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 #include <linux/if_vlan.h>
  28
  29 #include <net/sock.h>
  30
  31 #include "vhost.h"
  32
  33 static int experimental_zcopytx = 1;
  34 module_param(experimental_zcopytx, int, 0444);
  35 MODULE_PARM_DESC(experimental_zcopytx, "Enable Zero Copy TX;"
  36                                        " 1 -Enable; 0 - Disable");
  37
  38 /* Max number of bytes transferred before requeueing the job.
  39  * Using this limit prevents one virtqueue from starving others. */
  40 #define VHOST_NET_WEIGHT 0x80000
  41
  42 /* MAX number of TX used buffers for outstanding zerocopy */
  43 #define VHOST_MAX_PEND 128
  44 #define VHOST_GOODCOPY_LEN 256
  45
  46 /*
  47  * For transmit, used buffer len is unused; we override it to track buffer
  48  * status internally; used for zerocopy tx only.
  49  */
  50 /* Lower device DMA failed */
  51 #define VHOST_DMA_FAILED_LEN    3
  52 /* Lower device DMA done */
  53 #define VHOST_DMA_DONE_LEN      2
  54 /* Lower device DMA in progress */
  55 #define VHOST_DMA_IN_PROGRESS   1
  56 /* Buffer unused */
  57 #define VHOST_DMA_CLEAR_LEN     0
  58
  59 #define VHOST_DMA_IS_DONE(len) ((len) >= VHOST_DMA_DONE_LEN)
  60
  61 enum {
  62         VHOST_NET_VQ_RX = 0,
  63         VHOST_NET_VQ_TX = 1,
  64         VHOST_NET_VQ_MAX = 2,
  65 };
  66
  67 enum vhost_net_poll_state {
  68         VHOST_NET_POLL_DISABLED = 0,
  69         VHOST_NET_POLL_STARTED = 1,
  70         VHOST_NET_POLL_STOPPED = 2,
  71 };
  72
  73 struct vhost_net {
  74         struct vhost_dev dev;
  75         struct vhost_virtqueue vqs[VHOST_NET_VQ_MAX];
  76         struct vhost_poll poll[VHOST_NET_VQ_MAX];
  77         /* Tells us whether we are polling a socket for TX.
  78          * We only do this when socket buffer fills up.
  79          * Protected by tx vq lock. */
  80         enum vhost_net_poll_state tx_poll_state;
  81         /* Number of TX recently submitted.
  82          * Protected by tx vq lock. */
  83         unsigned tx_packets;
  84         /* Number of times zerocopy TX recently failed.
  85          * Protected by tx vq lock. */
  86         unsigned tx_zcopy_err;
  87         /* Flush in progress. Protected by tx vq lock. */
  88         bool tx_flush;
  89 };
  90
  91 static void vhost_net_tx_packet(struct vhost_net *net)
  92 {
  93         ++net->tx_packets;
  94         if (net->tx_packets < 1024)
  95                 return;
  96         net->tx_packets = 0;
  97         net->tx_zcopy_err = 0;
  98 }
  99
 100 static void vhost_net_tx_err(struct vhost_net *net)
 101 {
 102         ++net->tx_zcopy_err;
 103 }
 104
 105 static bool vhost_net_tx_select_zcopy(struct vhost_net *net)
 106 {
 107         /* TX flush waits for outstanding DMAs to be done.
 108          * Don't start new DMAs.
 109          */
 110         return !net->tx_flush &&
 111                 net->tx_packets / 64 >= net->tx_zcopy_err;
 112 }
 113
 114 static bool vhost_sock_zcopy(struct socket *sock)
 115 {
 116         return unlikely(experimental_zcopytx) &&
 117                 sock_flag(sock->sk, SOCK_ZEROCOPY);
 118 }
 119
 120 /* Pop first len bytes from iovec. Return number of segments used. */
 121 static int move_iovec_hdr(struct iovec *from, struct iovec *to,
 122                           size_t len, int iov_count)
 123 {
 124         int seg = 0;
 125         size_t size;
 126
 127         while (len && seg < iov_count) {
 128                 size = min(from->iov_len, len);
 129                 to->iov_base = from->iov_base;
 130                 to->iov_len = size;
 131                 from->iov_len -= size;
 132                 from->iov_base += size;
 133                 len -= size;
 134                 ++from;
 135                 ++to;
 136                 ++seg;
 137         }
 138         return seg;
 139 }
 140 /* Copy iovec entries for len bytes from iovec. */
 141 static void copy_iovec_hdr(const struct iovec *from, struct iovec *to,
 142                            size_t len, int iovcount)
 143 {
 144         int seg = 0;
 145         size_t size;
 146
 147         while (len && seg < iovcount) {
 148                 size = min(from->iov_len, len);
 149                 to->iov_base = from->iov_base;
 150                 to->iov_len = size;
 151                 len -= size;
 152                 ++from;
 153                 ++to;
 154                 ++seg;
 155         }
 156 }
 157
 158 /* Caller must have TX VQ lock */
 159 static void tx_poll_stop(struct vhost_net *net)
 160 {
 161         if (likely(net->tx_poll_state != VHOST_NET_POLL_STARTED))
 162                 return;
 163         vhost_poll_stop(net->poll + VHOST_NET_VQ_TX);
 164         net->tx_poll_state = VHOST_NET_POLL_STOPPED;
 165 }
 166
 167 /* Caller must have TX VQ lock */
 168 static void tx_poll_start(struct vhost_net *net, struct socket *sock)
 169 {
 170         if (unlikely(net->tx_poll_state != VHOST_NET_POLL_STOPPED))
 171                 return;
 172         vhost_poll_start(net->poll + VHOST_NET_VQ_TX, sock->file);
 173         net->tx_poll_state = VHOST_NET_POLL_STARTED;
 174 }
 175
 176 /* In case of DMA done not in order in lower device driver for some reason.
