 vhost_hlen = 0;
781 sock_hlen = hdr_len;
782 }
783 mutex_lock(&n->dev.mutex);
784 if ((features & (1 << VHOST_F_LOG_ALL)) &&
785 !vhost_log_access_ok(&n->dev)) {
786 mutex_unlock(&n->dev.mutex);
787 return -EFAULT;
788 }
789 n->dev.acked_features = features;
790 smp_wmb();
791 for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
792 mutex_lock(&n->vqs[i].mutex);
793 n->vqs[i].vhost_hlen = vhost_hlen;
794 n->vqs[i].sock_hlen = sock_hlen;
795 mutex_unlock(&n->vqs[i].mutex);
796 }
797 vhost_net_flush(n);
798 mutex_unlock(&n->dev.mutex);
799 return 0;
800}
801
802static long vhost_net_ioctl(struct file *f, unsigned int ioctl,
803 unsigned long arg)
804{
805 struct vhost_net *n = f->private_data;
806 void __user *argp = (void __user *)arg;
807 u64 __user *featurep = argp;
808 struct vhost_vring_file backend;
809 u64 features;
810 int r;
811
812 switch (ioctl) {
813 case VHOST_NET_SET_BACKEND:
814 if (copy_from_user(&backend, argp, sizeof backend))
815 return -EFAULT;
816 return vhost_net_set_backend(n, backend.index, backend.fd);
817 case VHOST_GET_FEATURES:
818 features = VHOST_FEATURES;
819 if (copy_to_user(featurep, &features, sizeof features))
820 return -EFAULT;
821 return 0;
822 case VHOST_SET_FEATURES:
823 if (copy_from_user(&features, featurep, sizeof features))
824 return -EFAULT;
825 if (features & ~VHOST_FEATURES)
826 return -EOPNOTSUPP;
827 return vhost_net_set_features(n, features);
828 case VHOST_RESET_OWNER:
829 return vhost_net_reset_owner(n);
830 default:
831 mutex_lock(&n->dev.mutex);
832 r = vhost_dev_ioctl(&n->dev, ioctl, arg);
833 vhost_net_flush(n);
834 mutex_unlock(&n->dev.mutex);
835 return r;
836 }
837}
838
839#ifdef CONFIG_COMPAT
840static long vhost_net_compat_ioctl(struct file *f, unsigned int ioctl,
841 unsigned long arg)
842{
843 return vhost_net_ioctl(f, ioctl, (unsigned long)compat_ptr(arg));
844}
845#endif
846
847static const struct file_operations vhost_net_fops = {
848 .owner = THIS_MODULE,
849 .release = vhost_net_release,
850 .unlocked_ioctl = vhost_net_ioctl,
851#ifdef CONFIG_COMPAT
852 .compat_ioctl = vhost_net_compat_ioctl,
853#endif
854 .open = vhost_net_open,
855 .llseek = noop_llseek,
856};
857
858static struct miscdevice vhost_net_misc = {
859 MISC_DYNAMIC_MINOR,
860 "vhost-net",
861 &vhost_net_fops,
862};
863
864static int vhost_net_init(void)
865{
866 if (experimental_zcopytx)
867 vhost_enable_zcopy(VHOST_NET_VQ_TX);
868 return misc_register(&vhost_net_misc);
869}
870module_init(vhost_net_init);
871
872static void vhost_net_exit(void)
873{
874 misc_deregister(&vhost_net_misc);
875}
876module_exit(vhost_net_exit);
877
878MODULE_VERSION("0.0.1");
879MODULE_LICENSE("GPL v2");
880MODULE_AUTHOR("Michael S. Tsirkin");
881MODULE_DESCRIPTION("Host kernel accelerator for virtio net");
1/* Copyright (C) 2009 Red Hat, Inc.
2 * Author: Michael S. Tsirkin <mst@redhat.com>
3 *
4 * This work is licensed under the terms of the GNU GPL, version 2.
5 *
6 * virtio-net server in host kernel.
7 */
8
9#include <linux/compat.h>
10#include <linux/eventfd.h>
11#include <linux/vhost.h>
12#include <linux/virtio_net.h>
13#include <linux/miscdevice.h>
14#include <linux/module.h>
15#include <linux/moduleparam.h>
16#include <linux/mutex.h>
17#include <linux/workqueue.h>
18#include <linux/file.h>
19#include <linux/slab.h>
20
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#include <linux/if_vlan.h>
27
28#include <net/sock.h>
29
30#include "vhost.h"
31
32static int experimental_zcopytx = 1;
33module_param(experimental_zcopytx, int, 0444);
34MODULE_PARM_DESC(experimental_zcopytx, "Enable Zero Copy TX;"
35 " 1 -Enable; 0 - Disable");
36
37/* Max number of bytes transferred before requeueing the job.
38 * Using this limit prevents one virtqueue from starving others. */
39#define VHOST_NET_WEIGHT 0x80000
40
41/* MAX number of TX used buffers for outstanding zerocopy */
42#define VHOST_MAX_PEND 128
43#define VHOST_GOODCOPY_LEN 256
44
45/*
46 * For transmit, used buffer len is unused; we override it to track buffer
47 * status internally; used for zerocopy tx only.
