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/sched/clock.h>
  21 #include <linux/sched/signal.h>
  22 #include <linux/vmalloc.h>
  23
  24 #include <linux/net.h>
  25 #include <linux/if_packet.h>
  26 #include <linux/if_arp.h>
  27 #include <linux/if_tun.h>
  28 #include <linux/if_macvlan.h>
  29 #include <linux/if_tap.h>
  30 #include <linux/if_vlan.h>
  31
  32 #include <net/sock.h>
  33
  34 #include "vhost.h"
  35
  36 static int experimental_zcopytx = 1;
  37 module_param(experimental_zcopytx, int, 0444);
  38 MODULE_PARM_DESC(experimental_zcopytx, "Enable Zero Copy TX;"
  39                                        " 1 -Enable; 0 - Disable");
  40
  41 /* Max number of bytes transferred before requeueing the job.
  42  * Using this limit prevents one virtqueue from starving others. */
  43 #define VHOST_NET_WEIGHT 0x80000
  44
  45 /* MAX number of TX used buffers for outstanding zerocopy */
  46 #define VHOST_MAX_PEND 128
  47 #define VHOST_GOODCOPY_LEN 256
  48
  49 /*
  50  * For transmit, used buffer len is unused; we override it to track buffer
  51  * status internally; used for zerocopy tx only.
  52  */
  53 /* Lower device DMA failed */
  54 #define VHOST_DMA_FAILED_LEN    ((__force __virtio32)3)
  55 /* Lower device DMA done */
  56 #define VHOST_DMA_DONE_LEN      ((__force __virtio32)2)
  57 /* Lower device DMA in progress */
  58 #define VHOST_DMA_IN_PROGRESS   ((__force __virtio32)1)
  59 /* Buffer unused */
  60 #define VHOST_DMA_CLEAR_LEN     ((__force __virtio32)0)
  61
  62 #define VHOST_DMA_IS_DONE(len) ((__force u32)(len) >= (__force u32)VHOST_DMA_DONE_LEN)
  63
  64 enum {
  65         VHOST_NET_FEATURES = VHOST_FEATURES |
  66                          (1ULL << VHOST_NET_F_VIRTIO_NET_HDR) |
  67                          (1ULL << VIRTIO_NET_F_MRG_RXBUF) |
  68                          (1ULL << VIRTIO_F_IOMMU_PLATFORM)
  69 };
  70
  71 enum {
  72         VHOST_NET_VQ_RX = 0,
  73         VHOST_NET_VQ_TX = 1,
  74         VHOST_NET_VQ_MAX = 2,
  75 };
  76
  77 struct vhost_net_ubuf_ref {
  78         /* refcount follows semantics similar to kref:
  79          *  0: object is released
  80          *  1: no outstanding ubufs
  81          * >1: outstanding ubufs
  82          */
  83         atomic_t refcount;
  84         wait_queue_head_t wait;
  85         struct vhost_virtqueue *vq;
  86 };
  87
  88 struct vhost_net_virtqueue {
  89         struct vhost_virtqueue vq;
  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 /* In case of DMA done not in order in lower device driver for some reason.
 238  * upend_idx is used to track end of used idx, done_idx is used to track head
 239  * of used idx. Once lower device DMA done contiguously, we will signal KVM
 240  * guest used idx.
 241  */
 242 static void vhost_zerocopy_signal_used(struct vhost_net *net,
 243                                        struct vhost_virtqueue *vq)
 244 {
 245         struct vhost_net_virtqueue *nvq =
 246                 container_of(vq, struct vhost_net_virtqueue, vq);
 247         int i, add;
 248         int j = 0;
 249
 250         for (i = nvq->done_idx; i != nvq->upend_idx; i = (i + 1) % UIO_MAXIOV) {
 251                 if (vq->heads[i].len == VHOST_DMA_FAILED_LEN)
 252                         vhost_net_tx_err(net);
 253                 if (VHOST_DMA_IS_DONE(vq->heads[i].len)) {
 254                         vq->heads[i].len = VHOST_DMA_CLEAR_LEN;
 255                         ++j;
 256                 } else
 257                         break;
 258         }
 259         while (j) {
 260                 add = min(UIO_MAXIOV - nvq->done_idx, j);
 261                 vhost_add_used_and_signal_n(vq->dev, vq,
 262                                             &vq->heads[nvq->done_idx], add);
 263                 nvq->done_idx = (nvq->done_idx + add) % UIO_MAXIOV;
 264                 j -= add;
 265         }
 266 }
 267
 268 static void vhost_zerocopy_callback(struct ubuf_info *ubuf, bool success)
 269 {
 270         struct vhost_net_ubuf_ref *ubufs = ubuf->ctx;
 271         struct vhost_virtqueue *vq = ubufs->vq;
 272         int cnt;
 273
 274         rcu_read_lock_bh();
 275
 276         /* set len to mark this desc buffers done DMA */
 277         vq->heads[ubuf->desc].len = success ?
 278                 VHOST_DMA_DONE_LEN : VHOST_DMA_FAILED_LEN;
 279         cnt = vhost_net_ubuf_put(ubufs);
 280
 281         /*
 282          * Trigger polling thread if guest stopped submitting new buffers:
 283          * in this case, the refcount after decrement will eventually reach 1.
 284          * We also trigger polling periodically after each 16 packets
 285          * (the value 16 here is more or less arbitrary, it's tuned to trigger
 286          * less than 10% of times).
