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/file.h>
  19 #include <linux/slab.h>
  20
  21 #include <linux/net.h>
  22 #include <linux/if_packet.h>
  23 #include <linux/if_arp.h>
  24 #include <linux/if_tun.h>
  25 #include <linux/if_macvlan.h>
  26 #include <linux/if_vlan.h>
  27
  28 #include <net/sock.h>
  29
  30 #include "vhost.h"
  31
  32 static int experimental_zcopytx = 1;
  33 module_param(experimental_zcopytx, int, 0444);
  34 MODULE_PARM_DESC(experimental_zcopytx, "Enable Zero Copy TX;"
  35                                        " 1 -Enable; 0 - Disable");
  36
  37 /* Max number of bytes transferred before requeueing the job.
  38  * Using this limit prevents one virtqueue from starving others. */
  39 #define VHOST_NET_WEIGHT 0x80000
  40
  41 /* MAX number of TX used buffers for outstanding zerocopy */
  42 #define VHOST_MAX_PEND 128
  43 #define VHOST_GOODCOPY_LEN 256
  44
  45 /*
  46  * For transmit, used buffer len is unused; we override it to track buffer
  47  * status internally; used for zerocopy tx only.
  48  */
  49 /* Lower device DMA failed */
  50 #define VHOST_DMA_FAILED_LEN    3
  51 /* Lower device DMA done */
  52 #define VHOST_DMA_DONE_LEN      2
  53 /* Lower device DMA in progress */
  54 #define VHOST_DMA_IN_PROGRESS   1
  55 /* Buffer unused */
  56 #define VHOST_DMA_CLEAR_LEN     0
  57
  58 #define VHOST_DMA_IS_DONE(len) ((len) >= VHOST_DMA_DONE_LEN)
  59
  60 enum {
  61         VHOST_NET_FEATURES = VHOST_FEATURES |
  62                          (1ULL << VHOST_NET_F_VIRTIO_NET_HDR) |
  63                          (1ULL << VIRTIO_NET_F_MRG_RXBUF),
  64 };
  65
  66 enum {
  67         VHOST_NET_VQ_RX = 0,
  68         VHOST_NET_VQ_TX = 1,
  69         VHOST_NET_VQ_MAX = 2,
  70 };
  71
  72 struct vhost_net_ubuf_ref {
  73         struct kref kref;
  74         wait_queue_head_t wait;
  75         struct vhost_virtqueue *vq;
  76 };
  77
  78 struct vhost_net_virtqueue {
  79         struct vhost_virtqueue vq;
  80         /* hdr is used to store the virtio header.
  81          * Since each iovec has >= 1 byte length, we never need more than
  82          * header length entries to store the header. */
  83         struct iovec hdr[sizeof(struct virtio_net_hdr_mrg_rxbuf)];
  84         size_t vhost_hlen;
  85         size_t sock_hlen;
  86         /* vhost zerocopy support fields below: */
  87         /* last used idx for outstanding DMA zerocopy buffers */
  88         int upend_idx;
  89         /* first used idx for DMA done zerocopy buffers */
  90         int done_idx;
  91         /* an array of userspace buffers info */
  92         struct ubuf_info *ubuf_info;
  93         /* Reference counting for outstanding ubufs.
  94          * Protected by vq mutex. Writers must also take device mutex. */
  95         struct vhost_net_ubuf_ref *ubufs;
  96 };
  97
  98 struct vhost_net {
  99         struct vhost_dev dev;
 100         struct vhost_net_virtqueue vqs[VHOST_NET_VQ_MAX];
 101         struct vhost_poll poll[VHOST_NET_VQ_MAX];
 102         /* Number of TX recently submitted.
 103          * Protected by tx vq lock. */
 104         unsigned tx_packets;
 105         /* Number of times zerocopy TX recently failed.
