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