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/mmu_context.h>
  14 #include <linux/miscdevice.h>
  15 #include <linux/module.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 /* Max number of bytes transferred before requeueing the job.
  33  * Using this limit prevents one virtqueue from starving others. */
  34 #define VHOST_NET_WEIGHT 0x80000
  35
  36 enum {
  37         VHOST_NET_VQ_RX = 0,
  38         VHOST_NET_VQ_TX = 1,
  39         VHOST_NET_VQ_MAX = 2,
  40 };
  41
  42 enum vhost_net_poll_state {
  43         VHOST_NET_POLL_DISABLED = 0,
  44         VHOST_NET_POLL_STARTED = 1,
  45         VHOST_NET_POLL_STOPPED = 2,
  46 };
  47
  48 struct vhost_net {
  49         struct vhost_dev dev;
  50         struct vhost_virtqueue vqs[VHOST_NET_VQ_MAX];
  51         struct vhost_poll poll[VHOST_NET_VQ_MAX];
  52         /* Tells us whether we are polling a socket for TX.
  53          * We only do this when socket buffer fills up.
  54          * Protected by tx vq lock. */
  55         enum vhost_net_poll_state tx_poll_state;
  56 };
  57
  58 /* Pop first len bytes from iovec. Return number of segments used. */
  59 static int move_iovec_hdr(struct iovec *from, struct iovec *to,
  60                           size_t len, int iov_count)
  61 {
  62         int seg = 0;
  63         size_t size;
  64         while (len && seg < iov_count) {
  65                 size = min(from->iov_len, len);
  66                 to->iov_base = from->iov_base;
  67                 to->iov_len = size;
  68                 from->iov_len -= size;
  69                 from->iov_base += size;
  70                 len -= size;
  71                 ++from;
  72                 ++to;
  73                 ++seg;
  74         }
  75         return seg;
  76 }
  77 /* Copy iovec entries for len bytes from iovec. */
  78 static void copy_iovec_hdr(const struct iovec *from, struct iovec *to,
  79                            size_t len, int iovcount)
  80 {
  81         int seg = 0;
  82         size_t size;
  83         while (len && seg < iovcount) {
  84                 size = min(from->iov_len, len);
  85                 to->iov_base = from->iov_base;
  86                 to->iov_len = size;
  87                 len -= size;
  88                 ++from;
  89                 ++to;
  90                 ++seg;
  91         }
  92 }
  93
  94 /* Caller must have TX VQ lock */
  95 static void tx_poll_stop(struct vhost_net *net)
  96 {
  97         if (likely(net->tx_poll_state != VHOST_NET_POLL_STARTED))
  98                 return;
  99         vhost_poll_stop(net->poll + VHOST_NET_VQ_TX);
 100         net->tx_poll_state = VHOST_NET_POLL_STOPPED;
 101 }
 102
 103 /* Caller must have TX VQ lock */
 104 static void tx_poll_start(struct vhost_net *net, struct socket *sock)
 105 {
 106         if (unlikely(net->tx_poll_state != VHOST_NET_POLL_STOPPED))
 107                 return;
 108         vhost_poll_start(net->poll + VHOST_NET_VQ_TX, sock->file);
 109         net->tx_poll_state = VHOST_NET_POLL_STARTED;
 110 }
 111
 112 /* Expects to be always run from workqueue - which acts as
 113  * read-size critical section for our kind of RCU. */
 114 static void handle_tx(struct vhost_net *net)
 115 {
 116         struct vhost_virtqueue *vq = &net->dev.vqs[VHOST_NET_VQ_TX];
 117         unsigned out, in, s;
 118         int head;
 119         struct msghdr msg = {
 120                 .msg_name = NULL,
 121                 .msg_namelen = 0,
 122                 .msg_control = NULL,
 123                 .msg_controllen = 0,
 124                 .msg_iov = vq->iov,
 125                 .msg_flags = MSG_DONTWAIT,
 126         };
 127         size_t len, total_len = 0;
 128         int err, wmem;
 129         size_t hdr_size;
 130         struct socket *sock;
 131
 132         sock = rcu_dereference_check(vq->private_data,
 133                                      lockdep_is_held(&vq->mutex));
 134         if (!sock)
