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/rcupdate.h>
  19 #include <linux/file.h>
  20 #include <linux/slab.h>
  21
  22 #include <linux/net.h>
  23 #include <linux/if_packet.h>
  24 #include <linux/if_arp.h>
  25 #include <linux/if_tun.h>
  26 #include <linux/if_macvlan.h>
  27
  28 #include <net/sock.h>
  29
  30 #include "vhost.h"
  31
  32 static int experimental_zcopytx;
  33 module_param(experimental_zcopytx, int, 0444);
  34 MODULE_PARM_DESC(experimental_zcopytx, "Enable Experimental Zero Copy TX");
  35
  36 /* Max number of bytes transferred before requeueing the job.
  37  * Using this limit prevents one virtqueue from starving others. */
  38 #define VHOST_NET_WEIGHT 0x80000
  39
  40 /* MAX number of TX used buffers for outstanding zerocopy */
  41 #define VHOST_MAX_PEND 128
  42 #define VHOST_GOODCOPY_LEN 256
  43
  44 enum {
  45         VHOST_NET_VQ_RX = 0,
  46         VHOST_NET_VQ_TX = 1,
  47         VHOST_NET_VQ_MAX = 2,
  48 };
  49
  50 enum vhost_net_poll_state {
  51         VHOST_NET_POLL_DISABLED = 0,
  52         VHOST_NET_POLL_STARTED = 1,
  53         VHOST_NET_POLL_STOPPED = 2,
  54 };
  55
  56 struct vhost_net {
  57         struct vhost_dev dev;
  58         struct vhost_virtqueue vqs[VHOST_NET_VQ_MAX];
  59         struct vhost_poll poll[VHOST_NET_VQ_MAX];
  60         /* Tells us whether we are polling a socket for TX.
  61          * We only do this when socket buffer fills up.
  62          * Protected by tx vq lock. */
  63         enum vhost_net_poll_state tx_poll_state;
  64 };
  65
  66 static bool vhost_sock_zcopy(struct socket *sock)
  67 {
  68         return unlikely(experimental_zcopytx) &&
  69                 sock_flag(sock->sk, SOCK_ZEROCOPY);
  70 }
  71
  72 /* Pop first len bytes from iovec. Return number of segments used. */
  73 static int move_iovec_hdr(struct iovec *from, struct iovec *to,
  74                           size_t len, int iov_count)
  75 {
  76         int seg = 0;
  77         size_t size;
  78
  79         while (len && seg < iov_count) {
  80                 size = min(from->iov_len, len);
  81                 to->iov_base = from->iov_base;
  82                 to->iov_len = size;
  83                 from->iov_len -= size;
  84                 from->iov_base += size;
  85                 len -= size;
  86                 ++from;
  87                 ++to;
  88                 ++seg;
  89         }
  90         return seg;
  91 }
  92 /* Copy iovec entries for len bytes from iovec. */
  93 static void copy_iovec_hdr(const struct iovec *from, struct iovec *to,
  94                            size_t len, int iovcount)
  95 {
  96         int seg = 0;
  97         size_t size;
  98
  99         while (len && seg < iovcount) {
 100                 size = min(from->iov_len, len);
 101                 to->iov_base = from->iov_base;
 102                 to->iov_len = size;
 103                 len -= size;
 104                 ++from;
 105                 ++to;
 106                 ++seg;
 107         }
 108 }
 109
 110 /* Caller must have TX VQ lock */
 111 static void tx_poll_stop(struct vhost_net *net)
 112 {
 113         if (likely(net->tx_poll_state != VHOST_NET_POLL_STARTED))
 114                 return;
 115         vhost_poll_stop(net->poll + VHOST_NET_VQ_TX);
 116         net->tx_poll_state = VHOST_NET_POLL_STOPPED;
 117 }
 118
 119 /* Caller must have TX VQ lock */
 120 static void tx_poll_start(struct vhost_net *net, struct socket *sock)
 121 {
 122         if (unlikely(net->tx_poll_state != VHOST_NET_POLL_STOPPED))
 123                 return;
 124         vhost_poll_start(net->poll + VHOST_NET_VQ_TX, sock->file);
 125         net->tx_poll_state = VHOST_NET_POLL_STARTED;
 126 }
 127
 128 /* Expects to be always run from workqueue - which acts as
 129  * read-size critical section for our kind of RCU. */
 130 static void handle_tx(struct vhost_net *net)
 131 {
 132         struct vhost_virtqueue *vq = &net->dev.vqs[VHOST_NET_VQ_TX];
 133         unsigned out, in, s;
 134         int head;
 135         struct msghdr msg = {
 136                 .msg_name = NULL,
 137                 .msg_namelen = 0,
 138                 .msg_control = NULL,
 139                 .msg_controllen = 0,
 140                 .msg_iov = vq->iov,