 287          */
 288         if (cnt <= 1 || !(cnt % 16))
 289                 vhost_poll_queue(&vq->poll);
 290
 291         rcu_read_unlock_bh();
 292 }
 293
 294 static inline unsigned long busy_clock(void)
 295 {
 296         return local_clock() >> 10;
 297 }
 298
 299 static bool vhost_can_busy_poll(struct vhost_dev *dev,
 300                                 unsigned long endtime)
 301 {
 302         return likely(!need_resched()) &&
 303                likely(!time_after(busy_clock(), endtime)) &&
 304                likely(!signal_pending(current)) &&
 305                !vhost_has_work(dev);
 306 }
 307
 308 static void vhost_net_disable_vq(struct vhost_net *n,
 309                                  struct vhost_virtqueue *vq)
 310 {
 311         struct vhost_net_virtqueue *nvq =
 312                 container_of(vq, struct vhost_net_virtqueue, vq);
 313         struct vhost_poll *poll = n->poll + (nvq - n->vqs);
 314         if (!vq->private_data)
 315                 return;
 316         vhost_poll_stop(poll);
 317 }
 318
 319 static int vhost_net_enable_vq(struct vhost_net *n,
 320                                 struct vhost_virtqueue *vq)
 321 {
 322         struct vhost_net_virtqueue *nvq =
 323                 container_of(vq, struct vhost_net_virtqueue, vq);
 324         struct vhost_poll *poll = n->poll + (nvq - n->vqs);
 325         struct socket *sock;
 326
 327         sock = vq->private_data;
 328         if (!sock)
 329                 return 0;
 330
 331         return vhost_poll_start(poll, sock->file);
 332 }
 333
 334 static int vhost_net_tx_get_vq_desc(struct vhost_net *net,
 335                                     struct vhost_virtqueue *vq,
 336                                     struct iovec iov[], unsigned int iov_size,
 337                                     unsigned int *out_num, unsigned int *in_num)
 338 {
 339         unsigned long uninitialized_var(endtime);
 340         int r = vhost_get_vq_desc(vq, vq->iov, ARRAY_SIZE(vq->iov),
 341                                   out_num, in_num, NULL, NULL);
 342
 343         if (r == vq->num && vq->busyloop_timeout) {
 344                 preempt_disable();
 345                 endtime = busy_clock() + vq->busyloop_timeout;
 346                 while (vhost_can_busy_poll(vq->dev, endtime) &&
 347                        vhost_vq_avail_empty(vq->dev, vq))
 348                         cpu_relax();
 349                 preempt_enable();
 350                 r = vhost_get_vq_desc(vq, vq->iov, ARRAY_SIZE(vq->iov),
 351                                       out_num, in_num, NULL, NULL);
 352         }
 353
 354         return r;
 355 }
 356
 357 static bool vhost_exceeds_maxpend(struct vhost_net *net)
 358 {
 359         struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_TX];
 360         struct vhost_virtqueue *vq = &nvq->vq;
 361
 362         return (nvq->upend_idx + vq->num - VHOST_MAX_PEND) % UIO_MAXIOV
 363                 == nvq->done_idx;
 364 }
 365
 366 /* Expects to be always run from workqueue - which acts as
 367  * read-size critical section for our kind of RCU. */
 368 static void handle_tx(struct vhost_net *net)
 369 {
 370         struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_TX];
 371         struct vhost_virtqueue *vq = &nvq->vq;
 372         unsigned out, in;
 373         int head;
 374         struct msghdr msg = {
 375                 .msg_name = NULL,
 376                 .msg_namelen = 0,
 377                 .msg_control = NULL,
 378                 .msg_controllen = 0,
 379                 .msg_flags = MSG_DONTWAIT,
 380         };
 381         size_t len, total_len = 0;
 382         int err;
 383         size_t hdr_size;
 384         struct socket *sock;
 385         struct vhost_net_ubuf_ref *uninitialized_var(ubufs);
 386         bool zcopy, zcopy_used;
 387
 388         mutex_lock(&vq->mutex);
 389         sock = vq->private_data;
 390         if (!sock)
 391                 goto out;
 392
 393         if (!vq_iotlb_prefetch(vq))
 394                 goto out;
 395
 396         vhost_disable_notify(&net->dev, vq);
 397
 398         hdr_size = nvq->vhost_hlen;
 399         zcopy = nvq->ubufs;
 400
 401         for (;;) {
 402                 /* Release DMAs done buffers first */
 403                 if (zcopy)
 404                         vhost_zerocopy_signal_used(net, vq);
 405
 406                 /* If more outstanding DMAs, queue the work.
