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 #include <linux/sched/clock.h>
  21 #include <linux/sched/signal.h>
  22 #include <linux/vmalloc.h>
  23
  24 #include <linux/net.h>
  25 #include <linux/if_packet.h>
  26 #include <linux/if_arp.h>
  27 #include <linux/if_tun.h>
  28 #include <linux/if_macvlan.h>
  29 #include <linux/if_tap.h>
  30 #include <linux/if_vlan.h>
  31 #include <linux/skb_array.h>
  32 #include <linux/skbuff.h>
  33
  34 #include <net/sock.h>
  35 #include <net/xdp.h>
  36
  37 #include "vhost.h"
  38
  39 static int experimental_zcopytx = 1;
  40 module_param(experimental_zcopytx, int, 0444);
  41 MODULE_PARM_DESC(experimental_zcopytx, "Enable Zero Copy TX;"
  42                                        " 1 -Enable; 0 - Disable");
  43
  44 /* Max number of bytes transferred before requeueing the job.
  45  * Using this limit prevents one virtqueue from starving others. */
  46 #define VHOST_NET_WEIGHT 0x80000
  47
  48 /* Max number of packets transferred before requeueing the job.
  49  * Using this limit prevents one virtqueue from starving others with small
  50  * pkts.
  51  */
  52 #define VHOST_NET_PKT_WEIGHT 256
  53
  54 /* MAX number of TX used buffers for outstanding zerocopy */
  55 #define VHOST_MAX_PEND 128
  56 #define VHOST_GOODCOPY_LEN 256
  57
  58 /*
  59  * For transmit, used buffer len is unused; we override it to track buffer
  60  * status internally; used for zerocopy tx only.
  61  */
  62 /* Lower device DMA failed */
  63 #define VHOST_DMA_FAILED_LEN    ((__force __virtio32)3)
  64 /* Lower device DMA done */
  65 #define VHOST_DMA_DONE_LEN      ((__force __virtio32)2)
  66 /* Lower device DMA in progress */
  67 #define VHOST_DMA_IN_PROGRESS   ((__force __virtio32)1)
  68 /* Buffer unused */
  69 #define VHOST_DMA_CLEAR_LEN     ((__force __virtio32)0)
  70
  71 #define VHOST_DMA_IS_DONE(len) ((__force u32)(len) >= (__force u32)VHOST_DMA_DONE_LEN)
  72
  73 enum {
  74         VHOST_NET_FEATURES = VHOST_FEATURES |
  75                          (1ULL << VHOST_NET_F_VIRTIO_NET_HDR) |
  76                          (1ULL << VIRTIO_NET_F_MRG_RXBUF) |
  77                          (1ULL << VIRTIO_F_IOMMU_PLATFORM)
  78 };
  79
  80 enum {
  81         VHOST_NET_BACKEND_FEATURES = (1ULL << VHOST_BACKEND_F_IOTLB_MSG_V2)
  82 };
  83
  84 enum {
  85         VHOST_NET_VQ_RX = 0,
  86         VHOST_NET_VQ_TX = 1,
  87         VHOST_NET_VQ_MAX = 2,
  88 };
  89
  90 struct vhost_net_ubuf_ref {
  91         /* refcount follows semantics similar to kref:
  92          *  0: object is released
  93          *  1: no outstanding ubufs
  94          * >1: outstanding ubufs
  95          */
  96         atomic_t refcount;
  97         wait_queue_head_t wait;
  98         struct vhost_virtqueue *vq;
  99 };
 100
 101 #define VHOST_NET_BATCH 64
 102 struct vhost_net_buf {
 103         void **queue;
 104         int tail;
 105         int head;
 106 };
 107
 108 struct vhost_net_virtqueue {
 109         struct vhost_virtqueue vq;
 110         size_t vhost_hlen;
 111         size_t sock_hlen;
 112         /* vhost zerocopy support fields below: */
 113         /* last used idx for outstanding DMA zerocopy buffers */
 114         int upend_idx;
 115         /* For TX, first used idx for DMA done zerocopy buffers
 116          * For RX, number of batched heads
 117          */
 118         int done_idx;
 119         /* Number of XDP frames batched */
 120         int batched_xdp;
 121         /* an array of userspace buffers info */
 122         struct ubuf_info *ubuf_info;
 123         /* Reference counting for outstanding ubufs.
 124          * Protected by vq mutex. Writers must also take device mutex. */
 125         struct vhost_net_ubuf_ref *ubufs;
 126         struct ptr_ring *rx_ring;
 127         struct vhost_net_buf rxq;
 128         /* Batched XDP buffs */
 129         struct xdp_buff *xdp;
 130 };
 131
 132 struct vhost_net {
 133         struct vhost_dev dev;
 134         struct vhost_net_virtqueue vqs[VHOST_NET_VQ_MAX];
 135         struct vhost_poll poll[VHOST_NET_VQ_MAX];
 136         /* Number of TX recently submitted.
 137          * Protected by tx vq lock. */
 138         unsigned tx_packets;
 139         /* Number of times zerocopy TX recently failed.
 140          * Protected by tx vq lock. */
 141         unsigned tx_zcopy_err;
 142         /* Flush in progress. Protected by tx vq lock. */
 143         bool tx_flush;
 144         /* Private page frag */
 145         struct page_frag page_frag;
 146         /* Refcount bias of page frag */
 147         int refcnt_bias;
 148 };
 149
 150 static unsigned vhost_net_zcopy_mask __read_mostly;
 151
 152 static void *vhost_net_buf_get_ptr(struct vhost_net_buf *rxq)
 153 {
 154         if (rxq->tail != rxq->head)
 155                 return rxq->queue[rxq->head];
 156         else
 157                 return NULL;
 158 }
 159
 160 static int vhost_net_buf_get_size(struct vhost_net_buf *rxq)
 161 {
 162         return rxq->tail - rxq->head;
 163 }
 164
 165 static int vhost_net_buf_is_empty(struct vhost_net_buf *rxq)
 166 {
 167         return rxq->tail == rxq->head;
 168 }
 169
 170 static void *vhost_net_buf_consume(struct vhost_net_buf *rxq)
 171 {
 172         void *ret = vhost_net_buf_get_ptr(rxq);
 173         ++rxq->head;
 174         return ret;
 175 }
 176
 177 static int vhost_net_buf_produce(struct vhost_net_virtqueue *nvq)
 178 {
 179         struct vhost_net_buf *rxq = &nvq->rxq;
 180
 181         rxq->head = 0;
 182         rxq->tail = ptr_ring_consume_batched(nvq->rx_ring, rxq->queue,
 183                                               VHOST_NET_BATCH);
 184         return rxq->tail;
 185 }
 186
 187 static void vhost_net_buf_unproduce(struct vhost_net_virtqueue *nvq)
 188 {
 189         struct vhost_net_buf *rxq = &nvq->rxq;
 190
 191         if (nvq->rx_ring && !vhost_net_buf_is_empty(rxq)) {
 192                 ptr_ring_unconsume(nvq->rx_ring, rxq->queue + rxq->head,
 193                                    vhost_net_buf_get_size(rxq),
 194                                    tun_ptr_free);
 195                 rxq->head = rxq->tail = 0;
 196         }
 197 }
 198
 199 static int vhost_net_buf_peek_len(void *ptr)
 200 {
 201         if (tun_is_xdp_frame(ptr)) {
 202                 struct xdp_frame *xdpf = tun_ptr_to_xdp(ptr);
 203
 204                 return xdpf->len;
 205         }
 206
 207         return __skb_array_len_with_tag(ptr);
 208 }
 209
 210 static int vhost_net_buf_peek(struct vhost_net_virtqueue *nvq)
 211 {
 212         struct vhost_net_buf *rxq = &nvq->rxq;
 213
 214         if (!vhost_net_buf_is_empty(rxq))
 215                 goto out;
 216
 217         if (!vhost_net_buf_produce(nvq))
 218                 return 0;
 219
 220 out:
 221         return vhost_net_buf_peek_len(vhost_net_buf_get_ptr(rxq));
 222 }
 223
 224 static void vhost_net_buf_init(struct vhost_net_buf *rxq)
 225 {
 226         rxq->head = rxq->tail = 0;
 227 }
 228
 229 static void vhost_net_enable_zcopy(int vq)
 230 {
 231         vhost_net_zcopy_mask |= 0x1 << vq;
 232 }
 233
 234 static struct vhost_net_ubuf_ref *
 235 vhost_net_ubuf_alloc(struct vhost_virtqueue *vq, bool zcopy)
 236 {
 237         struct vhost_net_ubuf_ref *ubufs;
 238         /* No zero copy backend? Nothing to count. */
 239         if (!zcopy)
 240                 return NULL;
 241         ubufs = kmalloc(sizeof(*ubufs), GFP_KERNEL);
 242         if (!ubufs)
 243                 return ERR_PTR(-ENOMEM);
 244         atomic_set(&ubufs->refcount, 1);
 245         init_waitqueue_head(&ubufs->wait);
 246         ubufs->vq = vq;
 247         return ubufs;
 248 }
 249
 250 static int vhost_net_ubuf_put(struct vhost_net_ubuf_ref *ubufs)
 251 {
 252         int r = atomic_sub_return(1, &ubufs->refcount);
 253         if (unlikely(!r))
 254                 wake_up(&ubufs->wait);
 255         return r;
 256 }
 257
 258 static void vhost_net_ubuf_put_and_wait(struct vhost_net_ubuf_ref *ubufs)
 259 {
 260         vhost_net_ubuf_put(ubufs);
 261         wait_event(ubufs->wait, !atomic_read(&ubufs->refcount));
 262 }
 263
 264 static void vhost_net_ubuf_put_wait_and_free(struct vhost_net_ubuf_ref *ubufs)
 265 {
 266         vhost_net_ubuf_put_and_wait(ubufs);
 267         kfree(ubufs);
 268 }
 269
 270 static void vhost_net_clear_ubuf_info(struct vhost_net *n)
 271 {
 272         int i;
 273
 274         for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
 275                 kfree(n->vqs[i].ubuf_info);
 276                 n->vqs[i].ubuf_info = NULL;
 277         }
 278 }
 279
 280 static int vhost_net_set_ubuf_info(struct vhost_net *n)