48 */
49/* Lower device DMA failed */
50#define VHOST_DMA_FAILED_LEN 3
51/* Lower device DMA done */
52#define VHOST_DMA_DONE_LEN 2
53/* Lower device DMA in progress */
54#define VHOST_DMA_IN_PROGRESS 1
55/* Buffer unused */
56#define VHOST_DMA_CLEAR_LEN 0
57
58#define VHOST_DMA_IS_DONE(len) ((len) >= VHOST_DMA_DONE_LEN)
59
60enum {
61 VHOST_NET_FEATURES = VHOST_FEATURES |
62 (1ULL << VHOST_NET_F_VIRTIO_NET_HDR) |
63 (1ULL << VIRTIO_NET_F_MRG_RXBUF),
64};
65
66enum {
67 VHOST_NET_VQ_RX = 0,
68 VHOST_NET_VQ_TX = 1,
69 VHOST_NET_VQ_MAX = 2,
70};
71
72struct vhost_net_ubuf_ref {
73 /* refcount follows semantics similar to kref:
74 * 0: object is released
75 * 1: no outstanding ubufs
76 * >1: outstanding ubufs
77 */
78 atomic_t refcount;
79 wait_queue_head_t wait;
80 struct vhost_virtqueue *vq;
81};
82
83struct vhost_net_virtqueue {
84 struct vhost_virtqueue vq;
85 /* hdr is used to store the virtio header.
86 * Since each iovec has >= 1 byte length, we never need more than
87 * header length entries to store the header. */
88 struct iovec hdr[sizeof(struct virtio_net_hdr_mrg_rxbuf)];
89 size_t vhost_hlen;
90 size_t sock_hlen;
91 /* vhost zerocopy support fields below: */
92 /* last used idx for outstanding DMA zerocopy buffers */
93 int upend_idx;
94 /* first used idx for DMA done zerocopy buffers */
95 int done_idx;
96 /* an array of userspace buffers info */
97 struct ubuf_info *ubuf_info;
98 /* Reference counting for outstanding ubufs.
99 * Protected by vq mutex. Writers must also take device mutex. */
100 struct vhost_net_ubuf_ref *ubufs;
101};
102
103struct vhost_net {
104 struct vhost_dev dev;
105 struct vhost_net_virtqueue vqs[VHOST_NET_VQ_MAX];
106 struct vhost_poll poll[VHOST_NET_VQ_MAX];
107 /* Number of TX recently submitted.
108 * Protected by tx vq lock. */
109 unsigned tx_packets;
110 /* Number of times zerocopy TX recently failed.
111 * Protected by tx vq lock. */
112 unsigned tx_zcopy_err;
113 /* Flush in progress. Protected by tx vq lock. */
114 bool tx_flush;
115};
116
117static unsigned vhost_net_zcopy_mask __read_mostly;
118
119static void vhost_net_enable_zcopy(int vq)
120{
121 vhost_net_zcopy_mask |= 0x1 << vq;
122}
123
124static struct vhost_net_ubuf_ref *
125vhost_net_ubuf_alloc(struct vhost_virtqueue *vq, bool zcopy)
126{
127 struct vhost_net_ubuf_ref *ubufs;
128 /* No zero copy backend? Nothing to count. */
129 if (!zcopy)
130 return NULL;
131 ubufs = kmalloc(sizeof(*ubufs), GFP_KERNEL);
132 if (!ubufs)
133 return ERR_PTR(-ENOMEM);
134 atomic_set(&ubufs->refcount, 1);
135 init_waitqueue_head(&ubufs->wait);
136 ubufs->vq = vq;
137 return ubufs;
138}
139
140static int vhost_net_ubuf_put(struct vhost_net_ubuf_ref *ubufs)
141{
142 int r = atomic_sub_return(1, &ubufs->refcount);
143 if (unlikely(!r))
144 wake_up(&ubufs->wait);
145 return r;
146}
147
148static void vhost_net_ubuf_put_and_wait(struct vhost_net_ubuf_ref *ubufs)
149{
150 vhost_net_ubuf_put(ubufs);
151 wait_event(ubufs->wait, !atomic_read(&ubufs->refcount));
152}
153
154static void vhost_net_ubuf_put_wait_and_free(struct vhost_net_ubuf_ref *ubufs)
155{
156 vhost_net_ubuf_put_and_wait(ubufs);
157 kfree(ubufs);
158}
159
160static void vhost_net_clear_ubuf_info(struct vhost_net *n)
161{
162 int i;
163
164 for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
165 kfree(n->vqs[i].ubuf_info);
166 n->vqs[i].ubuf_info = NULL;
167 }
168}
169
170static int vhost_net_set_ubuf_info(struct vhost_net *n)
171{
172 bool zcopy;
173 int i;
174
175 for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
176 zcopy = vhost_net_zcopy_mask & (0x1 << i);
177 if (!zcopy)
178 continue;
179 n->vqs[i].ubuf_info = kmalloc(sizeof(*n->vqs[i].ubuf_info) *
180 UIO_MAXIOV, GFP_KERNEL);
181 if (!n->vqs[i].ubuf_info)
182 goto err;
183 }
184 return 0;
185
186err:
187 vhost_net_clear_ubuf_info(n);
188 return -ENOMEM;
189}
190
191static void vhost_net_vq_reset(struct vhost_net *n)
192{
193 int i;
194
195 vhost_net_clear_ubuf_info(n);
196
197 for (i = 0; i < VHOST_NET_VQ_MAX; i++) {
198 n->vqs[i].done_idx = 0;
199 n->vqs[i].upend_idx = 0;
200 n->vqs[i].ubufs = NULL;
201 n->vqs[i].vhost_hlen = 0;
202 n->vqs[i].sock_hlen = 0;
203 }
204
205}
206
207static void vhost_net_tx_packet(struct vhost_net *net)
208{
209 ++net->tx_packets;
210 if (net->tx_packets < 1024)
211 return;
212 net->tx_packets = 0;
213 net->tx_zcopy_err = 0;
214}
215
216static void vhost_net_tx_err(struct vhost_net *net)
217{
218 ++net->tx_zcopy_err;
219}
220
221static bool vhost_net_tx_select_zcopy(struct vhost_net *net)
222{
223 /* TX flush waits for outstanding DMAs to be done.
