drivers/vhost/net.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /* Copyright (C) 2009 Red Hat, Inc.
   3  * Author: Michael S. Tsirkin <mst@redhat.com>
   4  *
   5  * virtio-net server in host kernel.
   6  */
   7
   8 #include <linux/compat.h>
   9 #include <linux/eventfd.h>
  10 #include <linux/vhost.h>
  11 #include <linux/virtio_net.h>
  12 #include <linux/miscdevice.h>
  13 #include <linux/module.h>
  14 #include <linux/moduleparam.h>
  15 #include <linux/mutex.h>
  16 #include <linux/workqueue.h>
  17 #include <linux/file.h>
  18 #include <linux/slab.h>
  19 #include <linux/sched/clock.h>
  20 #include <linux/sched/signal.h>
  21 #include <linux/vmalloc.h>
  22
  23 #include <linux/net.h>
  24 #include <linux/if_packet.h>
  25 #include <linux/if_arp.h>
  26 #include <linux/if_tun.h>
  27 #include <linux/if_macvlan.h>
  28 #include <linux/if_tap.h>
  29 #include <linux/if_vlan.h>
  30 #include <linux/skb_array.h>
  31 #include <linux/skbuff.h>
  32
  33 #include <net/sock.h>
  34 #include <net/xdp.h>
  35
  36 #include "vhost.h"
  37
  38 static int experimental_zcopytx = 0;
  39 module_param(experimental_zcopytx, int, 0444);
  40 MODULE_PARM_DESC(experimental_zcopytx, "Enable Zero Copy TX;"
  41                                        " 1 -Enable; 0 - Disable");
  42
  43 /* Max number of bytes transferred before requeueing the job.
  44  * Using this limit prevents one virtqueue from starving others. */
  45 #define VHOST_NET_WEIGHT 0x80000
  46
  47 /* Max number of packets transferred before requeueing the job.
  48  * Using this limit prevents one virtqueue from starving others with small
  49  * pkts.
  50  */
  51 #define VHOST_NET_PKT_WEIGHT 256
  52
  53 /* MAX number of TX used buffers for outstanding zerocopy */
  54 #define VHOST_MAX_PEND 128
  55 #define VHOST_GOODCOPY_LEN 256
  56
  57 /*
  58  * For transmit, used buffer len is unused; we override it to track buffer
  59  * status internally; used for zerocopy tx only.
  60  */
  61 /* Lower device DMA failed */
  62 #define VHOST_DMA_FAILED_LEN    ((__force __virtio32)3)
  63 /* Lower device DMA done */
  64 #define VHOST_DMA_DONE_LEN      ((__force __virtio32)2)
  65 /* Lower device DMA in progress */
  66 #define VHOST_DMA_IN_PROGRESS   ((__force __virtio32)1)
  67 /* Buffer unused */
  68 #define VHOST_DMA_CLEAR_LEN     ((__force __virtio32)0)
  69
  70 #define VHOST_DMA_IS_DONE(len) ((__force u32)(len) >= (__force u32)VHOST_DMA_DONE_LEN)
  71
  72 enum {
  73         VHOST_NET_FEATURES = VHOST_FEATURES |
  74                          (1ULL << VHOST_NET_F_VIRTIO_NET_HDR) |
  75                          (1ULL << VIRTIO_NET_F_MRG_RXBUF) |
  76                          (1ULL << VIRTIO_F_ACCESS_PLATFORM) |
  77                          (1ULL << VIRTIO_F_RING_RESET)
  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_msgzc *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 cache */
 145         struct page_frag_cache pf_cache;
 146 };
 147
 148 static unsigned vhost_net_zcopy_mask __read_mostly;
 149
 150 static void *vhost_net_buf_get_ptr(struct vhost_net_buf *rxq)
 151 {
 152         if (rxq->tail != rxq->head)
 153                 return rxq->queue[rxq->head];
 154         else
 155                 return NULL;
 156 }
 157
 158 static int vhost_net_buf_get_size(struct vhost_net_buf *rxq)
 159 {
 160         return rxq->tail - rxq->head;
 161 }
 162
 163 static int vhost_net_buf_is_empty(struct vhost_net_buf *rxq)
 164 {
 165         return rxq->tail == rxq->head;
 166 }
 167
 168 static void *vhost_net_buf_consume(struct vhost_net_buf *rxq)
 169 {
 170         void *ret = vhost_net_buf_get_ptr(rxq);
 171         ++rxq->head;
 172         return ret;
 173 }
 174
 175 static int vhost_net_buf_produce(struct vhost_net_virtqueue *nvq)
 176 {
 177         struct vhost_net_buf *rxq = &nvq->rxq;
 178
 179         rxq->head = 0;