 281 {
 282         bool zcopy;
 283         int i;
 284
 285         for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
 286                 zcopy = vhost_net_zcopy_mask & (0x1 << i);
 287                 if (!zcopy)
 288                         continue;
 289                 n->vqs[i].ubuf_info =
 290                         kmalloc_array(UIO_MAXIOV,
 291                                       sizeof(*n->vqs[i].ubuf_info),
 292                                       GFP_KERNEL);
 293                 if  (!n->vqs[i].ubuf_info)
 294                         goto err;
 295         }
 296         return 0;
 297
 298 err:
 299         vhost_net_clear_ubuf_info(n);
 300         return -ENOMEM;
 301 }
 302
 303 static void vhost_net_vq_reset(struct vhost_net *n)
 304 {
 305         int i;
 306
 307         vhost_net_clear_ubuf_info(n);
 308
 309         for (i = 0; i < VHOST_NET_VQ_MAX; i++) {
 310                 n->vqs[i].done_idx = 0;
 311                 n->vqs[i].upend_idx = 0;
 312                 n->vqs[i].ubufs = NULL;
 313                 n->vqs[i].vhost_hlen = 0;
 314                 n->vqs[i].sock_hlen = 0;
 315                 vhost_net_buf_init(&n->vqs[i].rxq);
 316         }
 317
 318 }
 319
 320 static void vhost_net_tx_packet(struct vhost_net *net)
 321 {
 322         ++net->tx_packets;
 323         if (net->tx_packets < 1024)
 324                 return;
 325         net->tx_packets = 0;
 326         net->tx_zcopy_err = 0;
 327 }
 328
 329 static void vhost_net_tx_err(struct vhost_net *net)
 330 {
 331         ++net->tx_zcopy_err;
 332 }
 333
 334 static bool vhost_net_tx_select_zcopy(struct vhost_net *net)
 335 {
 336         /* TX flush waits for outstanding DMAs to be done.
 337          * Don't start new DMAs.
 338          */
 339         return !net->tx_flush &&
 340                 net->tx_packets / 64 >= net->tx_zcopy_err;
 341 }
 342
 343 static bool vhost_sock_zcopy(struct socket *sock)
 344 {
 345         return unlikely(experimental_zcopytx) &&
 346                 sock_flag(sock->sk, SOCK_ZEROCOPY);
 347 }
 348
 349 static bool vhost_sock_xdp(struct socket *sock)
 350 {
 351         return sock_flag(sock->sk, SOCK_XDP);
 352 }
 353
 354 /* In case of DMA done not in order in lower device driver for some reason.
 355  * upend_idx is used to track end of used idx, done_idx is used to track head
 356  * of used idx. Once lower device DMA done contiguously, we will signal KVM
 357  * guest used idx.
 358  */
 359 static void vhost_zerocopy_signal_used(struct vhost_net *net,
 360                                        struct vhost_virtqueue *vq)
 361 {
 362         struct vhost_net_virtqueue *nvq =
 363                 container_of(vq, struct vhost_net_virtqueue, vq);
 364         int i, add;
 365         int j = 0;
 366
 367         for (i = nvq->done_idx; i != nvq->upend_idx; i = (i + 1) % UIO_MAXIOV) {
 368                 if (vq->heads[i].len == VHOST_DMA_FAILED_LEN)
 369                         vhost_net_tx_err(net);
 370                 if (VHOST_DMA_IS_DONE(vq->heads[i].len)) {
 371                         vq->heads[i].len = VHOST_DMA_CLEAR_LEN;
 372                         ++j;
 373                 } else
 374                         break;
 375         }
 376         while (j) {
 377                 add = min(UIO_MAXIOV - nvq->done_idx, j);
 378                 vhost_add_used_and_signal_n(vq->dev, vq,
 379                                             &vq->heads[nvq->done_idx], add);
 380                 nvq->done_idx = (nvq->done_idx + add) % UIO_MAXIOV;
 381                 j -= add;
 382         }
 383 }
 384
 385 static void vhost_zerocopy_callback(struct ubuf_info *ubuf, bool success)
 386 {
 387         struct vhost_net_ubuf_ref *ubufs = ubuf->ctx;
 388         struct vhost_virtqueue *vq = ubufs->vq;
 389         int cnt;
 390
 391         rcu_read_lock_bh();
 392
 393         /* set len to mark this desc buffers done DMA */
 394         vq->heads[ubuf->desc].len = success ?
 395                 VHOST_DMA_DONE_LEN : VHOST_DMA_FAILED_LEN;
 396         cnt = vhost_net_ubuf_put(ubufs);
 397
 398         /*
 399          * Trigger polling thread if guest stopped submitting new buffers:
 400          * in this case, the refcount after decrement will eventually reach 1.
 401          * We also trigger polling periodically after each 16 packets
 402          * (the value 16 here is more or less arbitrary, it's tuned to trigger
 403          * less than 10% of times).
 404          */
 405         if (cnt <= 1 || !(cnt % 16))
 406                 vhost_poll_queue(&vq->poll);
 407
 408         rcu_read_unlock_bh();
 409 }
 410
 411 static inline unsigned long busy_clock(void)
 412 {
 413         return local_clock() >> 10;
 414 }
 415
 416 static bool vhost_can_busy_poll(unsigned long endtime)
 417 {
 418         return likely(!need_resched() && !time_after(busy_clock(), endtime) &&
 419                       !signal_pending(current));
 420 }
 421
 422 static void vhost_net_disable_vq(struct vhost_net *n,
 423                                  struct vhost_virtqueue *vq)
 424 {
 425         struct vhost_net_virtqueue *nvq =
 426                 container_of(vq, struct vhost_net_virtqueue, vq);
 427         struct vhost_poll *poll = n->poll + (nvq - n->vqs);
 428         if (!vq->private_data)
 429                 return;
 430         vhost_poll_stop(poll);
 431 }
 432
 433 static int vhost_net_enable_vq(struct vhost_net *n,
 434                                 struct vhost_virtqueue *vq)
 435 {
 436         struct vhost_net_virtqueue *nvq =
 437                 container_of(vq, struct vhost_net_virtqueue, vq);
 438         struct vhost_poll *poll = n->poll + (nvq - n->vqs);
 439         struct socket *sock;
 440
 441         sock = vq->private_data;
 442         if (!sock)
 443                 return 0;
 444
 445         return vhost_poll_start(poll, sock->file);
 446 }
 447
 448 static void vhost_net_signal_used(struct vhost_net_virtqueue *nvq)
 449 {
 450         struct vhost_virtqueue *vq = &nvq->vq;
 451         struct vhost_dev *dev = vq->dev;
 452
 453         if (!nvq->done_idx)
 454                 return;
 455
 456         vhost_add_used_and_signal_n(dev, vq, vq->heads, nvq->done_idx);
 457         nvq->done_idx = 0;
 458 }
 459
 460 static void vhost_tx_batch(struct vhost_net *net,
 461                            struct vhost_net_virtqueue *nvq,
 462                            struct socket *sock,
 463                            struct msghdr *msghdr)
 464 {
 465         struct tun_msg_ctl ctl = {
 466                 .type = TUN_MSG_PTR,
 467                 .num = nvq->batched_xdp,
 468                 .ptr = nvq->xdp,
 469         };
 470         int err;
 471
 472         if (nvq->batched_xdp == 0)
 473                 goto signal_used;
 474
 475         msghdr->msg_control = &ctl;
 476         err = sock->ops->sendmsg(sock, msghdr, 0);
 477         if (unlikely(err < 0)) {
 478                 vq_err(&nvq->vq, "Fail to batch sending packets\n");
 479                 return;
 480         }
 481
 482 signal_used:
 483         vhost_net_signal_used(nvq);
 484         nvq->batched_xdp = 0;
 485 }
 486
 487 static int sock_has_rx_data(struct socket *sock)
 488 {
 489         if (unlikely(!sock))
 490                 return 0;
 491
 492         if (sock->ops->peek_len)
 493                 return sock->ops->peek_len(sock);
 494
 495         return skb_queue_empty(&sock->sk->sk_receive_queue);
 496 }
 497
 498 static void vhost_net_busy_poll_try_queue(struct vhost_net *net,
 499                                           struct vhost_virtqueue *vq)
 500 {
 501         if (!vhost_vq_avail_empty(&net->dev, vq)) {
 502                 vhost_poll_queue(&vq->poll);
 503         } else if (unlikely(vhost_enable_notify(&net->dev, vq))) {
 504                 vhost_disable_notify(&net->dev, vq);
 505                 vhost_poll_queue(&vq->poll);
 506         }
 507 }
 508
 509 static void vhost_net_busy_poll(struct vhost_net *net,
 510                                 struct vhost_virtqueue *rvq,
 511                                 struct vhost_virtqueue *tvq,
 512                                 bool *busyloop_intr,
 513                                 bool poll_rx)
 514 {
 515         unsigned long busyloop_timeout;
 516         unsigned long endtime;
 517         struct socket *sock;
 518         struct vhost_virtqueue *vq = poll_rx ? tvq : rvq;
 519
 520         /* Try to hold the vq mutex of the paired virtqueue. We can't
 521          * use mutex_lock() here since we could not guarantee a
 522          * consistenet lock ordering.