224 * Don't start new DMAs.
225 */
226 return !net->tx_flush &&
227 net->tx_packets / 64 >= net->tx_zcopy_err;
228}
229
230static bool vhost_sock_zcopy(struct socket *sock)
231{
232 return unlikely(experimental_zcopytx) &&
233 sock_flag(sock->sk, SOCK_ZEROCOPY);
234}
235
236/* Pop first len bytes from iovec. Return number of segments used. */
237static int move_iovec_hdr(struct iovec *from, struct iovec *to,
238 size_t len, int iov_count)
239{
240 int seg = 0;
241 size_t size;
242
243 while (len && seg < iov_count) {
244 size = min(from->iov_len, len);
245 to->iov_base = from->iov_base;
246 to->iov_len = size;
247 from->iov_len -= size;
248 from->iov_base += size;
249 len -= size;
250 ++from;
251 ++to;
252 ++seg;
253 }
254 return seg;
255}
256/* Copy iovec entries for len bytes from iovec. */
257static void copy_iovec_hdr(const struct iovec *from, struct iovec *to,
258 size_t len, int iovcount)
259{
260 int seg = 0;
261 size_t size;
262
263 while (len && seg < iovcount) {
264 size = min(from->iov_len, len);
265 to->iov_base = from->iov_base;
266 to->iov_len = size;
267 len -= size;
268 ++from;
269 ++to;
270 ++seg;
271 }
272}
273
274/* In case of DMA done not in order in lower device driver for some reason.
275 * upend_idx is used to track end of used idx, done_idx is used to track head
276 * of used idx. Once lower device DMA done contiguously, we will signal KVM
277 * guest used idx.
278 */
279static void vhost_zerocopy_signal_used(struct vhost_net *net,
280 struct vhost_virtqueue *vq)
281{
282 struct vhost_net_virtqueue *nvq =
283 container_of(vq, struct vhost_net_virtqueue, vq);
284 int i, add;
285 int j = 0;
286
287 for (i = nvq->done_idx; i != nvq->upend_idx; i = (i + 1) % UIO_MAXIOV) {
288 if (vq->heads[i].len == VHOST_DMA_FAILED_LEN)
289 vhost_net_tx_err(net);
290 if (VHOST_DMA_IS_DONE(vq->heads[i].len)) {
291 vq->heads[i].len = VHOST_DMA_CLEAR_LEN;
292 ++j;
293 } else
294 break;
295 }
296 while (j) {
297 add = min(UIO_MAXIOV - nvq->done_idx, j);
298 vhost_add_used_and_signal_n(vq->dev, vq,
299 &vq->heads[nvq->done_idx], add);
300 nvq->done_idx = (nvq->done_idx + add) % UIO_MAXIOV;
301 j -= add;
302 }
303}
304
305static void vhost_zerocopy_callback(struct ubuf_info *ubuf, bool success)
306{
307 struct vhost_net_ubuf_ref *ubufs = ubuf->ctx;
308 struct vhost_virtqueue *vq = ubufs->vq;
309 int cnt;
310
311 rcu_read_lock_bh();
312
313 /* set len to mark this desc buffers done DMA */
314 vq->heads[ubuf->desc].len = success ?
315 VHOST_DMA_DONE_LEN : VHOST_DMA_FAILED_LEN;
316 cnt = vhost_net_ubuf_put(ubufs);
317
318 /*
319 * Trigger polling thread if guest stopped submitting new buffers:
320 * in this case, the refcount after decrement will eventually reach 1.
321 * We also trigger polling periodically after each 16 packets
322 * (the value 16 here is more or less arbitrary, it's tuned to trigger
323 * less than 10% of times).
324 */
325 if (cnt <= 1 || !(cnt % 16))
326 vhost_poll_queue(&vq->poll);
327
328 rcu_read_unlock_bh();
329}
330
331/* Expects to be always run from workqueue - which acts as
332 * read-size critical section for our kind of RCU. */
333static void handle_tx(struct vhost_net *net)
334{
335 struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_TX];
336 struct vhost_virtqueue *vq = &nvq->vq;
337 unsigned out, in, s;
338 int head;
339 struct msghdr msg = {
340 .msg_name = NULL,
341 .msg_namelen = 0,
342 .msg_control = NULL,
343 .msg_controllen = 0,
344 .msg_iov = vq->iov,
345 .msg_flags = MSG_DONTWAIT,
346 };
347 size_t len, total_len = 0;
348 int err;
349 size_t hdr_size;
350 struct socket *sock;
351 struct vhost_net_ubuf_ref *uninitialized_var(ubufs);
352 bool zcopy, zcopy_used;
353
354 mutex_lock(&vq->mutex);
355 sock = vq->private_data;
356 if (!sock)
357 goto out;
358
359 vhost_disable_notify(&net->dev, vq);
360
361 hdr_size = nvq->vhost_hlen;
362 zcopy = nvq->ubufs;
363
364 for (;;) {
365 /* Release DMAs done buffers first */
366 if (zcopy)
367 vhost_zerocopy_signal_used(net, vq);
368
369 /* If more outstanding DMAs, queue the work.
