linux/drivers/vhost/net.c
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   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
  32static int experimental_zcopytx = 1;
  33module_param(experimental_zcopytx, int, 0444);
  34MODULE_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
  60enum {
  61        VHOST_NET_FEATURES = VHOST_FEATURES |
  62                         (1ULL << VHOST_NET_F_VIRTIO_NET_HDR) |
  63                         (1ULL << VIRTIO_NET_F_MRG_RXBUF),
  64};
  65
  66enum {
  67        VHOST_NET_VQ_RX = 0,
  68        VHOST_NET_VQ_TX = 1,
  69        VHOST_NET_VQ_MAX = 2,
  70};
  71
  72struct vhost_net_ubuf_ref {
  73        struct kref kref;
  74        wait_queue_head_t wait;
  75        struct vhost_virtqueue *vq;
  76};
  77
  78struct 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
  98struct 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
 112static unsigned vhost_net_zcopy_mask __read_mostly;
 113
 114static void vhost_net_enable_zcopy(int vq)
 115{
 116        vhost_net_zcopy_mask |= 0x1 << vq;
 117}
 118
 119static 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
 127static struct vhost_net_ubuf_ref *
 128vhost_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
 143static void vhost_net_ubuf_put(struct vhost_net_ubuf_ref *ubufs)
 144{
 145        kref_put(&ubufs->kref, vhost_net_zerocopy_done_signal);
 146}
 147
 148static 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
 154static 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
 160static 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
 170static 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
 186err:
 187        vhost_net_clear_ubuf_info(n);
 188        return -ENOMEM;
 189}
 190
 191static 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
 207static 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
 216static void vhost_net_tx_err(struct vhost_net *net)
 217{
 218        ++net->tx_zcopy_err;
 219}
 220
 221static 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
 230static 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. */
 237static 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. */
 257static 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 */
 279static 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
 305static 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        /* set len to mark this desc buffers done DMA */
 312        vq->heads[ubuf->desc].len = success ?
 313                VHOST_DMA_DONE_LEN : VHOST_DMA_FAILED_LEN;
 314        vhost_net_ubuf_put(ubufs);
 315
 316        /*
 317         * Trigger polling thread if guest stopped submitting new buffers:
 318         * in this case, the refcount after decrement will eventually reach 1
 319         * so here it is 2.
 320         * We also trigger polling periodically after each 16 packets
 321         * (the value 16 here is more or less arbitrary, it's tuned to trigger
 322         * less than 10% of times).
 323         */
 324        if (cnt <= 2 || !(cnt % 16))
 325                vhost_poll_queue(&vq->poll);
 326}
 327
 328/* Expects to be always run from workqueue - which acts as
 329 * read-size critical section for our kind of RCU. */
 330static void handle_tx(struct vhost_net *net)
 331{
 332        struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_TX];
 333        struct vhost_virtqueue *vq = &nvq->vq;
 334        unsigned out, in, s;
 335        int head;
 336        struct msghdr msg = {
 337                .msg_name = NULL,
 338                .msg_namelen = 0,
 339                .msg_control = NULL,
 340                .msg_controllen = 0,
 341                .msg_iov = vq->iov,
 342                .msg_flags = MSG_DONTWAIT,
 343        };
 344        size_t len, total_len = 0;
 345        int err;
 346        size_t hdr_size;
 347        struct socket *sock;
 348        struct vhost_net_ubuf_ref *uninitialized_var(ubufs);
 349        bool zcopy, zcopy_used;
 350
 351        mutex_lock(&vq->mutex);
 352        sock = vq->private_data;
 353        if (!sock)
 354                goto out;
 355
 356        vhost_disable_notify(&net->dev, vq);
 357
 358        hdr_size = nvq->vhost_hlen;
 359        zcopy = nvq->ubufs;
 360
 361        for (;;) {
 362                /* Release DMAs done buffers first */
 363                if (zcopy)
 364                        vhost_zerocopy_signal_used(net, vq);
 365
 366                /* If more outstanding DMAs, queue the work.