 407                  * Handle upend_idx wrap around
 408                  */
 409                 if (unlikely(vhost_exceeds_maxpend(net)))
 410                         break;
 411
 412                 head = vhost_net_tx_get_vq_desc(net, vq, vq->iov,
 413                                                 ARRAY_SIZE(vq->iov),
 414                                                 &out, &in);
 415                 /* On error, stop handling until the next kick. */
 416                 if (unlikely(head < 0))
 417                         break;
 418                 /* Nothing new?  Wait for eventfd to tell us they refilled. */
 419                 if (head == vq->num) {
 420                         if (unlikely(vhost_enable_notify(&net->dev, vq))) {
 421                                 vhost_disable_notify(&net->dev, vq);
 422                                 continue;
 423                         }
 424                         break;
 425                 }
 426                 if (in) {
 427                         vq_err(vq, "Unexpected descriptor format for TX: "
 428                                "out %d, int %d\n", out, in);
 429                         break;
 430                 }
 431                 /* Skip header. TODO: support TSO. */
 432                 len = iov_length(vq->iov, out);
 433                 iov_iter_init(&msg.msg_iter, WRITE, vq->iov, out, len);
 434                 iov_iter_advance(&msg.msg_iter, hdr_size);
 435                 /* Sanity check */
 436                 if (!msg_data_left(&msg)) {
 437                         vq_err(vq, "Unexpected header len for TX: "
 438                                "%zd expected %zd\n",
 439                                len, hdr_size);
 440                         break;
 441                 }
 442                 len = msg_data_left(&msg);
 443
 444                 zcopy_used = zcopy && len >= VHOST_GOODCOPY_LEN
 445                                    && (nvq->upend_idx + 1) % UIO_MAXIOV !=
 446                                       nvq->done_idx
 447                                    && vhost_net_tx_select_zcopy(net);
 448
 449                 /* use msg_control to pass vhost zerocopy ubuf info to skb */
 450                 if (zcopy_used) {
 451                         struct ubuf_info *ubuf;
 452                         ubuf = nvq->ubuf_info + nvq->upend_idx;
 453
 454                         vq->heads[nvq->upend_idx].id = cpu_to_vhost32(vq, head);
 455                         vq->heads[nvq->upend_idx].len = VHOST_DMA_IN_PROGRESS;
 456                         ubuf->callback = vhost_zerocopy_callback;
 457                         ubuf->ctx = nvq->ubufs;
 458                         ubuf->desc = nvq->upend_idx;
 459                         msg.msg_control = ubuf;
 460                         msg.msg_controllen = sizeof(ubuf);
 461                         ubufs = nvq->ubufs;
 462                         atomic_inc(&ubufs->refcount);
 463                         nvq->upend_idx = (nvq->upend_idx + 1) % UIO_MAXIOV;
 464                 } else {
 465                         msg.msg_control = NULL;
 466                         ubufs = NULL;
 467                 }
 468
 469                 total_len += len;
 470                 if (total_len < VHOST_NET_WEIGHT &&
 471                     !vhost_vq_avail_empty(&net->dev, vq) &&
 472                     likely(!vhost_exceeds_maxpend(net))) {
 473                         msg.msg_flags |= MSG_MORE;
 474                 } else {
 475                         msg.msg_flags &= ~MSG_MORE;
 476                 }
 477
 478                 /* TODO: Check specific error and bomb out unless ENOBUFS? */
 479                 err = sock->ops->sendmsg(sock, &msg, len);
 480                 if (unlikely(err < 0)) {
 481                         if (zcopy_used) {
 482                                 vhost_net_ubuf_put(ubufs);
 483                                 nvq->upend_idx = ((unsigned)nvq->upend_idx - 1)
 484                                         % UIO_MAXIOV;
 485                         }
 486                         vhost_discard_vq_desc(vq, 1);
 487                         break;
 488                 }
 489                 if (err != len)
 490                         pr_debug("Truncated TX packet: "
 491                                  " len %d != %zd\n", err, len);
 492                 if (!zcopy_used)
 493                         vhost_add_used_and_signal(&net->dev, vq, head, 0);
 494                 else
 495                         vhost_zerocopy_signal_used(net, vq);
 496                 vhost_net_tx_packet(net);
 497                 if (unlikely(total_len >= VHOST_NET_WEIGHT)) {
 498                         vhost_poll_queue(&vq->poll);
 499                         break;
 500                 }
 501         }
 502 out:
 503         mutex_unlock(&vq->mutex);
 504 }
 505
 506 static int peek_head_len(struct sock *sk)
 507 {
 508         struct socket *sock = sk->sk_socket;
 509         struct sk_buff *head;
 510         int len = 0;
 511         unsigned long flags;
 512
 513         if (sock->ops->peek_len)
 514                 return sock->ops->peek_len(sock);
 515
 516         spin_lock_irqsave(&sk->sk_receive_queue.lock, flags);
 517         head = skb_peek(&sk->sk_receive_queue);
 518         if (likely(head)) {
 519                 len = head->len;
 520                 if (skb_vlan_tag_present(head))
 521                         len += VLAN_HLEN;
 522         }
 523
 524         spin_unlock_irqrestore(&sk->sk_receive_queue.lock, flags);
 525         return len;
 526 }
 527
 528 static int sk_has_rx_data(struct sock *sk)
 529 {
 530         struct socket *sock = sk->sk_socket;
 531
 532         if (sock->ops->peek_len)
 533                 return sock->ops->peek_len(sock);
 534
 535         return skb_queue_empty(&sk->sk_receive_queue);
 536 }
 537
 538 static int vhost_net_rx_peek_head_len(struct vhost_net *net, struct sock *sk)
 539 {
 540         struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_TX];
 541         struct vhost_virtqueue *vq = &nvq->vq;
 542         unsigned long uninitialized_var(endtime);
 543         int len = peek_head_len(sk);
 544
 545         if (!len && vq->busyloop_timeout) {
 546                 /* Both tx vq and rx socket were polled here */
 547                 mutex_lock(&vq->mutex);
 548                 vhost_disable_notify(&net->dev, vq);
 549
 550                 preempt_disable();
 551                 endtime = busy_clock() + vq->busyloop_timeout;
 552
 553                 while (vhost_can_busy_poll(&net->dev, endtime) &&
 554                        !sk_has_rx_data(sk) &&
 555                        vhost_vq_avail_empty(&net->dev, vq))
 556                         cpu_relax();
 557
 558                 preempt_enable();
 559
 560                 if (vhost_enable_notify(&net->dev, vq))
 561                         vhost_poll_queue(&vq->poll);
 562                 mutex_unlock(&vq->mutex);
 563
 564                 len = peek_head_len(sk);
 565         }
 566
 567         return len;
 568 }
 569
 570 /* This is a multi-buffer version of vhost_get_desc, that works if
 571  *      vq has read descriptors only.