 135                 return;
 136
 137         wmem = atomic_read(&sock->sk->sk_wmem_alloc);
 138         if (wmem >= sock->sk->sk_sndbuf) {
 139                 mutex_lock(&vq->mutex);
 140                 tx_poll_start(net, sock);
 141                 mutex_unlock(&vq->mutex);
 142                 return;
 143         }
 144
 145         use_mm(net->dev.mm);
 146         mutex_lock(&vq->mutex);
 147         vhost_disable_notify(vq);
 148
 149         if (wmem < sock->sk->sk_sndbuf / 2)
 150                 tx_poll_stop(net);
 151         hdr_size = vq->vhost_hlen;
 152
 153         for (;;) {
 154                 head = vhost_get_vq_desc(&net->dev, vq, vq->iov,
 155                                          ARRAY_SIZE(vq->iov),
 156                                          &out, &in,
 157                                          NULL, NULL);
 158                 /* On error, stop handling until the next kick. */
 159                 if (unlikely(head < 0))
 160                         break;
 161                 /* Nothing new?  Wait for eventfd to tell us they refilled. */
 162                 if (head == vq->num) {
 163                         wmem = atomic_read(&sock->sk->sk_wmem_alloc);
 164                         if (wmem >= sock->sk->sk_sndbuf * 3 / 4) {
 165                                 tx_poll_start(net, sock);
 166                                 set_bit(SOCK_ASYNC_NOSPACE, &sock->flags);
 167                                 break;
 168                         }
 169                         if (unlikely(vhost_enable_notify(vq))) {
 170                                 vhost_disable_notify(vq);
 171                                 continue;
 172                         }
 173                         break;
 174                 }
 175                 if (in) {
 176                         vq_err(vq, "Unexpected descriptor format for TX: "
 177                                "out %d, int %d\n", out, in);
 178                         break;
 179                 }
 180                 /* Skip header. TODO: support TSO. */
 181                 s = move_iovec_hdr(vq->iov, vq->hdr, hdr_size, out);
 182                 msg.msg_iovlen = out;
 183                 len = iov_length(vq->iov, out);
 184                 /* Sanity check */
 185                 if (!len) {
 186                         vq_err(vq, "Unexpected header len for TX: "
 187                                "%zd expected %zd\n",
 188                                iov_length(vq->hdr, s), hdr_size);
 189                         break;
 190                 }
 191                 /* TODO: Check specific error and bomb out unless ENOBUFS? */
 192                 err = sock->ops->sendmsg(NULL, sock, &msg, len);
 193                 if (unlikely(err < 0)) {
 194                         vhost_discard_vq_desc(vq, 1);
 195                         tx_poll_start(net, sock);
 196                         break;
 197                 }
 198                 if (err != len)
 199                         pr_debug("Truncated TX packet: "
 200                                  " len %d != %zd\n", err, len);
 201                 vhost_add_used_and_signal(&net->dev, vq, head, 0);
 202                 total_len += len;
 203                 if (unlikely(total_len >= VHOST_NET_WEIGHT)) {
 204                         vhost_poll_queue(&vq->poll);
 205                         break;
 206                 }
 207         }
 208
 209         mutex_unlock(&vq->mutex);
 210         unuse_mm(net->dev.mm);
 211 }
 212
 213 static int peek_head_len(struct sock *sk)
 214 {
 215         struct sk_buff *head;
 216         int len = 0;
 217
 218         lock_sock(sk);
 219         head = skb_peek(&sk->sk_receive_queue);
 220         if (head)
 221                 len = head->len;
 222         release_sock(sk);
 223         return len;
 224 }
 225
 226 /* This is a multi-buffer version of vhost_get_desc, that works if
 227  *      vq has read descriptors only.