370 * Handle upend_idx wrap around
371 */
372 if (unlikely((nvq->upend_idx + vq->num - VHOST_MAX_PEND)
373 % UIO_MAXIOV == nvq->done_idx))
374 break;
375
376 head = vhost_get_vq_desc(&net->dev, vq, vq->iov,
377 ARRAY_SIZE(vq->iov),
378 &out, &in,
379 NULL, NULL);
380 /* On error, stop handling until the next kick. */
381 if (unlikely(head < 0))
382 break;
383 /* Nothing new? Wait for eventfd to tell us they refilled. */
384 if (head == vq->num) {
385 if (unlikely(vhost_enable_notify(&net->dev, vq))) {
386 vhost_disable_notify(&net->dev, vq);
387 continue;
388 }
389 break;
390 }
391 if (in) {
392 vq_err(vq, "Unexpected descriptor format for TX: "
393 "out %d, int %d\n", out, in);
394 break;
395 }
396 /* Skip header. TODO: support TSO. */
397 s = move_iovec_hdr(vq->iov, nvq->hdr, hdr_size, out);
398 msg.msg_iovlen = out;
399 len = iov_length(vq->iov, out);
400 /* Sanity check */
401 if (!len) {
402 vq_err(vq, "Unexpected header len for TX: "
403 "%zd expected %zd\n",
404 iov_length(nvq->hdr, s), hdr_size);
405 break;
406 }
407
408 zcopy_used = zcopy && len >= VHOST_GOODCOPY_LEN
409 && (nvq->upend_idx + 1) % UIO_MAXIOV !=
410 nvq->done_idx
411 && vhost_net_tx_select_zcopy(net);
412
413 /* use msg_control to pass vhost zerocopy ubuf info to skb */
414 if (zcopy_used) {
415 struct ubuf_info *ubuf;
416 ubuf = nvq->ubuf_info + nvq->upend_idx;
417
418 vq->heads[nvq->upend_idx].id = head;
419 vq->heads[nvq->upend_idx].len = VHOST_DMA_IN_PROGRESS;
420 ubuf->callback = vhost_zerocopy_callback;
421 ubuf->ctx = nvq->ubufs;
422 ubuf->desc = nvq->upend_idx;
423 msg.msg_control = ubuf;
424 msg.msg_controllen = sizeof(ubuf);
425 ubufs = nvq->ubufs;
426 atomic_inc(&ubufs->refcount);
427 nvq->upend_idx = (nvq->upend_idx + 1) % UIO_MAXIOV;
428 } else {
429 msg.msg_control = NULL;
430 ubufs = NULL;
431 }
432 /* TODO: Check specific error and bomb out unless ENOBUFS? */
433 err = sock->ops->sendmsg(NULL, sock, &msg, len);
434 if (unlikely(err < 0)) {
435 if (zcopy_used) {
436 vhost_net_ubuf_put(ubufs);
437 nvq->upend_idx = ((unsigned)nvq->upend_idx - 1)
438 % UIO_MAXIOV;
439 }
440 vhost_discard_vq_desc(vq, 1);
441 break;
442 }
443 if (err != len)
444 pr_debug("Truncated TX packet: "
445 " len %d != %zd\n", err, len);
446 if (!zcopy_used)
447 vhost_add_used_and_signal(&net->dev, vq, head, 0);
448 else
449 vhost_zerocopy_signal_used(net, vq);
450 total_len += len;
451 vhost_net_tx_packet(net);
452 if (unlikely(total_len >= VHOST_NET_WEIGHT)) {
453 vhost_poll_queue(&vq->poll);
454 break;
455 }
456 }
457out:
458 mutex_unlock(&vq->mutex);
459}
460
461static int peek_head_len(struct sock *sk)
462{
463 struct sk_buff *head;
464 int len = 0;
465 unsigned long flags;
466
467 spin_lock_irqsave(&sk->sk_receive_queue.lock, flags);
468 head = skb_peek(&sk->sk_receive_queue);
469 if (likely(head)) {
470 len = head->len;
471 if (vlan_tx_tag_present(head))
472 len += VLAN_HLEN;
473 }
474
475 spin_unlock_irqrestore(&sk->sk_receive_queue.lock, flags);
476 return len;
477}
478
479/* This is a multi-buffer version of vhost_get_desc, that works if
480 * vq has read descriptors only.
481 * @vq - the relevant virtqueue
482 * @datalen - data length we'll be reading
483 * @iovcount - returned count of io vectors we fill
484 * @log - vhost log
485 * @log_num - log offset
486 * @quota - headcount quota, 1 for big buffer
487 * returns number of buffer heads allocated, negative on error
488 */
489static int get_rx_bufs(struct vhost_virtqueue *vq,
490 struct vring_used_elem *heads,
491 int datalen,
492 unsigned *iovcount,
493 struct vhost_log *log,
494 unsigned *log_num,
495 unsigned int quota)
496{
497 unsigned int out, in;
498 int seg = 0;
499 int headcount = 0;
500 unsigned d;
501 int r, nlogs = 0;
502
503 while (datalen > 0 && headcount < quota) {
504 if (unlikely(seg >= UIO_MAXIOV)) {
505 r = -ENOBUFS;
506 goto err;
507 }
508 r = vhost_get_vq_desc(vq->dev, vq, vq->iov + seg,
509 ARRAY_SIZE(vq->iov) - seg, &out,
510 &in, log, log_num);
511 if (unlikely(r < 0))
512 goto err;
513
514 d = r;
515 if (d == vq->num) {
516 r = 0;
517 goto err;
518 }
519 if (unlikely(out || in <= 0)) {
520 vq_err(vq, "unexpected descriptor format for RX: "
521 "out %d, in %d\n", out, in);
522 r = -EINVAL;
523 goto err;
524 }
525 if (unlikely(log)) {
526 nlogs += *log_num;
527 log += *log_num;
528 }
529 heads[headcount].id = d;
530 heads[headcount].len = iov_length(vq->iov + seg, in);
531 datalen -= heads[headcount].len;
532 ++headcount;
533 seg += in;
534 }
535 heads[headcount - 1].len += datalen;
536 *iovcount = seg;
537 if (unlikely(log))
538 *log_num = nlogs;
539
540 /* Detect overrun */
541 if (unlikely(datalen > 0)) {
542 r = UIO_MAXIOV + 1;
543 goto err;
544 }
545 return headcount;
546err:
547 vhost_discard_vq_desc(vq, headcount);
548 return r;
549}
550
551/* Expects to be always run from workqueue - which acts as
552 * read-size critical section for our kind of RCU. */
553static void handle_rx(struct vhost_net *net)
554{
555 struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_RX];
556 struct vhost_virtqueue *vq = &nvq->vq;
557 unsigned uninitialized_var(in), log;
558 struct vhost_log *vq_log;
559 struct msghdr msg = {
560 .msg_name = NULL,
561 .msg_namelen = 0,
562 .msg_control = NULL, /* FIXME: get and handle RX aux data. */
563 .msg_controllen = 0,
564 .msg_iov = vq->iov,
565 .msg_flags = MSG_DONTWAIT,
566 };
567 struct virtio_net_hdr_mrg_rxbuf hdr = {
568 .hdr.flags = 0,
569 .hdr.gso_type = VIRTIO_NET_HDR_GSO_NONE
570 };
571 size_t total_len = 0;
572 int err, mergeable;
573 s16 headcount;
574 size_t vhost_hlen, sock_hlen;
575 size_t vhost_len, sock_len;
576 struct socket *sock;
577
578 mutex_lock(&vq->mutex);
579 sock = vq->private_data;
580 if (!sock)
581 goto out;
582 vhost_disable_notify(&net->dev, vq);
583
584 vhost_hlen = nvq->vhost_hlen;
585 sock_hlen = nvq->sock_hlen;
586
587 vq_log = unlikely(vhost_has_feature(&net->dev, VHOST_F_LOG_ALL)) ?