 141                 .msg_flags = MSG_DONTWAIT,
 142         };
 143         size_t len, total_len = 0;
 144         int err, wmem;
 145         size_t hdr_size;
 146         struct socket *sock;
 147         struct vhost_ubuf_ref *uninitialized_var(ubufs);
 148         bool zcopy;
 149
 150         /* TODO: check that we are running from vhost_worker? */
 151         sock = rcu_dereference_check(vq->private_data, 1);
 152         if (!sock)
 153                 return;
 154
 155         wmem = atomic_read(&sock->sk->sk_wmem_alloc);
 156         if (wmem >= sock->sk->sk_sndbuf) {
 157                 mutex_lock(&vq->mutex);
 158                 tx_poll_start(net, sock);
 159                 mutex_unlock(&vq->mutex);
 160                 return;
 161         }
 162
 163         mutex_lock(&vq->mutex);
 164         vhost_disable_notify(&net->dev, vq);
 165
 166         if (wmem < sock->sk->sk_sndbuf / 2)
 167                 tx_poll_stop(net);
 168         hdr_size = vq->vhost_hlen;
 169         zcopy = vhost_sock_zcopy(sock);
 170
 171         for (;;) {
 172                 /* Release DMAs done buffers first */
 173                 if (zcopy)
 174                         vhost_zerocopy_signal_used(vq);
 175
 176                 head = vhost_get_vq_desc(&net->dev, vq, vq->iov,
 177                                          ARRAY_SIZE(vq->iov),
 178                                          &out, &in,
 179                                          NULL, NULL);
 180                 /* On error, stop handling until the next kick. */
 181                 if (unlikely(head < 0))
 182                         break;
 183                 /* Nothing new?  Wait for eventfd to tell us they refilled. */
 184                 if (head == vq->num) {
 185                         int num_pends;
 186
 187                         wmem = atomic_read(&sock->sk->sk_wmem_alloc);
 188                         if (wmem >= sock->sk->sk_sndbuf * 3 / 4) {
 189                                 tx_poll_start(net, sock);
 190                                 set_bit(SOCK_ASYNC_NOSPACE, &sock->flags);
 191                                 break;
 192                         }
 193                         /* If more outstanding DMAs, queue the work.
 194                          * Handle upend_idx wrap around
 195                          */
 196                         num_pends = likely(vq->upend_idx >= vq->done_idx) ?
 197                                     (vq->upend_idx - vq->done_idx) :
 198                                     (vq->upend_idx + UIO_MAXIOV - vq->done_idx);
 199                         if (unlikely(num_pends > VHOST_MAX_PEND)) {
 200                                 tx_poll_start(net, sock);
 201                                 set_bit(SOCK_ASYNC_NOSPACE, &sock->flags);
 202                                 break;
 203                         }
 204                         if (unlikely(vhost_enable_notify(&net->dev, vq))) {
 205                                 vhost_disable_notify(&net->dev, vq);
 206                                 continue;
 207                         }
 208                         break;
 209                 }
 210                 if (in) {
 211                         vq_err(vq, "Unexpected descriptor format for TX: "
 212                                "out %d, int %d\n", out, in);
 213                         break;
 214                 }
 215                 /* Skip header. TODO: support TSO. */
 216                 s = move_iovec_hdr(vq->iov, vq->hdr, hdr_size, out);
 217                 msg.msg_iovlen = out;
 218                 len = iov_length(vq->iov, out);
 219                 /* Sanity check */
 220                 if (!len) {
 221                         vq_err(vq, "Unexpected header len for TX: "
 222                                "%zd expected %zd\n",
 223                                iov_length(vq->hdr, s), hdr_size);
 224                         break;
 225                 }
 226                 /* use msg_control to pass vhost zerocopy ubuf info to skb */
 227                 if (zcopy) {
 228                         vq->heads[vq->upend_idx].id = head;
 229                         if (len < VHOST_GOODCOPY_LEN) {
 230                                 /* copy don't need to wait for DMA done */
