Version:  2.0.40 2.2.26 2.4.37 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 3.15 3.16 3.17

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 #include <linux/vmalloc.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         /* refcount follows semantics similar to kref:
 75          *  0: object is released
 76          *  1: no outstanding ubufs
 77          * >1: outstanding ubufs
 78          */
 79         atomic_t refcount;
 80         wait_queue_head_t wait;
 81         struct vhost_virtqueue *vq;
 82 };
 83 
 84 struct vhost_net_virtqueue {
 85         struct vhost_virtqueue vq;
 86         /* hdr is used to store the virtio header.
 87          * Since each iovec has >= 1 byte length, we never need more than
 88          * header length entries to store the header. */
 89         struct iovec hdr[sizeof(struct virtio_net_hdr_mrg_rxbuf)];
 90         size_t vhost_hlen;
 91         size_t sock_hlen;
 92         /* vhost zerocopy support fields below: */
 93         /* last used idx for outstanding DMA zerocopy buffers */
 94         int upend_idx;
 95         /* first used idx for DMA done zerocopy buffers */
 96         int done_idx;
 97         /* an array of userspace buffers info */
 98         struct ubuf_info *ubuf_info;
 99         /* Reference counting for outstanding ubufs.
100          * Protected by vq mutex. Writers must also take device mutex. */
101         struct vhost_net_ubuf_ref *ubufs;
102 };
103 
104 struct vhost_net {
105         struct vhost_dev dev;
106         struct vhost_net_virtqueue vqs[VHOST_NET_VQ_MAX];
107         struct vhost_poll poll[VHOST_NET_VQ_MAX];
108         /* Number of TX recently submitted.
109          * Protected by tx vq lock. */
110         unsigned tx_packets;
111         /* Number of times zerocopy TX recently failed.
112          * Protected by tx vq lock. */
113         unsigned tx_zcopy_err;
114         /* Flush in progress. Protected by tx vq lock. */
115         bool tx_flush;
116 };
117 
118 static unsigned vhost_net_zcopy_mask __read_mostly;
119 
120 static void vhost_net_enable_zcopy(int vq)
121 {
122         vhost_net_zcopy_mask |= 0x1 << vq;
123 }
124 
125 static struct vhost_net_ubuf_ref *
126 vhost_net_ubuf_alloc(struct vhost_virtqueue *vq, bool zcopy)
127 {
128         struct vhost_net_ubuf_ref *ubufs;
129         /* No zero copy backend? Nothing to count. */
130         if (!zcopy)
131                 return NULL;
132         ubufs = kmalloc(sizeof(*ubufs), GFP_KERNEL);
133         if (!ubufs)
134                 return ERR_PTR(-ENOMEM);
135         atomic_set(&ubufs->refcount, 1);
136         init_waitqueue_head(&ubufs->wait);
137         ubufs->vq = vq;
138         return ubufs;
139 }
140 
141 static int vhost_net_ubuf_put(struct vhost_net_ubuf_ref *ubufs)
142 {
143         int r = atomic_sub_return(1, &ubufs->refcount);
144         if (unlikely(!r))
145                 wake_up(&ubufs->wait);
146         return r;
147 }
148 
149 static void vhost_net_ubuf_put_and_wait(struct vhost_net_ubuf_ref *ubufs)
150 {
151         vhost_net_ubuf_put(ubufs);
152         wait_event(ubufs->wait, !atomic_read(&ubufs->refcount));
153 }
154 
155 static void vhost_net_ubuf_put_wait_and_free(struct vhost_net_ubuf_ref *ubufs)
156 {
157         vhost_net_ubuf_put_and_wait(ubufs);
158         kfree(ubufs);
159 }
160 
161 static void vhost_net_clear_ubuf_info(struct vhost_net *n)
162 {
163         int i;
164 
165         for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
166                 kfree(n->vqs[i].ubuf_info);
167                 n->vqs[i].ubuf_info = NULL;
168         }
169 }
170 
171 static int vhost_net_set_ubuf_info(struct vhost_net *n)
172 {
173         bool zcopy;
174         int i;
175 
176         for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
177                 zcopy = vhost_net_zcopy_mask & (0x1 << i);
178                 if (!zcopy)
179                         continue;
180                 n->vqs[i].ubuf_info = kmalloc(sizeof(*n->vqs[i].ubuf_info) *
181                                               UIO_MAXIOV, GFP_KERNEL);
182                 if  (!n->vqs[i].ubuf_info)
183                         goto err;
184         }
185         return 0;
186 
187 err:
188         vhost_net_clear_ubuf_info(n);
189         return -ENOMEM;
190 }
191 
192 static void vhost_net_vq_reset(struct vhost_net *n)
193 {
194         int i;
195 
196         vhost_net_clear_ubuf_info(n);
197 
198         for (i = 0; i < VHOST_NET_VQ_MAX; i++) {
199                 n->vqs[i].done_idx = 0;
200                 n->vqs[i].upend_idx = 0;
201                 n->vqs[i].ubufs = NULL;
202                 n->vqs[i].vhost_hlen = 0;
203                 n->vqs[i].sock_hlen = 0;
204         }
205 
206 }
207 
208 static void vhost_net_tx_packet(struct vhost_net *net)
209 {
210         ++net->tx_packets;
211         if (net->tx_packets < 1024)
212                 return;
213         net->tx_packets = 0;
214         net->tx_zcopy_err = 0;
215 }
216 
217 static void vhost_net_tx_err(struct vhost_net *net)
218 {
219         ++net->tx_zcopy_err;
220 }
221 
222 static bool vhost_net_tx_select_zcopy(struct vhost_net *net)
223 {
224         /* TX flush waits for outstanding DMAs to be done.