588 vq->log : NULL;
589 mergeable = vhost_has_feature(&net->dev, VIRTIO_NET_F_MRG_RXBUF);
590
591 while ((sock_len = peek_head_len(sock->sk))) {
592 sock_len += sock_hlen;
593 vhost_len = sock_len + vhost_hlen;
594 headcount = get_rx_bufs(vq, vq->heads, vhost_len,
595 &in, vq_log, &log,
596 likely(mergeable) ? UIO_MAXIOV : 1);
597 /* On error, stop handling until the next kick. */
598 if (unlikely(headcount < 0))
599 break;
600 /* On overrun, truncate and discard */
601 if (unlikely(headcount > UIO_MAXIOV)) {
602 msg.msg_iovlen = 1;
603 err = sock->ops->recvmsg(NULL, sock, &msg,
604 1, MSG_DONTWAIT | MSG_TRUNC);
605 pr_debug("Discarded rx packet: len %zd\n", sock_len);
606 continue;
607 }
608 /* OK, now we need to know about added descriptors. */
609 if (!headcount) {
610 if (unlikely(vhost_enable_notify(&net->dev, vq))) {
611 /* They have slipped one in as we were
612 * doing that: check again. */
613 vhost_disable_notify(&net->dev, vq);
614 continue;
615 }
616 /* Nothing new? Wait for eventfd to tell us
617 * they refilled. */
618 break;
619 }
620 /* We don't need to be notified again. */
621 if (unlikely((vhost_hlen)))
622 /* Skip header. TODO: support TSO. */
623 move_iovec_hdr(vq->iov, nvq->hdr, vhost_hlen, in);
624 else
625 /* Copy the header for use in VIRTIO_NET_F_MRG_RXBUF:
626 * needed because recvmsg can modify msg_iov. */
627 copy_iovec_hdr(vq->iov, nvq->hdr, sock_hlen, in);
628 msg.msg_iovlen = in;
629 err = sock->ops->recvmsg(NULL, sock, &msg,
630 sock_len, MSG_DONTWAIT | MSG_TRUNC);
631 /* Userspace might have consumed the packet meanwhile:
632 * it's not supposed to do this usually, but might be hard
633 * to prevent. Discard data we got (if any) and keep going. */
634 if (unlikely(err != sock_len)) {
635 pr_debug("Discarded rx packet: "
636 " len %d, expected %zd\n", err, sock_len);
637 vhost_discard_vq_desc(vq, headcount);
638 continue;
639 }
640 if (unlikely(vhost_hlen) &&
641 memcpy_toiovecend(nvq->hdr, (unsigned char *)&hdr, 0,
642 vhost_hlen)) {
643 vq_err(vq, "Unable to write vnet_hdr at addr %p\n",
644 vq->iov->iov_base);
645 break;
646 }
647 /* TODO: Should check and handle checksum. */
648 if (likely(mergeable) &&
649 memcpy_toiovecend(nvq->hdr, (unsigned char *)&headcount,
650 offsetof(typeof(hdr), num_buffers),
651 sizeof hdr.num_buffers)) {
652 vq_err(vq, "Failed num_buffers write");
653 vhost_discard_vq_desc(vq, headcount);
654 break;
655 }
656 vhost_add_used_and_signal_n(&net->dev, vq, vq->heads,
657 headcount);
658 if (unlikely(vq_log))
659 vhost_log_write(vq, vq_log, log, vhost_len);
660 total_len += vhost_len;
661 if (unlikely(total_len >= VHOST_NET_WEIGHT)) {
662 vhost_poll_queue(&vq->poll);
663 break;
664 }
665 }
666out:
667 mutex_unlock(&vq->mutex);
668}
669
670static void handle_tx_kick(struct vhost_work *work)
671{
672 struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
673 poll.work);
674 struct vhost_net *net = container_of(vq->dev, struct vhost_net, dev);
675
676 handle_tx(net);
677}
678
679static void handle_rx_kick(struct vhost_work *work)
680{
681 struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
682 poll.work);
683 struct vhost_net *net = container_of(vq->dev, struct vhost_net, dev);
684
685 handle_rx(net);
686}
687
688static void handle_tx_net(struct vhost_work *work)
689{
690 struct vhost_net *net = container_of(work, struct vhost_net,
691 poll[VHOST_NET_VQ_TX].work);
692 handle_tx(net);
693}
694
695static void handle_rx_net(struct vhost_work *work)
696{
697 struct vhost_net *net = container_of(work, struct vhost_net,
698 poll[VHOST_NET_VQ_RX].work);
699 handle_rx(net);
700}
701
702static int vhost_net_open(struct inode *inode, struct file *f)
703{
704 struct vhost_net *n = kmalloc(sizeof *n, GFP_KERNEL);
705 struct vhost_dev *dev;
706 struct vhost_virtqueue **vqs;
707 int i;
708
709 if (!n)
710 return -ENOMEM;
711 vqs = kmalloc(VHOST_NET_VQ_MAX * sizeof(*vqs), GFP_KERNEL);