 106          * Protected by tx vq lock. */
 107         unsigned tx_zcopy_err;
 108         /* Flush in progress. Protected by tx vq lock. */
 109         bool tx_flush;
 110 };
 111
 112 static unsigned vhost_net_zcopy_mask __read_mostly;
 113
 114 static void vhost_net_enable_zcopy(int vq)
 115 {
 116         vhost_net_zcopy_mask |= 0x1 << vq;
 117 }
 118
 119 static void vhost_net_zerocopy_done_signal(struct kref *kref)
 120 {
 121         struct vhost_net_ubuf_ref *ubufs;
 122
 123         ubufs = container_of(kref, struct vhost_net_ubuf_ref, kref);
 124         wake_up(&ubufs->wait);
 125 }
 126
 127 static struct vhost_net_ubuf_ref *
 128 vhost_net_ubuf_alloc(struct vhost_virtqueue *vq, bool zcopy)
 129 {
 130         struct vhost_net_ubuf_ref *ubufs;
 131         /* No zero copy backend? Nothing to count. */
 132         if (!zcopy)
 133                 return NULL;
 134         ubufs = kmalloc(sizeof(*ubufs), GFP_KERNEL);
 135         if (!ubufs)
 136                 return ERR_PTR(-ENOMEM);
 137         kref_init(&ubufs->kref);
 138         init_waitqueue_head(&ubufs->wait);
 139         ubufs->vq = vq;
 140         return ubufs;
 141 }
 142
 143 static void vhost_net_ubuf_put(struct vhost_net_ubuf_ref *ubufs)
 144 {
 145         kref_put(&ubufs->kref, vhost_net_zerocopy_done_signal);
 146 }
 147
 148 static void vhost_net_ubuf_put_and_wait(struct vhost_net_ubuf_ref *ubufs)
 149 {
 150         kref_put(&ubufs->kref, vhost_net_zerocopy_done_signal);
 151         wait_event(ubufs->wait, !atomic_read(&ubufs->kref.refcount));
 152 }
 153
 154 static void vhost_net_ubuf_put_wait_and_free(struct vhost_net_ubuf_ref *ubufs)
 155 {
 156         vhost_net_ubuf_put_and_wait(ubufs);
 157         kfree(ubufs);
 158 }
 159
 160 static void vhost_net_clear_ubuf_info(struct vhost_net *n)
 161 {
 162         int i;
 163
 164         for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
 165                 kfree(n->vqs[i].ubuf_info);
 166                 n->vqs[i].ubuf_info = NULL;
 167         }
 168 }
 169
 170 static int vhost_net_set_ubuf_info(struct vhost_net *n)
 171 {
 172         bool zcopy;
 173         int i;
 174
 175         for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
 176                 zcopy = vhost_net_zcopy_mask & (0x1 << i);
 177                 if (!zcopy)
 178                         continue;
 179                 n->vqs[i].ubuf_info = kmalloc(sizeof(*n->vqs[i].ubuf_info) *
 180                                               UIO_MAXIOV, GFP_KERNEL);
 181                 if  (!n->vqs[i].ubuf_info)
 182                         goto err;
 183         }
 184         return 0;
 185
 186 err:
 187         vhost_net_clear_ubuf_info(n);
 188         return -ENOMEM;
 189 }
 190
 191 static void vhost_net_vq_reset(struct vhost_net *n)
 192 {
 193         int i;
 194
 195         vhost_net_clear_ubuf_info(n);
 196
 197         for (i = 0; i < VHOST_NET_VQ_MAX; i++) {
 198                 n->vqs[i].done_idx = 0;
 199                 n->vqs[i].upend_idx = 0;
 200                 n->vqs[i].ubufs = NULL;
 201                 n->vqs[i].vhost_hlen = 0;
 202                 n->vqs[i].sock_hlen = 0;
 203         }
 204
 205 }
 206
 207 static void vhost_net_tx_packet(struct vhost_net *net)
 208 {
 209         ++net->tx_packets;
 210         if (net->tx_packets < 1024)
 211                 return;
 212         net->tx_packets = 0;
 213         net->tx_zcopy_err = 0;
 214 }
 215
 216 static void vhost_net_tx_err(struct vhost_net *net)
 217 {
 218         ++net->tx_zcopy_err;
 219 }
 220
 221 static bool vhost_net_tx_select_zcopy(struct vhost_net *net)
 222 {
 223         /* TX flush waits for outstanding DMAs to be done.
 224          * Don't start new DMAs.
 225          */
 226         return !net->tx_flush &&
 227                 net->tx_packets / 64 >= net->tx_zcopy_err;
 228 }
 229
 230 static bool vhost_sock_zcopy(struct socket *sock)
 231 {
 232         return unlikely(experimental_zcopytx) &&
 233                 sock_flag(sock->sk, SOCK_ZEROCOPY);
 234 }
 235
 236 /* Pop first len bytes from iovec. Return number of segments used. */
 237 static int move_iovec_hdr(struct iovec *from, struct iovec *to,
 238                           size_t len, int iov_count)
 239 {
 240         int seg = 0;
 241         size_t size;
 242
 243         while (len && seg < iov_count) {
 244                 size = min(from->iov_len, len);
 245                 to->iov_base = from->iov_base;
 246                 to->iov_len = size;
 247                 from->iov_len -= size;
 248                 from->iov_base += size;
 249                 len -= size;
 250                 ++from;
 251                 ++to;
 252                 ++seg;
 253         }
 254         return seg;
 255 }
 256 /* Copy iovec entries for len bytes from iovec. */
 257 static void copy_iovec_hdr(const struct iovec *from, struct iovec *to,
 258                            size_t len, int iovcount)
 259 {
 260         int seg = 0;
 261         size_t size;
 262
 263         while (len && seg < iovcount) {
 264                 size = min(from->iov_len, len);
 265                 to->iov_base = from->iov_base;
 266                 to->iov_len = size;
 267                 len -= size;
 268                 ++from;
 269                 ++to;
 270                 ++seg;
 271         }
 272 }
 273
 274 /* In case of DMA done not in order in lower device driver for some reason.
 275  * upend_idx is used to track end of used idx, done_idx is used to track head
 276  * of used idx. Once lower device DMA done contiguously, we will signal KVM
 277  * guest used idx.
