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_tap.h>
  28 #include <linux/if_vlan.h>
  29
  30 #include <net/sock.h>
  31
  32 #include "vhost.h"
  33
  34 static int experimental_zcopytx = 1;
  35 module_param(experimental_zcopytx, int, 0444);
  36 MODULE_PARM_DESC(experimental_zcopytx, "Enable Zero Copy TX;"
  37                                        " 1 -Enable; 0 - Disable");
  38
  39 /* Max number of bytes transferred before requeueing the job.
  40  * Using this limit prevents one virtqueue from starving others. */
  41 #define VHOST_NET_WEIGHT 0x80000
  42
  43 /* MAX number of TX used buffers for outstanding zerocopy */
  44 #define VHOST_MAX_PEND 128
  45 #define VHOST_GOODCOPY_LEN 256
  46
  47 /*
  48  * For transmit, used buffer len is unused; we override it to track buffer
  49  * status internally; used for zerocopy tx only.
  50  */
  51 /* Lower device DMA failed */
  52 #define VHOST_DMA_FAILED_LEN    ((__force __virtio32)3)
  53 /* Lower device DMA done */
  54 #define VHOST_DMA_DONE_LEN      ((__force __virtio32)2)
  55 /* Lower device DMA in progress */
  56 #define VHOST_DMA_IN_PROGRESS   ((__force __virtio32)1)
  57 /* Buffer unused */
  58 #define VHOST_DMA_CLEAR_LEN     ((__force __virtio32)0)
  59
  60 #define VHOST_DMA_IS_DONE(len) ((__force u32)(len) >= (__force u32)VHOST_DMA_DONE_LEN)
  61
  62 enum {
  63         VHOST_NET_FEATURES = VHOST_FEATURES |
  64                          (1ULL << VHOST_NET_F_VIRTIO_NET_HDR) |
  65                          (1ULL << VIRTIO_NET_F_MRG_RXBUF) |
  66                          (1ULL << VIRTIO_F_IOMMU_PLATFORM)
  67 };
  68
  69 enum {
  70         VHOST_NET_VQ_RX = 0,
  71         VHOST_NET_VQ_TX = 1,
  72         VHOST_NET_VQ_MAX = 2,
  73 };
  74
  75 struct vhost_net_ubuf_ref {
  76         /* refcount follows semantics similar to kref:
  77          *  0: object is released
  78          *  1: no outstanding ubufs
  79          * >1: outstanding ubufs
  80          */
  81         atomic_t refcount;
  82         wait_queue_head_t wait;
  83         struct vhost_virtqueue *vq;
  84 };
  85
  86 struct vhost_net_virtqueue {
  87         struct vhost_virtqueue vq;
  88         size_t vhost_hlen;
  89         size_t sock_hlen;
  90         /* vhost zerocopy support fields below: */
  91         /* last used idx for outstanding DMA zerocopy buffers */
  92         int upend_idx;
  93         /* first used idx for DMA done zerocopy buffers */
  94         int done_idx;
  95         /* an array of userspace buffers info */
  96         struct ubuf_info *ubuf_info;
  97         /* Reference counting for outstanding ubufs.
  98          * Protected by vq mutex. Writers must also take device mutex. */
  99         struct vhost_net_ubuf_ref *ubufs;
 100 };
 101
 102 struct vhost_net {
 103         struct vhost_dev dev;
 104         struct vhost_net_virtqueue vqs[VHOST_NET_VQ_MAX];
 105         struct vhost_poll poll[VHOST_NET_VQ_MAX];
 106         /* Number of TX recently submitted.
 107          * Protected by tx vq lock. */
 108         unsigned tx_packets;
 109         /* Number of times zerocopy TX recently failed.
 110          * Protected by tx vq lock. */
 111         unsigned tx_zcopy_err;
 112         /* Flush in progress. Protected by tx vq lock. */
 113         bool tx_flush;
 114 };
 115
 116 static unsigned vhost_net_zcopy_mask __read_mostly;
 117
 118 static void vhost_net_enable_zcopy(int vq)
 119 {
 120         vhost_net_zcopy_mask |= 0x1 << vq;
 121 }
 122
 123 static struct vhost_net_ubuf_ref *
 124 vhost_net_ubuf_alloc(struct vhost_virtqueue *vq, bool zcopy)
 125 {
 126         struct vhost_net_ubuf_ref *ubufs;
 127         /* No zero copy backend? Nothing to count. */
 128         if (!zcopy)
 129                 return NULL;
 130         ubufs = kmalloc(sizeof(*ubufs), GFP_KERNEL);
 131         if (!ubufs)
 132                 return ERR_PTR(-ENOMEM);
 133         atomic_set(&ubufs->refcount, 1);
 134         init_waitqueue_head(&ubufs->wait);
 135         ubufs->vq = vq;
 136         return ubufs;
 137 }
 138
 139 static int vhost_net_ubuf_put(struct vhost_net_ubuf_ref *ubufs)
 140 {
 141         int r = atomic_sub_return(1, &ubufs->refcount);
 142         if (unlikely(!r))
 143                 wake_up(&ubufs->wait);
 144         return r;
 145 }
 146
 147 static void vhost_net_ubuf_put_and_wait(struct vhost_net_ubuf_ref *ubufs)
 148 {
 149         vhost_net_ubuf_put(ubufs);
 150         wait_event(ubufs->wait, !atomic_read(&ubufs->refcount));
 151 }
 152
 153 static void vhost_net_ubuf_put_wait_and_free(struct vhost_net_ubuf_ref *ubufs)
 154 {
 155         vhost_net_ubuf_put_and_wait(ubufs);
 156         kfree(ubufs);
 157 }
 158
 159 static void vhost_net_clear_ubuf_info(struct vhost_net *n)
 160 {
 161         int i;
 162
 163         for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
 164                 kfree(n->vqs[i].ubuf_info);
 165                 n->vqs[i].ubuf_info = NULL;
 166         }
 167 }
 168
 169 static int vhost_net_set_ubuf_info(struct vhost_net *n)
 170 {
 171         bool zcopy;
 172         int i;
 173
 174         for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
 175                 zcopy = vhost_net_zcopy_mask & (0x1 << i);
 176                 if (!zcopy)
 177                         continue;
 178                 n->vqs[i].ubuf_info = kmalloc(sizeof(*n->vqs[i].ubuf_info) *
 179                                               UIO_MAXIOV, GFP_KERNEL);
 180                 if  (!n->vqs[i].ubuf_info)
 181                         goto err;
 182         }
 183         return 0;
 184
 185 err:
 186         vhost_net_clear_ubuf_info(n);
 187         return -ENOMEM;
 188 }
 189
 190 static void vhost_net_vq_reset(struct vhost_net *n)
 191 {
 192         int i;
 193
 194         vhost_net_clear_ubuf_info(n);
 195
 196         for (i = 0; i < VHOST_NET_VQ_MAX; i++) {
 197                 n->vqs[i].done_idx = 0;
 198                 n->vqs[i].upend_idx = 0;
 199                 n->vqs[i].ubufs = NULL;
 200                 n->vqs[i].vhost_hlen = 0;
 201                 n->vqs[i].sock_hlen = 0;
 202         }
 203
 204 }
 205
 206 static void vhost_net_tx_packet(struct vhost_net *net)
 207 {
 208         ++net->tx_packets;
 209         if (net->tx_packets < 1024)
 210                 return;
 211         net->tx_packets = 0;
 212         net->tx_zcopy_err = 0;
 213 }
 214
 215 static void vhost_net_tx_err(struct vhost_net *net)
 216 {
 217         ++net->tx_zcopy_err;
 218 }
 219
 220 static bool vhost_net_tx_select_zcopy(struct vhost_net *net)
 221 {
 222         /* TX flush waits for outstanding DMAs to be done.