 177  * upend_idx is used to track end of used idx, done_idx is used to track head
 178  * of used idx. Once lower device DMA done contiguously, we will signal KVM
 179  * guest used idx.
 180  */
 181 static int vhost_zerocopy_signal_used(struct vhost_net *net,
 182                                       struct vhost_virtqueue *vq)
 183 {
 184         int i;
 185         int j = 0;
 186
 187         for (i = vq->done_idx; i != vq->upend_idx; i = (i + 1) % UIO_MAXIOV) {
 188                 if (vq->heads[i].len == VHOST_DMA_FAILED_LEN)
 189                         vhost_net_tx_err(net);
 190                 if (VHOST_DMA_IS_DONE(vq->heads[i].len)) {
 191                         vq->heads[i].len = VHOST_DMA_CLEAR_LEN;
 192                         vhost_add_used_and_signal(vq->dev, vq,
 193                                                   vq->heads[i].id, 0);
 194                         ++j;
 195                 } else
 196                         break;
 197         }
 198         if (j)
 199                 vq->done_idx = i;
 200         return j;
 201 }
 202
 203 static void vhost_zerocopy_callback(struct ubuf_info *ubuf, bool success)
 204 {
 205         struct vhost_ubuf_ref *ubufs = ubuf->ctx;
 206         struct vhost_virtqueue *vq = ubufs->vq;
 207         int cnt = atomic_read(&ubufs->kref.refcount);
 208
 209         /*
 210          * Trigger polling thread if guest stopped submitting new buffers:
 211          * in this case, the refcount after decrement will eventually reach 1
 212          * so here it is 2.
 213          * We also trigger polling periodically after each 16 packets
 214          * (the value 16 here is more or less arbitrary, it's tuned to trigger
 215          * less than 10% of times).
 216          */
 217         if (cnt <= 2 || !(cnt % 16))
 218                 vhost_poll_queue(&vq->poll);
 219         /* set len to mark this desc buffers done DMA */
 220         vq->heads[ubuf->desc].len = success ?
 221                 VHOST_DMA_DONE_LEN : VHOST_DMA_FAILED_LEN;
 222         vhost_ubuf_put(ubufs);
 223 }
 224
 225 /* Expects to be always run from workqueue - which acts as
 226  * read-size critical section for our kind of RCU. */
 227 static void handle_tx(struct vhost_net *net)
 228 {
 229         struct vhost_virtqueue *vq = &net->dev.vqs[VHOST_NET_VQ_TX];
 230         unsigned out, in, s;
 231         int head;
 232         struct msghdr msg = {
 233                 .msg_name = NULL,
 234                 .msg_namelen = 0,
 235                 .msg_control = NULL,
 236                 .msg_controllen = 0,
 237                 .msg_iov = vq->iov,
 238                 .msg_flags = MSG_DONTWAIT,
 239         };
 240         size_t len, total_len = 0;
 241         int err, wmem;
 242         size_t hdr_size;
 243         struct socket *sock;
 244         struct vhost_ubuf_ref *uninitialized_var(ubufs);
 245         bool zcopy, zcopy_used;
 246
 247         /* TODO: check that we are running from vhost_worker? */
 248         sock = rcu_dereference_check(vq->private_data, 1);
 249         if (!sock)
 250                 return;
 251
 252         wmem = atomic_read(&sock->sk->sk_wmem_alloc);
 253         if (wmem >= sock->sk->sk_sndbuf) {
 254                 mutex_lock(&vq->mutex);
 255                 tx_poll_start(net, sock);
 256                 mutex_unlock(&vq->mutex);
 257                 return;
 258         }
 259
 260         mutex_lock(&vq->mutex);
 261         vhost_disable_notify(&net->dev, vq);
 262
 263         if (wmem < sock->sk->sk_sndbuf / 2)
 264                 tx_poll_stop(net);
 265         hdr_size = vq->vhost_hlen;
 266         zcopy = vq->ubufs;
 267
 268         for (;;) {
 269                 /* Release DMAs done buffers first */
 270                 if (zcopy)
 271                         vhost_zerocopy_signal_used(net, vq);
 272
 273                 head = vhost_get_vq_desc(&net->dev, vq, vq->iov,
 274                                          ARRAY_SIZE(vq->iov),
 275                                          &out, &in,
 276                                          NULL, NULL);
 277                 /* On error, stop handling until the next kick. */
 278                 if (unlikely(head < 0))
 279                         break;
 280                 /* Nothing new?  Wait for eventfd to tell us they refilled. */
 281                 if (head == vq->num) {
 282                         int num_pends;
 283
 284                         wmem = atomic_read(&sock->sk->sk_wmem_alloc);
 285                         if (wmem >= sock->sk->sk_sndbuf * 3 / 4) {
 286                                 tx_poll_start(net, sock);
 287                                 set_bit(SOCK_ASYNC_NOSPACE, &sock->flags);
 288                                 break;
 289                         }
 290                         /* If more outstanding DMAs, queue the work.