 228  * @vq          - the relevant virtqueue
 229  * @datalen     - data length we'll be reading
 230  * @iovcount    - returned count of io vectors we fill
 231  * @log         - vhost log
 232  * @log_num     - log offset
 233  *      returns number of buffer heads allocated, negative on error
 234  */
 235 static int get_rx_bufs(struct vhost_virtqueue *vq,
 236                        struct vring_used_elem *heads,
 237                        int datalen,
 238                        unsigned *iovcount,
 239                        struct vhost_log *log,
 240                        unsigned *log_num)
 241 {
 242         unsigned int out, in;
 243         int seg = 0;
 244         int headcount = 0;
 245         unsigned d;
 246         int r, nlogs = 0;
 247
 248         while (datalen > 0) {
 249                 if (unlikely(seg >= VHOST_NET_MAX_SG)) {
 250                         r = -ENOBUFS;
 251                         goto err;
 252                 }
 253                 d = vhost_get_vq_desc(vq->dev, vq, vq->iov + seg,
 254                                       ARRAY_SIZE(vq->iov) - seg, &out,
 255                                       &in, log, log_num);
 256                 if (d == vq->num) {
 257                         r = 0;
 258                         goto err;
 259                 }
 260                 if (unlikely(out || in <= 0)) {
 261                         vq_err(vq, "unexpected descriptor format for RX: "
 262                                 "out %d, in %d\n", out, in);
 263                         r = -EINVAL;
 264                         goto err;
 265                 }
 266                 if (unlikely(log)) {
 267                         nlogs += *log_num;
 268                         log += *log_num;
 269                 }
 270                 heads[headcount].id = d;
 271                 heads[headcount].len = iov_length(vq->iov + seg, in);
 272                 datalen -= heads[headcount].len;
 273                 ++headcount;
 274                 seg += in;
 275         }
 276         heads[headcount - 1].len += datalen;
 277         *iovcount = seg;
 278         if (unlikely(log))
 279                 *log_num = nlogs;
 280         return headcount;
 281 err:
 282         vhost_discard_vq_desc(vq, headcount);
 283         return r;
 284 }
 285
 286 /* Expects to be always run from workqueue - which acts as
 287  * read-size critical section for our kind of RCU. */
 288 static void handle_rx_big(struct vhost_net *net)
 289 {
 290         struct vhost_virtqueue *vq = &net->dev.vqs[VHOST_NET_VQ_RX];
 291         unsigned out, in, log, s;
 292         int head;
 293         struct vhost_log *vq_log;
 294         struct msghdr msg = {
 295                 .msg_name = NULL,
 296                 .msg_namelen = 0,
 297                 .msg_control = NULL, /* FIXME: get and handle RX aux data. */
 298                 .msg_controllen = 0,
 299                 .msg_iov = vq->iov,
 300                 .msg_flags = MSG_DONTWAIT,
 301         };
 302
 303         struct virtio_net_hdr hdr = {
 304                 .flags = 0,
 305                 .gso_type = VIRTIO_NET_HDR_GSO_NONE
 306         };
 307
 308         size_t len, total_len = 0;
 309         int err;
 310         size_t hdr_size;
 311         struct socket *sock = rcu_dereference(vq->private_data);
 312         if (!sock || skb_queue_empty(&sock->sk->sk_receive_queue))
 313                 return;
 314
 315         use_mm(net->dev.mm);
 316         mutex_lock(&vq->mutex);
 317         vhost_disable_notify(vq);
 318         hdr_size = vq->vhost_hlen;
 319
 320         vq_log = unlikely(vhost_has_feature(&net->dev, VHOST_F_LOG_ALL)) ?
 321                 vq->log : NULL;
 322
 323         for (;;) {
 324                 head = vhost_get_vq_desc(&net->dev, vq, vq->iov,
 325                                          ARRAY_SIZE(vq->iov),
 326                                          &out, &in,
 327                                          vq_log, &log);
 328                 /* On error, stop handling until the next kick. */
 329                 if (unlikely(head < 0))
 330                         break;
 331                 /* OK, now we need to know about added descriptors. */
 332                 if (head == vq->num) {
 333                         if (unlikely(vhost_enable_notify(vq))) {
 334                                 /* They have slipped one in as we were