 523          */
 524         if (!mutex_trylock(&vq->mutex))
 525                 return;
 526
 527         vhost_disable_notify(&net->dev, vq);
 528         sock = rvq->private_data;
 529
 530         busyloop_timeout = poll_rx ? rvq->busyloop_timeout:
 531                                      tvq->busyloop_timeout;
 532
 533         preempt_disable();
 534         endtime = busy_clock() + busyloop_timeout;
 535
 536         while (vhost_can_busy_poll(endtime)) {
 537                 if (vhost_has_work(&net->dev)) {
 538                         *busyloop_intr = true;
 539                         break;
 540                 }
 541
 542                 if ((sock_has_rx_data(sock) &&
 543                      !vhost_vq_avail_empty(&net->dev, rvq)) ||
 544                     !vhost_vq_avail_empty(&net->dev, tvq))
 545                         break;
 546
 547                 cpu_relax();
 548         }
 549
 550         preempt_enable();
 551
 552         if (poll_rx || sock_has_rx_data(sock))
 553                 vhost_net_busy_poll_try_queue(net, vq);
 554         else if (!poll_rx) /* On tx here, sock has no rx data. */
 555                 vhost_enable_notify(&net->dev, rvq);
 556
 557         mutex_unlock(&vq->mutex);
 558 }
 559
 560 static int vhost_net_tx_get_vq_desc(struct vhost_net *net,
 561                                     struct vhost_net_virtqueue *tnvq,
 562                                     unsigned int *out_num, unsigned int *in_num,
 563                                     struct msghdr *msghdr, bool *busyloop_intr)
 564 {
 565         struct vhost_net_virtqueue *rnvq = &net->vqs[VHOST_NET_VQ_RX];
 566         struct vhost_virtqueue *rvq = &rnvq->vq;
 567         struct vhost_virtqueue *tvq = &tnvq->vq;
 568
 569         int r = vhost_get_vq_desc(tvq, tvq->iov, ARRAY_SIZE(tvq->iov),
 570                                   out_num, in_num, NULL, NULL);
 571
 572         if (r == tvq->num && tvq->busyloop_timeout) {
 573                 /* Flush batched packets first */
 574                 if (!vhost_sock_zcopy(tvq->private_data))
 575                         vhost_tx_batch(net, tnvq, tvq->private_data, msghdr);
 576
 577                 vhost_net_busy_poll(net, rvq, tvq, busyloop_intr, false);
 578
 579                 r = vhost_get_vq_desc(tvq, tvq->iov, ARRAY_SIZE(tvq->iov),
 580                                       out_num, in_num, NULL, NULL);
 581         }
 582
 583         return r;
 584 }
 585
 586 static bool vhost_exceeds_maxpend(struct vhost_net *net)
 587 {
 588         struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_TX];
 589         struct vhost_virtqueue *vq = &nvq->vq;
 590
 591         return (nvq->upend_idx + UIO_MAXIOV - nvq->done_idx) % UIO_MAXIOV >
 592                min_t(unsigned int, VHOST_MAX_PEND, vq->num >> 2);
 593 }
 594
 595 static size_t init_iov_iter(struct vhost_virtqueue *vq, struct iov_iter *iter,
 596                             size_t hdr_size, int out)
 597 {
 598         /* Skip header. TODO: support TSO. */
 599         size_t len = iov_length(vq->iov, out);
 600
 601         iov_iter_init(iter, WRITE, vq->iov, out, len);
 602         iov_iter_advance(iter, hdr_size);
 603
 604         return iov_iter_count(iter);
 605 }
 606
 607 static int get_tx_bufs(struct vhost_net *net,
 608                        struct vhost_net_virtqueue *nvq,
 609                        struct msghdr *msg,
 610                        unsigned int *out, unsigned int *in,
 611                        size_t *len, bool *busyloop_intr)
 612 {
 613         struct vhost_virtqueue *vq = &nvq->vq;
 614         int ret;
 615
 616         ret = vhost_net_tx_get_vq_desc(net, nvq, out, in, msg, busyloop_intr);
 617
 618         if (ret < 0 || ret == vq->num)
 619                 return ret;
 620
 621         if (*in) {
 622                 vq_err(vq, "Unexpected descriptor format for TX: out %d, int %d\n",
 623                         *out, *in);
 624                 return -EFAULT;
 625         }
 626
 627         /* Sanity check */
 628         *len = init_iov_iter(vq, &msg->msg_iter, nvq->vhost_hlen, *out);
 629         if (*len == 0) {
 630                 vq_err(vq, "Unexpected header len for TX: %zd expected %zd\n",
 631                         *len, nvq->vhost_hlen);
 632                 return -EFAULT;
 633         }
 634
 635         return ret;
 636 }
 637
 638 static bool tx_can_batch(struct vhost_virtqueue *vq, size_t total_len)
 639 {
 640         return total_len < VHOST_NET_WEIGHT &&
 641                !vhost_vq_avail_empty(vq->dev, vq);
 642 }
 643
 644 #define SKB_FRAG_PAGE_ORDER     get_order(32768)
 645
 646 static bool vhost_net_page_frag_refill(struct vhost_net *net, unsigned int sz,
 647                                        struct page_frag *pfrag, gfp_t gfp)
 648 {
 649         if (pfrag->page) {
 650                 if (pfrag->offset + sz <= pfrag->size)
 651                         return true;
 652                 __page_frag_cache_drain(pfrag->page, net->refcnt_bias);
 653         }
 654
 655         pfrag->offset = 0;
 656         net->refcnt_bias = 0;
 657         if (SKB_FRAG_PAGE_ORDER) {
 658                 /* Avoid direct reclaim but allow kswapd to wake */
 659                 pfrag->page = alloc_pages((gfp & ~__GFP_DIRECT_RECLAIM) |
 660                                           __GFP_COMP | __GFP_NOWARN |
 661                                           __GFP_NORETRY,
 662                                           SKB_FRAG_PAGE_ORDER);
 663                 if (likely(pfrag->page)) {
 664                         pfrag->size = PAGE_SIZE << SKB_FRAG_PAGE_ORDER;
 665                         goto done;
 666                 }
 667         }
 668         pfrag->page = alloc_page(gfp);
 669         if (likely(pfrag->page)) {
 670                 pfrag->size = PAGE_SIZE;
 671                 goto done;
 672         }
 673         return false;
 674
 675 done:
 676         net->refcnt_bias = USHRT_MAX;
 677         page_ref_add(pfrag->page, USHRT_MAX - 1);
 678         return true;
 679 }
 680
 681 #define VHOST_NET_RX_PAD (NET_IP_ALIGN + NET_SKB_PAD)
 682
 683 static int vhost_net_build_xdp(struct vhost_net_virtqueue *nvq,
 684                                struct iov_iter *from)
 685 {
 686         struct vhost_virtqueue *vq = &nvq->vq;
 687         struct vhost_net *net = container_of(vq->dev, struct vhost_net,
 688                                              dev);
 689         struct socket *sock = vq->private_data;
 690         struct page_frag *alloc_frag = &net->page_frag;
 691         struct virtio_net_hdr *gso;
 692         struct xdp_buff *xdp = &nvq->xdp[nvq->batched_xdp];
 693         struct tun_xdp_hdr *hdr;
 694         size_t len = iov_iter_count(from);
 695         int headroom = vhost_sock_xdp(sock) ? XDP_PACKET_HEADROOM : 0;
 696         int buflen = SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
 697         int pad = SKB_DATA_ALIGN(VHOST_NET_RX_PAD + headroom + nvq->sock_hlen);
 698         int sock_hlen = nvq->sock_hlen;
 699         void *buf;
 700         int copied;
 701
 702         if (unlikely(len < nvq->sock_hlen))
 703                 return -EFAULT;
 704
 705         if (SKB_DATA_ALIGN(len + pad) +
 706             SKB_DATA_ALIGN(sizeof(struct skb_shared_info)) > PAGE_SIZE)
 707                 return -ENOSPC;
 708
 709         buflen += SKB_DATA_ALIGN(len + pad);
 710         alloc_frag->offset = ALIGN((u64)alloc_frag->offset, SMP_CACHE_BYTES);
 711         if (unlikely(!vhost_net_page_frag_refill(net, buflen,
 712                                                  alloc_frag, GFP_KERNEL)))
 713                 return -ENOMEM;
 714
 715         buf = (char *)page_address(alloc_frag->page) + alloc_frag->offset;
 716         copied = copy_page_from_iter(alloc_frag->page,
 717                                      alloc_frag->offset +
 718                                      offsetof(struct tun_xdp_hdr, gso),
 719                                      sock_hlen, from);
 720         if (copied != sock_hlen)
 721                 return -EFAULT;
 722
 723         hdr = buf;
 724         gso = &hdr->gso;
 725
 726         if ((gso->flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) &&
 727             vhost16_to_cpu(vq, gso->csum_start) +
 728             vhost16_to_cpu(vq, gso->csum_offset) + 2 >
 729             vhost16_to_cpu(vq, gso->hdr_len)) {
 730                 gso->hdr_len = cpu_to_vhost16(vq,