 278  */
 279 static void vhost_zerocopy_signal_used(struct vhost_net *net,
 280                                        struct vhost_virtqueue *vq)
 281 {
 282         struct vhost_net_virtqueue *nvq =
 283                 container_of(vq, struct vhost_net_virtqueue, vq);
 284         int i, add;
 285         int j = 0;
 286
 287         for (i = nvq->done_idx; i != nvq->upend_idx; i = (i + 1) % UIO_MAXIOV) {
 288                 if (vq->heads[i].len == VHOST_DMA_FAILED_LEN)
 289                         vhost_net_tx_err(net);
 290                 if (VHOST_DMA_IS_DONE(vq->heads[i].len)) {
 291                         vq->heads[i].len = VHOST_DMA_CLEAR_LEN;
 292                         ++j;
 293                 } else
 294                         break;
 295         }
 296         while (j) {
 297                 add = min(UIO_MAXIOV - nvq->done_idx, j);
 298                 vhost_add_used_and_signal_n(vq->dev, vq,
 299                                             &vq->heads[nvq->done_idx], add);
 300                 nvq->done_idx = (nvq->done_idx + add) % UIO_MAXIOV;
 301                 j -= add;
 302         }
 303 }
 304
 305 static void vhost_zerocopy_callback(struct ubuf_info *ubuf, bool success)
 306 {
 307         struct vhost_net_ubuf_ref *ubufs = ubuf->ctx;
 308         struct vhost_virtqueue *vq = ubufs->vq;
 309         int cnt = atomic_read(&ubufs->kref.refcount);
 310
 311         /*
 312          * Trigger polling thread if guest stopped submitting new buffers:
 313          * in this case, the refcount after decrement will eventually reach 1
 314          * so here it is 2.
 315          * We also trigger polling periodically after each 16 packets
 316          * (the value 16 here is more or less arbitrary, it's tuned to trigger
 317          * less than 10% of times).
 318          */
 319         if (cnt <= 2 || !(cnt % 16))
 320                 vhost_poll_queue(&vq->poll);
 321         /* set len to mark this desc buffers done DMA */
 322         vq->heads[ubuf->desc].len = success ?
 323                 VHOST_DMA_DONE_LEN : VHOST_DMA_FAILED_LEN;
 324         vhost_net_ubuf_put(ubufs);
 325 }
 326
 327 /* Expects to be always run from workqueue - which acts as
 328  * read-size critical section for our kind of RCU. */
 329 static void handle_tx(struct vhost_net *net)
 330 {
 331         struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_TX];
 332         struct vhost_virtqueue *vq = &nvq->vq;
 333         unsigned out, in, s;
 334         int head;
 335         struct msghdr msg = {
 336                 .msg_name = NULL,
 337                 .msg_namelen = 0,
 338                 .msg_control = NULL,
 339                 .msg_controllen = 0,
 340                 .msg_iov = vq->iov,
 341                 .msg_flags = MSG_DONTWAIT,
 342         };
 343         size_t len, total_len = 0;
 344         int err;
 345         size_t hdr_size;
 346         struct socket *sock;
 347         struct vhost_net_ubuf_ref *uninitialized_var(ubufs);
 348         bool zcopy, zcopy_used;
 349
 350         mutex_lock(&vq->mutex);
 351         sock = vq->private_data;
 352         if (!sock)
 353                 goto out;
 354
 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
 408                 zcopy_used = zcopy && len >= VHOST_GOODCOPY_LEN
 409                                    && (nvq->upend_idx + 1) % UIO_MAXIOV !=
 410                                       nvq->done_idx
 411                                    && vhost_net_tx_select_zcopy(net);
 412
 413                 /* use msg_control to pass vhost zerocopy ubuf info to skb */
 414                 if (zcopy_used) {
 415                         struct ubuf_info *ubuf;
 416                         ubuf = nvq->ubuf_info + nvq->upend_idx;
 417
 418                         vq->heads[nvq->upend_idx].id = head;
 419                         vq->heads[nvq->upend_idx].len = VHOST_DMA_IN_PROGRESS;
 420                         ubuf->callback = vhost_zerocopy_callback;
 421                         ubuf->ctx = nvq->ubufs;
 422                         ubuf->desc = nvq->upend_idx;
 423                         msg.msg_control = ubuf;
 424                         msg.msg_controllen = sizeof(ubuf);
 425                         ubufs = nvq->ubufs;
 426                         kref_get(&ubufs->kref);
 427                         nvq->upend_idx = (nvq->upend_idx + 1) % UIO_MAXIOV;
 428                 } else {
 429                         msg.msg_control = NULL;
 430                         ubufs = NULL;
 431                 }
 432                 /* TODO: Check specific error and bomb out unless ENOBUFS? */
 433                 err = sock->ops->sendmsg(NULL, sock, &msg, len);
 434                 if (unlikely(err < 0)) {
 435                         if (zcopy_used) {
 436                                 vhost_net_ubuf_put(ubufs);
 437                                 nvq->upend_idx = ((unsigned)nvq->upend_idx - 1)
 438                                         % UIO_MAXIOV;
 439                         }
 440                         vhost_discard_vq_desc(vq, 1);
 441                         break;
 442                 }
 443                 if (err != len)
 444                         pr_debug("Truncated TX packet: "
 445                                  " len %d != %zd\n", err, len);
 446                 if (!zcopy_used)
 447                         vhost_add_used_and_signal(&net->dev, vq, head, 0);
 448                 else
 449                         vhost_zerocopy_signal_used(net, vq);
 450                 total_len += len;
 451                 vhost_net_tx_packet(net);
 452                 if (unlikely(total_len >= VHOST_NET_WEIGHT)) {
 453                         vhost_poll_queue(&vq->poll);
 454                         break;
 455                 }
 456         }
 457 out:
 458         mutex_unlock(&vq->mutex);
 459 }
 460
 461 static int peek_head_len(struct sock *sk)
 462 {
 463         struct sk_buff *head;
 464         int len = 0;
 465         unsigned long flags;
 466
 467         spin_lock_irqsave(&sk->sk_receive_queue.lock, flags);
 468         head = skb_peek(&sk->sk_receive_queue);
 469         if (likely(head)) {
 470                 len = head->len;
 471                 if (vlan_tx_tag_present(head))
 472                         len += VLAN_HLEN;
 473         }
 474
 475         spin_unlock_irqrestore(&sk->sk_receive_queue.lock, flags);
 476         return len;
 477 }
 478
 479 /* This is a multi-buffer version of vhost_get_desc, that works if
 480  *      vq has read descriptors only.