 572  * @vq          - the relevant virtqueue
 573  * @datalen     - data length we'll be reading
 574  * @iovcount    - returned count of io vectors we fill
 575  * @log         - vhost log
 576  * @log_num     - log offset
 577  * @quota       - headcount quota, 1 for big buffer
 578  *      returns number of buffer heads allocated, negative on error
 579  */
 580 static int get_rx_bufs(struct vhost_virtqueue *vq,
 581                        struct vring_used_elem *heads,
 582                        int datalen,
 583                        unsigned *iovcount,
 584                        struct vhost_log *log,
 585                        unsigned *log_num,
 586                        unsigned int quota)
 587 {
 588         unsigned int out, in;
 589         int seg = 0;
 590         int headcount = 0;
 591         unsigned d;
 592         int r, nlogs = 0;
 593         /* len is always initialized before use since we are always called with
 594          * datalen > 0.
 595          */
 596         u32 uninitialized_var(len);
 597
 598         while (datalen > 0 && headcount < quota) {
 599                 if (unlikely(seg >= UIO_MAXIOV)) {
 600                         r = -ENOBUFS;
 601                         goto err;
 602                 }
 603                 r = vhost_get_vq_desc(vq, vq->iov + seg,
 604                                       ARRAY_SIZE(vq->iov) - seg, &out,
 605                                       &in, log, log_num);
 606                 if (unlikely(r < 0))
 607                         goto err;
 608
 609                 d = r;
 610                 if (d == vq->num) {
 611                         r = 0;
 612                         goto err;
 613                 }
 614                 if (unlikely(out || in <= 0)) {
 615                         vq_err(vq, "unexpected descriptor format for RX: "
 616                                 "out %d, in %d\n", out, in);
 617                         r = -EINVAL;
 618                         goto err;
 619                 }
 620                 if (unlikely(log)) {
 621                         nlogs += *log_num;
 622                         log += *log_num;
 623                 }
 624                 heads[headcount].id = cpu_to_vhost32(vq, d);
 625                 len = iov_length(vq->iov + seg, in);
 626                 heads[headcount].len = cpu_to_vhost32(vq, len);
 627                 datalen -= len;
 628                 ++headcount;
 629                 seg += in;
 630         }
 631         heads[headcount - 1].len = cpu_to_vhost32(vq, len + datalen);
 632         *iovcount = seg;
 633         if (unlikely(log))
 634                 *log_num = nlogs;
 635
 636         /* Detect overrun */
 637         if (unlikely(datalen > 0)) {
 638                 r = UIO_MAXIOV + 1;
 639                 goto err;
 640         }
 641         return headcount;
 642 err:
 643         vhost_discard_vq_desc(vq, headcount);
 644         return r;
 645 }
 646
 647 /* Expects to be always run from workqueue - which acts as
 648  * read-size critical section for our kind of RCU. */
 649 static void handle_rx(struct vhost_net *net)
 650 {
 651         struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_RX];
 652         struct vhost_virtqueue *vq = &nvq->vq;
 653         unsigned uninitialized_var(in), log;
 654         struct vhost_log *vq_log;
 655         struct msghdr msg = {
 656                 .msg_name = NULL,
 657                 .msg_namelen = 0,
 658                 .msg_control = NULL, /* FIXME: get and handle RX aux data. */
 659                 .msg_controllen = 0,
 660                 .msg_flags = MSG_DONTWAIT,
 661         };
 662         struct virtio_net_hdr hdr = {
 663                 .flags = 0,
 664                 .gso_type = VIRTIO_NET_HDR_GSO_NONE
 665         };
 666         size_t total_len = 0;
 667         int err, mergeable;
 668         s16 headcount;
 669         size_t vhost_hlen, sock_hlen;
 670         size_t vhost_len, sock_len;
 671         struct socket *sock;
 672         struct iov_iter fixup;
 673         __virtio16 num_buffers;
 674
 675         mutex_lock(&vq->mutex);
 676         sock = vq->private_data;
 677         if (!sock)
 678                 goto out;
 679
 680         if (!vq_iotlb_prefetch(vq))
 681                 goto out;
 682
 683         vhost_disable_notify(&net->dev, vq);
 684         vhost_net_disable_vq(net, vq);
 685
 686         vhost_hlen = nvq->vhost_hlen;
 687         sock_hlen = nvq->sock_hlen;
 688
 689         vq_log = unlikely(vhost_has_feature(vq, VHOST_F_LOG_ALL)) ?
 690                 vq->log : NULL;
 691         mergeable = vhost_has_feature(vq, VIRTIO_NET_F_MRG_RXBUF);
 692
 693         while ((sock_len = vhost_net_rx_peek_head_len(net, sock->sk))) {
 694                 sock_len += sock_hlen;
 695                 vhost_len = sock_len + vhost_hlen;
 696                 headcount = get_rx_bufs(vq, vq->heads, vhost_len,
 697                                         &in, vq_log, &log,
 698                                         likely(mergeable) ? UIO_MAXIOV : 1);
 699                 /* On error, stop handling until the next kick. */
 700                 if (unlikely(headcount < 0))
 701                         goto out;
 702                 /* On overrun, truncate and discard */
 703                 if (unlikely(headcount > UIO_MAXIOV)) {
 704                         iov_iter_init(&msg.msg_iter, READ, vq->iov, 1, 1);
 705                         err = sock->ops->recvmsg(sock, &msg,
 706                                                  1, MSG_DONTWAIT | MSG_TRUNC);
 707                         pr_debug("Discarded rx packet: len %zd\n", sock_len);
 708                         continue;
 709                 }
 710                 /* OK, now we need to know about added descriptors. */
 711                 if (!headcount) {
 712                         if (unlikely(vhost_enable_notify(&net->dev, vq))) {
 713                                 /* They have slipped one in as we were
 714                                  * doing that: check again. */
 715                                 vhost_disable_notify(&net->dev, vq);
 716                                 continue;
 717                         }
 718                         /* Nothing new?  Wait for eventfd to tell us
 719                          * they refilled. */
 720                         goto out;
 721                 }
 722                 /* We don't need to be notified again. */
 723                 iov_iter_init(&msg.msg_iter, READ, vq->iov, in, vhost_len);
 724                 fixup = msg.msg_iter;
 725                 if (unlikely((vhost_hlen))) {
 726                         /* We will supply the header ourselves
 727                          * TODO: support TSO.