 731                                vhost16_to_cpu(vq, gso->csum_start) +
 732                                vhost16_to_cpu(vq, gso->csum_offset) + 2);
 733
 734                 if (vhost16_to_cpu(vq, gso->hdr_len) > len)
 735                         return -EINVAL;
 736         }
 737
 738         len -= sock_hlen;
 739         copied = copy_page_from_iter(alloc_frag->page,
 740                                      alloc_frag->offset + pad,
 741                                      len, from);
 742         if (copied != len)
 743                 return -EFAULT;
 744
 745         xdp->data_hard_start = buf;
 746         xdp->data = buf + pad;
 747         xdp->data_end = xdp->data + len;
 748         hdr->buflen = buflen;
 749
 750         --net->refcnt_bias;
 751         alloc_frag->offset += buflen;
 752
 753         ++nvq->batched_xdp;
 754
 755         return 0;
 756 }
 757
 758 static void handle_tx_copy(struct vhost_net *net, struct socket *sock)
 759 {
 760         struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_TX];
 761         struct vhost_virtqueue *vq = &nvq->vq;
 762         unsigned out, in;
 763         int head;
 764         struct msghdr msg = {
 765                 .msg_name = NULL,
 766                 .msg_namelen = 0,
 767                 .msg_control = NULL,
 768                 .msg_controllen = 0,
 769                 .msg_flags = MSG_DONTWAIT,
 770         };
 771         size_t len, total_len = 0;
 772         int err;
 773         int sent_pkts = 0;
 774         bool sock_can_batch = (sock->sk->sk_sndbuf == INT_MAX);
 775
 776         do {
 777                 bool busyloop_intr = false;
 778
 779                 if (nvq->done_idx == VHOST_NET_BATCH)
 780                         vhost_tx_batch(net, nvq, sock, &msg);
 781
 782                 head = get_tx_bufs(net, nvq, &msg, &out, &in, &len,
 783                                    &busyloop_intr);
 784                 /* On error, stop handling until the next kick. */
 785                 if (unlikely(head < 0))
 786                         break;
 787                 /* Nothing new?  Wait for eventfd to tell us they refilled. */
 788                 if (head == vq->num) {
 789                         if (unlikely(busyloop_intr)) {
 790                                 vhost_poll_queue(&vq->poll);
 791                         } else if (unlikely(vhost_enable_notify(&net->dev,
 792                                                                 vq))) {
 793                                 vhost_disable_notify(&net->dev, vq);
 794                                 continue;
 795                         }
 796                         break;
 797                 }
 798
 799                 total_len += len;
 800
 801                 /* For simplicity, TX batching is only enabled if
 802                  * sndbuf is unlimited.
 803                  */
 804                 if (sock_can_batch) {
 805                         err = vhost_net_build_xdp(nvq, &msg.msg_iter);
 806                         if (!err) {
 807                                 goto done;
 808                         } else if (unlikely(err != -ENOSPC)) {
 809                                 vhost_tx_batch(net, nvq, sock, &msg);
 810                                 vhost_discard_vq_desc(vq, 1);
 811                                 vhost_net_enable_vq(net, vq);
 812                                 break;
 813                         }
 814
 815                         /* We can't build XDP buff, go for single
 816                          * packet path but let's flush batched
 817                          * packets.
 818                          */
 819                         vhost_tx_batch(net, nvq, sock, &msg);
 820                         msg.msg_control = NULL;
 821                 } else {
 822                         if (tx_can_batch(vq, total_len))
 823                                 msg.msg_flags |= MSG_MORE;
 824                         else
 825                                 msg.msg_flags &= ~MSG_MORE;
 826                 }
 827
 828                 /* TODO: Check specific error and bomb out unless ENOBUFS? */
 829                 err = sock->ops->sendmsg(sock, &msg, len);
 830                 if (unlikely(err < 0)) {
 831                         vhost_discard_vq_desc(vq, 1);
 832                         vhost_net_enable_vq(net, vq);
 833                         break;
 834                 }
 835                 if (err != len)
 836                         pr_debug("Truncated TX packet: len %d != %zd\n",
 837                                  err, len);
 838 done:
 839                 vq->heads[nvq->done_idx].id = cpu_to_vhost32(vq, head);
 840                 vq->heads[nvq->done_idx].len = 0;
 841                 ++nvq->done_idx;
 842         } while (likely(!vhost_exceeds_weight(vq, ++sent_pkts, total_len)));
 843
 844         vhost_tx_batch(net, nvq, sock, &msg);
 845 }
 846
 847 static void handle_tx_zerocopy(struct vhost_net *net, struct socket *sock)
 848 {
 849         struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_TX];
 850         struct vhost_virtqueue *vq = &nvq->vq;
 851         unsigned out, in;
 852         int head;
 853         struct msghdr msg = {
 854                 .msg_name = NULL,
 855                 .msg_namelen = 0,
 856                 .msg_control = NULL,
 857                 .msg_controllen = 0,
 858                 .msg_flags = MSG_DONTWAIT,
 859         };
 860         struct tun_msg_ctl ctl;
 861         size_t len, total_len = 0;
 862         int err;
 863         struct vhost_net_ubuf_ref *uninitialized_var(ubufs);
 864         bool zcopy_used;
 865         int sent_pkts = 0;
 866
 867         do {
 868                 bool busyloop_intr;
 869
 870                 /* Release DMAs done buffers first */
 871                 vhost_zerocopy_signal_used(net, vq);
 872
 873                 busyloop_intr = false;
 874                 head = get_tx_bufs(net, nvq, &msg, &out, &in, &len,
 875                                    &busyloop_intr);
 876                 /* On error, stop handling until the next kick. */
 877                 if (unlikely(head < 0))
 878                         break;
 879                 /* Nothing new?  Wait for eventfd to tell us they refilled. */
 880                 if (head == vq->num) {
 881                         if (unlikely(busyloop_intr)) {
 882                                 vhost_poll_queue(&vq->poll);
 883                         } else if (unlikely(vhost_enable_notify(&net->dev, vq))) {
 884                                 vhost_disable_notify(&net->dev, vq);
 885                                 continue;
 886                         }
 887                         break;
 888                 }
 889
 890                 zcopy_used = len >= VHOST_GOODCOPY_LEN
 891                              && !vhost_exceeds_maxpend(net)
 892                              && vhost_net_tx_select_zcopy(net);
 893
 894                 /* use msg_control to pass vhost zerocopy ubuf info to skb */
 895                 if (zcopy_used) {
 896                         struct ubuf_info *ubuf;
 897                         ubuf = nvq->ubuf_info + nvq->upend_idx;
 898
 899                         vq->heads[nvq->upend_idx].id = cpu_to_vhost32(vq, head);
 900                         vq->heads[nvq->upend_idx].len = VHOST_DMA_IN_PROGRESS;
 901                         ubuf->callback = vhost_zerocopy_callback;
 902                         ubuf->ctx = nvq->ubufs;
 903                         ubuf->desc = nvq->upend_idx;
 904                         refcount_set(&ubuf->refcnt, 1);
 905                         msg.msg_control = &ctl;
 906                         ctl.type = TUN_MSG_UBUF;
 907                         ctl.ptr = ubuf;
 908                         msg.msg_controllen = sizeof(ctl);
 909                         ubufs = nvq->ubufs;
 910                         atomic_inc(&ubufs->refcount);
 911                         nvq->upend_idx = (nvq->upend_idx + 1) % UIO_MAXIOV;
 912                 } else {
 913                         msg.msg_control = NULL;
 914                         ubufs = NULL;
 915                 }
 916                 total_len += len;
 917                 if (tx_can_batch(vq, total_len) &&
 918                     likely(!vhost_exceeds_maxpend(net))) {
 919                         msg.msg_flags |= MSG_MORE;
 920                 } else {
 921                         msg.msg_flags &= ~MSG_MORE;