 367                 * Handle upend_idx wrap around
 368                 */
 369                if (unlikely((nvq->upend_idx + vq->num - VHOST_MAX_PEND)
 370                              % UIO_MAXIOV == nvq->done_idx))
 371                        break;
 372
 373                head = vhost_get_vq_desc(&net->dev, vq, vq->iov,
 374                                         ARRAY_SIZE(vq->iov),
 375                                         &out, &in,
 376                                         NULL, NULL);
 377                /* On error, stop handling until the next kick. */
 378                if (unlikely(head < 0))
 379                        break;
 380                /* Nothing new?  Wait for eventfd to tell us they refilled. */
 381                if (head == vq->num) {
 382                        if (unlikely(vhost_enable_notify(&net->dev, vq))) {
 383                                vhost_disable_notify(&net->dev, vq);
 384                                continue;
 385                        }
 386                        break;
 387                }
 388                if (in) {
 389                        vq_err(vq, "Unexpected descriptor format for TX: "
 390                               "out %d, int %d\n", out, in);
 391                        break;
 392                }
 393                /* Skip header. TODO: support TSO. */
 394                s = move_iovec_hdr(vq->iov, nvq->hdr, hdr_size, out);
 395                msg.msg_iovlen = out;
 396                len = iov_length(vq->iov, out);
 397                /* Sanity check */
 398                if (!len) {
 399                        vq_err(vq, "Unexpected header len for TX: "
 400                               "%zd expected %zd\n",
 401                               iov_length(nvq->hdr, s), hdr_size);
 402                        break;
 403                }
 404
 405                zcopy_used = zcopy && len >= VHOST_GOODCOPY_LEN
 406                                   && (nvq->upend_idx + 1) % UIO_MAXIOV !=
 407                                      nvq->done_idx
 408                                   && vhost_net_tx_select_zcopy(net);
 409
 410                /* use msg_control to pass vhost zerocopy ubuf info to skb */
 411                if (zcopy_used) {
 412                        struct ubuf_info *ubuf;
 413                        ubuf = nvq->ubuf_info + nvq->upend_idx;
 414
 415                        vq->heads[nvq->upend_idx].id = head;
 416                        vq->heads[nvq->upend_idx].len = VHOST_DMA_IN_PROGRESS;
 417                        ubuf->callback = vhost_zerocopy_callback;
 418                        ubuf->ctx = nvq->ubufs;
 419                        ubuf->desc = nvq->upend_idx;
 420                        msg.msg_control = ubuf;
 421                        msg.msg_controllen = sizeof(ubuf);
 422                        ubufs = nvq->ubufs;
 423                        kref_get(&ubufs->kref);
 424                        nvq->upend_idx = (nvq->upend_idx + 1) % UIO_MAXIOV;
 425                } else {
 426                        msg.msg_control = NULL;
 427                        ubufs = NULL;
 428                }
 429                /* TODO: Check specific error and bomb out unless ENOBUFS? */
 430                err = sock->ops->sendmsg(NULL, sock, &msg, len);
 431                if (unlikely(err < 0)) {
 432                        if (zcopy_used) {
 433                                vhost_net_ubuf_put(ubufs);
 434                                nvq->upend_idx = ((unsigned)nvq->upend_idx - 1)
 435                                        % UIO_MAXIOV;
 436                        }
 437                        vhost_discard_vq_desc(vq, 1);
 438                        break;
 439                }
 440                if (err != len)
 441                        pr_debug("Truncated TX packet: "
 442                                 " len %d != %zd\n", err, len);
 443                if (!zcopy_used)
 444                        vhost_add_used_and_signal(&net->dev, vq, head, 0);
 445                else
 446                        vhost_zerocopy_signal_used(net, vq);
 447                total_len += len;
 448                vhost_net_tx_packet(net);
 449                if (unlikely(total_len >= VHOST_NET_WEIGHT)) {
 450                        vhost_poll_queue(&vq->poll);
 451                        break;
 452                }
 453        }
 454out:
 455        mutex_unlock(&vq->mutex);
 456}
 457
 458static int peek_head_len(struct sock *sk)
 459{
 460        struct sk_buff *head;
 461        int len = 0;
 462        unsigned long flags;
 463
 464        spin_lock_irqsave(&sk->sk_receive_queue.lock, flags);
 465        head = skb_peek(&sk->sk_receive_queue);
 466        if (likely(head)) {
 467                len = head->len;
 468                if (vlan_tx_tag_present(head))
 469                        len += VLAN_HLEN;
 470        }
 471
 472        spin_unlock_irqrestore(&sk->sk_receive_queue.lock, flags);
 473        return len;
 474}
 475
 476/* This is a multi-buffer version of vhost_get_desc, that works if
 477 *      vq has read descriptors only.