 728                          */
 729                         iov_iter_advance(&msg.msg_iter, vhost_hlen);
 730                 }
 731                 err = sock->ops->recvmsg(sock, &msg,
 732                                          sock_len, MSG_DONTWAIT | MSG_TRUNC);
 733                 /* Userspace might have consumed the packet meanwhile:
 734                  * it's not supposed to do this usually, but might be hard
 735                  * to prevent. Discard data we got (if any) and keep going. */
 736                 if (unlikely(err != sock_len)) {
 737                         pr_debug("Discarded rx packet: "
 738                                  " len %d, expected %zd\n", err, sock_len);
 739                         vhost_discard_vq_desc(vq, headcount);
 740                         continue;
 741                 }
 742                 /* Supply virtio_net_hdr if VHOST_NET_F_VIRTIO_NET_HDR */
 743                 if (unlikely(vhost_hlen)) {
 744                         if (copy_to_iter(&hdr, sizeof(hdr),
 745                                          &fixup) != sizeof(hdr)) {
 746                                 vq_err(vq, "Unable to write vnet_hdr "
 747                                        "at addr %p\n", vq->iov->iov_base);
 748                                 goto out;
 749                         }
 750                 } else {
 751                         /* Header came from socket; we'll need to patch
 752                          * ->num_buffers over if VIRTIO_NET_F_MRG_RXBUF
 753                          */
 754                         iov_iter_advance(&fixup, sizeof(hdr));
 755                 }
 756                 /* TODO: Should check and handle checksum. */
 757
 758                 num_buffers = cpu_to_vhost16(vq, headcount);
 759                 if (likely(mergeable) &&
 760                     copy_to_iter(&num_buffers, sizeof num_buffers,
 761                                  &fixup) != sizeof num_buffers) {
 762                         vq_err(vq, "Failed num_buffers write");
 763                         vhost_discard_vq_desc(vq, headcount);
 764                         goto out;
 765                 }
 766                 vhost_add_used_and_signal_n(&net->dev, vq, vq->heads,
 767                                             headcount);
 768                 if (unlikely(vq_log))
 769                         vhost_log_write(vq, vq_log, log, vhost_len);
 770                 total_len += vhost_len;
 771                 if (unlikely(total_len >= VHOST_NET_WEIGHT)) {
 772                         vhost_poll_queue(&vq->poll);
 773                         goto out;
 774                 }
 775         }
 776         vhost_net_enable_vq(net, vq);
 777 out:
 778         mutex_unlock(&vq->mutex);
 779 }
 780
 781 static void handle_tx_kick(struct vhost_work *work)
 782 {
 783         struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
 784                                                   poll.work);
 785         struct vhost_net *net = container_of(vq->dev, struct vhost_net, dev);
 786
 787         handle_tx(net);
 788 }
 789
 790 static void handle_rx_kick(struct vhost_work *work)
 791 {
 792         struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
 793                                                   poll.work);
 794         struct vhost_net *net = container_of(vq->dev, struct vhost_net, dev);
 795
 796         handle_rx(net);
 797 }
 798
 799 static void handle_tx_net(struct vhost_work *work)
 800 {
 801         struct vhost_net *net = container_of(work, struct vhost_net,
 802                                              poll[VHOST_NET_VQ_TX].work);
 803         handle_tx(net);
 804 }
 805
 806 static void handle_rx_net(struct vhost_work *work)
 807 {
 808         struct vhost_net *net = container_of(work, struct vhost_net,
 809                                              poll[VHOST_NET_VQ_RX].work);
 810         handle_rx(net);
 811 }
 812
 813 static int vhost_net_open(struct inode *inode, struct file *f)
 814 {
 815         struct vhost_net *n;
 816         struct vhost_dev *dev;
 817         struct vhost_virtqueue **vqs;
 818         int i;
 819
 820         n = kvmalloc(sizeof *n, GFP_KERNEL | __GFP_REPEAT);
 821         if (!n)
 822                 return -ENOMEM;
 823         vqs = kmalloc(VHOST_NET_VQ_MAX * sizeof(*vqs), GFP_KERNEL);
 824         if (!vqs) {
 825                 kvfree(n);
 826                 return -ENOMEM;
 827         }
 828
 829         dev = &n->dev;
 830         vqs[VHOST_NET_VQ_TX] = &n->vqs[VHOST_NET_VQ_TX].vq;
 831         vqs[VHOST_NET_VQ_RX] = &n->vqs[VHOST_NET_VQ_RX].vq;
 832         n->vqs[VHOST_NET_VQ_TX].vq.handle_kick = handle_tx_kick;
