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