 481  * @vq          - the relevant virtqueue
 482  * @datalen     - data length we'll be reading
 483  * @iovcount    - returned count of io vectors we fill
 484  * @log         - vhost log
 485  * @log_num     - log offset
 486  * @quota       - headcount quota, 1 for big buffer
 487  *      returns number of buffer heads allocated, negative on error
 488  */
 489 static int get_rx_bufs(struct vhost_virtqueue *vq,
 490                        struct vring_used_elem *heads,
 491                        int datalen,
 492                        unsigned *iovcount,
 493                        struct vhost_log *log,
 494                        unsigned *log_num,
 495                        unsigned int quota)
 496 {
 497         unsigned int out, in;
 498         int seg = 0;
 499         int headcount = 0;
 500         unsigned d;
 501         int r, nlogs = 0;
 502
 503         while (datalen > 0 && headcount < quota) {
 504                 if (unlikely(seg >= UIO_MAXIOV)) {
 505                         r = -ENOBUFS;
 506                         goto err;
 507                 }
 508                 d = vhost_get_vq_desc(vq->dev, vq, vq->iov + seg,
 509                                       ARRAY_SIZE(vq->iov) - seg, &out,
 510                                       &in, log, log_num);
 511                 if (d == vq->num) {
 512                         r = 0;
 513                         goto err;
 514                 }
 515                 if (unlikely(out || in <= 0)) {
 516                         vq_err(vq, "unexpected descriptor format for RX: "
 517                                 "out %d, in %d\n", out, in);
 518                         r = -EINVAL;
 519                         goto err;
 520                 }
 521                 if (unlikely(log)) {
 522                         nlogs += *log_num;
 523                         log += *log_num;
 524                 }
 525                 heads[headcount].id = d;
 526                 heads[headcount].len = iov_length(vq->iov + seg, in);
 527                 datalen -= heads[headcount].len;
 528                 ++headcount;
 529                 seg += in;
 530         }
 531         heads[headcount - 1].len += datalen;
 532         *iovcount = seg;
 533         if (unlikely(log))
 534                 *log_num = nlogs;
 535         return headcount;
 536 err:
 537         vhost_discard_vq_desc(vq, headcount);
 538         return r;
 539 }
 540
 541 /* Expects to be always run from workqueue - which acts as
 542  * read-size critical section for our kind of RCU. */
 543 static void handle_rx(struct vhost_net *net)
 544 {
 545         struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_RX];
 546         struct vhost_virtqueue *vq = &nvq->vq;
 547         unsigned uninitialized_var(in), log;
 548         struct vhost_log *vq_log;
 549         struct msghdr msg = {
 550                 .msg_name = NULL,
 551                 .msg_namelen = 0,
 552                 .msg_control = NULL, /* FIXME: get and handle RX aux data. */
 553                 .msg_controllen = 0,
 554                 .msg_iov = vq->iov,
 555                 .msg_flags = MSG_DONTWAIT,
 556         };
 557         struct virtio_net_hdr_mrg_rxbuf hdr = {
 558                 .hdr.flags = 0,
 559                 .hdr.gso_type = VIRTIO_NET_HDR_GSO_NONE
 560         };
 561         size_t total_len = 0;
 562         int err, mergeable;
 563         s16 headcount;
 564         size_t vhost_hlen, sock_hlen;
 565         size_t vhost_len, sock_len;
 566         struct socket *sock;
 567
 568         mutex_lock(&vq->mutex);
 569         sock = vq->private_data;
 570         if (!sock)
 571                 goto out;
 572         vhost_disable_notify(&net->dev, vq);
 573
 574         vhost_hlen = nvq->vhost_hlen;
 575         sock_hlen = nvq->sock_hlen;
 576
 577         vq_log = unlikely(vhost_has_feature(&net->dev, VHOST_F_LOG_ALL)) ?