 223          * Don't start new DMAs.
 224          */
 225         return !net->tx_flush &&
 226                 net->tx_packets / 64 >= net->tx_zcopy_err;
 227 }
 228
 229 static bool vhost_sock_zcopy(struct socket *sock)
 230 {
 231         return unlikely(experimental_zcopytx) &&
 232                 sock_flag(sock->sk, SOCK_ZEROCOPY);
 233 }
 234
 235 /* In case of DMA done not in order in lower device driver for some reason.
 236  * upend_idx is used to track end of used idx, done_idx is used to track head
 237  * of used idx. Once lower device DMA done contiguously, we will signal KVM
 238  * guest used idx.
 239  */
 240 static void vhost_zerocopy_signal_used(struct vhost_net *net,
 241                                        struct vhost_virtqueue *vq)
 242 {
 243         struct vhost_net_virtqueue *nvq =
 244                 container_of(vq, struct vhost_net_virtqueue, vq);
 245         int i, add;
 246         int j = 0;
 247
 248         for (i = nvq->done_idx; i != nvq->upend_idx; i = (i + 1) % UIO_MAXIOV) {
 249                 if (vq->heads[i].len == VHOST_DMA_FAILED_LEN)
 250                         vhost_net_tx_err(net);
 251                 if (VHOST_DMA_IS_DONE(vq->heads[i].len)) {
 252                         vq->heads[i].len = VHOST_DMA_CLEAR_LEN;
 253                         ++j;
 254                 } else
 255                         break;
 256         }
 257         while (j) {
 258                 add = min(UIO_MAXIOV - nvq->done_idx, j);
 259                 vhost_add_used_and_signal_n(vq->dev, vq,
 260                                             &vq->heads[nvq->done_idx], add);
 261                 nvq->done_idx = (nvq->done_idx + add) % UIO_MAXIOV;
 262                 j -= add;
 263         }
 264 }
 265
 266 static void vhost_zerocopy_callback(struct ubuf_info *ubuf, bool success)
 267 {
 268         struct vhost_net_ubuf_ref *ubufs = ubuf->ctx;
 269         struct vhost_virtqueue *vq = ubufs->vq;
 270         int cnt;
 271
 272         rcu_read_lock_bh();
 273
 274         /* set len to mark this desc buffers done DMA */
 275         vq->heads[ubuf->desc].len = success ?
 276                 VHOST_DMA_DONE_LEN : VHOST_DMA_FAILED_LEN;
 277         cnt = vhost_net_ubuf_put(ubufs);
 278
 279         /*
 280          * Trigger polling thread if guest stopped submitting new buffers:
 281          * in this case, the refcount after decrement will eventually reach 1.
 282          * We also trigger polling periodically after each 16 packets
 283          * (the value 16 here is more or less arbitrary, it's tuned to trigger
 284          * less than 10% of times).
 285          */
 286         if (cnt <= 1 || !(cnt % 16))
 287                 vhost_poll_queue(&vq->poll);
 288
 289         rcu_read_unlock_bh();
 290 }
 291
 292 static inline unsigned long busy_clock(void)
 293 {
 294         return local_clock() >> 10;
 295 }
 296
 297 static bool vhost_can_busy_poll(struct vhost_dev *dev,
 298                                 unsigned long endtime)
 299 {
 300         return likely(!need_resched()) &&
 301                likely(!time_after(busy_clock(), endtime)) &&
 302                likely(!signal_pending(current)) &&
 303                !vhost_has_work(dev);
 304 }
 305
 306 static void vhost_net_disable_vq(struct vhost_net *n,
 307                                  struct vhost_virtqueue *vq)
 308 {
 309         struct vhost_net_virtqueue *nvq =
 310                 container_of(vq, struct vhost_net_virtqueue, vq);
 311         struct vhost_poll *poll = n->poll + (nvq - n->vqs);
 312         if (!vq->private_data)
 313                 return;
 314         vhost_poll_stop(poll);
 315 }
 316
 317 static int vhost_net_enable_vq(struct vhost_net *n,
 318                                 struct vhost_virtqueue *vq)
 319 {
 320         struct vhost_net_virtqueue *nvq =
 321                 container_of(vq, struct vhost_net_virtqueue, vq);
 322         struct vhost_poll *poll = n->poll + (nvq - n->vqs);
 323         struct socket *sock;
 324
 325         sock = vq->private_data;
 326         if (!sock)
 327                 return 0;
 328
 329         return vhost_poll_start(poll, sock->file);
 330 }
 331
 332 static int vhost_net_tx_get_vq_desc(struct vhost_net *net,
 333                                     struct vhost_virtqueue *vq,
 334                                     struct iovec iov[], unsigned int iov_size,
 335                                     unsigned int *out_num, unsigned int *in_num)
 336 {
 337         unsigned long uninitialized_var(endtime);
 338         int r = vhost_get_vq_desc(vq, vq->iov, ARRAY_SIZE(vq->iov),
 339                                   out_num, in_num, NULL, NULL);
 340
 341         if (r == vq->num && vq->busyloop_timeout) {
 342                 preempt_disable();
 343                 endtime = busy_clock() + vq->busyloop_timeout;
 344                 while (vhost_can_busy_poll(vq->dev, endtime) &&
 345                        vhost_vq_avail_empty(vq->dev, vq))
 346                         cpu_relax();
 347                 preempt_enable();
 348                 r = vhost_get_vq_desc(vq, vq->iov, ARRAY_SIZE(vq->iov),
 349                                       out_num, in_num, NULL, NULL);
 350         }
 351
 352         return r;
 353 }
 354
 355 static bool vhost_exceeds_maxpend(struct vhost_net *net)
 356 {
 357         struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_TX];
 358         struct vhost_virtqueue *vq = &nvq->vq;
 359
 360         return (nvq->upend_idx + vq->num - VHOST_MAX_PEND) % UIO_MAXIOV
 361                 == nvq->done_idx;
 362 }
 363
 364 /* Expects to be always run from workqueue - which acts as
 365  * read-size critical section for our kind of RCU. */
 366 static void handle_tx(struct vhost_net *net)
 367 {
 368         struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_TX];
 369         struct vhost_virtqueue *vq = &nvq->vq;
 370         unsigned out, in;
 371         int head;
 372         struct msghdr msg = {
 373                 .msg_name = NULL,
 374                 .msg_namelen = 0,
 375                 .msg_control = NULL,
 376                 .msg_controllen = 0,
 377                 .msg_flags = MSG_DONTWAIT,
 378         };
 379         size_t len, total_len = 0;