 180         rxq->tail = ptr_ring_consume_batched(nvq->rx_ring, rxq->queue,
 181                                               VHOST_NET_BATCH);
 182         return rxq->tail;
 183 }
 184
 185 static void vhost_net_buf_unproduce(struct vhost_net_virtqueue *nvq)
 186 {
 187         struct vhost_net_buf *rxq = &nvq->rxq;
 188
 189         if (nvq->rx_ring && !vhost_net_buf_is_empty(rxq)) {
 190                 ptr_ring_unconsume(nvq->rx_ring, rxq->queue + rxq->head,
 191                                    vhost_net_buf_get_size(rxq),
 192                                    tun_ptr_free);
 193                 rxq->head = rxq->tail = 0;
 194         }
 195 }
 196
 197 static int vhost_net_buf_peek_len(void *ptr)
 198 {
 199         if (tun_is_xdp_frame(ptr)) {
 200                 struct xdp_frame *xdpf = tun_ptr_to_xdp(ptr);
 201
 202                 return xdpf->len;
 203         }
 204
 205         return __skb_array_len_with_tag(ptr);
 206 }
 207
 208 static int vhost_net_buf_peek(struct vhost_net_virtqueue *nvq)
 209 {
 210         struct vhost_net_buf *rxq = &nvq->rxq;
 211
 212         if (!vhost_net_buf_is_empty(rxq))
 213                 goto out;
 214
 215         if (!vhost_net_buf_produce(nvq))
 216                 return 0;
 217
 218 out:
 219         return vhost_net_buf_peek_len(vhost_net_buf_get_ptr(rxq));
 220 }
 221
 222 static void vhost_net_buf_init(struct vhost_net_buf *rxq)
 223 {
 224         rxq->head = rxq->tail = 0;
 225 }
 226
 227 static void vhost_net_enable_zcopy(int vq)
 228 {
 229         vhost_net_zcopy_mask |= 0x1 << vq;
 230 }
 231
 232 static struct vhost_net_ubuf_ref *
 233 vhost_net_ubuf_alloc(struct vhost_virtqueue *vq, bool zcopy)
 234 {
 235         struct vhost_net_ubuf_ref *ubufs;
 236         /* No zero copy backend? Nothing to count. */
 237         if (!zcopy)
 238                 return NULL;
 239         ubufs = kmalloc(sizeof(*ubufs), GFP_KERNEL);
 240         if (!ubufs)
 241                 return ERR_PTR(-ENOMEM);
 242         atomic_set(&ubufs->refcount, 1);
 243         init_waitqueue_head(&ubufs->wait);
 244         ubufs->vq = vq;
 245         return ubufs;
 246 }
 247
 248 static int vhost_net_ubuf_put(struct vhost_net_ubuf_ref *ubufs)
 249 {
 250         int r = atomic_sub_return(1, &ubufs->refcount);
 251         if (unlikely(!r))
 252                 wake_up(&ubufs->wait);
 253         return r;
 254 }
 255
 256 static void vhost_net_ubuf_put_and_wait(struct vhost_net_ubuf_ref *ubufs)
 257 {
 258         vhost_net_ubuf_put(ubufs);
 259         wait_event(ubufs->wait, !atomic_read(&ubufs->refcount));
 260 }
 261
 262 static void vhost_net_ubuf_put_wait_and_free(struct vhost_net_ubuf_ref *ubufs)
 263 {
 264         vhost_net_ubuf_put_and_wait(ubufs);
 265         kfree(ubufs);
 266 }
 267
 268 static void vhost_net_clear_ubuf_info(struct vhost_net *n)
 269 {
 270         int i;
 271
 272         for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
 273                 kfree(n->vqs[i].ubuf_info);
 274                 n->vqs[i].ubuf_info = NULL;
 275         }
 276 }
 277
 278 static int vhost_net_set_ubuf_info(struct vhost_net *n)
 279 {
 280         bool zcopy;
 281         int i;
 282
 283         for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
 284                 zcopy = vhost_net_zcopy_mask & (0x1 << i);
 285                 if (!zcopy)
 286                         continue;
 287                 n->vqs[i].ubuf_info =
 288                         kmalloc_array(UIO_MAXIOV,
 289                                       sizeof(*n->vqs[i].ubuf_info),
 290                                       GFP_KERNEL);
 291                 if  (!n->vqs[i].ubuf_info)
 292                         goto err;
 293         }
 294         return 0;
 295
 296 err:
 297         vhost_net_clear_ubuf_info(n);
 298         return -ENOMEM;
 299 }
 300