 231                                 vq->heads[vq->upend_idx].len =
 232                                                         VHOST_DMA_DONE_LEN;
 233                                 msg.msg_control = NULL;
 234                                 msg.msg_controllen = 0;
 235                                 ubufs = NULL;
 236                         } else {
 237                                 struct ubuf_info *ubuf = &vq->ubuf_info[head];
 238
 239                                 vq->heads[vq->upend_idx].len = len;
 240                                 ubuf->callback = vhost_zerocopy_callback;
 241                                 ubuf->arg = vq->ubufs;
 242                                 ubuf->desc = vq->upend_idx;
 243                                 msg.msg_control = ubuf;
 244                                 msg.msg_controllen = sizeof(ubuf);
 245                                 ubufs = vq->ubufs;
 246                                 kref_get(&ubufs->kref);
 247                         }
 248                         vq->upend_idx = (vq->upend_idx + 1) % UIO_MAXIOV;
 249                 }
 250                 /* TODO: Check specific error and bomb out unless ENOBUFS? */
 251                 err = sock->ops->sendmsg(NULL, sock, &msg, len);
 252                 if (unlikely(err < 0)) {
 253                         if (zcopy) {
 254                                 if (ubufs)
 255                                         vhost_ubuf_put(ubufs);
 256                                 vq->upend_idx = ((unsigned)vq->upend_idx - 1) %
 257                                         UIO_MAXIOV;
 258                         }
 259                         vhost_discard_vq_desc(vq, 1);
 260                         tx_poll_start(net, sock);
 261                         break;
 262                 }
 263                 if (err != len)
 264                         pr_debug("Truncated TX packet: "
 265                                  " len %d != %zd\n", err, len);
 266                 if (!zcopy)
 267                         vhost_add_used_and_signal(&net->dev, vq, head, 0);
 268                 total_len += len;
 269                 if (unlikely(total_len >= VHOST_NET_WEIGHT)) {
 270                         vhost_poll_queue(&vq->poll);
 271                         break;
 272                 }
 273         }
 274
 275         mutex_unlock(&vq->mutex);
 276 }
 277
 278 static int peek_head_len(struct sock *sk)
 279 {
 280         struct sk_buff *head;
 281         int len = 0;
 282         unsigned long flags;
 283
 284         spin_lock_irqsave(&sk->sk_receive_queue.lock, flags);
 285         head = skb_peek(&sk->sk_receive_queue);
 286         if (likely(head))
 287                 len = head->len;
 288         spin_unlock_irqrestore(&sk->sk_receive_queue.lock, flags);
 289         return len;
 290 }
 291
 292 /* This is a multi-buffer version of vhost_get_desc, that works if
 293  *      vq has read descriptors only.
 294  * @vq          - the relevant virtqueue
 295  * @datalen     - data length we'll be reading
 296  * @iovcount    - returned count of io vectors we fill
 297  * @log         - vhost log
 298  * @log_num     - log offset
 299  * @quota       - headcount quota, 1 for big buffer
 300  *      returns number of buffer heads allocated, negative on error
 301  */
 302 static int get_rx_bufs(struct vhost_virtqueue *vq,
 303                        struct vring_used_elem *heads,
 304                        int datalen,
 305                        unsigned *iovcount,
 306                        struct vhost_log *log,
 307                        unsigned *log_num,
 308                        unsigned int quota)
 309 {
 310         unsigned int out, in;
 311         int seg = 0;
 312         int headcount = 0;
 313         unsigned d;
 314         int r, nlogs = 0;
 315
 316         while (datalen > 0 && headcount < quota) {
 317                 if (unlikely(seg >= UIO_MAXIOV)) {
 318                         r = -ENOBUFS;
 319                         goto err;
 320                 }
 321                 d = vhost_get_vq_desc(vq->dev, vq, vq->iov + seg,
 322                                       ARRAY_SIZE(vq->iov) - seg, &out,
 323                                       &in, log, log_num);