 478 * @vq          - the relevant virtqueue
 479 * @datalen     - data length we'll be reading
 480 * @iovcount    - returned count of io vectors we fill
 481 * @log         - vhost log
 482 * @log_num     - log offset
 483 * @quota       - headcount quota, 1 for big buffer
 484 *      returns number of buffer heads allocated, negative on error
 485 */
 486static int get_rx_bufs(struct vhost_virtqueue *vq,
 487                       struct vring_used_elem *heads,
 488                       int datalen,
 489                       unsigned *iovcount,
 490                       struct vhost_log *log,
 491                       unsigned *log_num,
 492                       unsigned int quota)
 493{
 494        unsigned int out, in;
 495        int seg = 0;
 496        int headcount = 0;
 497        unsigned d;
 498        int r, nlogs = 0;
 499
 500        while (datalen > 0 && headcount < quota) {
 501                if (unlikely(seg >= UIO_MAXIOV)) {
 502                        r = -ENOBUFS;
 503                        goto err;
 504                }
 505                d = vhost_get_vq_desc(vq->dev, vq, vq->iov + seg,
 506                                      ARRAY_SIZE(vq->iov) - seg, &out,
 507                                      &in, log, log_num);
 508                if (d == vq->num) {
 509                        r = 0;
 510                        goto err;
 511                }
 512                if (unlikely(out || in <= 0)) {
 513                        vq_err(vq, "unexpected descriptor format for RX: "
 514                                "out %d, in %d\n", out, in);
 515                        r = -EINVAL;
 516                        goto err;
 517                }
 518                if (unlikely(log)) {
 519                        nlogs += *log_num;
 520                        log += *log_num;
 521                }
 522                heads[headcount].id = d;
 523                heads[headcount].len = iov_length(vq->iov + seg, in);
 524                datalen -= heads[headcount].len;
 525                ++headcount;
 526                seg += in;
 527        }
 528        heads[headcount - 1].len += datalen;
 529        *iovcount = seg;
 530        if (unlikely(log))
 531                *log_num = nlogs;
 532        return headcount;
 533err:
 534        vhost_discard_vq_desc(vq, headcount);
 535        return r;
 536}
 537
 538/* Expects to be always run from workqueue - which acts as
 539 * read-size critical section for our kind of RCU. */
 540static void handle_rx(struct vhost_net *net)
 541{
 542        struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_RX];
 543        struct vhost_virtqueue *vq = &nvq->vq;
 544        unsigned uninitialized_var(in), log;
 545        struct vhost_log *vq_log;
 546        struct msghdr msg = {
 547                .msg_name = NULL,
 548                .msg_namelen = 0,
 549                .msg_control = NULL, /* FIXME: get and handle RX aux data. */
 550                .msg_controllen = 0,
 551                .msg_iov = vq->iov,
 552                .msg_flags = MSG_DONTWAIT,
 553        };
 554        struct virtio_net_hdr_mrg_rxbuf hdr = {
 555                .hdr.flags = 0,
 556                .hdr.gso_type = VIRTIO_NET_HDR_GSO_NONE
 557        };
 558        size_t total_len = 0;
 559        int err, mergeable;
 560        s16 headcount;
 561        size_t vhost_hlen, sock_hlen;
 562        size_t vhost_len, sock_len;
 563        struct socket *sock;
 564
 565        mutex_lock(&vq->mutex);
 566        sock = vq->private_data;
 567        if (!sock)
 568                goto out;
 569        vhost_disable_notify(&net->dev, vq);
 570
 571        vhost_hlen = nvq->vhost_hlen;
 572        sock_hlen = nvq->sock_hlen;
 573
 574        vq_log = unlikely(vhost_has_feature(&net->dev, VHOST_F_LOG_ALL)) ?