712 if (!vqs) {
713 kfree(n);
714 return -ENOMEM;
715 }
716
717 dev = &n->dev;
718 vqs[VHOST_NET_VQ_TX] = &n->vqs[VHOST_NET_VQ_TX].vq;
719 vqs[VHOST_NET_VQ_RX] = &n->vqs[VHOST_NET_VQ_RX].vq;
720 n->vqs[VHOST_NET_VQ_TX].vq.handle_kick = handle_tx_kick;
721 n->vqs[VHOST_NET_VQ_RX].vq.handle_kick = handle_rx_kick;
722 for (i = 0; i < VHOST_NET_VQ_MAX; i++) {
723 n->vqs[i].ubufs = NULL;
724 n->vqs[i].ubuf_info = NULL;
725 n->vqs[i].upend_idx = 0;
726 n->vqs[i].done_idx = 0;
727 n->vqs[i].vhost_hlen = 0;
728 n->vqs[i].sock_hlen = 0;
729 }
730 vhost_dev_init(dev, vqs, VHOST_NET_VQ_MAX);
731
732 vhost_poll_init(n->poll + VHOST_NET_VQ_TX, handle_tx_net, POLLOUT, dev);
733 vhost_poll_init(n->poll + VHOST_NET_VQ_RX, handle_rx_net, POLLIN, dev);
734
735 f->private_data = n;
736
737 return 0;
738}
739
740static void vhost_net_disable_vq(struct vhost_net *n,
741 struct vhost_virtqueue *vq)
742{
743 struct vhost_net_virtqueue *nvq =
744 container_of(vq, struct vhost_net_virtqueue, vq);
745 struct vhost_poll *poll = n->poll + (nvq - n->vqs);
746 if (!vq->private_data)
747 return;
748 vhost_poll_stop(poll);
749}
750
751static int vhost_net_enable_vq(struct vhost_net *n,
752 struct vhost_virtqueue *vq)
753{
754 struct vhost_net_virtqueue *nvq =
755 container_of(vq, struct vhost_net_virtqueue, vq);
756 struct vhost_poll *poll = n->poll + (nvq - n->vqs);
757 struct socket *sock;
758
759 sock = vq->private_data;
760 if (!sock)
761 return 0;
762
763 return vhost_poll_start(poll, sock->file);
764}
765
766static struct socket *vhost_net_stop_vq(struct vhost_net *n,
767 struct vhost_virtqueue *vq)
768{
769 struct socket *sock;
770
771 mutex_lock(&vq->mutex);
772 sock = vq->private_data;
773 vhost_net_disable_vq(n, vq);
774 vq->private_data = NULL;
775 mutex_unlock(&vq->mutex);
776 return sock;
777}
778
779static void vhost_net_stop(struct vhost_net *n, struct socket **tx_sock,
780 struct socket **rx_sock)
781{
782 *tx_sock = vhost_net_stop_vq(n, &n->vqs[VHOST_NET_VQ_TX].vq);
783 *rx_sock = vhost_net_stop_vq(n, &n->vqs[VHOST_NET_VQ_RX].vq);
784}
785
786static void vhost_net_flush_vq(struct vhost_net *n, int index)
787{
788 vhost_poll_flush(n->poll + index);
789 vhost_poll_flush(&n->vqs[index].vq.poll);
790}
791
792static void vhost_net_flush(struct vhost_net *n)
793{
794 vhost_net_flush_vq(n, VHOST_NET_VQ_TX);
795 vhost_net_flush_vq(n, VHOST_NET_VQ_RX);
796 if (n->vqs[VHOST_NET_VQ_TX].ubufs) {
797 mutex_lock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
798 n->tx_flush = true;
799 mutex_unlock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
800 /* Wait for all lower device DMAs done. */
801 vhost_net_ubuf_put_and_wait(n->vqs[VHOST_NET_VQ_TX].ubufs);
802 mutex_lock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
803 n->tx_flush = false;
804 atomic_set(&n->vqs[VHOST_NET_VQ_TX].ubufs->refcount, 1);
805 mutex_unlock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
806 }
807}
808
809static int vhost_net_release(struct inode *inode, struct file *f)
810{
811 struct vhost_net *n = f->private_data;
812 struct socket *tx_sock;
813 struct socket *rx_sock;
814
815 vhost_net_stop(n, &tx_sock, &rx_sock);
816 vhost_net_flush(n);
817 vhost_dev_stop(&n->dev);
818 vhost_dev_cleanup(&n->dev, false);
819 vhost_net_vq_reset(n);
820 if (tx_sock)
821 sockfd_put(tx_sock);
822 if (rx_sock)
823 sockfd_put(rx_sock);
824 /* Make sure no callbacks are outstanding */
825 synchronize_rcu_bh();
826 /* We do an extra flush before freeing memory,
827 * since jobs can re-queue themselves. */
828 vhost_net_flush(n);
829 kfree(n->dev.vqs);
830 kfree(n);
831 return 0;
832}
833
834static struct socket *get_raw_socket(int fd)
835{
836 struct {
837 struct sockaddr_ll sa;
838 char buf[MAX_ADDR_LEN];
839 } uaddr;
840 int uaddr_len = sizeof uaddr, r;
841 struct socket *sock = sockfd_lookup(fd, &r);
842
843 if (!sock)
844 return ERR_PTR(-ENOTSOCK);
845