 324                 if (d == vq->num) {
 325                         r = 0;
 326                         goto err;
 327                 }
 328                 if (unlikely(out || in <= 0)) {
 329                         vq_err(vq, "unexpected descriptor format for RX: "
 330                                 "out %d, in %d\n", out, in);
 331                         r = -EINVAL;
 332                         goto err;
 333                 }
 334                 if (unlikely(log)) {
 335                         nlogs += *log_num;
 336                         log += *log_num;
 337                 }
 338                 heads[headcount].id = d;
 339                 heads[headcount].len = iov_length(vq->iov + seg, in);
 340                 datalen -= heads[headcount].len;
 341                 ++headcount;
 342                 seg += in;
 343         }
 344         heads[headcount - 1].len += datalen;
 345         *iovcount = seg;
 346         if (unlikely(log))
 347                 *log_num = nlogs;
 348         return headcount;
 349 err:
 350         vhost_discard_vq_desc(vq, headcount);
 351         return r;
 352 }
 353
 354 /* Expects to be always run from workqueue - which acts as
 355  * read-size critical section for our kind of RCU. */
 356 static void handle_rx(struct vhost_net *net)
 357 {
 358         struct vhost_virtqueue *vq = &net->dev.vqs[VHOST_NET_VQ_RX];
 359         unsigned uninitialized_var(in), log;
 360         struct vhost_log *vq_log;
 361         struct msghdr msg = {
 362                 .msg_name = NULL,
 363                 .msg_namelen = 0,
 364                 .msg_control = NULL, /* FIXME: get and handle RX aux data. */
 365                 .msg_controllen = 0,
 366                 .msg_iov = vq->iov,
 367                 .msg_flags = MSG_DONTWAIT,
 368         };
 369         struct virtio_net_hdr_mrg_rxbuf hdr = {
 370                 .hdr.flags = 0,
 371                 .hdr.gso_type = VIRTIO_NET_HDR_GSO_NONE
 372         };
 373         size_t total_len = 0;
 374         int err, headcount, mergeable;
 375         size_t vhost_hlen, sock_hlen;
 376         size_t vhost_len, sock_len;
 377         /* TODO: check that we are running from vhost_worker? */
 378         struct socket *sock = rcu_dereference_check(vq->private_data, 1);
 379
 380         if (!sock)
 381                 return;
 382
 383         mutex_lock(&vq->mutex);
 384         vhost_disable_notify(&net->dev, vq);
 385         vhost_hlen = vq->vhost_hlen;
 386         sock_hlen = vq->sock_hlen;
 387
 388         vq_log = unlikely(vhost_has_feature(&net->dev, VHOST_F_LOG_ALL)) ?
 389                 vq->log : NULL;
 390         mergeable = vhost_has_feature(&net->dev, VIRTIO_NET_F_MRG_RXBUF);
 391
 392         while ((sock_len = peek_head_len(sock->sk))) {
 393                 sock_len += sock_hlen;
 394                 vhost_len = sock_len + vhost_hlen;
 395                 headcount = get_rx_bufs(vq, vq->heads, vhost_len,
 396                                         &in, vq_log, &log,
 397                                         likely(mergeable) ? UIO_MAXIOV : 1);
 398                 /* On error, stop handling until the next kick. */
 399                 if (unlikely(headcount < 0))
 400                         break;
 401                 /* OK, now we need to know about added descriptors. */
 402                 if (!headcount) {
 403                         if (unlikely(vhost_enable_notify(&net->dev, vq))) {
 404                                 /* They have slipped one in as we were
 405                                  * doing that: check again. */
 406                                 vhost_disable_notify(&net->dev, vq);
 407                                 continue;
 408                         }
 409                         /* Nothing new?  Wait for eventfd to tell us
 410                          * they refilled. */
 411                         break;
 412                 }
 413                 /* We don't need to be notified again. */
 414                 if (unlikely((vhost_hlen)))
 415                         /* Skip header. TODO: support TSO. */
 416                         move_iovec_hdr(vq->iov, vq->hdr, vhost_hlen, in);
 417                 else