 291                          * Handle upend_idx wrap around
 292                          */
 293                         num_pends = likely(vq->upend_idx >= vq->done_idx) ?
 294                                     (vq->upend_idx - vq->done_idx) :
 295                                     (vq->upend_idx + UIO_MAXIOV - vq->done_idx);
 296                         if (unlikely(num_pends > VHOST_MAX_PEND)) {
 297                                 tx_poll_start(net, sock);
 298                                 set_bit(SOCK_ASYNC_NOSPACE, &sock->flags);
 299                                 break;
 300                         }
 301                         if (unlikely(vhost_enable_notify(&net->dev, vq))) {
 302                                 vhost_disable_notify(&net->dev, vq);
 303                                 continue;
 304                         }
 305                         break;
 306                 }
 307                 if (in) {
 308                         vq_err(vq, "Unexpected descriptor format for TX: "
 309                                "out %d, int %d\n", out, in);
 310                         break;
 311                 }
 312                 /* Skip header. TODO: support TSO. */
 313                 s = move_iovec_hdr(vq->iov, vq->hdr, hdr_size, out);
 314                 msg.msg_iovlen = out;
 315                 len = iov_length(vq->iov, out);
 316                 /* Sanity check */
 317                 if (!len) {
 318                         vq_err(vq, "Unexpected header len for TX: "
 319                                "%zd expected %zd\n",
 320                                iov_length(vq->hdr, s), hdr_size);
 321                         break;
 322                 }
 323                 zcopy_used = zcopy && (len >= VHOST_GOODCOPY_LEN ||
 324                                        vq->upend_idx != vq->done_idx);
 325
 326                 /* use msg_control to pass vhost zerocopy ubuf info to skb */
 327                 if (zcopy_used) {
 328                         vq->heads[vq->upend_idx].id = head;
 329                         if (!vhost_net_tx_select_zcopy(net) ||
 330                             len < VHOST_GOODCOPY_LEN) {
 331                                 /* copy don't need to wait for DMA done */
 332                                 vq->heads[vq->upend_idx].len =
 333                                                         VHOST_DMA_DONE_LEN;
 334                                 msg.msg_control = NULL;
 335                                 msg.msg_controllen = 0;
 336                                 ubufs = NULL;
 337                         } else {
 338                                 struct ubuf_info *ubuf = &vq->ubuf_info[head];
 339
 340                                 vq->heads[vq->upend_idx].len =
 341                                         VHOST_DMA_IN_PROGRESS;
 342                                 ubuf->callback = vhost_zerocopy_callback;
 343                                 ubuf->ctx = vq->ubufs;
 344                                 ubuf->desc = vq->upend_idx;
 345                                 msg.msg_control = ubuf;
 346                                 msg.msg_controllen = sizeof(ubuf);
 347                                 ubufs = vq->ubufs;
 348                                 kref_get(&ubufs->kref);
 349                         }
 350                         vq->upend_idx = (vq->upend_idx + 1) % UIO_MAXIOV;
 351                 }
 352                 /* TODO: Check specific error and bomb out unless ENOBUFS? */
 353                 err = sock->ops->sendmsg(NULL, sock, &msg, len);
 354                 if (unlikely(err < 0)) {
 355                         if (zcopy_used) {
 356                                 if (ubufs)
 357                                         vhost_ubuf_put(ubufs);
 358                                 vq->upend_idx = ((unsigned)vq->upend_idx - 1) %
 359                                         UIO_MAXIOV;
 360                         }
 361                         vhost_discard_vq_desc(vq, 1);
 362                         if (err == -EAGAIN || err == -ENOBUFS)
 363                                 tx_poll_start(net, sock);
 364                         break;
 365                 }
 366                 if (err != len)
 367                         pr_debug("Truncated TX packet: "
 368                                  " len %d != %zd\n", err, len);
 369                 if (!zcopy_used)
 370                         vhost_add_used_and_signal(&net->dev, vq, head, 0);
 371                 else
 372                         vhost_zerocopy_signal_used(net, vq);
 373                 total_len += len;
 374                 vhost_net_tx_packet(net);
 375                 if (unlikely(total_len >= VHOST_NET_WEIGHT)) {
 376                         vhost_poll_queue(&vq->poll);
 377                         break;
 378                 }
 379         }
 380
 381         mutex_unlock(&vq->mutex);
 382 }
 383
 384 static int peek_head_len(struct sock *sk)
 385 {
 386         struct sk_buff *head;
 387         int len = 0;
 388         unsigned long flags;
 389
 390         spin_lock_irqsave(&sk->sk_receive_queue.lock, flags);
 391         head = skb_peek(&sk->sk_receive_queue);
 392         if (likely(head)) {
 393                 len = head->len;
 394                 if (vlan_tx_tag_present(head))
 395                         len += VLAN_HLEN;
 396         }
 397
 398         spin_unlock_irqrestore(&sk->sk_receive_queue.lock, flags);
 399         return len;
 400 }
 401
 402 /* This is a multi-buffer version of vhost_get_desc, that works if
 403  *      vq has read descriptors only.