 335                                  * doing that: check again. */
 336                                 vhost_disable_notify(vq);
 337                                 continue;
 338                         }
 339                         /* Nothing new?  Wait for eventfd to tell us
 340                          * they refilled. */
 341                         break;
 342                 }
 343                 /* We don't need to be notified again. */
 344                 if (out) {
 345                         vq_err(vq, "Unexpected descriptor format for RX: "
 346                                "out %d, int %d\n",
 347                                out, in);
 348                         break;
 349                 }
 350                 /* Skip header. TODO: support TSO/mergeable rx buffers. */
 351                 s = move_iovec_hdr(vq->iov, vq->hdr, hdr_size, in);
 352                 msg.msg_iovlen = in;
 353                 len = iov_length(vq->iov, in);
 354                 /* Sanity check */
 355                 if (!len) {
 356                         vq_err(vq, "Unexpected header len for RX: "
 357                                "%zd expected %zd\n",
 358                                iov_length(vq->hdr, s), hdr_size);
 359                         break;
 360                 }
 361                 err = sock->ops->recvmsg(NULL, sock, &msg,
 362                                          len, MSG_DONTWAIT | MSG_TRUNC);
 363                 /* TODO: Check specific error and bomb out unless EAGAIN? */
 364                 if (err < 0) {
 365                         vhost_discard_vq_desc(vq, 1);
 366                         break;
 367                 }
 368                 /* TODO: Should check and handle checksum. */
 369                 if (err > len) {
 370                         pr_debug("Discarded truncated rx packet: "
 371                                  " len %d > %zd\n", err, len);
 372                         vhost_discard_vq_desc(vq, 1);
 373                         continue;
 374                 }
 375                 len = err;
 376                 err = memcpy_toiovec(vq->hdr, (unsigned char *)&hdr, hdr_size);
 377                 if (err) {
 378                         vq_err(vq, "Unable to write vnet_hdr at addr %p: %d\n",
 379                                vq->iov->iov_base, err);
 380                         break;
 381                 }
 382                 len += hdr_size;
 383                 vhost_add_used_and_signal(&net->dev, vq, head, len);
 384                 if (unlikely(vq_log))
 385                         vhost_log_write(vq, vq_log, log, len);
 386                 total_len += len;
 387                 if (unlikely(total_len >= VHOST_NET_WEIGHT)) {
 388                         vhost_poll_queue(&vq->poll);
 389                         break;
 390                 }
 391         }
 392
 393         mutex_unlock(&vq->mutex);
 394         unuse_mm(net->dev.mm);
 395 }
 396
 397 /* Expects to be always run from workqueue - which acts as
 398  * read-size critical section for our kind of RCU. */
 399 static void handle_rx_mergeable(struct vhost_net *net)
 400 {
 401         struct vhost_virtqueue *vq = &net->dev.vqs[VHOST_NET_VQ_RX];
 402         unsigned uninitialized_var(in), log;
 403         struct vhost_log *vq_log;
 404         struct msghdr msg = {
 405                 .msg_name = NULL,
 406                 .msg_namelen = 0,
 407                 .msg_control = NULL, /* FIXME: get and handle RX aux data. */
 408                 .msg_controllen = 0,
 409                 .msg_iov = vq->iov,
 410                 .msg_flags = MSG_DONTWAIT,
 411         };
 412
 413         struct virtio_net_hdr_mrg_rxbuf hdr = {
 414                 .hdr.flags = 0,
 415                 .hdr.gso_type = VIRTIO_NET_HDR_GSO_NONE
 416         };
 417
 418         size_t total_len = 0;
 419         int err, headcount;
 420         size_t vhost_hlen, sock_hlen;
 421         size_t vhost_len, sock_len;
 422         struct socket *sock = rcu_dereference(vq->private_data);
 423         if (!sock || skb_queue_empty(&sock->sk->sk_receive_queue))
 424                 return;
 425
 426         use_mm(net->dev.mm);
 427         mutex_lock(&vq->mutex);
 428         vhost_disable_notify(vq);
 429         vhost_hlen = vq->vhost_hlen;
 430         sock_hlen = vq->sock_hlen;
 431
 432         vq_log = unlikely(vhost_has_feature(&net->dev, VHOST_F_LOG_ALL)) ?