 418                         /* Copy the header for use in VIRTIO_NET_F_MRG_RXBUF:
 419                          * needed because recvmsg can modify msg_iov. */
 420                         copy_iovec_hdr(vq->iov, vq->hdr, sock_hlen, in);
 421                 msg.msg_iovlen = in;
 422                 err = sock->ops->recvmsg(NULL, sock, &msg,
 423                                          sock_len, MSG_DONTWAIT | MSG_TRUNC);
 424                 /* Userspace might have consumed the packet meanwhile:
 425                  * it's not supposed to do this usually, but might be hard
 426                  * to prevent. Discard data we got (if any) and keep going. */
 427                 if (unlikely(err != sock_len)) {
 428                         pr_debug("Discarded rx packet: "
 429                                  " len %d, expected %zd\n", err, sock_len);
 430                         vhost_discard_vq_desc(vq, headcount);
 431                         continue;
 432                 }
 433                 if (unlikely(vhost_hlen) &&
 434                     memcpy_toiovecend(vq->hdr, (unsigned char *)&hdr, 0,
 435                                       vhost_hlen)) {
 436                         vq_err(vq, "Unable to write vnet_hdr at addr %p\n",
 437                                vq->iov->iov_base);
 438                         break;
 439                 }
 440                 /* TODO: Should check and handle checksum. */
 441                 if (likely(mergeable) &&
 442                     memcpy_toiovecend(vq->hdr, (unsigned char *)&headcount,
 443                                       offsetof(typeof(hdr), num_buffers),
 444                                       sizeof hdr.num_buffers)) {
 445                         vq_err(vq, "Failed num_buffers write");
 446                         vhost_discard_vq_desc(vq, headcount);
 447                         break;
 448                 }
 449                 vhost_add_used_and_signal_n(&net->dev, vq, vq->heads,
 450                                             headcount);
 451                 if (unlikely(vq_log))
 452                         vhost_log_write(vq, vq_log, log, vhost_len);
 453                 total_len += vhost_len;
 454                 if (unlikely(total_len >= VHOST_NET_WEIGHT)) {
 455                         vhost_poll_queue(&vq->poll);
 456                         break;
 457                 }
 458         }
 459
 460         mutex_unlock(&vq->mutex);
 461 }
 462
 463 static void handle_tx_kick(struct vhost_work *work)
 464 {
 465         struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
 466                                                   poll.work);
 467         struct vhost_net *net = container_of(vq->dev, struct vhost_net, dev);
 468
 469         handle_tx(net);
 470 }
 471
 472 static void handle_rx_kick(struct vhost_work *work)
 473 {
 474         struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
 475                                                   poll.work);
 476         struct vhost_net *net = container_of(vq->dev, struct vhost_net, dev);
 477
 478         handle_rx(net);
 479 }
 480
 481 static void handle_tx_net(struct vhost_work *work)
 482 {
 483         struct vhost_net *net = container_of(work, struct vhost_net,
 484                                              poll[VHOST_NET_VQ_TX].work);
 485         handle_tx(net);
 486 }
 487
 488 static void handle_rx_net(struct vhost_work *work)
 489 {
 490         struct vhost_net *net = container_of(work, struct vhost_net,
 491                                              poll[VHOST_NET_VQ_RX].work);
 492         handle_rx(net);
 493 }
 494
 495 static int vhost_net_open(struct inode *inode, struct file *f)
 496 {
 497         struct vhost_net *n = kmalloc(sizeof *n, GFP_KERNEL);
 498         struct vhost_dev *dev;
 499         int r;
 500
 501         if (!n)
 502                 return -ENOMEM;
 503
 504         dev = &n->dev;
 505         n->vqs[VHOST_NET_VQ_TX].handle_kick = handle_tx_kick;
 506         n->vqs[VHOST_NET_VQ_RX].handle_kick = handle_rx_kick;
 507         r = vhost_dev_init(dev, n->vqs, VHOST_NET_VQ_MAX);
 508         if (r < 0) {
 509                 kfree(n);
 510                 return r;
 511         }
 512
 513         vhost_poll_init(n->poll + VHOST_NET_VQ_TX, handle_tx_net, POLLOUT, dev);