 404  * @vq          - the relevant virtqueue
 405  * @datalen     - data length we'll be reading
 406  * @iovcount    - returned count of io vectors we fill
 407  * @log         - vhost log
 408  * @log_num     - log offset
 409  * @quota       - headcount quota, 1 for big buffer
 410  *      returns number of buffer heads allocated, negative on error
 411  */
 412 static int get_rx_bufs(struct vhost_virtqueue *vq,
 413                        struct vring_used_elem *heads,
 414                        int datalen,
 415                        unsigned *iovcount,
 416                        struct vhost_log *log,
 417                        unsigned *log_num,
 418                        unsigned int quota)
 419 {
 420         unsigned int out, in;
 421         int seg = 0;
 422         int headcount = 0;
 423         unsigned d;
 424         int r, nlogs = 0;
 425
 426         while (datalen > 0 && headcount < quota) {
 427                 if (unlikely(seg >= UIO_MAXIOV)) {
 428                         r = -ENOBUFS;
 429                         goto err;
 430                 }
 431                 d = vhost_get_vq_desc(vq->dev, vq, vq->iov + seg,
 432                                       ARRAY_SIZE(vq->iov) - seg, &out,
 433                                       &in, log, log_num);
 434                 if (d == vq->num) {
 435                         r = 0;
 436                         goto err;
 437                 }
 438                 if (unlikely(out || in <= 0)) {
 439                         vq_err(vq, "unexpected descriptor format for RX: "
 440                                 "out %d, in %d\n", out, in);
 441                         r = -EINVAL;
 442                         goto err;
 443                 }
 444                 if (unlikely(log)) {
 445                         nlogs += *log_num;
 446                         log += *log_num;
 447                 }
 448                 heads[headcount].id = d;
 449                 heads[headcount].len = iov_length(vq->iov + seg, in);
 450                 datalen -= heads[headcount].len;
 451                 ++headcount;
 452                 seg += in;
 453         }
 454         heads[headcount - 1].len += datalen;
 455         *iovcount = seg;
 456         if (unlikely(log))
 457                 *log_num = nlogs;
 458         return headcount;
 459 err:
 460         vhost_discard_vq_desc(vq, headcount);
 461         return r;
 462 }
 463
 464 /* Expects to be always run from workqueue - which acts as
 465  * read-size critical section for our kind of RCU. */
 466 static void handle_rx(struct vhost_net *net)
 467 {
 468         struct vhost_virtqueue *vq = &net->dev.vqs[VHOST_NET_VQ_RX];
 469         unsigned uninitialized_var(in), log;
 470         struct vhost_log *vq_log;
 471         struct msghdr msg = {
 472                 .msg_name = NULL,
 473                 .msg_namelen = 0,
 474                 .msg_control = NULL, /* FIXME: get and handle RX aux data. */
 475                 .msg_controllen = 0,
 476                 .msg_iov = vq->iov,
 477                 .msg_flags = MSG_DONTWAIT,
 478         };
 479         struct virtio_net_hdr_mrg_rxbuf hdr = {
 480                 .hdr.flags = 0,
 481                 .hdr.gso_type = VIRTIO_NET_HDR_GSO_NONE
 482         };
 483         size_t total_len = 0;
 484         int err, mergeable;
 485         s16 headcount;
 486         size_t vhost_hlen, sock_hlen;
 487         size_t vhost_len, sock_len;
 488         /* TODO: check that we are running from vhost_worker? */
 489         struct socket *sock = rcu_dereference_check(vq->private_data, 1);
 490
 491         if (!sock)
 492                 return;
 493
 494         mutex_lock(&vq->mutex);
 495         vhost_disable_notify(&net->dev, vq);
 496         vhost_hlen = vq->vhost_hlen;
 497         sock_hlen = vq->sock_hlen;
 498
 499         vq_log = unlikely(vhost_has_feature(&net->dev, VHOST_F_LOG_ALL)) ?