 578                 vq->log : NULL;
 579         mergeable = vhost_has_feature(&net->dev, VIRTIO_NET_F_MRG_RXBUF);
 580
 581         while ((sock_len = peek_head_len(sock->sk))) {
 582                 sock_len += sock_hlen;
 583                 vhost_len = sock_len + vhost_hlen;
 584                 headcount = get_rx_bufs(vq, vq->heads, vhost_len,
 585                                         &in, vq_log, &log,
 586                                         likely(mergeable) ? UIO_MAXIOV : 1);
 587                 /* On error, stop handling until the next kick. */
 588                 if (unlikely(headcount < 0))
 589                         break;
 590                 /* OK, now we need to know about added descriptors. */
 591                 if (!headcount) {
 592                         if (unlikely(vhost_enable_notify(&net->dev, vq))) {
 593                                 /* They have slipped one in as we were
 594                                  * doing that: check again. */
 595                                 vhost_disable_notify(&net->dev, vq);
 596                                 continue;
 597                         }
 598                         /* Nothing new?  Wait for eventfd to tell us
 599                          * they refilled. */
 600                         break;
 601                 }
 602                 /* We don't need to be notified again. */
 603                 if (unlikely((vhost_hlen)))
 604                         /* Skip header. TODO: support TSO. */
 605                         move_iovec_hdr(vq->iov, nvq->hdr, vhost_hlen, in);
 606                 else
 607                         /* Copy the header for use in VIRTIO_NET_F_MRG_RXBUF:
 608                          * needed because recvmsg can modify msg_iov. */
 609                         copy_iovec_hdr(vq->iov, nvq->hdr, sock_hlen, in);
 610                 msg.msg_iovlen = in;
 611                 err = sock->ops->recvmsg(NULL, sock, &msg,
 612                                          sock_len, MSG_DONTWAIT | MSG_TRUNC);
 613                 /* Userspace might have consumed the packet meanwhile:
 614                  * it's not supposed to do this usually, but might be hard
 615                  * to prevent. Discard data we got (if any) and keep going. */
 616                 if (unlikely(err != sock_len)) {
 617                         pr_debug("Discarded rx packet: "
 618                                  " len %d, expected %zd\n", err, sock_len);
 619                         vhost_discard_vq_desc(vq, headcount);
 620                         continue;
 621                 }
 622                 if (unlikely(vhost_hlen) &&
 623                     memcpy_toiovecend(nvq->hdr, (unsigned char *)&hdr, 0,
 624                                       vhost_hlen)) {
 625                         vq_err(vq, "Unable to write vnet_hdr at addr %p\n",
 626                                vq->iov->iov_base);
 627                         break;
 628                 }
 629                 /* TODO: Should check and handle checksum. */
 630                 if (likely(mergeable) &&
 631                     memcpy_toiovecend(nvq->hdr, (unsigned char *)&headcount,
 632                                       offsetof(typeof(hdr), num_buffers),
 633                                       sizeof hdr.num_buffers)) {
 634                         vq_err(vq, "Failed num_buffers write");
 635                         vhost_discard_vq_desc(vq, headcount);
 636                         break;
 637                 }
 638                 vhost_add_used_and_signal_n(&net->dev, vq, vq->heads,
 639                                             headcount);
 640                 if (unlikely(vq_log))
 641                         vhost_log_write(vq, vq_log, log, vhost_len);
 642                 total_len += vhost_len;
 643                 if (unlikely(total_len >= VHOST_NET_WEIGHT)) {
 644                         vhost_poll_queue(&vq->poll);
 645                         break;
 646                 }
 647         }
 648 out:
 649         mutex_unlock(&vq->mutex);
 650 }
 651
 652 static void handle_tx_kick(struct vhost_work *work)
 653 {
 654         struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
 655                                                   poll.work);
 656         struct vhost_net *net = container_of(vq->dev, struct vhost_net, dev);
 657
 658         handle_tx(net);
 659 }
 660
 661 static void handle_rx_kick(struct vhost_work *work)
 662 {
 663         struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
 664                                                   poll.work);
 665         struct vhost_net *net = container_of(vq->dev, struct vhost_net, dev);
 666
 667         handle_rx(net);
 668 }
 669
 670 static void handle_tx_net(struct vhost_work *work)
 671 {
 672         struct vhost_net *net = container_of(work, struct vhost_net,
 673                                              poll[VHOST_NET_VQ_TX].work);
 674         handle_tx(net);
 675 }
 676
 677 static void handle_rx_net(struct vhost_work *work)
 678 {
 679         struct vhost_net *net = container_of(work, struct vhost_net,
 680                                              poll[VHOST_NET_VQ_RX].work);
 681         handle_rx(net);
 682 }
 683
 684 static int vhost_net_open(struct inode *inode, struct file *f)
 685 {
 686         struct vhost_net *n = kmalloc(sizeof *n, GFP_KERNEL);