 514         vhost_poll_init(n->poll + VHOST_NET_VQ_RX, handle_rx_net, POLLIN, dev);
 515         n->tx_poll_state = VHOST_NET_POLL_DISABLED;
 516
 517         f->private_data = n;
 518
 519         return 0;
 520 }
 521
 522 static void vhost_net_disable_vq(struct vhost_net *n,
 523                                  struct vhost_virtqueue *vq)
 524 {
 525         if (!vq->private_data)
 526                 return;
 527         if (vq == n->vqs + VHOST_NET_VQ_TX) {
 528                 tx_poll_stop(n);
 529                 n->tx_poll_state = VHOST_NET_POLL_DISABLED;
 530         } else
 531                 vhost_poll_stop(n->poll + VHOST_NET_VQ_RX);
 532 }
 533
 534 static void vhost_net_enable_vq(struct vhost_net *n,
 535                                 struct vhost_virtqueue *vq)
 536 {
 537         struct socket *sock;
 538
 539         sock = rcu_dereference_protected(vq->private_data,
 540                                          lockdep_is_held(&vq->mutex));
 541         if (!sock)
 542                 return;
 543         if (vq == n->vqs + VHOST_NET_VQ_TX) {
 544                 n->tx_poll_state = VHOST_NET_POLL_STOPPED;
 545                 tx_poll_start(n, sock);
 546         } else
 547                 vhost_poll_start(n->poll + VHOST_NET_VQ_RX, sock->file);
 548 }
 549
 550 static struct socket *vhost_net_stop_vq(struct vhost_net *n,
 551                                         struct vhost_virtqueue *vq)
 552 {
 553         struct socket *sock;
 554
 555         mutex_lock(&vq->mutex);
 556         sock = rcu_dereference_protected(vq->private_data,
 557                                          lockdep_is_held(&vq->mutex));
 558         vhost_net_disable_vq(n, vq);
 559         rcu_assign_pointer(vq->private_data, NULL);
 560         mutex_unlock(&vq->mutex);
 561         return sock;
 562 }
 563
 564 static void vhost_net_stop(struct vhost_net *n, struct socket **tx_sock,
 565                            struct socket **rx_sock)
 566 {
 567         *tx_sock = vhost_net_stop_vq(n, n->vqs + VHOST_NET_VQ_TX);
 568         *rx_sock = vhost_net_stop_vq(n, n->vqs + VHOST_NET_VQ_RX);
 569 }
 570
 571 static void vhost_net_flush_vq(struct vhost_net *n, int index)
 572 {
 573         vhost_poll_flush(n->poll + index);
 574         vhost_poll_flush(&n->dev.vqs[index].poll);
 575 }
 576
 577 static void vhost_net_flush(struct vhost_net *n)
 578 {
 579         vhost_net_flush_vq(n, VHOST_NET_VQ_TX);
 580         vhost_net_flush_vq(n, VHOST_NET_VQ_RX);
 581 }
 582
 583 static int vhost_net_release(struct inode *inode, struct file *f)
 584 {
 585         struct vhost_net *n = f->private_data;
 586         struct socket *tx_sock;
 587         struct socket *rx_sock;
 588
 589         vhost_net_stop(n, &tx_sock, &rx_sock);
 590         vhost_net_flush(n);
 591         vhost_dev_cleanup(&n->dev);
 592         if (tx_sock)
 593                 fput(tx_sock->file);
 594         if (rx_sock)
 595                 fput(rx_sock->file);
 596         /* We do an extra flush before freeing memory,
 597          * since jobs can re-queue themselves. */
 598         vhost_net_flush(n);
 599         kfree(n);
 600         return 0;
 601 }
 602
 603 static struct socket *get_raw_socket(int fd)
 604 {
 605         struct {
 606                 struct sockaddr_ll sa;
 607                 char  buf[MAX_ADDR_LEN];
 608         } uaddr;
 609         int uaddr_len = sizeof uaddr, r;
 610         struct socket *sock = sockfd_lookup(fd, &r);
 611
 612         if (!sock)
 613                 return ERR_PTR(-ENOTSOCK);
 614
 615         /* Parameter checking */
 616         if (sock->sk->sk_type != SOCK_RAW) {
 617                 r = -ESOCKTNOSUPPORT;
 618                 goto err;
 619         }
 620
 621         r = sock->ops->getname(sock, (struct sockaddr *)&uaddr.sa,
 622                                &uaddr_len, 0);
 623         if (r)
 624                 goto err;
 625
 626         if (uaddr.sa.sll_family != AF_PACKET) {
 627                 r = -EPFNOSUPPORT;
 628                 goto err;
 629         }
 630         return sock;
 631 err:
 632         fput(sock->file);
 633         return ERR_PTR(r);
 634 }
 635
 636 static struct socket *get_tap_socket(int fd)
 637 {