 380         int err;
 381         size_t hdr_size;
 382         struct socket *sock;
 383         struct vhost_net_ubuf_ref *uninitialized_var(ubufs);
 384         bool zcopy, zcopy_used;
 385
 386         mutex_lock(&vq->mutex);
 387         sock = vq->private_data;
 388         if (!sock)
 389                 goto out;
 390
 391         if (!vq_iotlb_prefetch(vq))
 392                 goto out;
 393
 394         vhost_disable_notify(&net->dev, vq);
 395
 396         hdr_size = nvq->vhost_hlen;
 397         zcopy = nvq->ubufs;
 398
 399         for (;;) {
 400                 /* Release DMAs done buffers first */
 401                 if (zcopy)
 402                         vhost_zerocopy_signal_used(net, vq);
 403
 404                 /* If more outstanding DMAs, queue the work.
 405                  * Handle upend_idx wrap around
 406                  */
 407                 if (unlikely(vhost_exceeds_maxpend(net)))
 408                         break;
 409
 410                 head = vhost_net_tx_get_vq_desc(net, vq, vq->iov,
 411                                                 ARRAY_SIZE(vq->iov),
 412                                                 &out, &in);
 413                 /* On error, stop handling until the next kick. */
 414                 if (unlikely(head < 0))
 415                         break;
 416                 /* Nothing new?  Wait for eventfd to tell us they refilled. */
 417                 if (head == vq->num) {
 418                         if (unlikely(vhost_enable_notify(&net->dev, vq))) {
 419                                 vhost_disable_notify(&net->dev, vq);
 420                                 continue;
 421                         }
 422                         break;
 423                 }
 424                 if (in) {
 425                         vq_err(vq, "Unexpected descriptor format for TX: "
 426                                "out %d, int %d\n", out, in);
 427                         break;
 428                 }
 429                 /* Skip header. TODO: support TSO. */
 430                 len = iov_length(vq->iov, out);
 431                 iov_iter_init(&msg.msg_iter, WRITE, vq->iov, out, len);
 432                 iov_iter_advance(&msg.msg_iter, hdr_size);
 433                 /* Sanity check */
 434                 if (!msg_data_left(&msg)) {
 435                         vq_err(vq, "Unexpected header len for TX: "
 436                                "%zd expected %zd\n",
 437                                len, hdr_size);
 438                         break;
 439                 }
 440                 len = msg_data_left(&msg);
 441
 442                 zcopy_used = zcopy && len >= VHOST_GOODCOPY_LEN
 443                                    && (nvq->upend_idx + 1) % UIO_MAXIOV !=
 444                                       nvq->done_idx
 445                                    && vhost_net_tx_select_zcopy(net);
 446
 447                 /* use msg_control to pass vhost zerocopy ubuf info to skb */
 448                 if (zcopy_used) {
 449                         struct ubuf_info *ubuf;
 450                         ubuf = nvq->ubuf_info + nvq->upend_idx;
 451
 452                         vq->heads[nvq->upend_idx].id = cpu_to_vhost32(vq, head);
 453                         vq->heads[nvq->upend_idx].len = VHOST_DMA_IN_PROGRESS;
 454                         ubuf->callback = vhost_zerocopy_callback;
 455                         ubuf->ctx = nvq->ubufs;
 456                         ubuf->desc = nvq->upend_idx;
 457                         msg.msg_control = ubuf;
 458                         msg.msg_controllen = sizeof(ubuf);
 459                         ubufs = nvq->ubufs;
 460                         atomic_inc(&ubufs->refcount);
 461                         nvq->upend_idx = (nvq->upend_idx + 1) % UIO_MAXIOV;
 462                 } else {
 463                         msg.msg_control = NULL;
 464                         ubufs = NULL;
 465                 }
 466
 467                 total_len += len;
 468                 if (total_len < VHOST_NET_WEIGHT &&
 469                     !vhost_vq_avail_empty(&net->dev, vq) &&
 470                     likely(!vhost_exceeds_maxpend(net))) {
 471                         msg.msg_flags |= MSG_MORE;
 472                 } else {
 473                         msg.msg_flags &= ~MSG_MORE;
 474                 }
 475
 476                 /* TODO: Check specific error and bomb out unless ENOBUFS? */
 477                 err = sock->ops->sendmsg(sock, &msg, len);
 478                 if (unlikely(err < 0)) {
 479                         if (zcopy_used) {
 480                                 vhost_net_ubuf_put(ubufs);
 481                                 nvq->upend_idx = ((unsigned)nvq->upend_idx - 1)
 482                                         % UIO_MAXIOV;
 483                         }
 484                         vhost_discard_vq_desc(vq, 1);
 485                         break;
 486                 }
 487                 if (err != len)
 488                         pr_debug("Truncated TX packet: "
 489                                  " len %d != %zd\n", err, len);
 490                 if (!zcopy_used)
 491                         vhost_add_used_and_signal(&net->dev, vq, head, 0);
 492                 else
 493                         vhost_zerocopy_signal_used(net, vq);
 494                 vhost_net_tx_packet(net);
 495                 if (unlikely(total_len >= VHOST_NET_WEIGHT)) {
 496                         vhost_poll_queue(&vq->poll);
 497                         break;
 498                 }
 499         }
 500 out:
 501         mutex_unlock(&vq->mutex);
 502 }
 503
 504 static int peek_head_len(struct sock *sk)
 505 {
 506         struct socket *sock = sk->sk_socket;
 507         struct sk_buff *head;
 508         int len = 0;
 509         unsigned long flags;
 510
 511         if (sock->ops->peek_len)
 512                 return sock->ops->peek_len(sock);
 513
 514         spin_lock_irqsave(&sk->sk_receive_queue.lock, flags);
 515         head = skb_peek(&sk->sk_receive_queue);
 516         if (likely(head)) {
 517                 len = head->len;
 518                 if (skb_vlan_tag_present(head))
 519                         len += VLAN_HLEN;
 520         }
 521