 575                vq->log : NULL;
 576        mergeable = vhost_has_feature(&net->dev, VIRTIO_NET_F_MRG_RXBUF);
 577
 578        while ((sock_len = peek_head_len(sock->sk))) {
 579                sock_len += sock_hlen;
 580                vhost_len = sock_len + vhost_hlen;
 581                headcount = get_rx_bufs(vq, vq->heads, vhost_len,
 582                                        &in, vq_log, &log,
 583                                        likely(mergeable) ? UIO_MAXIOV : 1);
 584                /* On error, stop handling until the next kick. */
 585                if (unlikely(headcount < 0))
 586                        break;
 587                /* OK, now we need to know about added descriptors. */
 588                if (!headcount) {
 589                        if (unlikely(vhost_enable_notify(&net->dev, vq))) {
 590                                /* They have slipped one in as we were
 591                                 * doing that: check again. */
 592                                vhost_disable_notify(&net->dev, vq);
 593                                continue;
 594                        }
 595                        /* Nothing new?  Wait for eventfd to tell us
 596                         * they refilled. */
 597                        break;
 598                }
 599                /* We don't need to be notified again. */
 600                if (unlikely((vhost_hlen)))
 601                        /* Skip header. TODO: support TSO. */
 602                        move_iovec_hdr(vq->iov, nvq->hdr, vhost_hlen, in);
 603                else
 604                        /* Copy the header for use in VIRTIO_NET_F_MRG_RXBUF:
 605                         * needed because recvmsg can modify msg_iov. */
 606                        copy_iovec_hdr(vq->iov, nvq->hdr, sock_hlen, in);
 607                msg.msg_iovlen = in;
 608                err = sock->ops->recvmsg(NULL, sock, &msg,
 609                                         sock_len, MSG_DONTWAIT | MSG_TRUNC);
 610                /* Userspace might have consumed the packet meanwhile:
 611                 * it's not supposed to do this usually, but might be hard
 612                 * to prevent. Discard data we got (if any) and keep going. */
 613                if (unlikely(err != sock_len)) {
 614                        pr_debug("Discarded rx packet: "
 615                                 " len %d, expected %zd\n", err, sock_len);
 616                        vhost_discard_vq_desc(vq, headcount);
 617                        continue;
 618                }
 619                if (unlikely(vhost_hlen) &&
 620                    memcpy_toiovecend(nvq->hdr, (unsigned char *)&hdr, 0,
 621                                      vhost_hlen)) {
 622                        vq_err(vq, "Unable to write vnet_hdr at addr %p\n",
 623                               vq->iov->iov_base);
 624                        break;
 625                }
 626                /* TODO: Should check and handle checksum. */
 627                if (likely(mergeable) &&
 628                    memcpy_toiovecend(nvq->hdr, (unsigned char *)&headcount,
 629                                      offsetof(typeof(hdr), num_buffers),
 630                                      sizeof hdr.num_buffers)) {
 631                        vq_err(vq, "Failed num_buffers write");
 632                        vhost_discard_vq_desc(vq, headcount);
 633                        break;
 634                }
 635                vhost_add_used_and_signal_n(&net->dev, vq, vq->heads,
 636                                            headcount);
 637                if (unlikely(vq_log))
 638                        vhost_log_write(vq, vq_log, log, vhost_len);
 639                total_len += vhost_len;
 640                if (unlikely(total_len >= VHOST_NET_WEIGHT)) {
 641                        vhost_poll_queue(&vq->poll);
 642                        break;
 643                }
 644        }
 645out:
 646        mutex_unlock(&vq->mutex);