 638         struct file *file = fget(fd);
 639         struct socket *sock;
 640
 641         if (!file)
 642                 return ERR_PTR(-EBADF);
 643         sock = tun_get_socket(file);
 644         if (!IS_ERR(sock))
 645                 return sock;
 646         sock = macvtap_get_socket(file);
 647         if (IS_ERR(sock))
 648                 fput(file);
 649         return sock;
 650 }
 651
 652 static struct socket *get_socket(int fd)
 653 {
 654         struct socket *sock;
 655
 656         /* special case to disable backend */
 657         if (fd == -1)
 658                 return NULL;
 659         sock = get_raw_socket(fd);
 660         if (!IS_ERR(sock))
 661                 return sock;
 662         sock = get_tap_socket(fd);
 663         if (!IS_ERR(sock))
 664                 return sock;
 665         return ERR_PTR(-ENOTSOCK);
 666 }
 667
 668 static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd)
 669 {
 670         struct socket *sock, *oldsock;
 671         struct vhost_virtqueue *vq;
 672         struct vhost_ubuf_ref *ubufs, *oldubufs = NULL;
 673         int r;
 674
 675         mutex_lock(&n->dev.mutex);
 676         r = vhost_dev_check_owner(&n->dev);
 677         if (r)
 678                 goto err;
 679
 680         if (index >= VHOST_NET_VQ_MAX) {
 681                 r = -ENOBUFS;
 682                 goto err;
 683         }
 684         vq = n->vqs + index;
 685         mutex_lock(&vq->mutex);
 686
 687         /* Verify that ring has been setup correctly. */
 688         if (!vhost_vq_access_ok(vq)) {
 689                 r = -EFAULT;
 690                 goto err_vq;
 691         }
 692         sock = get_socket(fd);
 693         if (IS_ERR(sock)) {
 694                 r = PTR_ERR(sock);
 695                 goto err_vq;
 696         }
 697
 698         /* start polling new socket */
 699         oldsock = rcu_dereference_protected(vq->private_data,
 700                                             lockdep_is_held(&vq->mutex));
 701         if (sock != oldsock) {
 702                 ubufs = vhost_ubuf_alloc(vq, sock && vhost_sock_zcopy(sock));
 703                 if (IS_ERR(ubufs)) {
 704                         r = PTR_ERR(ubufs);
 705                         goto err_ubufs;
 706                 }
 707                 oldubufs = vq->ubufs;
 708                 vq->ubufs = ubufs;
 709                 vhost_net_disable_vq(n, vq);
 710                 rcu_assign_pointer(vq->private_data, sock);
 711                 vhost_net_enable_vq(n, vq);
 712
 713                 r = vhost_init_used(vq);
 714                 if (r)
 715                         goto err_vq;
 716         }
 717
 718         mutex_unlock(&vq->mutex);
 719
 720         if (oldubufs) {
 721                 vhost_ubuf_put_and_wait(oldubufs);
 722                 mutex_lock(&vq->mutex);
 723                 vhost_zerocopy_signal_used(vq);
 724                 mutex_unlock(&vq->mutex);
 725         }
 726
 727         if (oldsock) {
 728                 vhost_net_flush_vq(n, index);
 729                 fput(oldsock->file);
 730         }
 731
 732         mutex_unlock(&n->dev.mutex);
 733         return 0;
 734
 735 err_ubufs:
 736         fput(sock->file);
 737 err_vq:
 738         mutex_unlock(&vq->mutex);
 739 err:
 740         mutex_unlock(&n->dev.mutex);
 741         return r;
 742 }
 743
 744 static long vhost_net_reset_owner(struct vhost_net *n)
 745 {
 746         struct socket *tx_sock = NULL;
 747         struct socket *rx_sock = NULL;
 748         long err;
 749
 750         mutex_lock(&n->dev.mutex);
 751         err = vhost_dev_check_owner(&n->dev);
 752         if (err)
 753                 goto done;
 754         vhost_net_stop(n, &tx_sock, &rx_sock);
 755         vhost_net_flush(n);
 756         err = vhost_dev_reset_owner(&n->dev);
 757 done:
 758         mutex_unlock(&n->dev.mutex);
 759         if (tx_sock)
 760                 fput(tx_sock->file);
 761         if (rx_sock)
 762                 fput(rx_sock->file);
 763         return err;
 764 }
 765
 766 static int vhost_net_set_features(struct vhost_net *n, u64 features)
 767 {
 768         size_t vhost_hlen, sock_hlen, hdr_len;
 769         int i;
 770
 771         hdr_len = (features & (1 << VIRTIO_NET_F_MRG_RXBUF)) ?