225          * Don't start new DMAs.
226          */
227         return !net->tx_flush &&
228                 net->tx_packets / 64 >= net->tx_zcopy_err;
229 }
230 
231 static bool vhost_sock_zcopy(struct socket *sock)
232 {
233         return unlikely(experimental_zcopytx) &&
234                 sock_flag(sock->sk, SOCK_ZEROCOPY);
235 }
236 
237 /* Pop first len bytes from iovec. Return number of segments used. */
238 static int move_iovec_hdr(struct iovec *from, struct iovec *to,
239                           size_t len, int iov_count)
240 {
241         int seg = 0;
242         size_t size;
243 
244         while (len && seg < iov_count) {
245                 size = min(from->iov_len, len);
246                 to->iov_base = from->iov_base;
247                 to->iov_len = size;
248                 from->iov_len -= size;
249                 from->iov_base += size;
250                 len -= size;
251                 ++from;
252                 ++to;
253                 ++seg;
254         }
255         return seg;
256 }
257 /* Copy iovec entries for len bytes from iovec. */
258 static void copy_iovec_hdr(const struct iovec *from, struct iovec *to,
259                            size_t len, int iovcount)
260 {
261         int seg = 0;
262         size_t size;
263 
264         while (len && seg < iovcount) {
265                 size = min(from->iov_len, len);
266                 to->iov_base = from->iov_base;
267                 to->iov_len = size;
268                 len -= size;
269                 ++from;
270                 ++to;
271                 ++seg;
272         }
273 }
274 
275 /* In case of DMA done not in order in lower device driver for some reason.
276  * upend_idx is used to track end of used idx, done_idx is used to track head
277  * of used idx. Once lower device DMA done contiguously, we will signal KVM
278  * guest used idx.
279  */
280 static void vhost_zerocopy_signal_used(struct vhost_net *net,
281                                        struct vhost_virtqueue *vq)
282 {
283         struct vhost_net_virtqueue *nvq =
284                 container_of(vq, struct vhost_net_virtqueue, vq);
285         int i, add;
286         int j = 0;
287 
288         for (i = nvq->done_idx; i != nvq->upend_idx; i = (i + 1) % UIO_MAXIOV) {
289                 if (vq->heads[i].len == VHOST_DMA_FAILED_LEN)
290                         vhost_net_tx_err(net);
291                 if (VHOST_DMA_IS_DONE(vq->heads[i].len)) {
292                         vq->heads[i].len = VHOST_DMA_CLEAR_LEN;
293                         ++j;
294                 } else
295                         break;
296         }
297         while (j) {
298                 add = min(UIO_MAXIOV - nvq->done_idx, j);
299                 vhost_add_used_and_signal_n(vq->dev, vq,
300                                             &vq->heads[nvq->done_idx], add);
301                 nvq->done_idx = (nvq->done_idx + add) % UIO_MAXIOV;
302                 j -= add;
303         }
304 }
305 
306 static void vhost_zerocopy_callback(struct ubuf_info *ubuf, bool success)
307 {
308         struct vhost_net_ubuf_ref *ubufs = ubuf->ctx;
309         struct vhost_virtqueue *vq = ubufs->vq;
310         int cnt;
311 
312         rcu_read_lock_bh();
313 
314         /* set len to mark this desc buffers done DMA */
315         vq->heads[ubuf->desc].len = success ?
316                 VHOST_DMA_DONE_LEN : VHOST_DMA_FAILED_LEN;
317         cnt = vhost_net_ubuf_put(ubufs);
318 
319         /*
320          * Trigger polling thread if guest stopped submitting new buffers:
321          * in this case, the refcount after decrement will eventually reach 1.
322          * We also trigger polling periodically after each 16 packets
323          * (the value 16 here is more or less arbitrary, it's tuned to trigger
324          * less than 10% of times).
325          */
326         if (cnt <= 1 || !(cnt % 16))
327                 vhost_poll_queue(&vq->poll);
328 
329         rcu_read_unlock_bh();
330 }
331 
332 /* Expects to be always run from workqueue - which acts as
333  * read-size critical section for our kind of RCU. */
334 static void handle_tx(struct vhost_net *net)
335 {
336         struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_TX];
337         struct vhost_virtqueue *vq = &nvq->vq;
338         unsigned out, in, s;
339         int head;
340         struct msghdr msg = {
341                 .msg_name = NULL,
342                 .msg_namelen = 0,
343                 .msg_control = NULL,
344                 .msg_controllen = 0,
345                 .msg_iov = vq->iov,
346                 .msg_flags = MSG_DONTWAIT,
347         };
348         size_t len, total_len = 0;
349         int err;
350         size_t hdr_size;
351         struct socket *sock;
352         struct vhost_net_ubuf_ref *uninitialized_var(ubufs);
353         bool zcopy, zcopy_used;
354 
355         mutex_lock(&vq->mutex);
356         sock = vq->private_data;
357         if (!sock)
358                 goto out;
359 
360         vhost_disable_notify(&net->dev, vq);
361 
362         hdr_size = nvq->vhost_hlen;
363         zcopy = nvq->ubufs;
364 
365         for (;;) {
366                 /* Release DMAs done buffers first */
367                 if (zcopy)
368                         vhost_zerocopy_signal_used(net, vq);
369 
370                 /* If more outstanding DMAs, queue the work.