 687         struct vhost_dev *dev;
 688         struct vhost_virtqueue **vqs;
 689         int r, i;
 690
 691         if (!n)
 692                 return -ENOMEM;
 693         vqs = kmalloc(VHOST_NET_VQ_MAX * sizeof(*vqs), GFP_KERNEL);
 694         if (!vqs) {
 695                 kfree(n);
 696                 return -ENOMEM;
 697         }
 698
 699         dev = &n->dev;
 700         vqs[VHOST_NET_VQ_TX] = &n->vqs[VHOST_NET_VQ_TX].vq;
 701         vqs[VHOST_NET_VQ_RX] = &n->vqs[VHOST_NET_VQ_RX].vq;
 702         n->vqs[VHOST_NET_VQ_TX].vq.handle_kick = handle_tx_kick;
 703         n->vqs[VHOST_NET_VQ_RX].vq.handle_kick = handle_rx_kick;
 704         for (i = 0; i < VHOST_NET_VQ_MAX; i++) {
 705                 n->vqs[i].ubufs = NULL;
 706                 n->vqs[i].ubuf_info = NULL;
 707                 n->vqs[i].upend_idx = 0;
 708                 n->vqs[i].done_idx = 0;
 709                 n->vqs[i].vhost_hlen = 0;
 710                 n->vqs[i].sock_hlen = 0;
 711         }
 712         r = vhost_dev_init(dev, vqs, VHOST_NET_VQ_MAX);
 713         if (r < 0) {
 714                 kfree(n);
 715                 kfree(vqs);
 716                 return r;
 717         }
 718
 719         vhost_poll_init(n->poll + VHOST_NET_VQ_TX, handle_tx_net, POLLOUT, dev);
 720         vhost_poll_init(n->poll + VHOST_NET_VQ_RX, handle_rx_net, POLLIN, dev);
 721
 722         f->private_data = n;
 723
 724         return 0;
 725 }
 726
 727 static void vhost_net_disable_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         if (!vq->private_data)
 734                 return;
 735         vhost_poll_stop(poll);
 736 }
 737
 738 static int vhost_net_enable_vq(struct vhost_net *n,
 739                                 struct vhost_virtqueue *vq)
 740 {
 741         struct vhost_net_virtqueue *nvq =
 742                 container_of(vq, struct vhost_net_virtqueue, vq);
 743         struct vhost_poll *poll = n->poll + (nvq - n->vqs);
 744         struct socket *sock;
 745
 746         sock = vq->private_data;
 747         if (!sock)
 748                 return 0;
 749
 750         return vhost_poll_start(poll, sock->file);
 751 }
 752
 753 static struct socket *vhost_net_stop_vq(struct vhost_net *n,
 754                                         struct vhost_virtqueue *vq)
 755 {
 756         struct socket *sock;
 757
 758         mutex_lock(&vq->mutex);
 759         sock = vq->private_data;
 760         vhost_net_disable_vq(n, vq);
 761         vq->private_data = NULL;
 762         mutex_unlock(&vq->mutex);
 763         return sock;
 764 }
 765
 766 static void vhost_net_stop(struct vhost_net *n, struct socket **tx_sock,
 767                            struct socket **rx_sock)
 768 {
 769         *tx_sock = vhost_net_stop_vq(n, &n->vqs[VHOST_NET_VQ_TX].vq);
 770         *rx_sock = vhost_net_stop_vq(n, &n->vqs[VHOST_NET_VQ_RX].vq);
 771 }
 772
 773 static void vhost_net_flush_vq(struct vhost_net *n, int index)
 774 {
 775         vhost_poll_flush(n->poll + index);
 776         vhost_poll_flush(&n->vqs[index].vq.poll);
 777 }
 778
 779 static void vhost_net_flush(struct vhost_net *n)
 780 {
 781         vhost_net_flush_vq(n, VHOST_NET_VQ_TX);
 782         vhost_net_flush_vq(n, VHOST_NET_VQ_RX);
 783         if (n->vqs[VHOST_NET_VQ_TX].ubufs) {
 784                 mutex_lock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
 785                 n->tx_flush = true;
 786                 mutex_unlock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
 787                 /* Wait for all lower device DMAs done. */
 788                 vhost_net_ubuf_put_and_wait(n->vqs[VHOST_NET_VQ_TX].ubufs);
 789                 mutex_lock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
 790                 n->tx_flush = false;
 791                 kref_init(&n->vqs[VHOST_NET_VQ_TX].ubufs->kref);
 792                 mutex_unlock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
 793         }
 794 }
 795
 796 static int vhost_net_release(struct inode *inode, struct file *f)
 797 {
 798         struct vhost_net *n = f->private_data;
 799         struct socket *tx_sock;
 800         struct socket *rx_sock;
 801
 802         vhost_net_stop(n, &tx_sock, &rx_sock);
 803         vhost_net_flush(n);
 804         vhost_dev_stop(&n->dev);
 805         vhost_dev_cleanup(&n->dev, false);
 806         vhost_net_vq_reset(n);
 807         if (tx_sock)
 808                 fput(tx_sock->file);
 809         if (rx_sock)
 810                 fput(rx_sock->file);
 811         /* We do an extra flush before freeing memory,
 812          * since jobs can re-queue themselves. */
 813         vhost_net_flush(n);
 814         kfree(n->dev.vqs);
 815         kfree(n);
 816         return 0;
 817 }
 818
 819 static struct socket *get_raw_socket(int fd)
 820 {
 821         struct {
 822                 struct sockaddr_ll sa;
 823                 char  buf[MAX_ADDR_LEN];
 824         } uaddr;
 825         int uaddr_len = sizeof uaddr, r;
 826         struct socket *sock = sockfd_lookup(fd, &r);
 827
 828         if (!sock)
 829                 return ERR_PTR(-ENOTSOCK);
 830
 831         /* Parameter checking */
 832         if (sock->sk->sk_type != SOCK_RAW) {
 833                 r = -ESOCKTNOSUPPORT;
 834                 goto err;
 835         }
 836
 837         r = sock->ops->getname(sock, (struct sockaddr *)&uaddr.sa,