 522         spin_unlock_irqrestore(&sk->sk_receive_queue.lock, flags);
 523         return len;
 524 }
 525
 526 static int sk_has_rx_data(struct sock *sk)
 527 {
 528         struct socket *sock = sk->sk_socket;
 529
 530         if (sock->ops->peek_len)
 531                 return sock->ops->peek_len(sock);
 532
 533         return skb_queue_empty(&sk->sk_receive_queue);
 534 }
 535
 536 static int vhost_net_rx_peek_head_len(struct vhost_net *net, struct sock *sk)
 537 {
 538         struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_TX];
 539         struct vhost_virtqueue *vq = &nvq->vq;
 540         unsigned long uninitialized_var(endtime);
 541         int len = peek_head_len(sk);
 542
 543         if (!len && vq->busyloop_timeout) {
 544                 /* Both tx vq and rx socket were polled here */
 545                 mutex_lock(&vq->mutex);
 546                 vhost_disable_notify(&net->dev, vq);
 547
 548                 preempt_disable();
 549                 endtime = busy_clock() + vq->busyloop_timeout;
 550
 551                 while (vhost_can_busy_poll(&net->dev, endtime) &&
 552                        !sk_has_rx_data(sk) &&
 553                        vhost_vq_avail_empty(&net->dev, vq))
 554                         cpu_relax();
 555
 556                 preempt_enable();
 557
 558                 if (vhost_enable_notify(&net->dev, vq))
 559                         vhost_poll_queue(&vq->poll);
 560                 mutex_unlock(&vq->mutex);
 561
 562                 len = peek_head_len(sk);
 563         }
 564
 565         return len;
 566 }
 567
 568 /* This is a multi-buffer version of vhost_get_desc, that works if
 569  *      vq has read descriptors only.
 570  * @vq          - the relevant virtqueue
 571  * @datalen     - data length we'll be reading
 572  * @iovcount    - returned count of io vectors we fill
 573  * @log         - vhost log
 574  * @log_num     - log offset
 575  * @quota       - headcount quota, 1 for big buffer
 576  *      returns number of buffer heads allocated, negative on error
 577  */
 578 static int get_rx_bufs(struct vhost_virtqueue *vq,
 579                        struct vring_used_elem *heads,
 580                        int datalen,
 581                        unsigned *iovcount,
 582                        struct vhost_log *log,
 583                        unsigned *log_num,
 584                        unsigned int quota)
 585 {
 586         unsigned int out, in;
 587         int seg = 0;
 588         int headcount = 0;
 589         unsigned d;
 590         int r, nlogs = 0;
 591         /* len is always initialized before use since we are always called with
 592          * datalen > 0.
 593          */
 594         u32 uninitialized_var(len);
 595
 596         while (datalen > 0 && headcount < quota) {
 597                 if (unlikely(seg >= UIO_MAXIOV)) {
 598                         r = -ENOBUFS;
 599                         goto err;
 600                 }
 601                 r = vhost_get_vq_desc(vq, vq->iov + seg,
 602                                       ARRAY_SIZE(vq->iov) - seg, &out,
 603                                       &in, log, log_num);
 604                 if (unlikely(r < 0))
 605                         goto err;
 606
 607                 d = r;
 608                 if (d == vq->num) {
 609                         r = 0;
 610                         goto err;
 611                 }
 612                 if (unlikely(out || in <= 0)) {
 613                         vq_err(vq, "unexpected descriptor format for RX: "
 614                                 "out %d, in %d\n", out, in);
 615                         r = -EINVAL;
 616                         goto err;
 617                 }
 618                 if (unlikely(log)) {
 619                         nlogs += *log_num;
 620                         log += *log_num;
 621                 }
 622                 heads[headcount].id = cpu_to_vhost32(vq, d);
 623                 len = iov_length(vq->iov + seg, in);
 624                 heads[headcount].len = cpu_to_vhost32(vq, len);
 625                 datalen -= len;
 626                 ++headcount;
 627                 seg += in;
 628         }
 629         heads[headcount - 1].len = cpu_to_vhost32(vq, len + datalen);
 630         *iovcount = seg;
 631         if (unlikely(log))
 632                 *log_num = nlogs;
 633
 634         /* Detect overrun */
 635         if (unlikely(datalen > 0)) {
 636                 r = UIO_MAXIOV + 1;
 637                 goto err;
 638         }
 639         return headcount;
 640 err:
 641         vhost_discard_vq_desc(vq, headcount);
 642         return r;
 643 }
 644
 645 /* Expects to be always run from workqueue - which acts as
 646  * read-size critical section for our kind of RCU. */
 647 static void handle_rx(struct vhost_net *net)
 648 {
 649         struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_RX];
 650         struct vhost_virtqueue *vq = &nvq->vq;
 651         unsigned uninitialized_var(in), log;
 652         struct vhost_log *vq_log;
 653         struct msghdr msg = {
 654                 .msg_name = NULL,
 655                 .msg_namelen = 0,
 656                 .msg_control = NULL, /* FIXME: get and handle RX aux data. */
 657                 .msg_controllen = 0,
 658                 .msg_flags = MSG_DONTWAIT,
 659         };
 660         struct virtio_net_hdr hdr = {
 661                 .flags = 0,
 662                 .gso_type = VIRTIO_NET_HDR_GSO_NONE
 663         };
 664         size_t total_len = 0;
 665         int err, mergeable;
 666         s16 headcount;
 667         size_t vhost_hlen, sock_hlen;
 668         size_t vhost_len, sock_len;
 669         struct socket *sock;
 670         struct iov_iter fixup;
 671         __virtio16 num_buffers;
 672
 673         mutex_lock(&vq->mutex);
 674         sock = vq->private_data;
 675         if (!sock)
 676                 goto out;
 677
 678         if (!vq_iotlb_prefetch(vq))
 679                 goto out;
 680
 681         vhost_disable_notify(&net->dev, vq);
 682         vhost_net_disable_vq(net, vq);
 683
 684         vhost_hlen = nvq->vhost_hlen;
 685         sock_hlen = nvq->sock_hlen;
 686
 687         vq_log = unlikely(vhost_has_feature(vq, VHOST_F_LOG_ALL)) ?