371                  * Handle upend_idx wrap around
372                  */
373                 if (unlikely((nvq->upend_idx + vq->num - VHOST_MAX_PEND)
374                               % UIO_MAXIOV == nvq->done_idx))
375                         break;
376 
377                 head = vhost_get_vq_desc(vq, vq->iov,
378                                          ARRAY_SIZE(vq->iov),
379                                          &out, &in,
380                                          NULL, NULL);
381                 /* On error, stop handling until the next kick. */
382                 if (unlikely(head < 0))
383                         break;
384                 /* Nothing new?  Wait for eventfd to tell us they refilled. */
385                 if (head == vq->num) {
386                         if (unlikely(vhost_enable_notify(&net->dev, vq))) {
387                                 vhost_disable_notify(&net->dev, vq);
388                                 continue;
389                         }
390                         break;
391                 }
392                 if (in) {
393                         vq_err(vq, "Unexpected descriptor format for TX: "
394                                "out %d, int %d\n", out, in);
395                         break;
396                 }
397                 /* Skip header. TODO: support TSO. */
398                 s = move_iovec_hdr(vq->iov, nvq->hdr, hdr_size, out);
399                 msg.msg_iovlen = out;
400                 len = iov_length(vq->iov, out);
401                 /* Sanity check */
402                 if (!len) {
403                         vq_err(vq, "Unexpected header len for TX: "
404                                "%zd expected %zd\n",
405                                iov_length(nvq->hdr, s), hdr_size);
406                         break;
407                 }
408 
409                 zcopy_used = zcopy && len >= VHOST_GOODCOPY_LEN
410                                    && (nvq->upend_idx + 1) % UIO_MAXIOV !=
411                                       nvq->done_idx
412                                    && vhost_net_tx_select_zcopy(net);
413 
414                 /* use msg_control to pass vhost zerocopy ubuf info to skb */
415                 if (zcopy_used) {
416                         struct ubuf_info *ubuf;
417                         ubuf = nvq->ubuf_info + nvq->upend_idx;
418 
419                         vq->heads[nvq->upend_idx].id = head;
420                         vq->heads[nvq->upend_idx].len = VHOST_DMA_IN_PROGRESS;
421                         ubuf->callback = vhost_zerocopy_callback;
422                         ubuf->ctx = nvq->ubufs;
423                         ubuf->desc = nvq->upend_idx;
424                         msg.msg_control = ubuf;
425                         msg.msg_controllen = sizeof(ubuf);
426                         ubufs = nvq->ubufs;
427                         atomic_inc(&ubufs->refcount);
428                         nvq->upend_idx = (nvq->upend_idx + 1) % UIO_MAXIOV;
429                 } else {
430                         msg.msg_control = NULL;
431                         ubufs = NULL;
432                 }
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                                 vhost_net_ubuf_put(ubufs);
438                                 nvq->upend_idx = ((unsigned)nvq->upend_idx - 1)
439                                         % UIO_MAXIOV;
440                         }
441                         vhost_discard_vq_desc(vq, 1);
442                         break;
443                 }
444                 if (err != len)
445                         pr_debug("Truncated TX packet: "
446                                  " len %d != %zd\n", err, len);
447                 if (!zcopy_used)
448                         vhost_add_used_and_signal(&net->dev, vq, head, 0);
449                 else
450                         vhost_zerocopy_signal_used(net, vq);
451                 total_len += len;
452                 vhost_net_tx_packet(net);
453                 if (unlikely(total_len >= VHOST_NET_WEIGHT)) {
454                         vhost_poll_queue(&vq->poll);
455                         break;
456                 }
457         }
458 out:
459         mutex_unlock(&vq->mutex);
460 }
461 
462 static int peek_head_len(struct sock *sk)
463 {
464         struct sk_buff *head;
465         int len = 0;
466         unsigned long flags;
467 
468         spin_lock_irqsave(&sk->sk_receive_queue.lock, flags);
469         head = skb_peek(&sk->sk_receive_queue);
470         if (likely(head)) {
471                 len = head->len;
472                 if (vlan_tx_tag_present(head))
473                         len += VLAN_HLEN;
474         }
475 
476         spin_unlock_irqrestore(&sk->sk_receive_queue.lock, flags);
477         return len;
478 }
479 
480 /* This is a multi-buffer version of vhost_get_desc, that works if
481  *      vq has read descriptors only.