 833         n->vqs[VHOST_NET_VQ_RX].vq.handle_kick = handle_rx_kick;
 834         for (i = 0; i < VHOST_NET_VQ_MAX; i++) {
 835                 n->vqs[i].ubufs = NULL;
 836                 n->vqs[i].ubuf_info = NULL;
 837                 n->vqs[i].upend_idx = 0;
 838                 n->vqs[i].done_idx = 0;
 839                 n->vqs[i].vhost_hlen = 0;
 840                 n->vqs[i].sock_hlen = 0;
 841         }
 842         vhost_dev_init(dev, vqs, VHOST_NET_VQ_MAX);
 843
 844         vhost_poll_init(n->poll + VHOST_NET_VQ_TX, handle_tx_net, POLLOUT, dev);
 845         vhost_poll_init(n->poll + VHOST_NET_VQ_RX, handle_rx_net, POLLIN, dev);
 846
 847         f->private_data = n;
 848
 849         return 0;
 850 }
 851
 852 static struct socket *vhost_net_stop_vq(struct vhost_net *n,
 853                                         struct vhost_virtqueue *vq)
 854 {
 855         struct socket *sock;
 856
 857         mutex_lock(&vq->mutex);
 858         sock = vq->private_data;
 859         vhost_net_disable_vq(n, vq);
 860         vq->private_data = NULL;
 861         mutex_unlock(&vq->mutex);
 862         return sock;
 863 }
 864
 865 static void vhost_net_stop(struct vhost_net *n, struct socket **tx_sock,
 866                            struct socket **rx_sock)
 867 {
 868         *tx_sock = vhost_net_stop_vq(n, &n->vqs[VHOST_NET_VQ_TX].vq);
 869         *rx_sock = vhost_net_stop_vq(n, &n->vqs[VHOST_NET_VQ_RX].vq);
 870 }
 871
 872 static void vhost_net_flush_vq(struct vhost_net *n, int index)
 873 {
 874         vhost_poll_flush(n->poll + index);
 875         vhost_poll_flush(&n->vqs[index].vq.poll);
 876 }
 877
 878 static void vhost_net_flush(struct vhost_net *n)
 879 {
 880         vhost_net_flush_vq(n, VHOST_NET_VQ_TX);
 881         vhost_net_flush_vq(n, VHOST_NET_VQ_RX);
 882         if (n->vqs[VHOST_NET_VQ_TX].ubufs) {
 883                 mutex_lock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
 884                 n->tx_flush = true;
 885                 mutex_unlock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
 886                 /* Wait for all lower device DMAs done. */
 887                 vhost_net_ubuf_put_and_wait(n->vqs[VHOST_NET_VQ_TX].ubufs);
 888                 mutex_lock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
 889                 n->tx_flush = false;
 890                 atomic_set(&n->vqs[VHOST_NET_VQ_TX].ubufs->refcount, 1);
 891                 mutex_unlock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
 892         }
 893 }
 894
 895 static int vhost_net_release(struct inode *inode, struct file *f)
 896 {
 897         struct vhost_net *n = f->private_data;
 898         struct socket *tx_sock;
 899         struct socket *rx_sock;
 900
 901         vhost_net_stop(n, &tx_sock, &rx_sock);
 902         vhost_net_flush(n);
 903         vhost_dev_stop(&n->dev);
 904         vhost_dev_cleanup(&n->dev, false);
 905         vhost_net_vq_reset(n);
 906         if (tx_sock)
 907                 sockfd_put(tx_sock);
 908         if (rx_sock)
 909                 sockfd_put(rx_sock);
 910         /* Make sure no callbacks are outstanding */
 911         synchronize_rcu_bh();
 912         /* We do an extra flush before freeing memory,
 913          * since jobs can re-queue themselves. */
 914         vhost_net_flush(n);
 915         kfree(n->dev.vqs);
 916         kvfree(n);
 917         return 0;
 918 }
 919
 920 static struct socket *get_raw_socket(int fd)
 921 {
 922         struct {
 923                 struct sockaddr_ll sa;
 924                 char  buf[MAX_ADDR_LEN];
 925         } uaddr;
 926         int uaddr_len = sizeof uaddr, r;
 927         struct socket *sock = sockfd_lookup(fd, &r);
 928
 929         if (!sock)
 930                 return ERR_PTR(-ENOTSOCK);
 931
 932         /* Parameter checking */
 933         if (sock->sk->sk_type != SOCK_RAW) {
 934                 r = -ESOCKTNOSUPPORT;
 935                 goto err;
 936         }
 937
 938         r = sock->ops->getname(sock, (struct sockaddr *)&uaddr.sa,
 939                                &uaddr_len, 0);
 940         if (r)
 941                 goto err;
 942
 943         if (uaddr.sa.sll_family != AF_PACKET) {
 944                 r = -EPFNOSUPPORT;
 945                 goto err;
 946         }
 947         return sock;
 948 err:
 949         sockfd_put(sock);
 950         return ERR_PTR(r);
 951 }
 952
 953 static struct socket *get_tap_socket(int fd)
 954 {
 955         struct file *file = fget(fd);
 956         struct socket *sock;
 957
 958         if (!file)
 959                 return ERR_PTR(-EBADF);
 960         sock = tun_get_socket(file);
 961         if (!IS_ERR(sock))
 962                 return sock;
 963         sock = tap_get_socket(file);