 838                                &uaddr_len, 0);
 839         if (r)
 840                 goto err;
 841
 842         if (uaddr.sa.sll_family != AF_PACKET) {
 843                 r = -EPFNOSUPPORT;
 844                 goto err;
 845         }
 846         return sock;
 847 err:
 848         fput(sock->file);
 849         return ERR_PTR(r);
 850 }
 851
 852 static struct socket *get_tap_socket(int fd)
 853 {
 854         struct file *file = fget(fd);
 855         struct socket *sock;
 856
 857         if (!file)
 858                 return ERR_PTR(-EBADF);
 859         sock = tun_get_socket(file);
 860         if (!IS_ERR(sock))
 861                 return sock;
 862         sock = macvtap_get_socket(file);
 863         if (IS_ERR(sock))
 864                 fput(file);
 865         return sock;
 866 }
 867
 868 static struct socket *get_socket(int fd)
 869 {
 870         struct socket *sock;
 871
 872         /* special case to disable backend */
 873         if (fd == -1)
 874                 return NULL;
 875         sock = get_raw_socket(fd);
 876         if (!IS_ERR(sock))
 877                 return sock;
 878         sock = get_tap_socket(fd);
 879         if (!IS_ERR(sock))
 880                 return sock;
 881         return ERR_PTR(-ENOTSOCK);
 882 }
 883
 884 static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd)
 885 {
 886         struct socket *sock, *oldsock;
 887         struct vhost_virtqueue *vq;
 888         struct vhost_net_virtqueue *nvq;
 889         struct vhost_net_ubuf_ref *ubufs, *oldubufs = NULL;
 890         int r;
 891
 892         mutex_lock(&n->dev.mutex);
 893         r = vhost_dev_check_owner(&n->dev);
 894         if (r)
 895                 goto err;
 896
 897         if (index >= VHOST_NET_VQ_MAX) {
 898                 r = -ENOBUFS;
 899                 goto err;
 900         }
 901         vq = &n->vqs[index].vq;
 902         nvq = &n->vqs[index];
 903         mutex_lock(&vq->mutex);
 904
 905         /* Verify that ring has been setup correctly. */
 906         if (!vhost_vq_access_ok(vq)) {
 907                 r = -EFAULT;
 908                 goto err_vq;
 909         }
 910         sock = get_socket(fd);
 911         if (IS_ERR(sock)) {
 912                 r = PTR_ERR(sock);
 913                 goto err_vq;
 914         }
 915
 916         /* start polling new socket */
 917         oldsock = vq->private_data;
 918         if (sock != oldsock) {
 919                 ubufs = vhost_net_ubuf_alloc(vq,
 920                                              sock && vhost_sock_zcopy(sock));
 921                 if (IS_ERR(ubufs)) {
 922                         r = PTR_ERR(ubufs);
 923                         goto err_ubufs;
 924                 }
 925
 926                 vhost_net_disable_vq(n, vq);
 927                 vq->private_data = sock;
 928                 r = vhost_init_used(vq);
 929                 if (r)
 930                         goto err_used;
 931                 r = vhost_net_enable_vq(n, vq);
 932                 if (r)
 933                         goto err_used;
 934
 935                 oldubufs = nvq->ubufs;
 936                 nvq->ubufs = ubufs;
 937
 938                 n->tx_packets = 0;
 939                 n->tx_zcopy_err = 0;
 940                 n->tx_flush = false;
 941         }
 942
 943         mutex_unlock(&vq->mutex);
 944
 945         if (oldubufs) {
 946                 vhost_net_ubuf_put_wait_and_free(oldubufs);
 947                 mutex_lock(&vq->mutex);
 948                 vhost_zerocopy_signal_used(n, vq);
 949                 mutex_unlock(&vq->mutex);
 950         }
 951
 952         if (oldsock) {
 953                 vhost_net_flush_vq(n, index);
 954                 fput(oldsock->file);
 955         }
 956
 957         mutex_unlock(&n->dev.mutex);
 958         return 0;
 959
 960 err_used:
 961         vq->private_data = oldsock;
 962         vhost_net_enable_vq(n, vq);
 963         if (ubufs)
 964                 vhost_net_ubuf_put_wait_and_free(ubufs);
 965 err_ubufs:
 966         fput(sock->file);
 967 err_vq:
 968         mutex_unlock(&vq->mutex);
 969 err:
 970         mutex_unlock(&n->dev.mutex);
 971         return r;
 972 }
 973
 974 static long vhost_net_reset_owner(struct vhost_net *n)
 975 {
 976         struct socket *tx_sock = NULL;
 977         struct socket *rx_sock = NULL;
 978         long err;
 979         struct vhost_memory *memory;
 980
 981         mutex_lock(&n->dev.mutex);
 982         err = vhost_dev_check_owner(&n->dev);
 983         if (err)
 984                 goto done;
 985         memory = vhost_dev_reset_owner_prepare();
 986         if (!memory) {
 987                 err = -ENOMEM;
 988                 goto done;
 989         }
 990         vhost_net_stop(n, &tx_sock, &rx_sock);
 991         vhost_net_flush(n);
 992         vhost_dev_reset_owner(&n->dev, memory);
 993         vhost_net_vq_reset(n);
 994 done:
 995         mutex_unlock(&n->dev.mutex);
 996         if (tx_sock)
 997                 fput(tx_sock->file);
 998         if (rx_sock)
 999                 fput(rx_sock->file);
1000         return err;
1001 }
1002
1003 static int vhost_net_set_features(struct vhost_net *n, u64 features)
1004 {
1005         size_t vhost_hlen, sock_hlen, hdr_len;
1006         int i;
1007
1008         hdr_len = (features & (1 << VIRTIO_NET_F_MRG_RXBUF)) ?