 500                 vq->log : NULL;
 501         mergeable = vhost_has_feature(&net->dev, VIRTIO_NET_F_MRG_RXBUF);
 502
 503         while ((sock_len = peek_head_len(sock->sk))) {
 504                 sock_len += sock_hlen;
 505                 vhost_len = sock_len + vhost_hlen;
 506                 headcount = get_rx_bufs(vq, vq->heads, vhost_len,
 507                                         &in, vq_log, &log,
 508                                         likely(mergeable) ? UIO_MAXIOV : 1);
 509                 /* On error, stop handling until the next kick. */
 510                 if (unlikely(headcount < 0))
 511                         break;
 512                 /* OK, now we need to know about added descriptors. */
 513                 if (!headcount) {
 514                         if (unlikely(vhost_enable_notify(&net->dev, vq))) {
 515                                 /* They have slipped one in as we were
 516                                  * doing that: check again. */
 517                                 vhost_disable_notify(&net->dev, vq);
 518                                 continue;
 519                         }
 520                         /* Nothing new?  Wait for eventfd to tell us
 521                          * they refilled. */
 522                         break;
 523                 }
 524                 /* We don't need to be notified again. */
 525                 if (unlikely((vhost_hlen)))
 526                         /* Skip header. TODO: support TSO. */
 527                         move_iovec_hdr(vq->iov, vq->hdr, vhost_hlen, in);
 528                 else
 529                         /* Copy the header for use in VIRTIO_NET_F_MRG_RXBUF:
 530                          * needed because recvmsg can modify msg_iov. */
 531                         copy_iovec_hdr(vq->iov, vq->hdr, sock_hlen, in);
 532                 msg.msg_iovlen = in;
 533                 err = sock->ops->recvmsg(NULL, sock, &msg,
 534                                          sock_len, MSG_DONTWAIT | MSG_TRUNC);
 535                 /* Userspace might have consumed the packet meanwhile:
 536                  * it's not supposed to do this usually, but might be hard
 537                  * to prevent. Discard data we got (if any) and keep going. */
 538                 if (unlikely(err != sock_len)) {
 539                         pr_debug("Discarded rx packet: "
 540                                  " len %d, expected %zd\n", err, sock_len);
 541                         vhost_discard_vq_desc(vq, headcount);
 542                         continue;
 543                 }
 544                 if (unlikely(vhost_hlen) &&
 545                     memcpy_toiovecend(vq->hdr, (unsigned char *)&hdr, 0,
 546                                       vhost_hlen)) {
 547                         vq_err(vq, "Unable to write vnet_hdr at addr %p\n",
 548                                vq->iov->iov_base);
 549                         break;
 550                 }
 551                 /* TODO: Should check and handle checksum. */
 552                 if (likely(mergeable) &&
 553                     memcpy_toiovecend(vq->hdr, (unsigned char *)&headcount,
 554                                       offsetof(typeof(hdr), num_buffers),
 555                                       sizeof hdr.num_buffers)) {
 556                         vq_err(vq, "Failed num_buffers write");
 557                         vhost_discard_vq_desc(vq, headcount);
 558                         break;
 559                 }
 560                 vhost_add_used_and_signal_n(&net->dev, vq, vq->heads,
 561                                             headcount);
 562                 if (unlikely(vq_log))
 563                         vhost_log_write(vq, vq_log, log, vhost_len);
 564                 total_len += vhost_len;
 565                 if (unlikely(total_len >= VHOST_NET_WEIGHT)) {
 566                         vhost_poll_queue(&vq->poll);
 567                         break;
 568                 }
 569         }
 570
 571         mutex_unlock(&vq->mutex);
 572 }
 573
 574 static void handle_tx_kick(struct vhost_work *work)
 575 {
 576         struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
 577                                                   poll.work);
 578         struct vhost_net *net = container_of(vq->dev, struct vhost_net, dev);
 579
 580         handle_tx(net);
 581 }
 582
 583 static void handle_rx_kick(struct vhost_work *work)
 584 {
 585         struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
 586                                                   poll.work);
 587         struct vhost_net *net = container_of(vq->dev, struct vhost_net, dev);
 588
 589         handle_rx(net);
 590 }
 591
 592 static void handle_tx_net(struct vhost_work *work)
 593 {
 594         struct vhost_net *net = container_of(work, struct vhost_net,
 595                                              poll[VHOST_NET_VQ_TX].work);
 596         handle_tx(net);
 597 }
 598
 599 static void handle_rx_net(struct vhost_work *work)
 600 {