 433                 vq->log : NULL;
 434
 435         while ((sock_len = peek_head_len(sock->sk))) {
 436                 sock_len += sock_hlen;
 437                 vhost_len = sock_len + vhost_hlen;
 438                 headcount = get_rx_bufs(vq, vq->heads, vhost_len,
 439                                         &in, vq_log, &log);
 440                 /* On error, stop handling until the next kick. */
 441                 if (unlikely(headcount < 0))
 442                         break;
 443                 /* OK, now we need to know about added descriptors. */
 444                 if (!headcount) {
 445                         if (unlikely(vhost_enable_notify(vq))) {
 446                                 /* They have slipped one in as we were
 447                                  * doing that: check again. */
 448                                 vhost_disable_notify(vq);
 449                                 continue;
 450                         }
 451                         /* Nothing new?  Wait for eventfd to tell us
 452                          * they refilled. */
 453                         break;
 454                 }
 455                 /* We don't need to be notified again. */
 456                 if (unlikely((vhost_hlen)))
 457                         /* Skip header. TODO: support TSO. */
 458                         move_iovec_hdr(vq->iov, vq->hdr, vhost_hlen, in);
 459                 else
 460                         /* Copy the header for use in VIRTIO_NET_F_MRG_RXBUF:
 461                          * needed because sendmsg can modify msg_iov. */
 462                         copy_iovec_hdr(vq->iov, vq->hdr, sock_hlen, in);
 463                 msg.msg_iovlen = in;
 464                 err = sock->ops->recvmsg(NULL, sock, &msg,
 465                                          sock_len, MSG_DONTWAIT | MSG_TRUNC);
 466                 /* Userspace might have consumed the packet meanwhile:
 467                  * it's not supposed to do this usually, but might be hard
 468                  * to prevent. Discard data we got (if any) and keep going. */
 469                 if (unlikely(err != sock_len)) {
 470                         pr_debug("Discarded rx packet: "
 471                                  " len %d, expected %zd\n", err, sock_len);
 472                         vhost_discard_vq_desc(vq, headcount);
 473                         continue;
 474                 }
 475                 if (unlikely(vhost_hlen) &&
 476                     memcpy_toiovecend(vq->hdr, (unsigned char *)&hdr, 0,
 477                                       vhost_hlen)) {
 478                         vq_err(vq, "Unable to write vnet_hdr at addr %p\n",
 479                                vq->iov->iov_base);
 480                         break;
 481                 }
 482                 /* TODO: Should check and handle checksum. */
 483                 if (vhost_has_feature(&net->dev, VIRTIO_NET_F_MRG_RXBUF) &&
 484                     memcpy_toiovecend(vq->hdr, (unsigned char *)&headcount,
 485                                       offsetof(typeof(hdr), num_buffers),
 486                                       sizeof hdr.num_buffers)) {
 487                         vq_err(vq, "Failed num_buffers write");
 488                         vhost_discard_vq_desc(vq, headcount);
 489                         break;
 490                 }
 491                 vhost_add_used_and_signal_n(&net->dev, vq, vq->heads,
 492                                             headcount);
 493                 if (unlikely(vq_log))
 494                         vhost_log_write(vq, vq_log, log, vhost_len);
 495                 total_len += vhost_len;
 496                 if (unlikely(total_len >= VHOST_NET_WEIGHT)) {
 497                         vhost_poll_queue(&vq->poll);
 498                         break;
 499                 }
 500         }
 501
 502         mutex_unlock(&vq->mutex);
 503         unuse_mm(net->dev.mm);
 504 }
 505
 506 static void handle_rx(struct vhost_net *net)
 507 {
 508         if (vhost_has_feature(&net->dev, VIRTIO_NET_F_MRG_RXBUF))
 509                 handle_rx_mergeable(net);
 510         else
 511                 handle_rx_big(net);
 512 }
 513
 514 static void handle_tx_kick(struct vhost_work *work)
 515 {
 516         struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
 517                                                   poll.work);
 518         struct vhost_net *net = container_of(vq->dev, struct vhost_net, dev);
 519
 520         handle_tx(net);
 521 }
 522
 523 static void handle_rx_kick(struct vhost_work *work)