482  * @vq          - the relevant virtqueue
483  * @datalen     - data length we'll be reading
484  * @iovcount    - returned count of io vectors we fill
485  * @log         - vhost log
486  * @log_num     - log offset
487  * @quota       - headcount quota, 1 for big buffer
488  *      returns number of buffer heads allocated, negative on error
489  */
490 static int get_rx_bufs(struct vhost_virtqueue *vq,
491                        struct vring_used_elem *heads,
492                        int datalen,
493                        unsigned *iovcount,
494                        struct vhost_log *log,
495                        unsigned *log_num,
496                        unsigned int quota)
497 {
498         unsigned int out, in;
499         int seg = 0;
500         int headcount = 0;
501         unsigned d;
502         int r, nlogs = 0;
503 
504         while (datalen > 0 && headcount < quota) {
505                 if (unlikely(seg >= UIO_MAXIOV)) {
506                         r = -ENOBUFS;
507                         goto err;
508                 }
509                 r = vhost_get_vq_desc(vq, vq->iov + seg,
510                                       ARRAY_SIZE(vq->iov) - seg, &out,
511                                       &in, log, log_num);
512                 if (unlikely(r < 0))
513                         goto err;
514 
515                 d = r;
516                 if (d == vq->num) {
517                         r = 0;
518                         goto err;
519                 }
520                 if (unlikely(out || in <= 0)) {
521                         vq_err(vq, "unexpected descriptor format for RX: "
522                                 "out %d, in %d\n", out, in);
523                         r = -EINVAL;
524                         goto err;
525                 }
526                 if (unlikely(log)) {
527                         nlogs += *log_num;
528                         log += *log_num;
529                 }
530                 heads[headcount].id = d;
531                 heads[headcount].len = iov_length(vq->iov + seg, in);
532                 datalen -= heads[headcount].len;
533                 ++headcount;
534                 seg += in;
535         }
536         heads[headcount - 1].len += datalen;
537         *iovcount = seg;
538         if (unlikely(log))
539                 *log_num = nlogs;
540 
541         /* Detect overrun */
542         if (unlikely(datalen > 0)) {
543                 r = UIO_MAXIOV + 1;
544                 goto err;
545         }
546         return headcount;
547 err:
548         vhost_discard_vq_desc(vq, headcount);
549         return r;
550 }
551 
552 /* Expects to be always run from workqueue - which acts as
553  * read-size critical section for our kind of RCU. */
554 static void handle_rx(struct vhost_net *net)
555 {
556         struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_RX];
557         struct vhost_virtqueue *vq = &nvq->vq;
558         unsigned uninitialized_var(in), log;
559         struct vhost_log *vq_log;
560         struct msghdr msg = {
561                 .msg_name = NULL,
562                 .msg_namelen = 0,
563                 .msg_control = NULL, /* FIXME: get and handle RX aux data. */
564                 .msg_controllen = 0,
565                 .msg_iov = vq->iov,
566                 .msg_flags = MSG_DONTWAIT,
567         };
568         struct virtio_net_hdr_mrg_rxbuf hdr = {
569                 .hdr.flags = 0,
570                 .hdr.gso_type = VIRTIO_NET_HDR_GSO_NONE
571         };
572         size_t total_len = 0;
573         int err, mergeable;
574         s16 headcount;
575         size_t vhost_hlen, sock_hlen;
576         size_t vhost_len, sock_len;
577         struct socket *sock;
578 
579         mutex_lock(&vq->mutex);
580         sock = vq->private_data;
581         if (!sock)
582                 goto out;
583         vhost_disable_notify(&net->dev, vq);
584 
585         vhost_hlen = nvq->vhost_hlen;
586         sock_hlen = nvq->sock_hlen;
587 
588         vq_log = unlikely(vhost_has_feature(vq, VHOST_F_LOG_ALL)) ?
589                 vq->log : NULL;
590         mergeable = vhost_has_feature(vq, VIRTIO_NET_F_MRG_RXBUF);
591 
592         while ((sock_len = peek_head_len(sock->sk))) {
593                 sock_len += sock_hlen;
594                 vhost_len = sock_len + vhost_hlen;
595                 headcount = get_rx_bufs(vq, vq->heads, vhost_len,
596                                         &in, vq_log, &log,
597                                         likely(mergeable) ? UIO_MAXIOV : 1);
598                 /* On error, stop handling until the next kick. */
599                 if (unlikely(headcount < 0))
600                         break;
601                 /* On overrun, truncate and discard */
602                 if (unlikely(headcount > UIO_MAXIOV)) {
603                         msg.msg_iovlen = 1;
604                         err = sock->ops->recvmsg(NULL, sock, &msg,
605                                                  1, MSG_DONTWAIT | MSG_TRUNC);
606                         pr_debug("Discarded rx packet: len %zd\n", sock_len);
607                         continue;