 601         struct vhost_net *net = container_of(work, struct vhost_net,
 602                                              poll[VHOST_NET_VQ_RX].work);
 603         handle_rx(net);
 604 }
 605
 606 static int vhost_net_open(struct inode *inode, struct file *f)
 607 {
 608         struct vhost_net *n = kmalloc(sizeof *n, GFP_KERNEL);
 609         struct vhost_dev *dev;
 610         int r;
 611
 612         if (!n)
 613                 return -ENOMEM;
 614
 615         dev = &n->dev;
 616         n->vqs[VHOST_NET_VQ_TX].handle_kick = handle_tx_kick;
 617         n->vqs[VHOST_NET_VQ_RX].handle_kick = handle_rx_kick;
 618         r = vhost_dev_init(dev, n->vqs, VHOST_NET_VQ_MAX);
 619         if (r < 0) {
 620                 kfree(n);
 621                 return r;
 622         }
 623
 624         vhost_poll_init(n->poll + VHOST_NET_VQ_TX, handle_tx_net, POLLOUT, dev);
 625         vhost_poll_init(n->poll + VHOST_NET_VQ_RX, handle_rx_net, POLLIN, dev);
 626         n->tx_poll_state = VHOST_NET_POLL_DISABLED;
 627
 628         f->private_data = n;
 629
 630         return 0;
 631 }
 632
 633 static void vhost_net_disable_vq(struct vhost_net *n,
 634                                  struct vhost_virtqueue *vq)
 635 {
 636         if (!vq->private_data)
 637                 return;
 638         if (vq == n->vqs + VHOST_NET_VQ_TX) {
 639                 tx_poll_stop(n);
 640                 n->tx_poll_state = VHOST_NET_POLL_DISABLED;
 641         } else
 642                 vhost_poll_stop(n->poll + VHOST_NET_VQ_RX);
 643 }
 644
 645 static void vhost_net_enable_vq(struct vhost_net *n,
 646                                 struct vhost_virtqueue *vq)
 647 {
 648         struct socket *sock;
 649
 650         sock = rcu_dereference_protected(vq->private_data,
 651                                          lockdep_is_held(&vq->mutex));
 652         if (!sock)
 653                 return;
 654         if (vq == n->vqs + VHOST_NET_VQ_TX) {
 655                 n->tx_poll_state = VHOST_NET_POLL_STOPPED;
 656                 tx_poll_start(n, sock);
 657         } else
 658                 vhost_poll_start(n->poll + VHOST_NET_VQ_RX, sock->file);
 659 }
 660
 661 static struct socket *vhost_net_stop_vq(struct vhost_net *n,
 662                                         struct vhost_virtqueue *vq)
 663 {
 664         struct socket *sock;
 665
 666         mutex_lock(&vq->mutex);
 667         sock = rcu_dereference_protected(vq->private_data,
 668                                          lockdep_is_held(&vq->mutex));
 669         vhost_net_disable_vq(n, vq);
 670         rcu_assign_pointer(vq->private_data, NULL);
 671         mutex_unlock(&vq->mutex);
 672         return sock;
 673 }
 674
 675 static void vhost_net_stop(struct vhost_net *n, struct socket **tx_sock,
 676                            struct socket **rx_sock)
 677 {
 678         *tx_sock = vhost_net_stop_vq(n, n->vqs + VHOST_NET_VQ_TX);
 679         *rx_sock = vhost_net_stop_vq(n, n->vqs + VHOST_NET_VQ_RX);
 680 }
 681
 682 static void vhost_net_flush_vq(struct vhost_net *n, int index)
 683 {
 684         vhost_poll_flush(n->poll + index);
 685         vhost_poll_flush(&n->dev.vqs[index].poll);
 686 }
 687
 688 static void vhost_net_flush(struct vhost_net *n)
 689 {
 690         vhost_net_flush_vq(n, VHOST_NET_VQ_TX);
 691         vhost_net_flush_vq(n, VHOST_NET_VQ_RX);
 692         if (n->dev.vqs[VHOST_NET_VQ_TX].ubufs) {
 693                 mutex_lock(&n->dev.vqs[VHOST_NET_VQ_TX].mutex);
 694                 n->tx_flush = true;
 695                 mutex_unlock(&n->dev.vqs[VHOST_NET_VQ_TX].mutex);
 696                 /* Wait for all lower device DMAs done. */
 697                 vhost_ubuf_put_and_wait(n->dev.vqs[VHOST_NET_VQ_TX].ubufs);
 698                 mutex_lock(&n->dev.vqs[VHOST_NET_VQ_TX].mutex);
 699                 n->tx_flush = false;
 700                 kref_init(&n->dev.vqs[VHOST_NET_VQ_TX].ubufs->kref);
 701                 mutex_unlock(&n->dev.vqs[VHOST_NET_VQ_TX].mutex);
 702         }
 703 }
 704
 705 static int vhost_net_release(struct inode *inode, struct file *f)
 706 {
 707         struct vhost_net *n = f->private_data;
 708         struct socket *tx_sock;
 709         struct socket *rx_sock;
 710
 711         vhost_net_stop(n, &tx_sock, &rx_sock);
 712         vhost_net_flush(n);
 713         vhost_dev_stop(&n->dev);
 714         vhost_dev_cleanup(&n->dev, false);
 715         if (tx_sock)
 716                 fput(tx_sock->file);
 717         if (rx_sock)
 718                 fput(rx_sock->file);
 719         /* We do an extra flush before freeing memory,
 720          * since jobs can re-queue themselves. */
 721         vhost_net_flush(n);
 722         kfree(n);
 723         return 0;
 724 }
 725
 726 static struct socket *get_raw_socket(int fd)
 727 {
 728         struct {
 729                 struct sockaddr_ll sa;
 730                 char  buf[MAX_ADDR_LEN];
 731         } uaddr;
 732         int uaddr_len = sizeof uaddr, r;
 733         struct socket *sock = sockfd_lookup(fd, &r);
 734
 735         if (!sock)
 736                 return ERR_PTR(-ENOTSOCK);