 647}
 648
 649static void handle_tx_kick(struct vhost_work *work)
 650{
 651        struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
 652                                                  poll.work);
 653        struct vhost_net *net = container_of(vq->dev, struct vhost_net, dev);
 654
 655        handle_tx(net);
 656}
 657
 658static void handle_rx_kick(struct vhost_work *work)
 659{
 660        struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
 661                                                  poll.work);
 662        struct vhost_net *net = container_of(vq->dev, struct vhost_net, dev);
 663
 664        handle_rx(net);
 665}
 666
 667static void handle_tx_net(struct vhost_work *work)
 668{
 669        struct vhost_net *net = container_of(work, struct vhost_net,
 670                                             poll[VHOST_NET_VQ_TX].work);
 671        handle_tx(net);
 672}
 673
 674static void handle_rx_net(struct vhost_work *work)
 675{
 676        struct vhost_net *net = container_of(work, struct vhost_net,
 677                                             poll[VHOST_NET_VQ_RX].work);
 678        handle_rx(net);
 679}
 680
 681static int vhost_net_open(struct inode *inode, struct file *f)
 682{
 683        struct vhost_net *n = kmalloc(sizeof *n, GFP_KERNEL);
 684        struct vhost_dev *dev;
 685        struct vhost_virtqueue **vqs;
 686        int r, i;
 687
 688        if (!n)
 689                return -ENOMEM;
 690        vqs = kmalloc(VHOST_NET_VQ_MAX * sizeof(*vqs), GFP_KERNEL);
 691        if (!vqs) {
 692                kfree(n);
 693                return -ENOMEM;
 694        }
 695
 696        dev = &n->dev;
 697        vqs[VHOST_NET_VQ_TX] = &n->vqs[VHOST_NET_VQ_TX].vq;
 698        vqs[VHOST_NET_VQ_RX] = &n->vqs[VHOST_NET_VQ_RX].vq;
 699        n->vqs[VHOST_NET_VQ_TX].vq.handle_kick = handle_tx_kick;
 700        n->vqs[VHOST_NET_VQ_RX].vq.handle_kick = handle_rx_kick;
 701        for (i = 0; i < VHOST_NET_VQ_MAX; i++) {
 702                n->vqs[i].ubufs = NULL;
 703                n->vqs[i].ubuf_info = NULL;
 704                n->vqs[i].upend_idx = 0;
 705                n->vqs[i].done_idx = 0;
 706                n->vqs[i].vhost_hlen = 0;
 707                n->vqs[i].sock_hlen = 0;
 708        }
 709        r = vhost_dev_init(dev, vqs, VHOST_NET_VQ_MAX);
 710        if (r < 0) {
 711                kfree(n);
 712                kfree(vqs);
 713                return r;
 714        }
 715
 716        vhost_poll_init(n->poll + VHOST_NET_VQ_TX, handle_tx_net, POLLOUT, dev);
 717        vhost_poll_init(n->poll + VHOST_NET_VQ_RX, handle_rx_net, POLLIN, dev);
 718
 719        f->private_data = n;
 720
 721        return 0;
 722}
 723
 724static void vhost_net_disable_vq(struct vhost_net *n,
 725                                 struct vhost_virtqueue *vq)
 726{
 727        struct vhost_net_virtqueue *nvq =
 728                container_of(vq, struct vhost_net_virtqueue, vq);
 729        struct vhost_poll *poll = n->poll + (nvq - n->vqs);
 730        if (!vq->private_data)
 731                return;
 732        vhost_poll_stop(poll);
 733}
 734
 735static int vhost_net_enable_vq(struct vhost_net *n,
 736                                struct vhost_virtqueue *vq)
 737{
 738        struct vhost_net_virtqueue *nvq =
 739                container_of(vq, struct vhost_net_virtqueue, vq);
 740        struct vhost_poll *poll = n->poll + (nvq - n->vqs);
 741        struct socket *sock;
 742
 743        sock = vq->private_data;
 744        if (!sock)
 745                return 0;
 746
 747        return vhost_poll_start(poll, sock->file);
 748}
 749
 750static struct socket *vhost_net_stop_vq(struct vhost_net *n,
 751                                        struct vhost_virtqueue *vq)
 752{
 753        struct socket *sock;
 754
 755        mutex_lock(&vq->mutex);
 756        sock = vq->private_data;
 757        vhost_net_disable_vq(n, vq);
 758        vq->private_data = NULL;
 759        mutex_unlock(&vq->mutex);