608                 }
609                 /* OK, now we need to know about added descriptors. */
610                 if (!headcount) {
611                         if (unlikely(vhost_enable_notify(&net->dev, vq))) {
612                                 /* They have slipped one in as we were
613                                  * doing that: check again. */
614                                 vhost_disable_notify(&net->dev, vq);
615                                 continue;
616                         }
617                         /* Nothing new?  Wait for eventfd to tell us
618                          * they refilled. */
619                         break;
620                 }
621                 /* We don't need to be notified again. */
622                 if (unlikely((vhost_hlen)))
623                         /* Skip header. TODO: support TSO. */
624                         move_iovec_hdr(vq->iov, nvq->hdr, vhost_hlen, in);
625                 else
626                         /* Copy the header for use in VIRTIO_NET_F_MRG_RXBUF:
627                          * needed because recvmsg can modify msg_iov. */
628                         copy_iovec_hdr(vq->iov, nvq->hdr, sock_hlen, in);
629                 msg.msg_iovlen = in;
630                 err = sock->ops->recvmsg(NULL, sock, &msg,
631                                          sock_len, MSG_DONTWAIT | MSG_TRUNC);
632                 /* Userspace might have consumed the packet meanwhile:
633                  * it's not supposed to do this usually, but might be hard
634                  * to prevent. Discard data we got (if any) and keep going. */
635                 if (unlikely(err != sock_len)) {
636                         pr_debug("Discarded rx packet: "
637                                  " len %d, expected %zd\n", err, sock_len);
638                         vhost_discard_vq_desc(vq, headcount);
639                         continue;
640                 }
641                 if (unlikely(vhost_hlen) &&
642                     memcpy_toiovecend(nvq->hdr, (unsigned char *)&hdr, 0,
643                                       vhost_hlen)) {
644                         vq_err(vq, "Unable to write vnet_hdr at addr %p\n",
645                                vq->iov->iov_base);
646                         break;
647                 }
648                 /* TODO: Should check and handle checksum. */
649                 if (likely(mergeable) &&
650                     memcpy_toiovecend(nvq->hdr, (unsigned char *)&headcount,
651                                       offsetof(typeof(hdr), num_buffers),
652                                       sizeof hdr.num_buffers)) {
653                         vq_err(vq, "Failed num_buffers write");
654                         vhost_discard_vq_desc(vq, headcount);
655                         break;
656                 }
657                 vhost_add_used_and_signal_n(&net->dev, vq, vq->heads,
658                                             headcount);
659                 if (unlikely(vq_log))
660                         vhost_log_write(vq, vq_log, log, vhost_len);
661                 total_len += vhost_len;
662                 if (unlikely(total_len >= VHOST_NET_WEIGHT)) {
663                         vhost_poll_queue(&vq->poll);
664                         break;
665                 }
666         }
667 out:
668         mutex_unlock(&vq->mutex);
669 }
670 
671 static void handle_tx_kick(struct vhost_work *work)
672 {
673         struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
674                                                   poll.work);
675         struct vhost_net *net = container_of(vq->dev, struct vhost_net, dev);
676 
677         handle_tx(net);
678 }
679 
680 static void handle_rx_kick(struct vhost_work *work)
681 {
682         struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
683                                                   poll.work);
684         struct vhost_net *net = container_of(vq->dev, struct vhost_net, dev);
685 
686         handle_rx(net);
687 }
688 
689 static void handle_tx_net(struct vhost_work *work)
690 {
691         struct vhost_net *net = container_of(work, struct vhost_net,
692                                              poll[VHOST_NET_VQ_TX].work);
693         handle_tx(net);
694 }
695 
696 static void handle_rx_net(struct vhost_work *work)
697 {
698         struct vhost_net *net = container_of(work, struct vhost_net,
699                                              poll[VHOST_NET_VQ_RX].work);
700         handle_rx(net);
701 }
702 
703 static int vhost_net_open(struct inode *inode, struct file *f)
704 {
705         struct vhost_net *n;
706         struct vhost_dev *dev;
707         struct vhost_virtqueue **vqs;
708         int i;
709 
710         n = kmalloc(sizeof *n, GFP_KERNEL | __GFP_NOWARN | __GFP_REPEAT);
711         if (!n) {
712                 n = vmalloc(sizeof *n);
713                 if (!n)
714                         return -ENOMEM;
715         }
716         vqs = kmalloc(VHOST_NET_VQ_MAX * sizeof(*vqs), GFP_KERNEL);
717         if (!vqs) {
718                 kvfree(n);
719                 return -ENOMEM;
720         }
721 
722         dev = &n->dev;