 922                 }
 923
 924                 /* TODO: Check specific error and bomb out unless ENOBUFS? */
 925                 err = sock->ops->sendmsg(sock, &msg, len);
 926                 if (unlikely(err < 0)) {
 927                         if (zcopy_used) {
 928                                 vhost_net_ubuf_put(ubufs);
 929                                 nvq->upend_idx = ((unsigned)nvq->upend_idx - 1)
 930                                         % UIO_MAXIOV;
 931                         }
 932                         vhost_discard_vq_desc(vq, 1);
 933                         vhost_net_enable_vq(net, vq);
 934                         break;
 935                 }
 936                 if (err != len)
 937                         pr_debug("Truncated TX packet: "
 938                                  " len %d != %zd\n", err, len);
 939                 if (!zcopy_used)
 940                         vhost_add_used_and_signal(&net->dev, vq, head, 0);
 941                 else
 942                         vhost_zerocopy_signal_used(net, vq);
 943                 vhost_net_tx_packet(net);
 944         } while (likely(!vhost_exceeds_weight(vq, ++sent_pkts, total_len)));
 945 }
 946
 947 /* Expects to be always run from workqueue - which acts as
 948  * read-size critical section for our kind of RCU. */
 949 static void handle_tx(struct vhost_net *net)
 950 {
 951         struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_TX];
 952         struct vhost_virtqueue *vq = &nvq->vq;
 953         struct socket *sock;
 954
 955         mutex_lock_nested(&vq->mutex, VHOST_NET_VQ_TX);
 956         sock = vq->private_data;
 957         if (!sock)
 958                 goto out;
 959
 960         if (!vq_iotlb_prefetch(vq))
 961                 goto out;
 962
 963         vhost_disable_notify(&net->dev, vq);
 964         vhost_net_disable_vq(net, vq);
 965
 966         if (vhost_sock_zcopy(sock))
 967                 handle_tx_zerocopy(net, sock);
 968         else
 969                 handle_tx_copy(net, sock);
 970
 971 out:
 972         mutex_unlock(&vq->mutex);
 973 }
 974
 975 static int peek_head_len(struct vhost_net_virtqueue *rvq, struct sock *sk)
 976 {
 977         struct sk_buff *head;
 978         int len = 0;
 979         unsigned long flags;
 980
 981         if (rvq->rx_ring)
 982                 return vhost_net_buf_peek(rvq);
 983
 984         spin_lock_irqsave(&sk->sk_receive_queue.lock, flags);
 985         head = skb_peek(&sk->sk_receive_queue);
 986         if (likely(head)) {
 987                 len = head->len;
 988                 if (skb_vlan_tag_present(head))
 989                         len += VLAN_HLEN;
 990         }
 991
 992         spin_unlock_irqrestore(&sk->sk_receive_queue.lock, flags);
 993         return len;
 994 }
 995
 996 static int vhost_net_rx_peek_head_len(struct vhost_net *net, struct sock *sk,
 997                                       bool *busyloop_intr)
 998 {
 999         struct vhost_net_virtqueue *rnvq = &net->vqs[VHOST_NET_VQ_RX];
1000         struct vhost_net_virtqueue *tnvq = &net->vqs[VHOST_NET_VQ_TX];
1001         struct vhost_virtqueue *rvq = &rnvq->vq;
1002         struct vhost_virtqueue *tvq = &tnvq->vq;
1003         int len = peek_head_len(rnvq, sk);
1004
1005         if (!len && rvq->busyloop_timeout) {
1006                 /* Flush batched heads first */
1007                 vhost_net_signal_used(rnvq);
1008                 /* Both tx vq and rx socket were polled here */
1009                 vhost_net_busy_poll(net, rvq, tvq, busyloop_intr, true);
1010
1011                 len = peek_head_len(rnvq, sk);
1012         }
1013
1014         return len;
1015 }
1016
1017 /* This is a multi-buffer version of vhost_get_desc, that works if
1018  *      vq has read descriptors only.
1019  * @vq          - the relevant virtqueue
1020  * @datalen     - data length we'll be reading
1021  * @iovcount    - returned count of io vectors we fill
1022  * @log         - vhost log
1023  * @log_num     - log offset
1024  * @quota       - headcount quota, 1 for big buffer
1025  *      returns number of buffer heads allocated, negative on error
1026  */
1027 static int get_rx_bufs(struct vhost_virtqueue *vq,
1028                        struct vring_used_elem *heads,
1029                        int datalen,
1030                        unsigned *iovcount,
1031                        struct vhost_log *log,
1032                        unsigned *log_num,
1033                        unsigned int quota)
1034 {
1035         unsigned int out, in;
1036         int seg = 0;
1037         int headcount = 0;
1038         unsigned d;
1039         int r, nlogs = 0;
1040         /* len is always initialized before use since we are always called with
1041          * datalen > 0.
1042          */
1043         u32 uninitialized_var(len);
1044
1045         while (datalen > 0 && headcount < quota) {
1046                 if (unlikely(seg >= UIO_MAXIOV)) {
1047                         r = -ENOBUFS;
1048                         goto err;
1049                 }
1050                 r = vhost_get_vq_desc(vq, vq->iov + seg,
1051                                       ARRAY_SIZE(vq->iov) - seg, &out,
1052                                       &in, log, log_num);
1053                 if (unlikely(r < 0))
1054                         goto err;
1055
1056                 d = r;
1057                 if (d == vq->num) {
1058                         r = 0;
1059                         goto err;
1060                 }
1061                 if (unlikely(out || in <= 0)) {
1062                         vq_err(vq, "unexpected descriptor format for RX: "
1063                                 "out %d, in %d\n", out, in);
1064                         r = -EINVAL;
1065                         goto err;
1066                 }
1067                 if (unlikely(log)) {
1068                         nlogs += *log_num;
1069                         log += *log_num;
1070                 }
1071                 heads[headcount].id = cpu_to_vhost32(vq, d);
1072                 len = iov_length(vq->iov + seg, in);
1073                 heads[headcount].len = cpu_to_vhost32(vq, len);
1074                 datalen -= len;
1075                 ++headcount;
1076                 seg += in;
1077         }
1078         heads[headcount - 1].len = cpu_to_vhost32(vq, len + datalen);
1079         *iovcount = seg;
1080         if (unlikely(log))
1081                 *log_num = nlogs;
1082
1083         /* Detect overrun */
1084         if (unlikely(datalen > 0)) {
1085                 r = UIO_MAXIOV + 1;
1086                 goto err;
1087         }
1088         return headcount;
1089 err:
1090         vhost_discard_vq_desc(vq, headcount);
1091         return r;
1092 }
1093
1094 /* Expects to be always run from workqueue - which acts as
1095  * read-size critical section for our kind of RCU. */
1096 static void handle_rx(struct vhost_net *net)
1097 {
1098         struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_RX];
1099         struct vhost_virtqueue *vq = &nvq->vq;
1100         unsigned uninitialized_var(in), log;
1101         struct vhost_log *vq_log;
1102         struct msghdr msg = {
1103                 .msg_name = NULL,
1104                 .msg_namelen = 0,
1105                 .msg_control = NULL, /* FIXME: get and handle RX aux data. */
1106                 .msg_controllen = 0,
1107                 .msg_flags = MSG_DONTWAIT,
1108         };
1109         struct virtio_net_hdr hdr = {
1110                 .flags = 0,
1111                 .gso_type = VIRTIO_NET_HDR_GSO_NONE
1112         };
1113         size_t total_len = 0;
1114         int err, mergeable;
1115         s16 headcount;
1116         size_t vhost_hlen, sock_hlen;
1117         size_t vhost_len, sock_len;
1118         bool busyloop_intr = false;
1119         struct socket *sock;
1120         struct iov_iter fixup;
1121         __virtio16 num_buffers;
1122         int recv_pkts = 0;
1123
1124         mutex_lock_nested(&vq->mutex, VHOST_NET_VQ_RX);
1125         sock = vq->private_data;
1126         if (!sock)
1127                 goto out;
1128
1129         if (!vq_iotlb_prefetch(vq))
1130                 goto out;
1131
1132         vhost_disable_notify(&net->dev, vq);
1133         vhost_net_disable_vq(net, vq);
1134
1135         vhost_hlen = nvq->vhost_hlen;
1136         sock_hlen = nvq->sock_hlen;
1137
1138         vq_log = unlikely(vhost_has_feature(vq, VHOST_F_LOG_ALL)) ?