 737
 738         /* Parameter checking */
 739         if (sock->sk->sk_type != SOCK_RAW) {
 740                 r = -ESOCKTNOSUPPORT;
 741                 goto err;
 742         }
 743
 744         r = sock->ops->getname(sock, (struct sockaddr *)&uaddr.sa,
 745                                &uaddr_len, 0);
 746         if (r)
 747                 goto err;
 748
 749         if (uaddr.sa.sll_family != AF_PACKET) {
 750                 r = -EPFNOSUPPORT;
 751                 goto err;
 752         }
 753         return sock;
 754 err:
 755         fput(sock->file);
 756         return ERR_PTR(r);
 757 }
 758
 759 static struct socket *get_tap_socket(int fd)
 760 {
 761         struct file *file = fget(fd);
 762         struct socket *sock;
 763
 764         if (!file)
 765                 return ERR_PTR(-EBADF);
 766         sock = tun_get_socket(file);
 767         if (!IS_ERR(sock))
 768                 return sock;
 769         sock = macvtap_get_socket(file);
 770         if (IS_ERR(sock))
 771                 fput(file);
 772         return sock;
 773 }
 774
 775 static struct socket *get_socket(int fd)
 776 {
 777         struct socket *sock;
 778
 779         /* special case to disable backend */
 780         if (fd == -1)
 781                 return NULL;
 782         sock = get_raw_socket(fd);
 783         if (!IS_ERR(sock))
 784                 return sock;
 785         sock = get_tap_socket(fd);
 786         if (!IS_ERR(sock))
 787                 return sock;
 788         return ERR_PTR(-ENOTSOCK);
 789 }
 790
 791 static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd)
 792 {
 793         struct socket *sock, *oldsock;
 794         struct vhost_virtqueue *vq;
 795         struct vhost_ubuf_ref *ubufs, *oldubufs = NULL;
 796         int r;
 797
 798         mutex_lock(&n->dev.mutex);
 799         r = vhost_dev_check_owner(&n->dev);
 800         if (r)
 801                 goto err;
 802
 803         if (index >= VHOST_NET_VQ_MAX) {
 804                 r = -ENOBUFS;
 805                 goto err;
 806         }
 807         vq = n->vqs + index;
 808         mutex_lock(&vq->mutex);
 809
 810         /* Verify that ring has been setup correctly. */
 811         if (!vhost_vq_access_ok(vq)) {
 812                 r = -EFAULT;
 813                 goto err_vq;
 814         }
 815         sock = get_socket(fd);
 816         if (IS_ERR(sock)) {
 817                 r = PTR_ERR(sock);
 818                 goto err_vq;
 819         }
 820
 821         /* start polling new socket */
 822         oldsock = rcu_dereference_protected(vq->private_data,
 823                                             lockdep_is_held(&vq->mutex));
 824         if (sock != oldsock) {
 825                 ubufs = vhost_ubuf_alloc(vq, sock && vhost_sock_zcopy(sock));
 826                 if (IS_ERR(ubufs)) {
 827                         r = PTR_ERR(ubufs);
 828                         goto err_ubufs;
 829                 }
 830                 oldubufs = vq->ubufs;
 831                 vq->ubufs = ubufs;
 832                 vhost_net_disable_vq(n, vq);
 833                 rcu_assign_pointer(vq->private_data, sock);
 834                 vhost_net_enable_vq(n, vq);
 835
 836                 r = vhost_init_used(vq);
 837                 if (r)
 838                         goto err_vq;
 839
 840                 n->tx_packets = 0;
 841                 n->tx_zcopy_err = 0;
 842                 n->tx_flush = false;
 843         }
 844
 845         mutex_unlock(&vq->mutex);
 846
 847         if (oldubufs) {
 848                 vhost_ubuf_put_and_wait(oldubufs);
 849                 mutex_lock(&vq->mutex);
 850                 vhost_zerocopy_signal_used(n, vq);
 851                 mutex_unlock(&vq->mutex);
 852         }
 853
 854         if (oldsock) {
 855                 vhost_net_flush_vq(n, index);
 856                 fput(oldsock->file);
 857         }
 858
 859         mutex_unlock(&n->dev.mutex);
 860         return 0;
 861
 862 err_ubufs:
 863         fput(sock->file);
 864 err_vq:
 865         mutex_unlock(&vq->mutex);
 866 err:
 867         mutex_unlock(&n->dev.mutex);
 868         return r;
 869 }
 870
 871 static long vhost_net_reset_owner(struct vhost_net *n)
 872 {
 873         struct socket *tx_sock = NULL;
 874         struct socket *rx_sock = NULL;
 875         long err;
 876
 877         mutex_lock(&n->dev.mutex);
 878         err = vhost_dev_check_owner(&n->dev);
 879         if (err)
 880                 goto done;
 881         vhost_net_stop(n, &tx_sock, &rx_sock);
 882         vhost_net_flush(n);
 883         err = vhost_dev_reset_owner(&n->dev);
 884 done:
 885         mutex_unlock(&n->dev.mutex);
 886         if (tx_sock)
 887                 fput(tx_sock->file);
 888         if (rx_sock)
 889                 fput(rx_sock->file);
 890         return err;
 891 }
 892
 893 static int vhost_net_set_features(struct vhost_net *n, u64 features)
 894 {
 895         size_t vhost_hlen, sock_hlen, hdr_len;
 896         int i;
 897
 898         hdr_len = (features & (1 << VIRTIO_NET_F_MRG_RXBUF)) ?