723         vqs[VHOST_NET_VQ_TX] = &n->vqs[VHOST_NET_VQ_TX].vq;
724         vqs[VHOST_NET_VQ_RX] = &n->vqs[VHOST_NET_VQ_RX].vq;
725         n->vqs[VHOST_NET_VQ_TX].vq.handle_kick = handle_tx_kick;
726         n->vqs[VHOST_NET_VQ_RX].vq.handle_kick = handle_rx_kick;
727         for (i = 0; i < VHOST_NET_VQ_MAX; i++) {
728                 n->vqs[i].ubufs = NULL;
729                 n->vqs[i].ubuf_info = NULL;
730                 n->vqs[i].upend_idx = 0;
731                 n->vqs[i].done_idx = 0;
732                 n->vqs[i].vhost_hlen = 0;
733                 n->vqs[i].sock_hlen = 0;
734         }
735         vhost_dev_init(dev, vqs, VHOST_NET_VQ_MAX);
736 
737         vhost_poll_init(n->poll + VHOST_NET_VQ_TX, handle_tx_net, POLLOUT, dev);
738         vhost_poll_init(n->poll + VHOST_NET_VQ_RX, handle_rx_net, POLLIN, dev);
739 
740         f->private_data = n;
741 
742         return 0;
743 }
744 
745 static void vhost_net_disable_vq(struct vhost_net *n,
746                                  struct vhost_virtqueue *vq)
747 {
748         struct vhost_net_virtqueue *nvq =
749                 container_of(vq, struct vhost_net_virtqueue, vq);
750         struct vhost_poll *poll = n->poll + (nvq - n->vqs);
751         if (!vq->private_data)
752                 return;
753         vhost_poll_stop(poll);
754 }
755 
756 static int vhost_net_enable_vq(struct vhost_net *n,
757                                 struct vhost_virtqueue *vq)
758 {
759         struct vhost_net_virtqueue *nvq =
760                 container_of(vq, struct vhost_net_virtqueue, vq);
761         struct vhost_poll *poll = n->poll + (nvq - n->vqs);
762         struct socket *sock;
763 
764         sock = vq->private_data;
765         if (!sock)
766                 return 0;
767 
768         return vhost_poll_start(poll, sock->file);
769 }
770 
771 static struct socket *vhost_net_stop_vq(struct vhost_net *n,
772                                         struct vhost_virtqueue *vq)
773 {
774         struct socket *sock;
775 
776         mutex_lock(&vq->mutex);
777         sock = vq->private_data;
778         vhost_net_disable_vq(n, vq);
779         vq->private_data = NULL;
780         mutex_unlock(&vq->mutex);
781         return sock;
782 }
783 
784 static void vhost_net_stop(struct vhost_net *n, struct socket **tx_sock,
785                            struct socket **rx_sock)
786 {
787         *tx_sock = vhost_net_stop_vq(n, &n->vqs[VHOST_NET_VQ_TX].vq);
788         *rx_sock = vhost_net_stop_vq(n, &n->vqs[VHOST_NET_VQ_RX].vq);
789 }
790 
791 static void vhost_net_flush_vq(struct vhost_net *n, int index)
792 {
793         vhost_poll_flush(n->poll + index);
794         vhost_poll_flush(&n->vqs[index].vq.poll);
795 }
796 
797 static void vhost_net_flush(struct vhost_net *n)
798 {
799         vhost_net_flush_vq(n, VHOST_NET_VQ_TX);
800         vhost_net_flush_vq(n, VHOST_NET_VQ_RX);
801         if (n->vqs[VHOST_NET_VQ_TX].ubufs) {
802                 mutex_lock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
803                 n->tx_flush = true;
804                 mutex_unlock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
805                 /* Wait for all lower device DMAs done. */
806                 vhost_net_ubuf_put_and_wait(n->vqs[VHOST_NET_VQ_TX].ubufs);
807                 mutex_lock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
808                 n->tx_flush = false;
809                 atomic_set(&n->vqs[VHOST_NET_VQ_TX].ubufs->refcount, 1);
810                 mutex_unlock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
811         }
812 }
813 
814 static int vhost_net_release(struct inode *inode, struct file *f)
815 {
816         struct vhost_net *n = f->private_data;
817         struct socket *tx_sock;
818         struct socket *rx_sock;
819 
820         vhost_net_stop(n, &tx_sock, &rx_sock);
821         vhost_net_flush(n);
822         vhost_dev_stop(&n->dev);
823         vhost_dev_cleanup(&n->dev, false);
824         vhost_net_vq_reset(n);
825         if (tx_sock)
826                 sockfd_put(tx_sock);
827         if (rx_sock)
828                 sockfd_put(rx_sock);
829         /* Make sure no callbacks are outstanding */
830         synchronize_rcu_bh();
831         /* We do an extra flush before freeing memory,
832          * since jobs can re-queue themselves. */
833         vhost_net_flush(n);
834         kfree(n->dev.vqs);
835         kvfree(n);
836         return 0;
837 }
838 
839 static struct socket *get_raw_socket(int fd)
840 {
841         struct {
842                 struct sockaddr_ll sa;
843                 char  buf[MAX_ADDR_LEN];
844         } uaddr;
845         int uaddr_len = sizeof uaddr, r;
846         struct socket *sock = sockfd_lookup(fd, &r);
847 
848         if (!sock)
849                 return ERR_PTR(-ENOTSOCK);
850 
851         /* Parameter checking */
852         if (sock->sk->sk_type != SOCK_RAW) {
853                 r = -ESOCKTNOSUPPORT;
854                 goto err;
855         }
856 
857         r = sock->ops->getname(sock, (struct sockaddr *)&uaddr.sa,
858                                &uaddr_len, 0);
859         if (r)