 760        return sock;
 761}
 762
 763static void vhost_net_stop(struct vhost_net *n, struct socket **tx_sock,
 764                           struct socket **rx_sock)
 765{
 766        *tx_sock = vhost_net_stop_vq(n, &n->vqs[VHOST_NET_VQ_TX].vq);
 767        *rx_sock = vhost_net_stop_vq(n, &n->vqs[VHOST_NET_VQ_RX].vq);
 768}
 769
 770static void vhost_net_flush_vq(struct vhost_net *n, int index)
 771{
 772        vhost_poll_flush(n->poll + index);
 773        vhost_poll_flush(&n->vqs[index].vq.poll);
 774}
 775
 776static void vhost_net_flush(struct vhost_net *n)
 777{
 778        vhost_net_flush_vq(n, VHOST_NET_VQ_TX);
 779        vhost_net_flush_vq(n, VHOST_NET_VQ_RX);
 780        if (n->vqs[VHOST_NET_VQ_TX].ubufs) {
 781                mutex_lock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
 782                n->tx_flush = true;
 783                mutex_unlock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
 784                /* Wait for all lower device DMAs done. */
 785                vhost_net_ubuf_put_and_wait(n->vqs[VHOST_NET_VQ_TX].ubufs);
 786                mutex_lock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
 787                n->tx_flush = false;
 788                kref_init(&n->vqs[VHOST_NET_VQ_TX].ubufs->kref);
 789                mutex_unlock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
 790        }
 791}
 792
 793static int vhost_net_release(struct inode *inode, struct file *f)
 794{
 795        struct vhost_net *n = f->private_data;
 796        struct socket *tx_sock;
 797        struct socket *rx_sock;
 798
 799        vhost_net_stop(n, &tx_sock, &rx_sock);
 800        vhost_net_flush(n);
 801        vhost_dev_stop(&n->dev);
 802        vhost_dev_cleanup(&n->dev, false);
 803        vhost_net_vq_reset(n);
 804        if (tx_sock)
 805                fput(tx_sock->file);
 806        if (rx_sock)
 807                fput(rx_sock->file);
 808        /* We do an extra flush before freeing memory,
 809         * since jobs can re-queue themselves. */
 810        vhost_net_flush(n);
 811        kfree(n->dev.vqs);
 812        kfree(n);
 813        return 0;
 814}
 815
 816static struct socket *get_raw_socket(int fd)
 817{
 818        struct {
 819                struct sockaddr_ll sa;
 820                char  buf[MAX_ADDR_LEN];
 821        } uaddr;
 822        int uaddr_len = sizeof uaddr, r;
 823        struct socket *sock = sockfd_lookup(fd, &r);
 824
 825        if (!sock)
 826                return ERR_PTR(-ENOTSOCK);
 827
 828        /* Parameter checking */
 829        if (sock->sk->sk_type != SOCK_RAW) {
 830                r = -ESOCKTNOSUPPORT;
 831                goto err;
 832        }
 833
 834        r = sock->ops->getname(sock, (struct sockaddr *)&uaddr.sa,
 835                               &uaddr_len, 0);
 836        if (r)
 837                goto err;
 838
 839        if (uaddr.sa.sll_family != AF_PACKET) {
 840                r = -EPFNOSUPPORT;
 841                goto err;
 842        }
 843        return sock;
 844err:
 845        fput(sock->file);
 846        return ERR_PTR(r);
 847}
 848
 849static struct socket *get_tap_socket(int fd)
 850{
 851        struct file *file = fget(fd);
 852        struct socket *sock;
 853
 854        if (!file)
 855                return ERR_PTR(-EBADF);
 856        sock = tun_get_socket(file);
 857        if (!IS_ERR(sock))
 858                return sock;
 859        sock = macvtap_get_socket(file);
 860        if (IS_ERR(sock))
 861                fput(file);
 862        return sock;
 863}
 864
 865static struct socket *get_socket(int fd)
 866{
 867        struct socket *sock;
 868
 869        /* special case to disable backend */
 870        if (fd == -1)
 871                return NULL;
 872        sock = get_raw_socket(fd);
 873        if (!IS_ERR(sock))
 874                return sock;
 875        sock = get_tap_socket(fd);
 876        if (!IS_ERR(sock))
 877                return sock;