 524 {
 525         struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
 526                                                   poll.work);
 527         struct vhost_net *net = container_of(vq->dev, struct vhost_net, dev);
 528
 529         handle_rx(net);
 530 }
 531
 532 static void handle_tx_net(struct vhost_work *work)
 533 {
 534         struct vhost_net *net = container_of(work, struct vhost_net,
 535                                              poll[VHOST_NET_VQ_TX].work);
 536         handle_tx(net);
 537 }
 538
 539 static void handle_rx_net(struct vhost_work *work)
 540 {
 541         struct vhost_net *net = container_of(work, struct vhost_net,
 542                                              poll[VHOST_NET_VQ_RX].work);
 543         handle_rx(net);
 544 }
 545
 546 static int vhost_net_open(struct inode *inode, struct file *f)
 547 {
 548         struct vhost_net *n = kmalloc(sizeof *n, GFP_KERNEL);
 549         struct vhost_dev *dev;
 550         int r;
 551
 552         if (!n)
 553                 return -ENOMEM;
 554
 555         dev = &n->dev;
 556         n->vqs[VHOST_NET_VQ_TX].handle_kick = handle_tx_kick;
 557         n->vqs[VHOST_NET_VQ_RX].handle_kick = handle_rx_kick;
 558         r = vhost_dev_init(dev, n->vqs, VHOST_NET_VQ_MAX);
 559         if (r < 0) {
 560                 kfree(n);
 561                 return r;
 562         }
 563
 564         vhost_poll_init(n->poll + VHOST_NET_VQ_TX, handle_tx_net, POLLOUT, dev);
 565         vhost_poll_init(n->poll + VHOST_NET_VQ_RX, handle_rx_net, POLLIN, dev);
 566         n->tx_poll_state = VHOST_NET_POLL_DISABLED;
 567
 568         f->private_data = n;
 569
 570         return 0;
 571 }
 572
 573 static void vhost_net_disable_vq(struct vhost_net *n,
 574                                  struct vhost_virtqueue *vq)
 575 {
 576         if (!vq->private_data)
 577                 return;
 578         if (vq == n->vqs + VHOST_NET_VQ_TX) {
 579                 tx_poll_stop(n);
 580                 n->tx_poll_state = VHOST_NET_POLL_DISABLED;
 581         } else
 582                 vhost_poll_stop(n->poll + VHOST_NET_VQ_RX);
 583 }
 584
 585 static void vhost_net_enable_vq(struct vhost_net *n,
 586                                 struct vhost_virtqueue *vq)
 587 {
 588         struct socket *sock;
 589
 590         sock = rcu_dereference_protected(vq->private_data,
 591                                          lockdep_is_held(&vq->mutex));
 592         if (!sock)
 593                 return;
 594         if (vq == n->vqs + VHOST_NET_VQ_TX) {
 595                 n->tx_poll_state = VHOST_NET_POLL_STOPPED;
 596                 tx_poll_start(n, sock);
 597         } else
 598                 vhost_poll_start(n->poll + VHOST_NET_VQ_RX, sock->file);
 599 }
 600
 601 static struct socket *vhost_net_stop_vq(struct vhost_net *n,
 602                                         struct vhost_virtqueue *vq)
 603 {
 604         struct socket *sock;
 605
 606         mutex_lock(&vq->mutex);
 607         sock = rcu_dereference_protected(vq->private_data,
 608                                          lockdep_is_held(&vq->mutex));
 609         vhost_net_disable_vq(n, vq);
 610         rcu_assign_pointer(vq->private_data, NULL);
 611         mutex_unlock(&vq->mutex);
 612         return sock;
 613 }
 614
 615 static void vhost_net_stop(struct vhost_net *n, struct socket **tx_sock,
 616                            struct socket **rx_sock)
 617 {
 618         *tx_sock = vhost_net_stop_vq(n, n->vqs + VHOST_NET_VQ_TX);
 619         *rx_sock = vhost_net_stop_vq(n, n->vqs + VHOST_NET_VQ_RX);
 620 }
 621
 622 static void vhost_net_flush_vq(struct vhost_net *n, int index)
 623 {
 624         vhost_poll_flush(n->poll + index);
 625         vhost_poll_flush(&n->dev.vqs[index].poll);
 626 }
 627
 628 static void vhost_net_flush(struct vhost_net *n)
 629 {
 630         vhost_net_flush_vq(n, VHOST_NET_VQ_TX);
 631         vhost_net_flush_vq(n, VHOST_NET_VQ_RX);
 632 }
 633
 634 static int vhost_net_release(struct inode *inode, struct file *f)
 635 {
 636         struct vhost_net *n = f->private_data;
 637         struct socket *tx_sock;
 638         struct socket *rx_sock;
 639
 640         vhost_net_stop(n, &tx_sock, &rx_sock);
 641         vhost_net_flush(n);
 642         vhost_dev_cleanup(&n->dev);
 643         if (tx_sock)
 644                 fput(tx_sock->file);
 645         if (rx_sock)
 646                 fput(rx_sock->file);
 647         /* We do an extra flush before freeing memory,
 648          * since jobs can re-queue themselves. */