1139                 vq->log : NULL;
1140         mergeable = vhost_has_feature(vq, VIRTIO_NET_F_MRG_RXBUF);
1141
1142         do {
1143                 sock_len = vhost_net_rx_peek_head_len(net, sock->sk,
1144                                                       &busyloop_intr);
1145                 if (!sock_len)
1146                         break;
1147                 sock_len += sock_hlen;
1148                 vhost_len = sock_len + vhost_hlen;
1149                 headcount = get_rx_bufs(vq, vq->heads + nvq->done_idx,
1150                                         vhost_len, &in, vq_log, &log,
1151                                         likely(mergeable) ? UIO_MAXIOV : 1);
1152                 /* On error, stop handling until the next kick. */
1153                 if (unlikely(headcount < 0))
1154                         goto out;
1155                 /* OK, now we need to know about added descriptors. */
1156                 if (!headcount) {
1157                         if (unlikely(busyloop_intr)) {
1158                                 vhost_poll_queue(&vq->poll);
1159                         } else if (unlikely(vhost_enable_notify(&net->dev, vq))) {
1160                                 /* They have slipped one in as we were
1161                                  * doing that: check again. */
1162                                 vhost_disable_notify(&net->dev, vq);
1163                                 continue;
1164                         }
1165                         /* Nothing new?  Wait for eventfd to tell us
1166                          * they refilled. */
1167                         goto out;
1168                 }
1169                 busyloop_intr = false;
1170                 if (nvq->rx_ring)
1171                         msg.msg_control = vhost_net_buf_consume(&nvq->rxq);
1172                 /* On overrun, truncate and discard */
1173                 if (unlikely(headcount > UIO_MAXIOV)) {
1174                         iov_iter_init(&msg.msg_iter, READ, vq->iov, 1, 1);
1175                         err = sock->ops->recvmsg(sock, &msg,
1176                                                  1, MSG_DONTWAIT | MSG_TRUNC);
1177                         pr_debug("Discarded rx packet: len %zd\n", sock_len);
1178                         continue;
1179                 }
1180                 /* We don't need to be notified again. */
1181                 iov_iter_init(&msg.msg_iter, READ, vq->iov, in, vhost_len);
1182                 fixup = msg.msg_iter;
1183                 if (unlikely((vhost_hlen))) {
1184                         /* We will supply the header ourselves
1185                          * TODO: support TSO.
1186                          */
1187                         iov_iter_advance(&msg.msg_iter, vhost_hlen);
1188                 }
1189                 err = sock->ops->recvmsg(sock, &msg,
1190                                          sock_len, MSG_DONTWAIT | MSG_TRUNC);
1191                 /* Userspace might have consumed the packet meanwhile:
1192                  * it's not supposed to do this usually, but might be hard
1193                  * to prevent. Discard data we got (if any) and keep going. */
1194                 if (unlikely(err != sock_len)) {
1195                         pr_debug("Discarded rx packet: "
1196                                  " len %d, expected %zd\n", err, sock_len);
1197                         vhost_discard_vq_desc(vq, headcount);
1198                         continue;
1199                 }
1200                 /* Supply virtio_net_hdr if VHOST_NET_F_VIRTIO_NET_HDR */
1201                 if (unlikely(vhost_hlen)) {
1202                         if (copy_to_iter(&hdr, sizeof(hdr),
1203                                          &fixup) != sizeof(hdr)) {
1204                                 vq_err(vq, "Unable to write vnet_hdr "
1205                                        "at addr %p\n", vq->iov->iov_base);
1206                                 goto out;
1207                         }
1208                 } else {
1209                         /* Header came from socket; we'll need to patch
1210                          * ->num_buffers over if VIRTIO_NET_F_MRG_RXBUF
1211                          */
1212                         iov_iter_advance(&fixup, sizeof(hdr));
1213                 }
1214                 /* TODO: Should check and handle checksum. */
1215
1216                 num_buffers = cpu_to_vhost16(vq, headcount);
1217                 if (likely(mergeable) &&
1218                     copy_to_iter(&num_buffers, sizeof num_buffers,
1219                                  &fixup) != sizeof num_buffers) {
1220                         vq_err(vq, "Failed num_buffers write");
1221                         vhost_discard_vq_desc(vq, headcount);
1222                         goto out;
1223                 }
1224                 nvq->done_idx += headcount;
1225                 if (nvq->done_idx > VHOST_NET_BATCH)
1226                         vhost_net_signal_used(nvq);
1227                 if (unlikely(vq_log))
1228                         vhost_log_write(vq, vq_log, log, vhost_len,
1229                                         vq->iov, in);
1230                 total_len += vhost_len;
1231         } while (likely(!vhost_exceeds_weight(vq, ++recv_pkts, total_len)));
1232
1233         if (unlikely(busyloop_intr))
1234                 vhost_poll_queue(&vq->poll);
1235         else if (!sock_len)
1236                 vhost_net_enable_vq(net, vq);
1237 out:
1238         vhost_net_signal_used(nvq);
1239         mutex_unlock(&vq->mutex);
1240 }
1241
1242 static void handle_tx_kick(struct vhost_work *work)
1243 {
1244         struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
1245                                                   poll.work);
1246         struct vhost_net *net = container_of(vq->dev, struct vhost_net, dev);
1247
1248         handle_tx(net);
1249 }
1250
1251 static void handle_rx_kick(struct vhost_work *work)
1252 {
1253         struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
1254                                                   poll.work);
1255         struct vhost_net *net = container_of(vq->dev, struct vhost_net, dev);
1256
1257         handle_rx(net);
1258 }
1259
1260 static void handle_tx_net(struct vhost_work *work)
1261 {
1262         struct vhost_net *net = container_of(work, struct vhost_net,
1263                                              poll[VHOST_NET_VQ_TX].work);
1264         handle_tx(net);
1265 }
1266
1267 static void handle_rx_net(struct vhost_work *work)
1268 {
1269         struct vhost_net *net = container_of(work, struct vhost_net,
1270                                              poll[VHOST_NET_VQ_RX].work);
1271         handle_rx(net);
1272 }
1273
1274 static int vhost_net_open(struct inode *inode, struct file *f)
1275 {
1276         struct vhost_net *n;
1277         struct vhost_dev *dev;
1278         struct vhost_virtqueue **vqs;
1279         void **queue;
1280         struct xdp_buff *xdp;
1281         int i;
1282
1283         n = kvmalloc(sizeof *n, GFP_KERNEL | __GFP_RETRY_MAYFAIL);
1284         if (!n)
1285                 return -ENOMEM;
1286         vqs = kmalloc_array(VHOST_NET_VQ_MAX, sizeof(*vqs), GFP_KERNEL);
1287         if (!vqs) {
1288                 kvfree(n);
1289                 return -ENOMEM;
1290         }
1291
1292         queue = kmalloc_array(VHOST_NET_BATCH, sizeof(void *),
1293                               GFP_KERNEL);
1294         if (!queue) {
1295                 kfree(vqs);
1296                 kvfree(n);
1297                 return -ENOMEM;
1298         }
1299         n->vqs[VHOST_NET_VQ_RX].rxq.queue = queue;
1300
1301         xdp = kmalloc_array(VHOST_NET_BATCH, sizeof(*xdp), GFP_KERNEL);
1302         if (!xdp) {
1303                 kfree(vqs);
1304                 kvfree(n);
1305                 kfree(queue);
1306                 return -ENOMEM;
1307         }
1308         n->vqs[VHOST_NET_VQ_TX].xdp = xdp;
1309
1310         dev = &n->dev;
1311         vqs[VHOST_NET_VQ_TX] = &n->vqs[VHOST_NET_VQ_TX].vq;
1312         vqs[VHOST_NET_VQ_RX] = &n->vqs[VHOST_NET_VQ_RX].vq;
1313         n->vqs[VHOST_NET_VQ_TX].vq.handle_kick = handle_tx_kick;
1314         n->vqs[VHOST_NET_VQ_RX].vq.handle_kick = handle_rx_kick;
1315         for (i = 0; i < VHOST_NET_VQ_MAX; i++) {
1316                 n->vqs[i].ubufs = NULL;
1317                 n->vqs[i].ubuf_info = NULL;
1318                 n->vqs[i].upend_idx = 0;
1319                 n->vqs[i].done_idx = 0;
1320                 n->vqs[i].batched_xdp = 0;
1321                 n->vqs[i].vhost_hlen = 0;
1322                 n->vqs[i].sock_hlen = 0;
1323                 n->vqs[i].rx_ring = NULL;
1324                 vhost_net_buf_init(&n->vqs[i].rxq);
1325         }
1326         vhost_dev_init(dev, vqs, VHOST_NET_VQ_MAX,
1327                        UIO_MAXIOV + VHOST_NET_BATCH,
1328                        VHOST_NET_PKT_WEIGHT, VHOST_NET_WEIGHT);
1329
1330         vhost_poll_init(n->poll + VHOST_NET_VQ_TX, handle_tx_net, EPOLLOUT, dev);
1331         vhost_poll_init(n->poll + VHOST_NET_VQ_RX, handle_rx_net, EPOLLIN, dev);
1332
1333         f->private_data = n;
1334         n->page_frag.page = NULL;
1335         n->refcnt_bias = 0;
1336
1337         return 0;
1338 }
1339
1340 static struct socket *vhost_net_stop_vq(struct vhost_net *n,
1341                                         struct vhost_virtqueue *vq)
1342 {
1343         struct socket *sock;
1344         struct vhost_net_virtqueue *nvq =
1345                 container_of(vq, struct vhost_net_virtqueue, vq);
1346
1347         mutex_lock(&vq->mutex);
1348         sock = vq->private_data;
1349         vhost_net_disable_vq(n, vq);
1350         vq->private_data = NULL;
1351         vhost_net_buf_unproduce(nvq);
1352         nvq->rx_ring = NULL;