 688                 vq->log : NULL;
 689         mergeable = vhost_has_feature(vq, VIRTIO_NET_F_MRG_RXBUF);
 690
 691         while ((sock_len = vhost_net_rx_peek_head_len(net, sock->sk))) {
 692                 sock_len += sock_hlen;
 693                 vhost_len = sock_len + vhost_hlen;
 694                 headcount = get_rx_bufs(vq, vq->heads, vhost_len,
 695                                         &in, vq_log, &log,
 696                                         likely(mergeable) ? UIO_MAXIOV : 1);
 697                 /* On error, stop handling until the next kick. */
 698                 if (unlikely(headcount < 0))
 699                         goto out;
 700                 /* On overrun, truncate and discard */
 701                 if (unlikely(headcount > UIO_MAXIOV)) {
 702                         iov_iter_init(&msg.msg_iter, READ, vq->iov, 1, 1);
 703                         err = sock->ops->recvmsg(sock, &msg,
 704                                                  1, MSG_DONTWAIT | MSG_TRUNC);
 705                         pr_debug("Discarded rx packet: len %zd\n", sock_len);
 706                         continue;
 707                 }
 708                 /* OK, now we need to know about added descriptors. */
 709                 if (!headcount) {
 710                         if (unlikely(vhost_enable_notify(&net->dev, vq))) {
 711                                 /* They have slipped one in as we were
 712                                  * doing that: check again. */
 713                                 vhost_disable_notify(&net->dev, vq);
 714                                 continue;
 715                         }
 716                         /* Nothing new?  Wait for eventfd to tell us
 717                          * they refilled. */
 718                         goto out;
 719                 }
 720                 /* We don't need to be notified again. */
 721                 iov_iter_init(&msg.msg_iter, READ, vq->iov, in, vhost_len);
 722                 fixup = msg.msg_iter;
 723                 if (unlikely((vhost_hlen))) {
 724                         /* We will supply the header ourselves
 725                          * TODO: support TSO.
 726                          */
 727                         iov_iter_advance(&msg.msg_iter, vhost_hlen);
 728                 }
 729                 err = sock->ops->recvmsg(sock, &msg,
 730                                          sock_len, MSG_DONTWAIT | MSG_TRUNC);
 731                 /* Userspace might have consumed the packet meanwhile:
 732                  * it's not supposed to do this usually, but might be hard
 733                  * to prevent. Discard data we got (if any) and keep going. */
 734                 if (unlikely(err != sock_len)) {
 735                         pr_debug("Discarded rx packet: "
 736                                  " len %d, expected %zd\n", err, sock_len);
 737                         vhost_discard_vq_desc(vq, headcount);
 738                         continue;
 739                 }
 740                 /* Supply virtio_net_hdr if VHOST_NET_F_VIRTIO_NET_HDR */
 741                 if (unlikely(vhost_hlen)) {
 742                         if (copy_to_iter(&hdr, sizeof(hdr),
 743                                          &fixup) != sizeof(hdr)) {
 744                                 vq_err(vq, "Unable to write vnet_hdr "
 745                                        "at addr %p\n", vq->iov->iov_base);
 746                                 goto out;
 747                         }
 748                 } else {
 749                         /* Header came from socket; we'll need to patch
 750                          * ->num_buffers over if VIRTIO_NET_F_MRG_RXBUF
 751                          */
 752                         iov_iter_advance(&fixup, sizeof(hdr));
 753                 }
 754                 /* TODO: Should check and handle checksum. */
 755
 756                 num_buffers = cpu_to_vhost16(vq, headcount);
 757                 if (likely(mergeable) &&
 758                     copy_to_iter(&num_buffers, sizeof num_buffers,
 759                                  &fixup) != sizeof num_buffers) {
 760                         vq_err(vq, "Failed num_buffers write");
 761                         vhost_discard_vq_desc(vq, headcount);
 762                         goto out;
 763                 }
 764                 vhost_add_used_and_signal_n(&net->dev, vq, vq->heads,
 765                                             headcount);
 766                 if (unlikely(vq_log))
 767                         vhost_log_write(vq, vq_log, log, vhost_len);
 768                 total_len += vhost_len;
 769                 if (unlikely(total_len >= VHOST_NET_WEIGHT)) {
 770                         vhost_poll_queue(&vq->poll);
 771                         goto out;
 772                 }
 773         }
 774         vhost_net_enable_vq(net, vq);
 775 out:
 776         mutex_unlock(&vq->mutex);
 777 }
 778
 779 static void handle_tx_kick(struct vhost_work *work)
 780 {
 781         struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
 782                                                   poll.work);
 783         struct vhost_net *net = container_of(vq->dev, struct vhost_net, dev);
 784
 785         handle_tx(net);
 786 }
 787
 788 static void handle_rx_kick(struct vhost_work *work)
 789 {
 790         struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
 791                                                   poll.work);