 649         vhost_net_flush(n);
 650         kfree(n);
 651         return 0;
 652 }
 653
 654 static struct socket *get_raw_socket(int fd)
 655 {
 656         struct {
 657                 struct sockaddr_ll sa;
 658                 char  buf[MAX_ADDR_LEN];
 659         } uaddr;
 660         int uaddr_len = sizeof uaddr, r;
 661         struct socket *sock = sockfd_lookup(fd, &r);
 662         if (!sock)
 663                 return ERR_PTR(-ENOTSOCK);
 664
 665         /* Parameter checking */
 666         if (sock->sk->sk_type != SOCK_RAW) {
 667                 r = -ESOCKTNOSUPPORT;
 668                 goto err;
 669         }
 670
 671         r = sock->ops->getname(sock, (struct sockaddr *)&uaddr.sa,
 672                                &uaddr_len, 0);
 673         if (r)
 674                 goto err;
 675
 676         if (uaddr.sa.sll_family != AF_PACKET) {
 677                 r = -EPFNOSUPPORT;
 678                 goto err;
 679         }
 680         return sock;
 681 err:
 682         fput(sock->file);
 683         return ERR_PTR(r);
 684 }
 685
 686 static struct socket *get_tap_socket(int fd)
 687 {
 688         struct file *file = fget(fd);
 689         struct socket *sock;
 690         if (!file)
 691                 return ERR_PTR(-EBADF);
 692         sock = tun_get_socket(file);
 693         if (!IS_ERR(sock))
 694                 return sock;
 695         sock = macvtap_get_socket(file);
 696         if (IS_ERR(sock))
 697                 fput(file);
 698         return sock;
 699 }
 700
 701 static struct socket *get_socket(int fd)
 702 {
 703         struct socket *sock;
 704         /* special case to disable backend */
 705         if (fd == -1)
 706                 return NULL;
 707         sock = get_raw_socket(fd);
 708         if (!IS_ERR(sock))
 709                 return sock;
 710         sock = get_tap_socket(fd);
 711         if (!IS_ERR(sock))
 712                 return sock;
 713         return ERR_PTR(-ENOTSOCK);
 714 }
 715
 716 static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd)
 717 {
 718         struct socket *sock, *oldsock;
 719         struct vhost_virtqueue *vq;
 720         int r;
 721
 722         mutex_lock(&n->dev.mutex);
 723         r = vhost_dev_check_owner(&n->dev);
 724         if (r)
 725                 goto err;
 726
 727         if (index >= VHOST_NET_VQ_MAX) {
 728                 r = -ENOBUFS;
 729                 goto err;
 730         }
 731         vq = n->vqs + index;
 732         mutex_lock(&vq->mutex);
 733
 734         /* Verify that ring has been setup correctly. */
 735         if (!vhost_vq_access_ok(vq)) {
 736                 r = -EFAULT;
 737                 goto err_vq;
 738         }
 739         sock = get_socket(fd);
 740         if (IS_ERR(sock)) {
 741                 r = PTR_ERR(sock);
 742                 goto err_vq;
 743         }
 744
 745         /* start polling new socket */
 746         oldsock = rcu_dereference_protected(vq->private_data,
 747                                             lockdep_is_held(&vq->mutex));
 748         if (sock != oldsock) {
 749                 vhost_net_disable_vq(n, vq);
 750                 rcu_assign_pointer(vq->private_data, sock);
 751                 vhost_net_enable_vq(n, vq);
 752         }
 753
 754         mutex_unlock(&vq->mutex);
 755
 756         if (oldsock) {
 757                 vhost_net_flush_vq(n, index);
 758                 fput(oldsock->file);
 759         }
 760
 761         mutex_unlock(&n->dev.mutex);
 762         return 0;
 763
 764 err_vq:
 765         mutex_unlock(&vq->mutex);
 766 err:
 767         mutex_unlock(&n->dev.mutex);
 768         return r;
 769 }
 770
 771 static long vhost_net_reset_owner(struct vhost_net *n)
 772 {
 773         struct socket *tx_sock = NULL;
 774         struct socket *rx_sock = NULL;
 775         long err;
 776         mutex_lock(&n->dev.mutex);
 777         err = vhost_dev_check_owner(&n->dev);
 778         if (err)
 779                 goto done;
 780         vhost_net_stop(n, &tx_sock, &rx_sock);
 781         vhost_net_flush(n);
 782         err = vhost_dev_reset_owner(&n->dev);
 783 done:
 784         mutex_unlock(&n->dev.mutex);
 785         if (tx_sock)
 786                 fput(tx_sock->file);
 787         if (rx_sock)
 788                 fput(rx_sock->file);
 789         return err;
 790 }
 791
 792 static int vhost_net_set_features(struct vhost_net *n, u64 features)
 793 {
 794         size_t vhost_hlen, sock_hlen, hdr_len;
 795         int i;
 796
 797         hdr_len = (features & (1 << VIRTIO_NET_F_MRG_RXBUF)) ?
