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