 964         if (IS_ERR(sock))
 965                 fput(file);
 966         return sock;
 967 }
 968
 969 static struct socket *get_socket(int fd)
 970 {
 971         struct socket *sock;
 972
 973         /* special case to disable backend */
 974         if (fd == -1)
 975                 return NULL;
 976         sock = get_raw_socket(fd);
 977         if (!IS_ERR(sock))
 978                 return sock;
 979         sock = get_tap_socket(fd);
 980         if (!IS_ERR(sock))
 981                 return sock;
 982         return ERR_PTR(-ENOTSOCK);
 983 }
 984
 985 static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd)
 986 {
 987         struct socket *sock, *oldsock;
 988         struct vhost_virtqueue *vq;
 989         struct vhost_net_virtqueue *nvq;
 990         struct vhost_net_ubuf_ref *ubufs, *oldubufs = NULL;
 991         int r;
 992
 993         mutex_lock(&n->dev.mutex);
 994         r = vhost_dev_check_owner(&n->dev);
 995         if (r)
 996                 goto err;
 997
 998         if (index >= VHOST_NET_VQ_MAX) {
 999                 r = -ENOBUFS;
1000                 goto err;
1001         }
1002         vq = &n->vqs[index].vq;
1003         nvq = &n->vqs[index];
1004         mutex_lock(&vq->mutex);
1005
1006         /* Verify that ring has been setup correctly. */
1007         if (!vhost_vq_access_ok(vq)) {
1008                 r = -EFAULT;
1009                 goto err_vq;
1010         }
1011         sock = get_socket(fd);
1012         if (IS_ERR(sock)) {
1013                 r = PTR_ERR(sock);
1014                 goto err_vq;
1015         }
1016
1017         /* start polling new socket */
1018         oldsock = vq->private_data;
1019         if (sock != oldsock) {
1020                 ubufs = vhost_net_ubuf_alloc(vq,
1021                                              sock && vhost_sock_zcopy(sock));
1022                 if (IS_ERR(ubufs)) {
1023                         r = PTR_ERR(ubufs);
1024                         goto err_ubufs;
1025                 }
1026
1027                 vhost_net_disable_vq(n, vq);
1028                 vq->private_data = sock;
1029                 r = vhost_vq_init_access(vq);
1030                 if (r)
1031                         goto err_used;
1032                 r = vhost_net_enable_vq(n, vq);
1033                 if (r)
1034                         goto err_used;
1035
1036                 oldubufs = nvq->ubufs;
1037                 nvq->ubufs = ubufs;
1038
1039                 n->tx_packets = 0;
1040                 n->tx_zcopy_err = 0;
1041                 n->tx_flush = false;
1042         }
1043
1044         mutex_unlock(&vq->mutex);
1045
1046         if (oldubufs) {
1047                 vhost_net_ubuf_put_wait_and_free(oldubufs);
1048                 mutex_lock(&vq->mutex);
1049                 vhost_zerocopy_signal_used(n, vq);
1050                 mutex_unlock(&vq->mutex);
1051         }
1052
1053         if (oldsock) {
1054                 vhost_net_flush_vq(n, index);
1055                 sockfd_put(oldsock);
1056         }
1057
1058         mutex_unlock(&n->dev.mutex);
1059         return 0;
1060
1061 err_used:
1062         vq->private_data = oldsock;
1063         vhost_net_enable_vq(n, vq);
1064         if (ubufs)
1065                 vhost_net_ubuf_put_wait_and_free(ubufs);
1066 err_ubufs:
1067         sockfd_put(sock);
1068 err_vq:
1069         mutex_unlock(&vq->mutex);
1070 err:
1071         mutex_unlock(&n->dev.mutex);
1072         return r;
1073 }
1074
1075 static long vhost_net_reset_owner(struct vhost_net *n)
1076 {
1077         struct socket *tx_sock = NULL;
1078         struct socket *rx_sock = NULL;
1079         long err;
1080         struct vhost_umem *umem;
1081
1082         mutex_lock(&n->dev.mutex);
1083         err = vhost_dev_check_owner(&n->dev);
1084         if (err)
1085                 goto done;
1086         umem = vhost_dev_reset_owner_prepare();
1087         if (!umem) {
1088                 err = -ENOMEM;
1089                 goto done;
1090         }
1091         vhost_net_stop(n, &tx_sock, &rx_sock);
1092         vhost_net_flush(n);
1093         vhost_dev_reset_owner(&n->dev, umem);
1094         vhost_net_vq_reset(n);
1095 done:
1096         mutex_unlock(&n->dev.mutex);
1097         if (tx_sock)
1098                 sockfd_put(tx_sock);
1099         if (rx_sock)
1100                 sockfd_put(rx_sock);
1101         return err;
1102 }
1103
1104 static int vhost_net_set_features(struct vhost_net *n, u64 features)
1105 {
1106         size_t vhost_hlen, sock_hlen, hdr_len;
1107         int i;
1108
1109         hdr_len = (features & ((1ULL << VIRTIO_NET_F_MRG_RXBUF) |
1110                                (1ULL << VIRTIO_F_VERSION_1))) ?