 878        return ERR_PTR(-ENOTSOCK);
 879}
 880
 881static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd)
 882{
 883        struct socket *sock, *oldsock;
 884        struct vhost_virtqueue *vq;
 885        struct vhost_net_virtqueue *nvq;
 886        struct vhost_net_ubuf_ref *ubufs, *oldubufs = NULL;
 887        int r;
 888
 889        mutex_lock(&n->dev.mutex);
 890        r = vhost_dev_check_owner(&n->dev);
 891        if (r)
 892                goto err;
 893
 894        if (index >= VHOST_NET_VQ_MAX) {
 895                r = -ENOBUFS;
 896                goto err;
 897        }
 898        vq = &n->vqs[index].vq;
 899        nvq = &n->vqs[index];
 900        mutex_lock(&vq->mutex);
 901
 902        /* Verify that ring has been setup correctly. */
 903        if (!vhost_vq_access_ok(vq)) {
 904                r = -EFAULT;
 905                goto err_vq;
 906        }
 907        sock = get_socket(fd);
 908        if (IS_ERR(sock)) {
 909                r = PTR_ERR(sock);
 910                goto err_vq;
 911        }
 912
 913        /* start polling new socket */
 914        oldsock = vq->private_data;
 915        if (sock != oldsock) {
 916                ubufs = vhost_net_ubuf_alloc(vq,
 917                                             sock && vhost_sock_zcopy(sock));
 918                if (IS_ERR(ubufs)) {
 919                        r = PTR_ERR(ubufs);
 920                        goto err_ubufs;
 921                }
 922
 923                vhost_net_disable_vq(n, vq);
 924                vq->private_data = sock;
 925                r = vhost_init_used(vq);
 926                if (r)
 927                        goto err_used;
 928                r = vhost_net_enable_vq(n, vq);
 929                if (r)
 930                        goto err_used;
 931
 932                oldubufs = nvq->ubufs;
 933                nvq->ubufs = ubufs;
 934
 935                n->tx_packets = 0;
 936                n->tx_zcopy_err = 0;
 937                n->tx_flush = false;
 938        }
 939
 940        mutex_unlock(&vq->mutex);
 941
 942        if (oldubufs) {
 943                vhost_net_ubuf_put_wait_and_free(oldubufs);
 944                mutex_lock(&vq->mutex);
 945                vhost_zerocopy_signal_used(n, vq);
 946                mutex_unlock(&vq->mutex);
 947        }
 948
 949        if (oldsock) {
 950                vhost_net_flush_vq(n, index);
 951                fput(oldsock->file);
 952        }
 953
 954        mutex_unlock(&n->dev.mutex);
 955        return 0;
 956
 957err_used:
 958        vq->private_data = oldsock;
 959        vhost_net_enable_vq(n, vq);
 960        if (ubufs)
 961                vhost_net_ubuf_put_wait_and_free(ubufs);
 962err_ubufs:
 963        fput(sock->file);
 964err_vq:
 965        mutex_unlock(&vq->mutex);
 966err:
 967        mutex_unlock(&n->dev.mutex);
 968        return r;
 969}
 970
 971static long vhost_net_reset_owner(struct vhost_net *n)
 972{
 973        struct socket *tx_sock = NULL;
 974        struct socket *rx_sock = NULL;
 975        long err;
 976        struct vhost_memory *memory;
 977
 978        mutex_lock(&n->dev.mutex);
 979        err = vhost_dev_check_owner(&n->dev);
 980        if (err)
 981                goto done;
 982        memory = vhost_dev_reset_owner_prepare();
 983        if (!memory) {
 984                err = -ENOMEM;
 985                goto done;
 986        }
 987        vhost_net_stop(n, &tx_sock, &rx_sock);
 988        vhost_net_flush(n);
 989        vhost_dev_reset_owner(&n->dev, memory);
 990        vhost_net_vq_reset(n);
 991done:
 992        mutex_unlock(&n->dev.mutex);
 993        if (tx_sock)
 994                fput(tx_sock->file);
 995        if (rx_sock)
 996                fput(rx_sock->file);
 997        return err;
 998}
 999
1000static int vhost_net_set_features(struct vhost_net *n, u64 features)
1001{
1002        size_t vhost_hlen, sock_hlen, hdr_len;
1003        int i;
1004
1005        hdr_len = (features & (1 << VIRTIO_NET_F_MRG_RXBUF)) ?