 301 static void vhost_net_vq_reset(struct vhost_net *n)
 302 {
 303         int i;
 304
 305         vhost_net_clear_ubuf_info(n);
 306
 307         for (i = 0; i < VHOST_NET_VQ_MAX; i++) {
 308                 n->vqs[i].done_idx = 0;
 309                 n->vqs[i].upend_idx = 0;
 310                 n->vqs[i].ubufs = NULL;
 311                 n->vqs[i].vhost_hlen = 0;
 312                 n->vqs[i].sock_hlen = 0;
 313                 vhost_net_buf_init(&n->vqs[i].rxq);
 314         }
 315
 316 }
 317
 318 static void vhost_net_tx_packet(struct vhost_net *net)
 319 {
 320         ++net->tx_packets;
 321         if (net->tx_packets < 1024)
 322                 return;
 323         net->tx_packets = 0;
 324         net->tx_zcopy_err = 0;
 325 }
 326
 327 static void vhost_net_tx_err(struct vhost_net *net)
 328 {
 329         ++net->tx_zcopy_err;
 330 }
 331
 332 static bool vhost_net_tx_select_zcopy(struct vhost_net *net)
 333 {
 334         /* TX flush waits for outstanding DMAs to be done.
 335          * Don't start new DMAs.
 336          */
 337         return !net->tx_flush &&
 338                 net->tx_packets / 64 >= net->tx_zcopy_err;
 339 }
 340
 341 static bool vhost_sock_zcopy(struct socket *sock)
 342 {
 343         return unlikely(experimental_zcopytx) &&
 344                 sock_flag(sock->sk, SOCK_ZEROCOPY);
 345 }
 346
 347 static bool vhost_sock_xdp(struct socket *sock)
 348 {
 349         return sock_flag(sock->sk, SOCK_XDP);
 350 }
 351
 352 /* In case of DMA done not in order in lower device driver for some reason.
 353  * upend_idx is used to track end of used idx, done_idx is used to track head
 354  * of used idx. Once lower device DMA done contiguously, we will signal KVM
 355  * guest used idx.
 356  */
 357 static void vhost_zerocopy_signal_used(struct vhost_net *net,
 358                                        struct vhost_virtqueue *vq)
 359 {
 360         struct vhost_net_virtqueue *nvq =
 361                 container_of(vq, struct vhost_net_virtqueue, vq);
 362         int i, add;
 363         int j = 0;
 364
 365         for (i = nvq->done_idx; i != nvq->upend_idx; i = (i + 1) % UIO_MAXIOV) {
 366                 if (vq->heads[i].len == VHOST_DMA_FAILED_LEN)
 367                         vhost_net_tx_err(net);
 368                 if (VHOST_DMA_IS_DONE(vq->heads[i].len)) {
 369                         vq->heads[i].len = VHOST_DMA_CLEAR_LEN;
 370                         ++j;
 371                 } else
 372                         break;
 373         }
 374         while (j) {
 375                 add = min(UIO_MAXIOV - nvq->done_idx, j);
 376                 vhost_add_used_and_signal_n(vq->dev, vq,
 377                                             &vq->heads[nvq->done_idx], add);
 378                 nvq->done_idx = (nvq->done_idx + add) % UIO_MAXIOV;
 379                 j -= add;
 380         }
 381 }
 382
 383 static void vhost_zerocopy_complete(struct sk_buff *skb,
 384                                     struct ubuf_info *ubuf_base, bool success)
 385 {
 386         struct ubuf_info_msgzc *ubuf = uarg_to_msgzc(ubuf_base);
 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 const struct ubuf_info_ops vhost_ubuf_ops = {
 412         .complete = vhost_zerocopy_complete,
 413 };
 414
 415 static inline unsigned long busy_clock(void)
 416 {
 417         return local_clock() >> 10;
 418 }
 419
 420 static bool vhost_can_busy_poll(unsigned long endtime)
 421 {
 422         return likely(!need_resched() && !time_after(busy_clock(), endtime) &&
 423                       !signal_pending(current));
 424 }
 425
 426 static void vhost_net_disable_vq(struct vhost_net *n,
 427                                  struct vhost_virtqueue *vq)
 428 {
 429         struct vhost_net_virtqueue *nvq =
 430                 container_of(vq, struct vhost_net_virtqueue, vq);
 431         struct vhost_poll *poll = n->poll + (nvq - n->vqs);