 792         struct vhost_net *net = container_of(vq->dev, struct vhost_net, dev);
 793
 794         handle_rx(net);
 795 }
 796
 797 static void handle_tx_net(struct vhost_work *work)
 798 {
 799         struct vhost_net *net = container_of(work, struct vhost_net,
 800                                              poll[VHOST_NET_VQ_TX].work);
 801         handle_tx(net);
 802 }
 803
 804 static void handle_rx_net(struct vhost_work *work)
 805 {
 806         struct vhost_net *net = container_of(work, struct vhost_net,
 807                                              poll[VHOST_NET_VQ_RX].work);
 808         handle_rx(net);
 809 }
 810
 811 static int vhost_net_open(struct inode *inode, struct file *f)
 812 {
 813         struct vhost_net *n;
 814         struct vhost_dev *dev;
 815         struct vhost_virtqueue **vqs;
 816         int i;
 817
 818         n = kmalloc(sizeof *n, GFP_KERNEL | __GFP_NOWARN | __GFP_REPEAT);
 819         if (!n) {
 820                 n = vmalloc(sizeof *n);
 821                 if (!n)
 822                         return -ENOMEM;
 823         }
 824         vqs = kmalloc(VHOST_NET_VQ_MAX * sizeof(*vqs), GFP_KERNEL);
 825         if (!vqs) {
 826                 kvfree(n);
 827                 return -ENOMEM;
 828         }
 829
 830         dev = &n->dev;
 831         vqs[VHOST_NET_VQ_TX] = &n->vqs[VHOST_NET_VQ_TX].vq;
 832         vqs[VHOST_NET_VQ_RX] = &n->vqs[VHOST_NET_VQ_RX].vq;
 833         n->vqs[VHOST_NET_VQ_TX].vq.handle_kick = handle_tx_kick;
 834         n->vqs[VHOST_NET_VQ_RX].vq.handle_kick = handle_rx_kick;
 835         for (i = 0; i < VHOST_NET_VQ_MAX; i++) {
 836                 n->vqs[i].ubufs = NULL;
 837                 n->vqs[i].ubuf_info = NULL;
 838                 n->vqs[i].upend_idx = 0;
 839                 n->vqs[i].done_idx = 0;
 840                 n->vqs[i].vhost_hlen = 0;
 841                 n->vqs[i].sock_hlen = 0;
 842         }
 843         vhost_dev_init(dev, vqs, VHOST_NET_VQ_MAX);
 844
 845         vhost_poll_init(n->poll + VHOST_NET_VQ_TX, handle_tx_net, POLLOUT, dev);
 846         vhost_poll_init(n->poll + VHOST_NET_VQ_RX, handle_rx_net, POLLIN, dev);
 847
 848         f->private_data = n;
 849
 850         return 0;
 851 }
 852
 853 static struct socket *vhost_net_stop_vq(struct vhost_net *n,
 854                                         struct vhost_virtqueue *vq)
 855 {
 856         struct socket *sock;
 857
 858         mutex_lock(&vq->mutex);
 859         sock = vq->private_data;
 860         vhost_net_disable_vq(n, vq);
 861         vq->private_data = NULL;
 862         mutex_unlock(&vq->mutex);
 863         return sock;
 864 }
 865
 866 static void vhost_net_stop(struct vhost_net *n, struct socket **tx_sock,
 867                            struct socket **rx_sock)
 868 {
 869         *tx_sock = vhost_net_stop_vq(n, &n->vqs[VHOST_NET_VQ_TX].vq);
 870         *rx_sock = vhost_net_stop_vq(n, &n->vqs[VHOST_NET_VQ_RX].vq);
 871 }
 872
 873 static void vhost_net_flush_vq(struct vhost_net *n, int index)
 874 {
 875         vhost_poll_flush(n->poll + index);
 876         vhost_poll_flush(&n->vqs[index].vq.poll);
 877 }
 878
 879 static void vhost_net_flush(struct vhost_net *n)
 880 {
 881         vhost_net_flush_vq(n, VHOST_NET_VQ_TX);
 882         vhost_net_flush_vq(n, VHOST_NET_VQ_RX);
 883         if (n->vqs[VHOST_NET_VQ_TX].ubufs) {
 884                 mutex_lock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
 885                 n->tx_flush = true;
 886                 mutex_unlock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
 887                 /* Wait for all lower device DMAs done. */
 888                 vhost_net_ubuf_put_and_wait(n->vqs[VHOST_NET_VQ_TX].ubufs);
 889                 mutex_lock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
 890                 n->tx_flush = false;
 891                 atomic_set(&n->vqs[VHOST_NET_VQ_TX].ubufs->refcount, 1);
 892                 mutex_unlock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
 893         }
 894 }
 895
 896 static int vhost_net_release(struct inode *inode, struct file *f)
 897 {
 898         struct vhost_net *n = f->private_data;
 899         struct socket *tx_sock;
 900         struct socket *rx_sock;
 901
 902         vhost_net_stop(n, &tx_sock, &rx_sock);
 903         vhost_net_flush(n);
 904         vhost_dev_stop(&n->dev);
 905         vhost_dev_cleanup(&n->dev, false);
 906         vhost_net_vq_reset(n);
 907         if (tx_sock)
 908                 sockfd_put(tx_sock);
 909         if (rx_sock)
 910                 sockfd_put(rx_sock);
 911         /* Make sure no callbacks are outstanding */
 912         synchronize_rcu_bh();
 913         /* We do an extra flush before freeing memory,
 914          * since jobs can re-queue themselves. */
 915         vhost_net_flush(n);
 916         kfree(n->dev.vqs);
 917         kvfree(n);
 918         return 0;
 919 }
 920
 921 static struct socket *get_raw_socket(int fd)
 922 {
 923         struct {
 924                 struct sockaddr_ll sa;
 925                 char  buf[MAX_ADDR_LEN];
 926         } uaddr;
 927         int uaddr_len = sizeof uaddr, r;
 928         struct socket *sock = sockfd_lookup(fd, &r);
 929
 930         if (!sock)
 931                 return ERR_PTR(-ENOTSOCK);
 932
 933         /* Parameter checking */
 934         if (sock->sk->sk_type != SOCK_RAW) {
 935                 r = -ESOCKTNOSUPPORT;
 936                 goto err;
 937         }
 938