860                 goto err;
861 
862         if (uaddr.sa.sll_family != AF_PACKET) {
863                 r = -EPFNOSUPPORT;
864                 goto err;
865         }
866         return sock;
867 err:
868         sockfd_put(sock);
869         return ERR_PTR(r);
870 }
871 
872 static struct socket *get_tap_socket(int fd)
873 {
874         struct file *file = fget(fd);
875         struct socket *sock;
876 
877         if (!file)
878                 return ERR_PTR(-EBADF);
879         sock = tun_get_socket(file);
880         if (!IS_ERR(sock))
881                 return sock;
882         sock = macvtap_get_socket(file);
883         if (IS_ERR(sock))
884                 fput(file);
885         return sock;
886 }
887 
888 static struct socket *get_socket(int fd)
889 {
890         struct socket *sock;
891 
892         /* special case to disable backend */
893         if (fd == -1)
894                 return NULL;
895         sock = get_raw_socket(fd);
896         if (!IS_ERR(sock))
897                 return sock;
898         sock = get_tap_socket(fd);
899         if (!IS_ERR(sock))
900                 return sock;
901         return ERR_PTR(-ENOTSOCK);
902 }
903 
904 static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd)
905 {
906         struct socket *sock, *oldsock;
907         struct vhost_virtqueue *vq;
908         struct vhost_net_virtqueue *nvq;
909         struct vhost_net_ubuf_ref *ubufs, *oldubufs = NULL;
910         int r;
911 
912         mutex_lock(&n->dev.mutex);
913         r = vhost_dev_check_owner(&n->dev);
914         if (r)
915                 goto err;
916 
917         if (index >= VHOST_NET_VQ_MAX) {
918                 r = -ENOBUFS;
919                 goto err;
920         }
921         vq = &n->vqs[index].vq;
922         nvq = &n->vqs[index];
923         mutex_lock(&vq->mutex);
924 
925         /* Verify that ring has been setup correctly. */
926         if (!vhost_vq_access_ok(vq)) {
927                 r = -EFAULT;
928                 goto err_vq;
929         }
930         sock = get_socket(fd);
931         if (IS_ERR(sock)) {
932                 r = PTR_ERR(sock);
933                 goto err_vq;
934         }
935 
936         /* start polling new socket */
937         oldsock = vq->private_data;
938         if (sock != oldsock) {
939                 ubufs = vhost_net_ubuf_alloc(vq,
940                                              sock && vhost_sock_zcopy(sock));
941                 if (IS_ERR(ubufs)) {
942                         r = PTR_ERR(ubufs);
943                         goto err_ubufs;
944                 }
945 
946                 vhost_net_disable_vq(n, vq);
947                 vq->private_data = sock;
948                 r = vhost_init_used(vq);
949                 if (r)
950                         goto err_used;
951                 r = vhost_net_enable_vq(n, vq);
952                 if (r)
953                         goto err_used;
954 
955                 oldubufs = nvq->ubufs;
956                 nvq->ubufs = ubufs;
957 
958                 n->tx_packets = 0;
959                 n->tx_zcopy_err = 0;
960                 n->tx_flush = false;
961         }
962 
963         mutex_unlock(&vq->mutex);
964 
965         if (oldubufs) {
966                 vhost_net_ubuf_put_wait_and_free(oldubufs);
967                 mutex_lock(&vq->mutex);
968                 vhost_zerocopy_signal_used(n, vq);
969                 mutex_unlock(&vq->mutex);
970         }
971 
972         if (oldsock) {
973                 vhost_net_flush_vq(n, index);
974                 sockfd_put(oldsock);
975         }
976 
977         mutex_unlock(&n->dev.mutex);
978         return 0;
979 
980 err_used:
981         vq->private_data = oldsock;
982         vhost_net_enable_vq(n, vq);
983         if (ubufs)
984                 vhost_net_ubuf_put_wait_and_free(ubufs);
985 err_ubufs:
986         sockfd_put(sock);
987 err_vq:
988         mutex_unlock(&vq->mutex);
989 err:
990         mutex_unlock(&n->dev.mutex);
991         return r;
992 }
993 
994 static long vhost_net_reset_owner(struct vhost_net *n)
995 {
996         struct socket *tx_sock = NULL;
997         struct socket *rx_sock = NULL;
998         long err;
999         struct vhost_memory *memory;
1000 
1001         mutex_lock(&n->dev.mutex);
1002         err = vhost_dev_check_owner(&n->dev);
1003         if (err)
1004                 goto done;
1005         memory = vhost_dev_reset_owner_prepare();
1006         if (!memory) {
1007                 err = -ENOMEM;
1008                 goto done;
1009         }
1010         vhost_net_stop(n, &tx_sock, &rx_sock);
1011         vhost_net_flush(n);
1012         vhost_dev_reset_owner(&n->dev, memory);
1013         vhost_net_vq_reset(n);
1014 done:
1015         mutex_unlock(&n->dev.mutex);
1016         if (tx_sock)
1017                 sockfd_put(tx_sock);
1018         if (rx_sock)
1019                 sockfd_put(rx_sock);
1020         return err;
1021 }
1022 
1023 static int vhost_net_set_features(struct vhost_net *n, u64 features)
1024 {
1025         size_t vhost_hlen, sock_hlen, hdr_len;
1026         int i;
1027 
1028         hdr_len = (features & (1 << VIRTIO_NET_F_MRG_RXBUF)) ?