 432         if (!vhost_vq_get_backend(vq))
 433                 return;
 434         vhost_poll_stop(poll);
 435 }
 436
 437 static int vhost_net_enable_vq(struct vhost_net *n,
 438                                 struct vhost_virtqueue *vq)
 439 {
 440         struct vhost_net_virtqueue *nvq =
 441                 container_of(vq, struct vhost_net_virtqueue, vq);
 442         struct vhost_poll *poll = n->poll + (nvq - n->vqs);
 443         struct socket *sock;
 444
 445         sock = vhost_vq_get_backend(vq);
 446         if (!sock)
 447                 return 0;
 448
 449         return vhost_poll_start(poll, sock->file);
 450 }
 451
 452 static void vhost_net_signal_used(struct vhost_net_virtqueue *nvq)
 453 {
 454         struct vhost_virtqueue *vq = &nvq->vq;
 455         struct vhost_dev *dev = vq->dev;
 456
 457         if (!nvq->done_idx)
 458                 return;
 459
 460         vhost_add_used_and_signal_n(dev, vq, vq->heads, nvq->done_idx);
 461         nvq->done_idx = 0;
 462 }
 463
 464 static void vhost_tx_batch(struct vhost_net *net,
 465                            struct vhost_net_virtqueue *nvq,
 466                            struct socket *sock,
 467                            struct msghdr *msghdr)
 468 {
 469         struct tun_msg_ctl ctl = {
 470                 .type = TUN_MSG_PTR,
 471                 .num = nvq->batched_xdp,
 472                 .ptr = nvq->xdp,
 473         };
 474         int i, err;
 475
 476         if (nvq->batched_xdp == 0)
 477                 goto signal_used;
 478
 479         msghdr->msg_control = &ctl;
 480         msghdr->msg_controllen = sizeof(ctl);
 481         err = sock->ops->sendmsg(sock, msghdr, 0);
 482         if (unlikely(err < 0)) {
 483                 vq_err(&nvq->vq, "Fail to batch sending packets\n");
 484
 485                 /* free pages owned by XDP; since this is an unlikely error path,
 486                  * keep it simple and avoid more complex bulk update for the
 487                  * used pages
 488                  */
 489                 for (i = 0; i < nvq->batched_xdp; ++i)
 490                         put_page(virt_to_head_page(nvq->xdp[i].data));
 491                 nvq->batched_xdp = 0;
 492                 nvq->done_idx = 0;
 493                 return;
 494         }
 495
 496 signal_used:
 497         vhost_net_signal_used(nvq);
 498         nvq->batched_xdp = 0;
 499 }
 500
 501 static int sock_has_rx_data(struct socket *sock)
 502 {
 503         if (unlikely(!sock))
 504                 return 0;
 505
 506         if (sock->ops->peek_len)
 507                 return sock->ops->peek_len(sock);
 508
 509         return skb_queue_empty(&sock->sk->sk_receive_queue);
 510 }
 511
 512 static void vhost_net_busy_poll_try_queue(struct vhost_net *net,
 513                                           struct vhost_virtqueue *vq)
 514 {
 515         if (!vhost_vq_avail_empty(&net->dev, vq)) {
 516                 vhost_poll_queue(&vq->poll);
 517         } else if (unlikely(vhost_enable_notify(&net->dev, vq))) {
 518                 vhost_disable_notify(&net->dev, vq);
 519                 vhost_poll_queue(&vq->poll);
 520         }
 521 }
 522
 523 static void vhost_net_busy_poll(struct vhost_net *net,
 524                                 struct vhost_virtqueue *rvq,
 525                                 struct vhost_virtqueue *tvq,
 526                                 bool *busyloop_intr,
 527                                 bool poll_rx)
 528 {
 529         unsigned long busyloop_timeout;
 530         unsigned long endtime;
 531         struct socket *sock;
 532         struct vhost_virtqueue *vq = poll_rx ? tvq : rvq;
 533
 534         /* Try to hold the vq mutex of the paired virtqueue. We can't
 535          * use mutex_lock() here since we could not guarantee a
 536          * consistenet lock ordering.