 939         r = sock->ops->getname(sock, (struct sockaddr *)&uaddr.sa,
 940                                &uaddr_len, 0);
 941         if (r)
 942                 goto err;
 943
 944         if (uaddr.sa.sll_family != AF_PACKET) {
 945                 r = -EPFNOSUPPORT;
 946                 goto err;
 947         }
 948         return sock;
 949 err:
 950         sockfd_put(sock);
 951         return ERR_PTR(r);
 952 }
 953
 954 static struct socket *get_tap_socket(int fd)
 955 {
 956         struct file *file = fget(fd);
 957         struct socket *sock;
 958
 959         if (!file)
 960                 return ERR_PTR(-EBADF);
 961         sock = tun_get_socket(file);
 962         if (!IS_ERR(sock))
 963                 return sock;
 964         sock = tap_get_socket(file);
 965         if (IS_ERR(sock))
 966                 fput(file);
 967         return sock;
 968 }
 969
 970 static struct socket *get_socket(int fd)
 971 {
 972         struct socket *sock;
 973
 974         /* special case to disable backend */
 975         if (fd == -1)
 976                 return NULL;
 977         sock = get_raw_socket(fd);
 978         if (!IS_ERR(sock))
 979                 return sock;
 980         sock = get_tap_socket(fd);
 981         if (!IS_ERR(sock))
 982                 return sock;
 983         return ERR_PTR(-ENOTSOCK);
 984 }
 985
 986 static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd)
 987 {
 988         struct socket *sock, *oldsock;
 989         struct vhost_virtqueue *vq;
 990         struct vhost_net_virtqueue *nvq;
 991         struct vhost_net_ubuf_ref *ubufs, *oldubufs = NULL;
 992         int r;
 993
 994         mutex_lock(&n->dev.mutex);
 995         r = vhost_dev_check_owner(&n->dev);
 996         if (r)
 997                 goto err;
 998
 999         if (index >= VHOST_NET_VQ_MAX) {
1000                 r = -ENOBUFS;
1001                 goto err;
1002         }
1003         vq = &n->vqs[index].vq;
1004         nvq = &n->vqs[index];
1005         mutex_lock(&vq->mutex);
1006
1007         /* Verify that ring has been setup correctly. */
1008         if (!vhost_vq_access_ok(vq)) {
1009                 r = -EFAULT;
1010                 goto err_vq;
1011         }
1012         sock = get_socket(fd);
1013         if (IS_ERR(sock)) {
1014                 r = PTR_ERR(sock);
1015                 goto err_vq;
1016         }
1017
1018         /* start polling new socket */
1019         oldsock = vq->private_data;
1020         if (sock != oldsock) {
1021                 ubufs = vhost_net_ubuf_alloc(vq,
1022                                              sock && vhost_sock_zcopy(sock));
1023                 if (IS_ERR(ubufs)) {
1024                         r = PTR_ERR(ubufs);
1025                         goto err_ubufs;
1026                 }
1027
1028                 vhost_net_disable_vq(n, vq);
1029                 vq->private_data = sock;
1030                 r = vhost_vq_init_access(vq);
1031                 if (r)
1032                         goto err_used;
1033                 r = vhost_net_enable_vq(n, vq);
1034                 if (r)
1035                         goto err_used;
1036
1037                 oldubufs = nvq->ubufs;
1038                 nvq->ubufs = ubufs;
1039
1040                 n->tx_packets = 0;
1041                 n->tx_zcopy_err = 0;
1042                 n->tx_flush = false;
1043         }
1044
1045         mutex_unlock(&vq->mutex);
1046
1047         if (oldubufs) {
1048                 vhost_net_ubuf_put_wait_and_free(oldubufs);
1049                 mutex_lock(&vq->mutex);
1050                 vhost_zerocopy_signal_used(n, vq);
1051                 mutex_unlock(&vq->mutex);
1052         }
1053
1054         if (oldsock) {
1055                 vhost_net_flush_vq(n, index);
1056                 sockfd_put(oldsock);
1057         }
1058
1059         mutex_unlock(&n->dev.mutex);
1060         return 0;
1061
1062 err_used:
1063         vq->private_data = oldsock;
1064         vhost_net_enable_vq(n, vq);
1065         if (ubufs)
1066                 vhost_net_ubuf_put_wait_and_free(ubufs);
1067 err_ubufs:
1068         sockfd_put(sock);
1069 err_vq:
1070         mutex_unlock(&vq->mutex);
1071 err:
1072         mutex_unlock(&n->dev.mutex);
1073         return r;
1074 }
1075
1076 static long vhost_net_reset_owner(struct vhost_net *n)
1077 {
1078         struct socket *tx_sock = NULL;
1079         struct socket *rx_sock = NULL;
1080         long err;
1081         struct vhost_umem *umem;
1082
1083         mutex_lock(&n->dev.mutex);
1084         err = vhost_dev_check_owner(&n->dev);
1085         if (err)
1086                 goto done;
1087         umem = vhost_dev_reset_owner_prepare();
1088         if (!umem) {
1089                 err = -ENOMEM;
1090                 goto done;
1091         }
1092         vhost_net_stop(n, &tx_sock, &rx_sock);
1093         vhost_net_flush(n);
1094         vhost_dev_reset_owner(&n->dev, umem);
1095         vhost_net_vq_reset(n);
1096 done:
1097         mutex_unlock(&n->dev.mutex);
1098         if (tx_sock)
1099                 sockfd_put(tx_sock);
1100         if (rx_sock)
1101                 sockfd_put(rx_sock);
1102         return err;
1103 }
1104
1105 static int vhost_net_set_features(struct vhost_net *n, u64 features)
1106 {
1107         size_t vhost_hlen, sock_hlen, hdr_len;
1108         int i;
1109
1110         hdr_len = (features & ((1ULL << VIRTIO_NET_F_MRG_RXBUF) |
1111                                (1ULL << VIRTIO_F_VERSION_1))) ?