1029                         sizeof(struct virtio_net_hdr_mrg_rxbuf) :
1030                         sizeof(struct virtio_net_hdr);
1031         if (features & (1 << VHOST_NET_F_VIRTIO_NET_HDR)) {
1032                 /* vhost provides vnet_hdr */
1033                 vhost_hlen = hdr_len;
1034                 sock_hlen = 0;
1035         } else {
1036                 /* socket provides vnet_hdr */
1037                 vhost_hlen = 0;
1038                 sock_hlen = hdr_len;
1039         }
1040         mutex_lock(&n->dev.mutex);
1041         if ((features & (1 << VHOST_F_LOG_ALL)) &&
1042             !vhost_log_access_ok(&n->dev)) {
1043                 mutex_unlock(&n->dev.mutex);
1044                 return -EFAULT;
1045         }
1046         for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
1047                 mutex_lock(&n->vqs[i].vq.mutex);
1048                 n->vqs[i].vq.acked_features = features;
1049                 n->vqs[i].vhost_hlen = vhost_hlen;
1050                 n->vqs[i].sock_hlen = sock_hlen;
1051                 mutex_unlock(&n->vqs[i].vq.mutex);
1052         }
1053         mutex_unlock(&n->dev.mutex);
1054         return 0;
1055 }
1056 
1057 static long vhost_net_set_owner(struct vhost_net *n)
1058 {
1059         int r;
1060 
1061         mutex_lock(&n->dev.mutex);
1062         if (vhost_dev_has_owner(&n->dev)) {
1063                 r = -EBUSY;
1064                 goto out;
1065         }
1066         r = vhost_net_set_ubuf_info(n);
1067         if (r)
1068                 goto out;
1069         r = vhost_dev_set_owner(&n->dev);
1070         if (r)
1071                 vhost_net_clear_ubuf_info(n);
1072         vhost_net_flush(n);
1073 out:
1074         mutex_unlock(&n->dev.mutex);
1075         return r;
1076 }
1077 
1078 static long vhost_net_ioctl(struct file *f, unsigned int ioctl,
1079                             unsigned long arg)
1080 {
1081         struct vhost_net *n = f->private_data;
1082         void __user *argp = (void __user *)arg;
1083         u64 __user *featurep = argp;
1084         struct vhost_vring_file backend;
1085         u64 features;
1086         int r;
1087 
1088         switch (ioctl) {
1089         case VHOST_NET_SET_BACKEND:
1090                 if (copy_from_user(&backend, argp, sizeof backend))
1091                         return -EFAULT;
1092                 return vhost_net_set_backend(n, backend.index, backend.fd);
1093         case VHOST_GET_FEATURES:
1094                 features = VHOST_NET_FEATURES;
1095                 if (copy_to_user(featurep, &features, sizeof features))
1096                         return -EFAULT;
1097                 return 0;
1098         case VHOST_SET_FEATURES:
1099                 if (copy_from_user(&features, featurep, sizeof features))
1100                         return -EFAULT;
1101                 if (features & ~VHOST_NET_FEATURES)
1102                         return -EOPNOTSUPP;
1103                 return vhost_net_set_features(n, features);
1104         case VHOST_RESET_OWNER:
1105                 return vhost_net_reset_owner(n);
1106         case VHOST_SET_OWNER:
1107                 return vhost_net_set_owner(n);
1108         default:
1109                 mutex_lock(&n->dev.mutex);
1110                 r = vhost_dev_ioctl(&n->dev, ioctl, argp);
1111                 if (r == -ENOIOCTLCMD)
1112                         r = vhost_vring_ioctl(&n->dev, ioctl, argp);
1113                 else
1114                         vhost_net_flush(n);
1115                 mutex_unlock(&n->dev.mutex);
1116                 return r;
1117         }
1118 }
1119 
1120 #ifdef CONFIG_COMPAT
1121 static long vhost_net_compat_ioctl(struct file *f, unsigned int ioctl,
1122                                    unsigned long arg)
1123 {
1124         return vhost_net_ioctl(f, ioctl, (unsigned long)compat_ptr(arg));
1125 }
1126 #endif
1127 
1128 static const struct file_operations vhost_net_fops = {
1129         .owner          = THIS_MODULE,
1130         .release        = vhost_net_release,
1131         .unlocked_ioctl = vhost_net_ioctl,
1132 #ifdef CONFIG_COMPAT
1133         .compat_ioctl   = vhost_net_compat_ioctl,
1134 #endif
1135         .open           = vhost_net_open,
1136         .llseek         = noop_llseek,
1137 };
1138 
1139 static struct miscdevice vhost_net_misc = {
1140         .minor = VHOST_NET_MINOR,
1141         .name = "vhost-net",
1142         .fops = &vhost_net_fops,
1143 };
1144 
1145 static int vhost_net_init(void)
1146 {
1147         if (experimental_zcopytx)
1148                 vhost_net_enable_zcopy(VHOST_NET_VQ_TX);
1149         return misc_register(&vhost_net_misc);
1150 }
1151 module_init(vhost_net_init);
1152 
1153 static void vhost_net_exit(void)
1154 {
1155         misc_deregister(&vhost_net_misc);
1156 }
1157 module_exit(vhost_net_exit);
1158 
1159 MODULE_VERSION("0.0.1");
1160 MODULE_LICENSE("GPL v2");
1161 MODULE_AUTHOR("Michael S. Tsirkin");
1162 MODULE_DESCRIPTION("Host kernel accelerator for virtio net");
1163 MODULE_ALIAS_MISCDEV(VHOST_NET_MINOR);
1164 MODULE_ALIAS("devname:vhost-net");
1165 

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