1111                         sizeof(struct virtio_net_hdr_mrg_rxbuf) :
1112                         sizeof(struct virtio_net_hdr);
1113         if (features & (1 << VHOST_NET_F_VIRTIO_NET_HDR)) {
1114                 /* vhost provides vnet_hdr */
1115                 vhost_hlen = hdr_len;
1116                 sock_hlen = 0;
1117         } else {
1118                 /* socket provides vnet_hdr */
1119                 vhost_hlen = 0;
1120                 sock_hlen = hdr_len;
1121         }
1122         mutex_lock(&n->dev.mutex);
1123         if ((features & (1 << VHOST_F_LOG_ALL)) &&
1124             !vhost_log_access_ok(&n->dev))
1125                 goto out_unlock;
1126
1127         if ((features & (1ULL << VIRTIO_F_IOMMU_PLATFORM))) {
1128                 if (vhost_init_device_iotlb(&n->dev, true))
1129                         goto out_unlock;
1130         }
1131
1132         for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
1133                 mutex_lock(&n->vqs[i].vq.mutex);
1134                 n->vqs[i].vq.acked_features = features;
1135                 n->vqs[i].vhost_hlen = vhost_hlen;
1136                 n->vqs[i].sock_hlen = sock_hlen;
1137                 mutex_unlock(&n->vqs[i].vq.mutex);
1138         }
1139         mutex_unlock(&n->dev.mutex);
1140         return 0;
1141
1142 out_unlock:
1143         mutex_unlock(&n->dev.mutex);
1144         return -EFAULT;
1145 }
1146
1147 static long vhost_net_set_owner(struct vhost_net *n)
1148 {
1149         int r;
1150
1151         mutex_lock(&n->dev.mutex);
1152         if (vhost_dev_has_owner(&n->dev)) {
1153                 r = -EBUSY;
1154                 goto out;
1155         }
1156         r = vhost_net_set_ubuf_info(n);
1157         if (r)
1158                 goto out;
1159         r = vhost_dev_set_owner(&n->dev);
1160         if (r)
1161                 vhost_net_clear_ubuf_info(n);
1162         vhost_net_flush(n);
1163 out:
1164         mutex_unlock(&n->dev.mutex);
1165         return r;
1166 }
1167
1168 static long vhost_net_ioctl(struct file *f, unsigned int ioctl,
1169                             unsigned long arg)
1170 {
1171         struct vhost_net *n = f->private_data;
1172         void __user *argp = (void __user *)arg;
1173         u64 __user *featurep = argp;
1174         struct vhost_vring_file backend;
1175         u64 features;
1176         int r;
1177
1178         switch (ioctl) {
1179         case VHOST_NET_SET_BACKEND:
1180                 if (copy_from_user(&backend, argp, sizeof backend))
1181                         return -EFAULT;
1182                 return vhost_net_set_backend(n, backend.index, backend.fd);
1183         case VHOST_GET_FEATURES:
1184                 features = VHOST_NET_FEATURES;
1185                 if (copy_to_user(featurep, &features, sizeof features))
1186                         return -EFAULT;
1187                 return 0;
1188         case VHOST_SET_FEATURES:
1189                 if (copy_from_user(&features, featurep, sizeof features))
1190                         return -EFAULT;
1191                 if (features & ~VHOST_NET_FEATURES)
1192                         return -EOPNOTSUPP;
1193                 return vhost_net_set_features(n, features);
1194         case VHOST_RESET_OWNER:
1195                 return vhost_net_reset_owner(n);
1196         case VHOST_SET_OWNER:
1197                 return vhost_net_set_owner(n);
1198         default:
1199                 mutex_lock(&n->dev.mutex);
1200                 r = vhost_dev_ioctl(&n->dev, ioctl, argp);
1201                 if (r == -ENOIOCTLCMD)
1202                         r = vhost_vring_ioctl(&n->dev, ioctl, argp);
1203                 else
1204                         vhost_net_flush(n);
1205                 mutex_unlock(&n->dev.mutex);
1206                 return r;
1207         }
1208 }
1209
1210 #ifdef CONFIG_COMPAT
1211 static long vhost_net_compat_ioctl(struct file *f, unsigned int ioctl,
1212                                    unsigned long arg)
1213 {
1214         return vhost_net_ioctl(f, ioctl, (unsigned long)compat_ptr(arg));
1215 }
1216 #endif
1217
1218 static ssize_t vhost_net_chr_read_iter(struct kiocb *iocb, struct iov_iter *to)
1219 {
1220         struct file *file = iocb->ki_filp;
1221         struct vhost_net *n = file->private_data;
1222         struct vhost_dev *dev = &n->dev;
1223         int noblock = file->f_flags & O_NONBLOCK;
1224
1225         return vhost_chr_read_iter(dev, to, noblock);
1226 }
1227
1228 static ssize_t vhost_net_chr_write_iter(struct kiocb *iocb,
1229                                         struct iov_iter *from)
1230 {
1231         struct file *file = iocb->ki_filp;
1232         struct vhost_net *n = file->private_data;
1233         struct vhost_dev *dev = &n->dev;
1234
1235         return vhost_chr_write_iter(dev, from);
1236 }
1237
1238 static unsigned int vhost_net_chr_poll(struct file *file, poll_table *wait)
1239 {
1240         struct vhost_net *n = file->private_data;
1241         struct vhost_dev *dev = &n->dev;
1242
1243         return vhost_chr_poll(file, dev, wait);
1244 }
1245
1246 static const struct file_operations vhost_net_fops = {
1247         .owner          = THIS_MODULE,
1248         .release        = vhost_net_release,
1249         .read_iter      = vhost_net_chr_read_iter,
1250         .write_iter     = vhost_net_chr_write_iter,
1251         .poll           = vhost_net_chr_poll,
1252         .unlocked_ioctl = vhost_net_ioctl,
1253 #ifdef CONFIG_COMPAT
1254         .compat_ioctl   = vhost_net_compat_ioctl,
1255 #endif
1256         .open           = vhost_net_open,
1257         .llseek         = noop_llseek,
1258 };
1259
1260 static struct miscdevice vhost_net_misc = {
1261         .minor = VHOST_NET_MINOR,
1262         .name = "vhost-net",
1263         .fops = &vhost_net_fops,
1264 };
1265
1266 static int vhost_net_init(void)
1267 {
1268         if (experimental_zcopytx)
1269                 vhost_net_enable_zcopy(VHOST_NET_VQ_TX);
1270         return misc_register(&vhost_net_misc);
1271 }
1272 module_init(vhost_net_init);
1273
1274 static void vhost_net_exit(void)
1275 {
1276         misc_deregister(&vhost_net_misc);
1277 }
1278 module_exit(vhost_net_exit);
1279
1280 MODULE_VERSION("0.0.1");
1281 MODULE_LICENSE("GPL v2");
1282 MODULE_AUTHOR("Michael S. Tsirkin");
1283 MODULE_DESCRIPTION("Host kernel accelerator for virtio net");
1284 MODULE_ALIAS_MISCDEV(VHOST_NET_MINOR);
1285 MODULE_ALIAS("devname:vhost-net");