 798                         sizeof(struct virtio_net_hdr_mrg_rxbuf) :
 799                         sizeof(struct virtio_net_hdr);
 800         if (features & (1 << VHOST_NET_F_VIRTIO_NET_HDR)) {
 801                 /* vhost provides vnet_hdr */
 802                 vhost_hlen = hdr_len;
 803                 sock_hlen = 0;
 804         } else {
 805                 /* socket provides vnet_hdr */
 806                 vhost_hlen = 0;
 807                 sock_hlen = hdr_len;
 808         }
 809         mutex_lock(&n->dev.mutex);
 810         if ((features & (1 << VHOST_F_LOG_ALL)) &&
 811             !vhost_log_access_ok(&n->dev)) {
 812                 mutex_unlock(&n->dev.mutex);
 813                 return -EFAULT;
 814         }
 815         n->dev.acked_features = features;
 816         smp_wmb();
 817         for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
 818                 mutex_lock(&n->vqs[i].mutex);
 819                 n->vqs[i].vhost_hlen = vhost_hlen;
 820                 n->vqs[i].sock_hlen = sock_hlen;
 821                 mutex_unlock(&n->vqs[i].mutex);
 822         }
 823         vhost_net_flush(n);
 824         mutex_unlock(&n->dev.mutex);
 825         return 0;
 826 }
 827
 828 static long vhost_net_ioctl(struct file *f, unsigned int ioctl,
 829                             unsigned long arg)
 830 {
 831         struct vhost_net *n = f->private_data;
 832         void __user *argp = (void __user *)arg;
 833         u64 __user *featurep = argp;
 834         struct vhost_vring_file backend;
 835         u64 features;
 836         int r;
 837         switch (ioctl) {
 838         case VHOST_NET_SET_BACKEND:
 839                 if (copy_from_user(&backend, argp, sizeof backend))
 840                         return -EFAULT;
 841                 return vhost_net_set_backend(n, backend.index, backend.fd);
 842         case VHOST_GET_FEATURES:
 843                 features = VHOST_FEATURES;
 844                 if (copy_to_user(featurep, &features, sizeof features))
 845                         return -EFAULT;
 846                 return 0;
 847         case VHOST_SET_FEATURES:
 848                 if (copy_from_user(&features, featurep, sizeof features))
 849                         return -EFAULT;
 850                 if (features & ~VHOST_FEATURES)
 851                         return -EOPNOTSUPP;
 852                 return vhost_net_set_features(n, features);
 853         case VHOST_RESET_OWNER:
 854                 return vhost_net_reset_owner(n);
 855         default:
 856                 mutex_lock(&n->dev.mutex);
 857                 r = vhost_dev_ioctl(&n->dev, ioctl, arg);
 858                 vhost_net_flush(n);
 859                 mutex_unlock(&n->dev.mutex);
 860                 return r;
 861         }
 862 }
 863
 864 #ifdef CONFIG_COMPAT
 865 static long vhost_net_compat_ioctl(struct file *f, unsigned int ioctl,
 866                                    unsigned long arg)
 867 {
 868         return vhost_net_ioctl(f, ioctl, (unsigned long)compat_ptr(arg));
 869 }
 870 #endif
 871
 872 static const struct file_operations vhost_net_fops = {
 873         .owner          = THIS_MODULE,
 874         .release        = vhost_net_release,
 875         .unlocked_ioctl = vhost_net_ioctl,
 876 #ifdef CONFIG_COMPAT
 877         .compat_ioctl   = vhost_net_compat_ioctl,
 878 #endif
 879         .open           = vhost_net_open,
 880 };
 881
 882 static struct miscdevice vhost_net_misc = {
 883         MISC_DYNAMIC_MINOR,
 884         "vhost-net",
 885         &vhost_net_fops,
 886 };
 887
 888 static int vhost_net_init(void)
 889 {
 890         return misc_register(&vhost_net_misc);
 891 }
 892 module_init(vhost_net_init);
 893
 894 static void vhost_net_exit(void)
 895 {
 896         misc_deregister(&vhost_net_misc);
 897 }
 898 module_exit(vhost_net_exit);
 899
 900 MODULE_VERSION("0.0.1");
 901 MODULE_LICENSE("GPL v2");
 902 MODULE_AUTHOR("Michael S. Tsirkin");
 903 MODULE_DESCRIPTION("Host kernel accelerator for virtio net");