1006                        sizeof(struct virtio_net_hdr_mrg_rxbuf) :
1007                        sizeof(struct virtio_net_hdr);
1008        if (features & (1 << VHOST_NET_F_VIRTIO_NET_HDR)) {
1009                /* vhost provides vnet_hdr */
1010                vhost_hlen = hdr_len;
1011                sock_hlen = 0;
1012        } else {
1013                /* socket provides vnet_hdr */
1014                vhost_hlen = 0;
1015                sock_hlen = hdr_len;
1016        }
1017        mutex_lock(&n->dev.mutex);
1018        if ((features & (1 << VHOST_F_LOG_ALL)) &&
1019            !vhost_log_access_ok(&n->dev)) {
1020                mutex_unlock(&n->dev.mutex);
1021                return -EFAULT;
1022        }
1023        n->dev.acked_features = features;
1024        smp_wmb();
1025        for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
1026                mutex_lock(&n->vqs[i].vq.mutex);
1027                n->vqs[i].vhost_hlen = vhost_hlen;
1028                n->vqs[i].sock_hlen = sock_hlen;
1029                mutex_unlock(&n->vqs[i].vq.mutex);
1030        }
1031        vhost_net_flush(n);
1032        mutex_unlock(&n->dev.mutex);
1033        return 0;
1034}
1035
1036static long vhost_net_set_owner(struct vhost_net *n)
1037{
1038        int r;
1039
1040        mutex_lock(&n->dev.mutex);
1041        if (vhost_dev_has_owner(&n->dev)) {
1042                r = -EBUSY;
1043                goto out;
1044        }
1045        r = vhost_net_set_ubuf_info(n);
1046        if (r)
1047                goto out;
1048        r = vhost_dev_set_owner(&n->dev);
1049        if (r)
1050                vhost_net_clear_ubuf_info(n);
1051        vhost_net_flush(n);
1052out:
1053        mutex_unlock(&n->dev.mutex);
1054        return r;
1055}
1056
1057static long vhost_net_ioctl(struct file *f, unsigned int ioctl,
1058                            unsigned long arg)
1059{
1060        struct vhost_net *n = f->private_data;
1061        void __user *argp = (void __user *)arg;
1062        u64 __user *featurep = argp;
1063        struct vhost_vring_file backend;
1064        u64 features;
1065        int r;
1066
1067        switch (ioctl) {
1068        case VHOST_NET_SET_BACKEND:
1069                if (copy_from_user(&backend, argp, sizeof backend))
1070                        return -EFAULT;
1071                return vhost_net_set_backend(n, backend.index, backend.fd);
1072        case VHOST_GET_FEATURES:
1073                features = VHOST_NET_FEATURES;
1074                if (copy_to_user(featurep, &features, sizeof features))
1075                        return -EFAULT;
1076                return 0;
1077        case VHOST_SET_FEATURES:
1078                if (copy_from_user(&features, featurep, sizeof features))
1079                        return -EFAULT;
1080                if (features & ~VHOST_NET_FEATURES)
1081                        return -EOPNOTSUPP;
1082                return vhost_net_set_features(n, features);
1083        case VHOST_RESET_OWNER:
1084                return vhost_net_reset_owner(n);
1085        case VHOST_SET_OWNER:
1086                return vhost_net_set_owner(n);
1087        default:
1088                mutex_lock(&n->dev.mutex);
1089                r = vhost_dev_ioctl(&n->dev, ioctl, argp);
1090                if (r == -ENOIOCTLCMD)
1091                        r = vhost_vring_ioctl(&n->dev, ioctl, argp);
1092                else
1093                        vhost_net_flush(n);
1094                mutex_unlock(&n->dev.mutex);
1095                return r;
1096        }
1097}
1098
1099#ifdef CONFIG_COMPAT
1100static long vhost_net_compat_ioctl(struct file *f, unsigned int ioctl,
1101                                   unsigned long arg)
1102{
1103        return vhost_net_ioctl(f, ioctl, (unsigned long)compat_ptr(arg));
1104}
1105#endif
1106
1107static const struct file_operations vhost_net_fops = {
1108        .owner          = THIS_MODULE,
1109        .release        = vhost_net_release,
1110        .unlocked_ioctl = vhost_net_ioctl,
1111#ifdef CONFIG_COMPAT
1112        .compat_ioctl   = vhost_net_compat_ioctl,
1113#endif
1114        .open           = vhost_net_open,
1115        .llseek         = noop_llseek,
1116};
1117
1118static struct miscdevice vhost_net_misc = {
1119        .minor = VHOST_NET_MINOR,
1120        .name = "vhost-net",
1121        .fops = &vhost_net_fops,
1122};
1123
1124static int vhost_net_init(void)
1125{
1126        if (experimental_zcopytx)
1127                vhost_net_enable_zcopy(VHOST_NET_VQ_TX);
1128        return misc_register(&vhost_net_misc);
1129}
1130module_init(vhost_net_init);
1131
1132static void vhost_net_exit(void)
1133{
1134        misc_deregister(&vhost_net_misc);
1135}
1136module_exit(vhost_net_exit);
1137
1138MODULE_VERSION("0.0.1");
1139MODULE_LICENSE("GPL v2");
1140MODULE_AUTHOR("Michael S. Tsirkin");
1141MODULE_DESCRIPTION("Host kernel accelerator for virtio net");
1142MODULE_ALIAS_MISCDEV(VHOST_NET_MINOR);
1143MODULE_ALIAS("devname:vhost-net");
1144
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