1353         mutex_unlock(&vq->mutex);
1354         return sock;
1355 }
1356
1357 static void vhost_net_stop(struct vhost_net *n, struct socket **tx_sock,
1358                            struct socket **rx_sock)
1359 {
1360         *tx_sock = vhost_net_stop_vq(n, &n->vqs[VHOST_NET_VQ_TX].vq);
1361         *rx_sock = vhost_net_stop_vq(n, &n->vqs[VHOST_NET_VQ_RX].vq);
1362 }
1363
1364 static void vhost_net_flush_vq(struct vhost_net *n, int index)
1365 {
1366         vhost_poll_flush(n->poll + index);
1367         vhost_poll_flush(&n->vqs[index].vq.poll);
1368 }
1369
1370 static void vhost_net_flush(struct vhost_net *n)
1371 {
1372         vhost_net_flush_vq(n, VHOST_NET_VQ_TX);
1373         vhost_net_flush_vq(n, VHOST_NET_VQ_RX);
1374         if (n->vqs[VHOST_NET_VQ_TX].ubufs) {
1375                 mutex_lock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
1376                 n->tx_flush = true;
1377                 mutex_unlock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
1378                 /* Wait for all lower device DMAs done. */
1379                 vhost_net_ubuf_put_and_wait(n->vqs[VHOST_NET_VQ_TX].ubufs);
1380                 mutex_lock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
1381                 n->tx_flush = false;
1382                 atomic_set(&n->vqs[VHOST_NET_VQ_TX].ubufs->refcount, 1);
1383                 mutex_unlock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
1384         }
1385 }
1386
1387 static int vhost_net_release(struct inode *inode, struct file *f)
1388 {
1389         struct vhost_net *n = f->private_data;
1390         struct socket *tx_sock;
1391         struct socket *rx_sock;
1392
1393         vhost_net_stop(n, &tx_sock, &rx_sock);
1394         vhost_net_flush(n);
1395         vhost_dev_stop(&n->dev);
1396         vhost_dev_cleanup(&n->dev);
1397         vhost_net_vq_reset(n);
1398         if (tx_sock)
1399                 sockfd_put(tx_sock);
1400         if (rx_sock)
1401                 sockfd_put(rx_sock);
1402         /* Make sure no callbacks are outstanding */
1403         synchronize_rcu();
1404         /* We do an extra flush before freeing memory,
1405          * since jobs can re-queue themselves. */
1406         vhost_net_flush(n);
1407         kfree(n->vqs[VHOST_NET_VQ_RX].rxq.queue);
1408         kfree(n->vqs[VHOST_NET_VQ_TX].xdp);
1409         kfree(n->dev.vqs);
1410         if (n->page_frag.page)
1411                 __page_frag_cache_drain(n->page_frag.page, n->refcnt_bias);
1412         kvfree(n);
1413         return 0;
1414 }
1415
1416 static struct socket *get_raw_socket(int fd)
1417 {
1418         struct {
1419                 struct sockaddr_ll sa;
1420                 char  buf[MAX_ADDR_LEN];
1421         } uaddr;
1422         int r;
1423         struct socket *sock = sockfd_lookup(fd, &r);
1424
1425         if (!sock)
1426                 return ERR_PTR(-ENOTSOCK);
1427
1428         /* Parameter checking */
1429         if (sock->sk->sk_type != SOCK_RAW) {
1430                 r = -ESOCKTNOSUPPORT;
1431                 goto err;
1432         }
1433
1434         r = sock->ops->getname(sock, (struct sockaddr *)&uaddr.sa, 0);
1435         if (r < 0)
1436                 goto err;
1437
1438         if (uaddr.sa.sll_family != AF_PACKET) {
1439                 r = -EPFNOSUPPORT;
1440                 goto err;
1441         }
1442         return sock;
1443 err:
1444         sockfd_put(sock);
1445         return ERR_PTR(r);
1446 }
1447
1448 static struct ptr_ring *get_tap_ptr_ring(int fd)
1449 {
1450         struct ptr_ring *ring;
1451         struct file *file = fget(fd);
1452
1453         if (!file)
1454                 return NULL;
1455         ring = tun_get_tx_ring(file);
1456         if (!IS_ERR(ring))
1457                 goto out;
1458         ring = tap_get_ptr_ring(file);
1459         if (!IS_ERR(ring))
1460                 goto out;
1461         ring = NULL;
1462 out:
1463         fput(file);
1464         return ring;
1465 }
1466
1467 static struct socket *get_tap_socket(int fd)
1468 {
1469         struct file *file = fget(fd);
1470         struct socket *sock;
1471
1472         if (!file)
1473                 return ERR_PTR(-EBADF);
1474         sock = tun_get_socket(file);
1475         if (!IS_ERR(sock))
1476                 return sock;
1477         sock = tap_get_socket(file);
1478         if (IS_ERR(sock))
1479                 fput(file);
1480         return sock;
1481 }
1482
1483 static struct socket *get_socket(int fd)
1484 {
1485         struct socket *sock;
1486
1487         /* special case to disable backend */
1488         if (fd == -1)
1489                 return NULL;
1490         sock = get_raw_socket(fd);
1491         if (!IS_ERR(sock))
1492                 return sock;
1493         sock = get_tap_socket(fd);
1494         if (!IS_ERR(sock))
1495                 return sock;
1496         return ERR_PTR(-ENOTSOCK);
1497 }
1498
1499 static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd)
1500 {
1501         struct socket *sock, *oldsock;
1502         struct vhost_virtqueue *vq;
1503         struct vhost_net_virtqueue *nvq;
1504         struct vhost_net_ubuf_ref *ubufs, *oldubufs = NULL;
1505         int r;
1506
1507         mutex_lock(&n->dev.mutex);
1508         r = vhost_dev_check_owner(&n->dev);
1509         if (r)
1510                 goto err;
1511
1512         if (index >= VHOST_NET_VQ_MAX) {
1513                 r = -ENOBUFS;
1514                 goto err;
1515         }
1516         vq = &n->vqs[index].vq;
1517         nvq = &n->vqs[index];
1518         mutex_lock(&vq->mutex);
1519
1520         /* Verify that ring has been setup correctly. */
1521         if (!vhost_vq_access_ok(vq)) {
1522                 r = -EFAULT;
1523                 goto err_vq;
1524         }
1525         sock = get_socket(fd);
1526         if (IS_ERR(sock)) {
1527                 r = PTR_ERR(sock);
1528                 goto err_vq;
1529         }
1530
1531         /* start polling new socket */
1532         oldsock = vq->private_data;
1533         if (sock != oldsock) {
1534                 ubufs = vhost_net_ubuf_alloc(vq,
1535                                              sock && vhost_sock_zcopy(sock));
1536                 if (IS_ERR(ubufs)) {
1537                         r = PTR_ERR(ubufs);
1538                         goto err_ubufs;
1539                 }
1540
1541                 vhost_net_disable_vq(n, vq);
1542                 vq->private_data = sock;
1543                 vhost_net_buf_unproduce(nvq);
1544                 r = vhost_vq_init_access(vq);
1545                 if (r)
1546                         goto err_used;
1547                 r = vhost_net_enable_vq(n, vq);
1548                 if (r)
1549                         goto err_used;
1550                 if (index == VHOST_NET_VQ_RX)
1551                         nvq->rx_ring = get_tap_ptr_ring(fd);
1552
1553                 oldubufs = nvq->ubufs;
1554                 nvq->ubufs = ubufs;
1555
1556                 n->tx_packets = 0;
1557                 n->tx_zcopy_err = 0;
1558                 n->tx_flush = false;
1559         }
1560
1561         mutex_unlock(&vq->mutex);
1562
1563         if (oldubufs) {
1564                 vhost_net_ubuf_put_wait_and_free(oldubufs);
1565                 mutex_lock(&vq->mutex);
1566                 vhost_zerocopy_signal_used(n, vq);
1567                 mutex_unlock(&vq->mutex);
1568         }
1569
1570         if (oldsock) {
1571                 vhost_net_flush_vq(n, index);
1572                 sockfd_put(oldsock);
1573         }
1574
1575         mutex_unlock(&n->dev.mutex);
1576         return 0;
1577
1578 err_used:
1579         vq->private_data = oldsock;
1580         vhost_net_enable_vq(n, vq);
1581         if (ubufs)
1582                 vhost_net_ubuf_put_wait_and_free(ubufs);
1583 err_ubufs:
1584         if (sock)
1585                 sockfd_put(sock);
1586 err_vq:
1587         mutex_unlock(&vq->mutex);
1588 err:
1589         mutex_unlock(&n->dev.mutex);
1590         return r;
1591 }
1592
1593 static long vhost_net_reset_owner(struct vhost_net *n)
1594 {
1595         struct socket *tx_sock = NULL;
1596         struct socket *rx_sock = NULL;
1597         long err;
1598         struct vhost_umem *umem;
1599
1600         mutex_lock(&n->dev.mutex);
1601         err = vhost_dev_check_owner(&n->dev);
1602         if (err)
1603                 goto done;
1604         umem = vhost_dev_reset_owner_prepare();
1605         if (!umem) {
1606                 err = -ENOMEM;
1607                 goto done;
1608         }
1609         vhost_net_stop(n, &tx_sock, &rx_sock);
1610         vhost_net_flush(n);
1611         vhost_dev_stop(&n->dev);
1612         vhost_dev_reset_owner(&n->dev, umem);
1613         vhost_net_vq_reset(n);
1614 done:
1615         mutex_unlock(&n->dev.mutex);
1616         if (tx_sock)
1617                 sockfd_put(tx_sock);
1618         if (rx_sock)
1619                 sockfd_put(rx_sock);
1620         return err;
1621 }
1622
1623 static int vhost_net_set_backend_features(struct vhost_net *n, u64 features)
1624 {
1625         int i;
1626
1627         mutex_lock(&n->dev.mutex);
1628         for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
1629                 mutex_lock(&n->vqs[i].vq.mutex);
1630                 n->vqs[i].vq.acked_backend_features = features;
1631                 mutex_unlock(&n->vqs[i].vq.mutex);
1632         }
1633         mutex_unlock(&n->dev.mutex);
1634
1635         return 0;
1636 }
1637
1638 static int vhost_net_set_features(struct vhost_net *n, u64 features)
1639 {
1640         size_t vhost_hlen, sock_hlen, hdr_len;
1641         int i;
1642
1643         hdr_len = (features & ((1ULL << VIRTIO_NET_F_MRG_RXBUF) |
1644                                (1ULL << VIRTIO_F_VERSION_1))) ?