1112                         sizeof(struct virtio_net_hdr_mrg_rxbuf) :
1113                         sizeof(struct virtio_net_hdr);
1114         if (features & (1 << VHOST_NET_F_VIRTIO_NET_HDR)) {
1115                 /* vhost provides vnet_hdr */
1116                 vhost_hlen = hdr_len;
1117                 sock_hlen = 0;
1118         } else {
1119                 /* socket provides vnet_hdr */
1120                 vhost_hlen = 0;
1121                 sock_hlen = hdr_len;
1122         }
1123         mutex_lock(&n->dev.mutex);
1124         if ((features & (1 << VHOST_F_LOG_ALL)) &&
1125             !vhost_log_access_ok(&n->dev))
1126                 goto out_unlock;
1127
1128         if ((features & (1ULL << VIRTIO_F_IOMMU_PLATFORM))) {
1129                 if (vhost_init_device_iotlb(&n->dev, true))
1130                         goto out_unlock;
1131         }
1132
1133         for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
1134                 mutex_lock(&n->vqs[i].vq.mutex);
1135                 n->vqs[i].vq.acked_features = features;
1136                 n->vqs[i].vhost_hlen = vhost_hlen;
1137                 n->vqs[i].sock_hlen = sock_hlen;
1138                 mutex_unlock(&n->vqs[i].vq.mutex);
1139         }
1140         mutex_unlock(&n->dev.mutex);
1141         return 0;
1142
1143 out_unlock:
1144         mutex_unlock(&n->dev.mutex);
1145         return -EFAULT;
1146 }
1147
1148 static long vhost_net_set_owner(struct vhost_net *n)
1149 {
1150         int r;
1151
1152         mutex_lock(&n->dev.mutex);
1153         if (vhost_dev_has_owner(&n->dev)) {
1154                 r = -EBUSY;
1155                 goto out;
1156         }
1157         r = vhost_net_set_ubuf_info(n);
1158         if (r)
1159                 goto out;
1160         r = vhost_dev_set_owner(&n->dev);
1161         if (r)
1162                 vhost_net_clear_ubuf_info(n);
1163         vhost_net_flush(n);
1164 out:
1165         mutex_unlock(&n->dev.mutex);
1166         return r;
1167 }
1168
1169 static long vhost_net_ioctl(struct file *f, unsigned int ioctl,
1170                             unsigned long arg)
1171 {
1172         struct vhost_net *n = f->private_data;
1173         void __user *argp = (void __user *)arg;
1174         u64 __user *featurep = argp;
1175         struct vhost_vring_file backend;
1176         u64 features;
1177         int r;
1178
1179         switch (ioctl) {
1180         case VHOST_NET_SET_BACKEND:
1181                 if (copy_from_user(&backend, argp, sizeof backend))
1182                         return -EFAULT;
1183                 return vhost_net_set_backend(n, backend.index, backend.fd);
1184         case VHOST_GET_FEATURES:
1185                 features = VHOST_NET_FEATURES;
1186                 if (copy_to_user(featurep, &features, sizeof features))
1187                         return -EFAULT;
1188                 return 0;
1189         case VHOST_SET_FEATURES:
1190                 if (copy_from_user(&features, featurep, sizeof features))
1191                         return -EFAULT;
1192                 if (features & ~VHOST_NET_FEATURES)
1193                         return -EOPNOTSUPP;
1194                 return vhost_net_set_features(n, features);
1195         case VHOST_RESET_OWNER:
1196                 return vhost_net_reset_owner(n);
1197         case VHOST_SET_OWNER:
1198                 return vhost_net_set_owner(n);
1199         default:
1200                 mutex_lock(&n->dev.mutex);
1201                 r = vhost_dev_ioctl(&n->dev, ioctl, argp);
1202                 if (r == -ENOIOCTLCMD)
1203                         r = vhost_vring_ioctl(&n->dev, ioctl, argp);
1204                 else
1205                         vhost_net_flush(n);
1206                 mutex_unlock(&n->dev.mutex);
1207                 return r;
1208         }
1209 }
1210
1211 #ifdef CONFIG_COMPAT
1212 static long vhost_net_compat_ioctl(struct file *f, unsigned int ioctl,
1213                                    unsigned long arg)
1214 {
1215         return vhost_net_ioctl(f, ioctl, (unsigned long)compat_ptr(arg));
1216 }
1217 #endif
1218
1219 static ssize_t vhost_net_chr_read_iter(struct kiocb *iocb, struct iov_iter *to)
1220 {
1221         struct file *file = iocb->ki_filp;
1222         struct vhost_net *n = file->private_data;
1223         struct vhost_dev *dev = &n->dev;
1224         int noblock = file->f_flags & O_NONBLOCK;
1225
1226         return vhost_chr_read_iter(dev, to, noblock);
1227 }
1228
1229 static ssize_t vhost_net_chr_write_iter(struct kiocb *iocb,
1230                                         struct iov_iter *from)
1231 {
1232         struct file *file = iocb->ki_filp;
1233         struct vhost_net *n = file->private_data;
1234         struct vhost_dev *dev = &n->dev;
1235
1236         return vhost_chr_write_iter(dev, from);
1237 }
1238
1239 static unsigned int vhost_net_chr_poll(struct file *file, poll_table *wait)
1240 {
1241         struct vhost_net *n = file->private_data;
1242         struct vhost_dev *dev = &n->dev;
1243
1244         return vhost_chr_poll(file, dev, wait);
1245 }
1246
1247 static const struct file_operations vhost_net_fops = {
1248         .owner          = THIS_MODULE,
1249         .release        = vhost_net_release,
1250         .read_iter      = vhost_net_chr_read_iter,
1251         .write_iter     = vhost_net_chr_write_iter,
1252         .poll           = vhost_net_chr_poll,
1253         .unlocked_ioctl = vhost_net_ioctl,
1254 #ifdef CONFIG_COMPAT
1255         .compat_ioctl   = vhost_net_compat_ioctl,
1256 #endif
1257         .open           = vhost_net_open,
1258         .llseek         = noop_llseek,
1259 };
1260
1261 static struct miscdevice vhost_net_misc = {
1262         .minor = VHOST_NET_MINOR,
1263         .name = "vhost-net",
1264         .fops = &vhost_net_fops,
1265 };
1266
1267 static int vhost_net_init(void)
1268 {
1269         if (experimental_zcopytx)
1270                 vhost_net_enable_zcopy(VHOST_NET_VQ_TX);
1271         return misc_register(&vhost_net_misc);
1272 }
1273 module_init(vhost_net_init);
1274
1275 static void vhost_net_exit(void)
1276 {
1277         misc_deregister(&vhost_net_misc);
1278 }
1279 module_exit(vhost_net_exit);
1280
1281 MODULE_VERSION("0.0.1");
1282 MODULE_LICENSE("GPL v2");
1283 MODULE_AUTHOR("Michael S. Tsirkin");
1284 MODULE_DESCRIPTION("Host kernel accelerator for virtio net");
1285 MODULE_ALIAS_MISCDEV(VHOST_NET_MINOR);
1286 MODULE_ALIAS("devname:vhost-net");