 899                         sizeof(struct virtio_net_hdr_mrg_rxbuf) :
 900                         sizeof(struct virtio_net_hdr);
 901         if (features & (1 << VHOST_NET_F_VIRTIO_NET_HDR)) {
 902                 /* vhost provides vnet_hdr */
 903                 vhost_hlen = hdr_len;
 904                 sock_hlen = 0;
 905         } else {
 906                 /* socket provides vnet_hdr */
 907                 vhost_hlen = 0;
 908                 sock_hlen = hdr_len;
 909         }
 910         mutex_lock(&n->dev.mutex);
 911         if ((features & (1 << VHOST_F_LOG_ALL)) &&
 912             !vhost_log_access_ok(&n->dev)) {
 913                 mutex_unlock(&n->dev.mutex);
 914                 return -EFAULT;
 915         }
 916         n->dev.acked_features = features;
 917         smp_wmb();
 918         for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
 919                 mutex_lock(&n->vqs[i].mutex);
 920                 n->vqs[i].vhost_hlen = vhost_hlen;
 921                 n->vqs[i].sock_hlen = sock_hlen;
 922                 mutex_unlock(&n->vqs[i].mutex);
 923         }
 924         vhost_net_flush(n);
 925         mutex_unlock(&n->dev.mutex);
 926         return 0;
 927 }
 928
 929 static long vhost_net_ioctl(struct file *f, unsigned int ioctl,
 930                             unsigned long arg)
 931 {
 932         struct vhost_net *n = f->private_data;
 933         void __user *argp = (void __user *)arg;
 934         u64 __user *featurep = argp;
 935         struct vhost_vring_file backend;
 936         u64 features;
 937         int r;
 938
 939         switch (ioctl) {
 940         case VHOST_NET_SET_BACKEND:
 941                 if (copy_from_user(&backend, argp, sizeof backend))
 942                         return -EFAULT;
 943                 return vhost_net_set_backend(n, backend.index, backend.fd);
 944         case VHOST_GET_FEATURES:
 945                 features = VHOST_NET_FEATURES;
 946                 if (copy_to_user(featurep, &features, sizeof features))
 947                         return -EFAULT;
 948                 return 0;
 949         case VHOST_SET_FEATURES:
 950                 if (copy_from_user(&features, featurep, sizeof features))
 951                         return -EFAULT;
 952                 if (features & ~VHOST_NET_FEATURES)
 953                         return -EOPNOTSUPP;
 954                 return vhost_net_set_features(n, features);
 955         case VHOST_RESET_OWNER:
 956                 return vhost_net_reset_owner(n);
 957         default:
 958                 mutex_lock(&n->dev.mutex);
 959                 r = vhost_dev_ioctl(&n->dev, ioctl, argp);
 960                 if (r == -ENOIOCTLCMD)
 961                         r = vhost_vring_ioctl(&n->dev, ioctl, argp);
 962                 else
 963                         vhost_net_flush(n);
 964                 mutex_unlock(&n->dev.mutex);
 965                 return r;
 966         }
 967 }
 968
 969 #ifdef CONFIG_COMPAT
 970 static long vhost_net_compat_ioctl(struct file *f, unsigned int ioctl,
 971                                    unsigned long arg)
 972 {
 973         return vhost_net_ioctl(f, ioctl, (unsigned long)compat_ptr(arg));
 974 }
 975 #endif
 976
 977 static const struct file_operations vhost_net_fops = {
 978         .owner          = THIS_MODULE,
 979         .release        = vhost_net_release,
 980         .unlocked_ioctl = vhost_net_ioctl,
 981 #ifdef CONFIG_COMPAT
 982         .compat_ioctl   = vhost_net_compat_ioctl,
 983 #endif
 984         .open           = vhost_net_open,
 985         .llseek         = noop_llseek,
 986 };
 987
 988 static struct miscdevice vhost_net_misc = {
 989         .minor = VHOST_NET_MINOR,
 990         .name = "vhost-net",
 991         .fops = &vhost_net_fops,
 992 };
 993
 994 static int vhost_net_init(void)
 995 {
 996         if (experimental_zcopytx)
 997                 vhost_enable_zcopy(VHOST_NET_VQ_TX);
 998         return misc_register(&vhost_net_misc);
 999 }
1000 module_init(vhost_net_init);
1001
1002 static void vhost_net_exit(void)
1003 {
1004         misc_deregister(&vhost_net_misc);
1005 }
1006 module_exit(vhost_net_exit);
1007
1008 MODULE_VERSION("0.0.1");
1009 MODULE_LICENSE("GPL v2");
1010 MODULE_AUTHOR("Michael S. Tsirkin");
1011 MODULE_DESCRIPTION("Host kernel accelerator for virtio net");
1012 MODULE_ALIAS_MISCDEV(VHOST_NET_MINOR);
1013 MODULE_ALIAS("devname:vhost-net");