1645                         sizeof(struct virtio_net_hdr_mrg_rxbuf) :
1646                         sizeof(struct virtio_net_hdr);
1647         if (features & (1 << VHOST_NET_F_VIRTIO_NET_HDR)) {
1648                 /* vhost provides vnet_hdr */
1649                 vhost_hlen = hdr_len;
1650                 sock_hlen = 0;
1651         } else {
1652                 /* socket provides vnet_hdr */
1653                 vhost_hlen = 0;
1654                 sock_hlen = hdr_len;
1655         }
1656         mutex_lock(&n->dev.mutex);
1657         if ((features & (1 << VHOST_F_LOG_ALL)) &&
1658             !vhost_log_access_ok(&n->dev))
1659                 goto out_unlock;
1660
1661         if ((features & (1ULL << VIRTIO_F_IOMMU_PLATFORM))) {
1662                 if (vhost_init_device_iotlb(&n->dev, true))
1663                         goto out_unlock;
1664         }
1665
1666         for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
1667                 mutex_lock(&n->vqs[i].vq.mutex);
1668                 n->vqs[i].vq.acked_features = features;
1669                 n->vqs[i].vhost_hlen = vhost_hlen;
1670                 n->vqs[i].sock_hlen = sock_hlen;
1671                 mutex_unlock(&n->vqs[i].vq.mutex);
1672         }
1673         mutex_unlock(&n->dev.mutex);
1674         return 0;
1675
1676 out_unlock:
1677         mutex_unlock(&n->dev.mutex);
1678         return -EFAULT;
1679 }
1680
1681 static long vhost_net_set_owner(struct vhost_net *n)
1682 {
1683         int r;
1684
1685         mutex_lock(&n->dev.mutex);
1686         if (vhost_dev_has_owner(&n->dev)) {
1687                 r = -EBUSY;
1688                 goto out;
1689         }
1690         r = vhost_net_set_ubuf_info(n);
1691         if (r)
1692                 goto out;
1693         r = vhost_dev_set_owner(&n->dev);
1694         if (r)
1695                 vhost_net_clear_ubuf_info(n);
1696         vhost_net_flush(n);
1697 out:
1698         mutex_unlock(&n->dev.mutex);
1699         return r;
1700 }
1701
1702 static long vhost_net_ioctl(struct file *f, unsigned int ioctl,
1703                             unsigned long arg)
1704 {
1705         struct vhost_net *n = f->private_data;
1706         void __user *argp = (void __user *)arg;
1707         u64 __user *featurep = argp;
1708         struct vhost_vring_file backend;
1709         u64 features;
1710         int r;
1711
1712         switch (ioctl) {
1713         case VHOST_NET_SET_BACKEND:
1714                 if (copy_from_user(&backend, argp, sizeof backend))
1715                         return -EFAULT;
1716                 return vhost_net_set_backend(n, backend.index, backend.fd);
1717         case VHOST_GET_FEATURES:
1718                 features = VHOST_NET_FEATURES;
1719                 if (copy_to_user(featurep, &features, sizeof features))
1720                         return -EFAULT;
1721                 return 0;
1722         case VHOST_SET_FEATURES:
1723                 if (copy_from_user(&features, featurep, sizeof features))
1724                         return -EFAULT;
1725                 if (features & ~VHOST_NET_FEATURES)
1726                         return -EOPNOTSUPP;
1727                 return vhost_net_set_features(n, features);
1728         case VHOST_GET_BACKEND_FEATURES:
1729                 features = VHOST_NET_BACKEND_FEATURES;
1730                 if (copy_to_user(featurep, &features, sizeof(features)))
1731                         return -EFAULT;
1732                 return 0;
1733         case VHOST_SET_BACKEND_FEATURES:
1734                 if (copy_from_user(&features, featurep, sizeof(features)))
1735                         return -EFAULT;
1736                 if (features & ~VHOST_NET_BACKEND_FEATURES)
1737                         return -EOPNOTSUPP;
1738                 return vhost_net_set_backend_features(n, features);
1739         case VHOST_RESET_OWNER:
1740                 return vhost_net_reset_owner(n);
1741         case VHOST_SET_OWNER:
1742                 return vhost_net_set_owner(n);
1743         default:
1744                 mutex_lock(&n->dev.mutex);
1745                 r = vhost_dev_ioctl(&n->dev, ioctl, argp);
1746                 if (r == -ENOIOCTLCMD)
1747                         r = vhost_vring_ioctl(&n->dev, ioctl, argp);
1748                 else
1749                         vhost_net_flush(n);
1750                 mutex_unlock(&n->dev.mutex);
1751                 return r;
1752         }
1753 }
1754
1755 #ifdef CONFIG_COMPAT
1756 static long vhost_net_compat_ioctl(struct file *f, unsigned int ioctl,
1757                                    unsigned long arg)
1758 {
1759         return vhost_net_ioctl(f, ioctl, (unsigned long)compat_ptr(arg));
1760 }
1761 #endif
1762
1763 static ssize_t vhost_net_chr_read_iter(struct kiocb *iocb, struct iov_iter *to)
1764 {
1765         struct file *file = iocb->ki_filp;
1766         struct vhost_net *n = file->private_data;
1767         struct vhost_dev *dev = &n->dev;
1768         int noblock = file->f_flags & O_NONBLOCK;
1769
1770         return vhost_chr_read_iter(dev, to, noblock);
1771 }
1772
1773 static ssize_t vhost_net_chr_write_iter(struct kiocb *iocb,
1774                                         struct iov_iter *from)
1775 {
1776         struct file *file = iocb->ki_filp;
1777         struct vhost_net *n = file->private_data;
1778         struct vhost_dev *dev = &n->dev;
1779
1780         return vhost_chr_write_iter(dev, from);
1781 }
1782
1783 static __poll_t vhost_net_chr_poll(struct file *file, poll_table *wait)
1784 {
1785         struct vhost_net *n = file->private_data;
1786         struct vhost_dev *dev = &n->dev;
1787
1788         return vhost_chr_poll(file, dev, wait);
1789 }
1790
1791 static const struct file_operations vhost_net_fops = {
1792         .owner          = THIS_MODULE,
1793         .release        = vhost_net_release,
1794         .read_iter      = vhost_net_chr_read_iter,
1795         .write_iter     = vhost_net_chr_write_iter,
1796         .poll           = vhost_net_chr_poll,
1797         .unlocked_ioctl = vhost_net_ioctl,
1798 #ifdef CONFIG_COMPAT
1799         .compat_ioctl   = vhost_net_compat_ioctl,
1800 #endif
1801         .open           = vhost_net_open,
1802         .llseek         = noop_llseek,
1803 };
1804
1805 static struct miscdevice vhost_net_misc = {
1806         .minor = VHOST_NET_MINOR,
1807         .name = "vhost-net",
1808         .fops = &vhost_net_fops,
1809 };
1810
1811 static int vhost_net_init(void)
1812 {
1813         if (experimental_zcopytx)
1814                 vhost_net_enable_zcopy(VHOST_NET_VQ_TX);
1815         return misc_register(&vhost_net_misc);
1816 }
1817 module_init(vhost_net_init);
1818
1819 static void vhost_net_exit(void)
1820 {
1821         misc_deregister(&vhost_net_misc);
1822 }
1823 module_exit(vhost_net_exit);
1824
1825 MODULE_VERSION("0.0.1");
1826 MODULE_LICENSE("GPL v2");
1827 MODULE_AUTHOR("Michael S. Tsirkin");
1828 MODULE_DESCRIPTION("Host kernel accelerator for virtio net");
1829 MODULE_ALIAS_MISCDEV(VHOST_NET_MINOR);
1830 MODULE_ALIAS("devname:vhost-net");