846 /* Parameter checking */
847 if (sock->sk->sk_type != SOCK_RAW) {
848 r = -ESOCKTNOSUPPORT;
849 goto err;
850 }
851
852 r = sock->ops->getname(sock, (struct sockaddr *)&uaddr.sa,
853 &uaddr_len, 0);
854 if (r)
855 goto err;
856
857 if (uaddr.sa.sll_family != AF_PACKET) {
858 r = -EPFNOSUPPORT;
859 goto err;
860 }
861 return sock;
862err:
863 sockfd_put(sock);
864 return ERR_PTR(r);
865}
866
867static struct socket *get_tap_socket(int fd)
868{
869 struct file *file = fget(fd);
870 struct socket *sock;
871
872 if (!file)
873 return ERR_PTR(-EBADF);
874 sock = tun_get_socket(file);
875 if (!IS_ERR(sock))
876 return sock;
877 sock = macvtap_get_socket(file);
878 if (IS_ERR(sock))
879 fput(file);
880 return sock;
881}
882
883static struct socket *get_socket(int fd)
884{
885 struct socket *sock;
886
887 /* special case to disable backend */
888 if (fd == -1)
889 return NULL;
890 sock = get_raw_socket(fd);
891 if (!IS_ERR(sock))
892 return sock;
893 sock = get_tap_socket(fd);
894 if (!IS_ERR(sock))
895 return sock;
896 return ERR_PTR(-ENOTSOCK);
897}
898
899static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd)
900{
901 struct socket *sock, *oldsock;
902 struct vhost_virtqueue *vq;
903 struct vhost_net_virtqueue *nvq;
904 struct vhost_net_ubuf_ref *ubufs, *oldubufs = NULL;
905 int r;
906
907 mutex_lock(&n->dev.mutex);
908 r = vhost_dev_check_owner(&n->dev);
909 if (r)
910 goto err;
911
912 if (index >= VHOST_NET_VQ_MAX) {
913 r = -ENOBUFS;
914 goto err;
915 }
916 vq = &n->vqs[index].vq;
917 nvq = &n->vqs[index];
918 mutex_lock(&vq->mutex);
919
920 /* Verify that ring has been setup correctly. */
921 if (!vhost_vq_access_ok(vq)) {
922 r = -EFAULT;
923 goto err_vq;
924 }
925 sock = get_socket(fd);
926 if (IS_ERR(sock)) {
927 r = PTR_ERR(sock);
928 goto err_vq;
929 }
930
931 /* start polling new socket */
932 oldsock = vq->private_data;
933 if (sock != oldsock) {
934 ubufs = vhost_net_ubuf_alloc(vq,
935 sock && vhost_sock_zcopy(sock));
936 if (IS_ERR(ubufs)) {
937 r = PTR_ERR(ubufs);
938 goto err_ubufs;
939 }
940
941 vhost_net_disable_vq(n, vq);
942 vq->private_data = sock;
943 r = vhost_init_used(vq);
944 if (r)
945 goto err_used;
946 r = vhost_net_enable_vq(n, vq);
947 if (r)
948 goto err_used;
949
950 oldubufs = nvq->ubufs;
951 nvq->ubufs = ubufs;
952
953 n->tx_packets = 0;
954 n->tx_zcopy_err = 0;
955 n->tx_flush = false;
956 }
957
958 mutex_unlock(&vq->mutex);
959
960 if (oldubufs) {
961 vhost_net_ubuf_put_wait_and_free(oldubufs);
962 mutex_lock(&vq->mutex);
963 vhost_zerocopy_signal_used(n, vq);
964 mutex_unlock(&vq->mutex);
965 }
966
967 if (oldsock) {
968 vhost_net_flush_vq(n, index);
969 sockfd_put(oldsock);
970 }
971
972 mutex_unlock(&n->dev.mutex);
973 return 0;
974
975err_used:
976 vq->private_data = oldsock;
977 vhost_net_enable_vq(n, vq);
978 if (ubufs)
979 vhost_net_ubuf_put_wait_and_free(ubufs);
980err_ubufs:
981 sockfd_put(sock);
982err_vq:
983 mutex_unlock(&vq->mutex);
984err:
985 mutex_unlock(&n->dev.mutex);
986 return r;
987}
988
989static long vhost_net_reset_owner(struct vhost_net *n)
990{
991 struct socket *tx_sock = NULL;
992 struct socket *rx_sock = NULL;
993 long err;
994 struct vhost_memory *memory;
995
996 mutex_lock(&n->dev.mutex);
997 err = vhost_dev_check_owner(&n->dev);
998 if (err)
999 goto done;
1000 memory = vhost_dev_reset_owner_prepare();
1001 if (!memory) {
1002 err = -ENOMEM;
1003 goto done;
1004 }
1005 vhost_net_stop(n, &tx_sock, &rx_sock);
1006 vhost_net_flush(n);
1007 vhost_dev_reset_owner(&n->dev, memory);
1008 vhost_net_vq_reset(n);
1009done:
1010 mutex_unlock(&n->dev.mutex);
1011 if (tx_sock)
1012 sockfd_put(tx_sock);
1013 if (rx_sock)
1014 sockfd_put(rx_sock);
1015 return err;
1016}
1017
1018static int vhost_net_set_features(struct vhost_net *n, u64 features)
1019{
1020 size_t vhost_hlen, sock_hlen, hdr_len;
1021 int i;
1022
1023 hdr_len = (features & (1 << VIRTIO_NET_F_MRG_RXBUF)) ?