 772                         sizeof(struct virtio_net_hdr_mrg_rxbuf) :
 773                         sizeof(struct virtio_net_hdr);
 774         if (features & (1 << VHOST_NET_F_VIRTIO_NET_HDR)) {
 775                 /* vhost provides vnet_hdr */
 776                 vhost_hlen = hdr_len;
 777                 sock_hlen = 0;
 778         } else {
 779                 /* socket provides vnet_hdr */
 780                 vhost_hlen = 0;
 781                 sock_hlen = hdr_len;
 782         }
 783         mutex_lock(&n->dev.mutex);
 784         if ((features & (1 << VHOST_F_LOG_ALL)) &&
 785             !vhost_log_access_ok(&n->dev)) {
 786                 mutex_unlock(&n->dev.mutex);
 787                 return -EFAULT;
 788         }
 789         n->dev.acked_features = features;
 790         smp_wmb();
 791         for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
 792                 mutex_lock(&n->vqs[i].mutex);
 793                 n->vqs[i].vhost_hlen = vhost_hlen;
 794                 n->vqs[i].sock_hlen = sock_hlen;
 795                 mutex_unlock(&n->vqs[i].mutex);
 796         }
 797         vhost_net_flush(n);
 798         mutex_unlock(&n->dev.mutex);
 799         return 0;
 800 }
 801
 802 static long vhost_net_ioctl(struct file *f, unsigned int ioctl,
 803                             unsigned long arg)
 804 {
 805         struct vhost_net *n = f->private_data;
 806         void __user *argp = (void __user *)arg;
 807         u64 __user *featurep = argp;
 808         struct vhost_vring_file backend;
 809         u64 features;
 810         int r;
 811
 812         switch (ioctl) {
 813         case VHOST_NET_SET_BACKEND:
 814                 if (copy_from_user(&backend, argp, sizeof backend))
 815                         return -EFAULT;
 816                 return vhost_net_set_backend(n, backend.index, backend.fd);
 817         case VHOST_GET_FEATURES:
 818                 features = VHOST_FEATURES;
 819                 if (copy_to_user(featurep, &features, sizeof features))
 820                         return -EFAULT;
 821                 return 0;
 822         case VHOST_SET_FEATURES:
 823                 if (copy_from_user(&features, featurep, sizeof features))
 824                         return -EFAULT;
 825                 if (features & ~VHOST_FEATURES)
 826                         return -EOPNOTSUPP;
 827                 return vhost_net_set_features(n, features);
 828         case VHOST_RESET_OWNER:
 829                 return vhost_net_reset_owner(n);
 830         default:
 831                 mutex_lock(&n->dev.mutex);
 832                 r = vhost_dev_ioctl(&n->dev, ioctl, arg);
 833                 vhost_net_flush(n);
 834                 mutex_unlock(&n->dev.mutex);
 835                 return r;
 836         }
 837 }
 838
 839 #ifdef CONFIG_COMPAT
 840 static long vhost_net_compat_ioctl(struct file *f, unsigned int ioctl,
 841                                    unsigned long arg)
 842 {
 843         return vhost_net_ioctl(f, ioctl, (unsigned long)compat_ptr(arg));
 844 }
 845 #endif
 846
 847 static const struct file_operations vhost_net_fops = {
 848         .owner          = THIS_MODULE,
 849         .release        = vhost_net_release,
 850         .unlocked_ioctl = vhost_net_ioctl,
 851 #ifdef CONFIG_COMPAT
 852         .compat_ioctl   = vhost_net_compat_ioctl,
 853 #endif
 854         .open           = vhost_net_open,
 855         .llseek         = noop_llseek,
 856 };
 857
 858 static struct miscdevice vhost_net_misc = {
 859         .minor = VHOST_NET_MINOR,
 860         .name = "vhost-net",
 861         .fops = &vhost_net_fops,
 862 };
 863
 864 static int vhost_net_init(void)
 865 {
 866         if (experimental_zcopytx)
 867                 vhost_enable_zcopy(VHOST_NET_VQ_TX);
 868         return misc_register(&vhost_net_misc);
 869 }
 870 module_init(vhost_net_init);
 871
 872 static void vhost_net_exit(void)
 873 {
 874         misc_deregister(&vhost_net_misc);
 875 }
 876 module_exit(vhost_net_exit);
 877
 878 MODULE_VERSION("0.0.1");
 879 MODULE_LICENSE("GPL v2");
 880 MODULE_AUTHOR("Michael S. Tsirkin");
 881 MODULE_DESCRIPTION("Host kernel accelerator for virtio net");
 882 MODULE_ALIAS_MISCDEV(VHOST_NET_MINOR);
 883 MODULE_ALIAS("devname:vhost-net");