1009                         sizeof(struct virtio_net_hdr_mrg_rxbuf) :
1010                         sizeof(struct virtio_net_hdr);
1011         if (features & (1 << VHOST_NET_F_VIRTIO_NET_HDR)) {
1012                 /* vhost provides vnet_hdr */
1013                 vhost_hlen = hdr_len;
1014                 sock_hlen = 0;
1015         } else {
1016                 /* socket provides vnet_hdr */
1017                 vhost_hlen = 0;
1018                 sock_hlen = hdr_len;
1019         }
1020         mutex_lock(&n->dev.mutex);
1021         if ((features & (1 << VHOST_F_LOG_ALL)) &&
1022             !vhost_log_access_ok(&n->dev)) {
1023                 mutex_unlock(&n->dev.mutex);
1024                 return -EFAULT;
1025         }
1026         n->dev.acked_features = features;
1027         smp_wmb();
1028         for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
1029                 mutex_lock(&n->vqs[i].vq.mutex);
1030                 n->vqs[i].vhost_hlen = vhost_hlen;
1031                 n->vqs[i].sock_hlen = sock_hlen;
1032                 mutex_unlock(&n->vqs[i].vq.mutex);
1033         }
1034         vhost_net_flush(n);
1035         mutex_unlock(&n->dev.mutex);
1036         return 0;
1037 }
1038
1039 static long vhost_net_set_owner(struct vhost_net *n)
1040 {
1041         int r;
1042
1043         mutex_lock(&n->dev.mutex);
1044         if (vhost_dev_has_owner(&n->dev)) {
1045                 r = -EBUSY;
1046                 goto out;
1047         }
1048         r = vhost_net_set_ubuf_info(n);
1049         if (r)
1050                 goto out;
1051         r = vhost_dev_set_owner(&n->dev);
1052         if (r)
1053                 vhost_net_clear_ubuf_info(n);
1054         vhost_net_flush(n);
1055 out:
1056         mutex_unlock(&n->dev.mutex);
1057         return r;
1058 }
1059
1060 static long vhost_net_ioctl(struct file *f, unsigned int ioctl,
1061                             unsigned long arg)
1062 {
1063         struct vhost_net *n = f->private_data;
1064         void __user *argp = (void __user *)arg;
1065         u64 __user *featurep = argp;
1066         struct vhost_vring_file backend;
1067         u64 features;
1068         int r;
1069
1070         switch (ioctl) {
1071         case VHOST_NET_SET_BACKEND:
1072                 if (copy_from_user(&backend, argp, sizeof backend))
1073                         return -EFAULT;
1074                 return vhost_net_set_backend(n, backend.index, backend.fd);
1075         case VHOST_GET_FEATURES:
1076                 features = VHOST_NET_FEATURES;
1077                 if (copy_to_user(featurep, &features, sizeof features))
1078                         return -EFAULT;
1079                 return 0;
1080         case VHOST_SET_FEATURES:
1081                 if (copy_from_user(&features, featurep, sizeof features))
1082                         return -EFAULT;
1083                 if (features & ~VHOST_NET_FEATURES)
1084                         return -EOPNOTSUPP;
1085                 return vhost_net_set_features(n, features);
1086         case VHOST_RESET_OWNER:
1087                 return vhost_net_reset_owner(n);
1088         case VHOST_SET_OWNER:
1089                 return vhost_net_set_owner(n);
1090         default:
1091                 mutex_lock(&n->dev.mutex);
1092                 r = vhost_dev_ioctl(&n->dev, ioctl, argp);
1093                 if (r == -ENOIOCTLCMD)
1094                         r = vhost_vring_ioctl(&n->dev, ioctl, argp);
1095                 else
1096                         vhost_net_flush(n);
1097                 mutex_unlock(&n->dev.mutex);
1098                 return r;
1099         }
1100 }
1101
1102 #ifdef CONFIG_COMPAT
1103 static long vhost_net_compat_ioctl(struct file *f, unsigned int ioctl,
1104                                    unsigned long arg)
1105 {
1106         return vhost_net_ioctl(f, ioctl, (unsigned long)compat_ptr(arg));
1107 }
1108 #endif
1109
1110 static const struct file_operations vhost_net_fops = {
1111         .owner          = THIS_MODULE,
1112         .release        = vhost_net_release,
1113         .unlocked_ioctl = vhost_net_ioctl,
1114 #ifdef CONFIG_COMPAT
1115         .compat_ioctl   = vhost_net_compat_ioctl,
1116 #endif
1117         .open           = vhost_net_open,
1118         .llseek         = noop_llseek,
1119 };
1120
1121 static struct miscdevice vhost_net_misc = {
1122         .minor = VHOST_NET_MINOR,
1123         .name = "vhost-net",
1124         .fops = &vhost_net_fops,
1125 };
1126
1127 static int vhost_net_init(void)
1128 {
1129         if (experimental_zcopytx)
1130                 vhost_net_enable_zcopy(VHOST_NET_VQ_TX);
1131         return misc_register(&vhost_net_misc);
1132 }
1133 module_init(vhost_net_init);
1134
1135 static void vhost_net_exit(void)
1136 {
1137         misc_deregister(&vhost_net_misc);
1138 }
1139 module_exit(vhost_net_exit);
1140
1141 MODULE_VERSION("0.0.1");
1142 MODULE_LICENSE("GPL v2");
1143 MODULE_AUTHOR("Michael S. Tsirkin");
1144 MODULE_DESCRIPTION("Host kernel accelerator for virtio net");
1145 MODULE_ALIAS_MISCDEV(VHOST_NET_MINOR);
1146 MODULE_ALIAS("devname:vhost-net");