Version:  2.6.34 2.6.35 2.6.36 2.6.37 2.6.38 2.6.39 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 3.10 3.11 3.12 3.13 3.14

Linux/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/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 
 32 static int experimental_zcopytx = 1;
 33 module_param(experimental_zcopytx, int, 0444);
 34 MODULE_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 
 60 enum {
 61         VHOST_NET_FEATURES = VHOST_FEATURES |
 62                          (1ULL << VHOST_NET_F_VIRTIO_NET_HDR) |
 63                          (1ULL << VIRTIO_NET_F_MRG_RXBUF),
 64 };
 65 
 66 enum {
 67         VHOST_NET_VQ_RX = 0,
 68         VHOST_NET_VQ_TX = 1,
 69         VHOST_NET_VQ_MAX = 2,
 70 };
 71 
 72 struct 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 
 83 struct 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 
103 struct 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 
117 static unsigned vhost_net_zcopy_mask __read_mostly;
118 
119 static void vhost_net_enable_zcopy(int vq)
120 {
121         vhost_net_zcopy_mask |= 0x1 << vq;
122 }
123 
124 static struct vhost_net_ubuf_ref *
125 vhost_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 
140 static 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 
148 static 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 
154 static 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 
160 static 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 
170 static 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 
186 err:
187         vhost_net_clear_ubuf_info(n);
188         return -ENOMEM;
189 }
190 
191 static 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 
207 static 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 
216 static void vhost_net_tx_err(struct vhost_net *net)
217 {
218         ++net->tx_zcopy_err;
219 }
220 
221 static 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 
230 static 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. */
237 static 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. */
257 static 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  */
279 static 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 
305 static 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. */
333 static 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         }
457 out:
458         mutex_unlock(&vq->mutex);
459 }
460 
461 static 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  */
489 static 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;
546 err:
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. */
553 static 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         }
666 out:
667         mutex_unlock(&vq->mutex);
668 }
669 
670 static 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 
679 static 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 
688 static 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 
695 static 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 
702 static 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 
740 static 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 
751 static 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 
766 static 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 
779 static 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 
786 static 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 
792 static 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 
809 static 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                 fput(tx_sock->file);
822         if (rx_sock)
823                 fput(rx_sock->file);
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 
834 static 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;
862 err:
863         fput(sock->file);
864         return ERR_PTR(r);
865 }
866 
867 static 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 
883 static 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 
899 static 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                 fput(oldsock->file);
970         }
971 
972         mutex_unlock(&n->dev.mutex);
973         return 0;
974 
975 err_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);
980 err_ubufs:
981         fput(sock->file);
982 err_vq:
983         mutex_unlock(&vq->mutex);
984 err:
985         mutex_unlock(&n->dev.mutex);
986         return r;
987 }
988 
989 static 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);
1009 done:
1010         mutex_unlock(&n->dev.mutex);
1011         if (tx_sock)
1012                 fput(tx_sock->file);
1013         if (rx_sock)
1014                 fput(rx_sock->file);
1015         return err;
1016 }
1017 
1018 static 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 
1054 static 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);
1070 out:
1071         mutex_unlock(&n->dev.mutex);
1072         return r;
1073 }
1074 
1075 static 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
1118 static 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 
1125 static 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 
1136 static struct miscdevice vhost_net_misc = {
1137         .minor = VHOST_NET_MINOR,
1138         .name = "vhost-net",
1139         .fops = &vhost_net_fops,
1140 };
1141 
1142 static 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 }
1148 module_init(vhost_net_init);
1149 
1150 static void vhost_net_exit(void)
1151 {
1152         misc_deregister(&vhost_net_misc);
1153 }
1154 module_exit(vhost_net_exit);
1155 
1156 MODULE_VERSION("0.0.1");
1157 MODULE_LICENSE("GPL v2");
1158 MODULE_AUTHOR("Michael S. Tsirkin");
1159 MODULE_DESCRIPTION("Host kernel accelerator for virtio net");
1160 MODULE_ALIAS_MISCDEV(VHOST_NET_MINOR);
1161 MODULE_ALIAS("devname:vhost-net");
1162 

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