1024 sizeof(struct virtio_net_hdr_mrg_rxbuf) :
1025 sizeof(struct virtio_net_hdr);
1026 if (features & (1 << VHOST_NET_F_VIRTIO_NET_HDR)) {
1027 /* vhost provides vnet_hdr */
1028 vhost_hlen = hdr_len;
1029 sock_hlen = 0;
1030 } else {
1031 /* socket provides vnet_hdr */
1032 vhost_hlen = 0;
1033 sock_hlen = hdr_len;
1034 }
1035 mutex_lock(&n->dev.mutex);
1036 if ((features & (1 << VHOST_F_LOG_ALL)) &&
1037 !vhost_log_access_ok(&n->dev)) {
1038 mutex_unlock(&n->dev.mutex);
1039 return -EFAULT;
1040 }
1041 n->dev.acked_features = features;
1042 smp_wmb();
1043 for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
1044 mutex_lock(&n->vqs[i].vq.mutex);
1045 n->vqs[i].vhost_hlen = vhost_hlen;
1046 n->vqs[i].sock_hlen = sock_hlen;
1047 mutex_unlock(&n->vqs[i].vq.mutex);
1048 }
1049 vhost_net_flush(n);
1050 mutex_unlock(&n->dev.mutex);
1051 return 0;
1052}
1053
1054static long vhost_net_set_owner(struct vhost_net *n)
1055{
1056 int r;
1057
1058 mutex_lock(&n->dev.mutex);
1059 if (vhost_dev_has_owner(&n->dev)) {
1060 r = -EBUSY;
1061 goto out;
1062 }
1063 r = vhost_net_set_ubuf_info(n);
1064 if (r)
1065 goto out;
1066 r = vhost_dev_set_owner(&n->dev);
1067 if (r)
1068 vhost_net_clear_ubuf_info(n);
1069 vhost_net_flush(n);
1070out:
1071 mutex_unlock(&n->dev.mutex);
1072 return r;
1073}
1074
1075static long vhost_net_ioctl(struct file *f, unsigned int ioctl,
1076 unsigned long arg)
1077{
1078 struct vhost_net *n = f->private_data;
1079 void __user *argp = (void __user *)arg;
1080 u64 __user *featurep = argp;
1081 struct vhost_vring_file backend;
1082 u64 features;
1083 int r;
1084
1085 switch (ioctl) {
1086 case VHOST_NET_SET_BACKEND:
1087 if (copy_from_user(&backend, argp, sizeof backend))
1088 return -EFAULT;
1089 return vhost_net_set_backend(n, backend.index, backend.fd);
1090 case VHOST_GET_FEATURES:
1091 features = VHOST_NET_FEATURES;
1092 if (copy_to_user(featurep, &features, sizeof features))
1093 return -EFAULT;
1094 return 0;
1095 case VHOST_SET_FEATURES:
1096 if (copy_from_user(&features, featurep, sizeof features))
1097 return -EFAULT;
1098 if (features & ~VHOST_NET_FEATURES)
1099 return -EOPNOTSUPP;
1100 return vhost_net_set_features(n, features);
1101 case VHOST_RESET_OWNER:
1102 return vhost_net_reset_owner(n);
1103 case VHOST_SET_OWNER:
1104 return vhost_net_set_owner(n);
1105 default:
1106 mutex_lock(&n->dev.mutex);
1107 r = vhost_dev_ioctl(&n->dev, ioctl, argp);
1108 if (r == -ENOIOCTLCMD)
1109 r = vhost_vring_ioctl(&n->dev, ioctl, argp);
1110 else
1111 vhost_net_flush(n);
1112 mutex_unlock(&n->dev.mutex);
1113 return r;
1114 }
1115}
1116
1117#ifdef CONFIG_COMPAT
1118static long vhost_net_compat_ioctl(struct file *f, unsigned int ioctl,
1119 unsigned long arg)
1120{
1121 return vhost_net_ioctl(f, ioctl, (unsigned long)compat_ptr(arg));
1122}
1123#endif
1124
1125static const struct file_operations vhost_net_fops = {
1126 .owner = THIS_MODULE,
1127 .release = vhost_net_release,
1128 .unlocked_ioctl = vhost_net_ioctl,
1129#ifdef CONFIG_COMPAT
1130 .compat_ioctl = vhost_net_compat_ioctl,
1131#endif
1132 .open = vhost_net_open,
1133 .llseek = noop_llseek,
1134};
1135
1136static struct miscdevice vhost_net_misc = {
1137 .minor = VHOST_NET_MINOR,
1138 .name = "vhost-net",
1139 .fops = &vhost_net_fops,
1140};
1141
1142static int vhost_net_init(void)
1143{
1144 if (experimental_zcopytx)
1145 vhost_net_enable_zcopy(VHOST_NET_VQ_TX);
1146 return misc_register(&vhost_net_misc);
1147}
1148module_init(vhost_net_init);
1149
1150static void vhost_net_exit(void)
1151{
1152 misc_deregister(&vhost_net_misc);
1153}
1154module_exit(vhost_net_exit);
1155
1156MODULE_VERSION("0.0.1");
1157MODULE_LICENSE("GPL v2");
1158MODULE_AUTHOR("Michael S. Tsirkin");
1159MODULE_DESCRIPTION("Host kernel accelerator for virtio net");
1160MODULE_ALIAS_MISCDEV(VHOST_NET_MINOR);
1161MODULE_ALIAS("devname:vhost-net");