 537          */
 538         if (!mutex_trylock(&vq->mutex))
 539                 return;
 540
 541         vhost_disable_notify(&net->dev, vq);
 542         sock = vhost_vq_get_backend(rvq);
 543
 544         busyloop_timeout = poll_rx ? rvq->busyloop_timeout:
 545                                      tvq->busyloop_timeout;
 546
 547         preempt_disable();
 548         endtime = busy_clock() + busyloop_timeout;
 549
 550         while (vhost_can_busy_poll(endtime)) {
 551                 if (vhost_vq_has_work(vq)) {
 552                         *busyloop_intr = true;
 553                         break;
 554                 }
 555
 556                 if ((sock_has_rx_data(sock) &&
 557                      !vhost_vq_avail_empty(&net->dev, rvq)) ||
 558                     !vhost_vq_avail_empty(&net->dev, tvq))
 559                         break;
 560
 561                 cpu_relax();
 562         }
 563
 564         preempt_enable();
 565
 566         if (poll_rx || sock_has_rx_data(sock))
 567                 vhost_net_busy_poll_try_queue(net, vq);
 568         else if (!poll_rx) /* On tx here, sock has no rx data. */
 569                 vhost_enable_notify(&net->dev, rvq);
 570
 571         mutex_unlock(&vq->mutex);
 572 }
 573
 574 static int vhost_net_tx_get_vq_desc(struct vhost_net *net,
 575                                     struct vhost_net_virtqueue *tnvq,
 576                                     unsigned int *out_num, unsigned int *in_num,
 577                                     struct msghdr *msghdr, bool *busyloop_intr)
 578 {
 579         struct vhost_net_virtqueue *rnvq = &net->vqs[VHOST_NET_VQ_RX];
 580         struct vhost_virtqueue *rvq = &rnvq->vq;
 581         struct vhost_virtqueue *tvq = &tnvq->vq;
 582
 583         int r = vhost_get_vq_desc(tvq, tvq->iov, ARRAY_SIZE(tvq->iov),
 584                                   out_num, in_num, NULL, NULL);
 585
 586         if (r == tvq->num && tvq->busyloop_timeout) {
 587                 /* Flush batched packets first */
 588                 if (!vhost_sock_zcopy(vhost_vq_get_backend(tvq)))
 589                         vhost_tx_batch(net, tnvq,
 590                                        vhost_vq_get_backend(tvq),
 591                                        msghdr);
 592
 593                 vhost_net_busy_poll(net, rvq, tvq, busyloop_intr, false);
 594
 595                 r = vhost_get_vq_desc(tvq, tvq->iov, ARRAY_SIZE(tvq->iov),
 596                                       out_num, in_num, NULL, NULL);
 597         }
 598
 599         return r;
 600 }
 601
 602 static bool vhost_exceeds_maxpend(struct vhost_net *net)
 603 {
 604         struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_TX];
 605         struct vhost_virtqueue *vq = &nvq->vq;
 606
 607         return (nvq->upend_idx + UIO_MAXIOV - nvq->done_idx) % UIO_MAXIOV >
 608                min_t(unsigned int, VHOST_MAX_PEND, vq->num >> 2);
 609 }
 610
 611 static size_t init_iov_iter(struct vhost_virtqueue *vq, struct iov_iter *iter,
 612                             size_t hdr_size, int out)
 613 {
 614         /* Skip header. TODO: support TSO. */
 615         size_t len = iov_length(vq->iov, out);
 616
 617         iov_iter_init(iter, ITER_SOURCE, vq->iov, out, len);
 618         iov_iter_advance(iter, hdr_size);
 619
 620         return iov_iter_count(iter);
 621 }
 622
 623 static int get_tx_bufs(struct vhost_net *net,
 624                        struct vhost_net_virtqueue *nvq,
 625                        struct msghdr *msg,
 626                        unsigned int *out, unsigned int *in,
 627                        size_t *len, bool *busyloop_intr)
 628 {
 629         struct vhost_virtqueue *vq = &nvq->vq;
 630         int ret;
 631
 632         ret = vhost_net_tx_get_vq_desc(net, nvq, out, in, msg, busyloop_intr);
 633
 634         if (ret < 0 || ret == vq->num)
 635                 return ret;
 636
 637         if (*in) {
 638                 vq_err(vq, "Unexpected descriptor format for TX: out %d, int %d\n",
 639                         *out, *in);
 640                 return -EFAULT;
 641         }
 642
 643         /* Sanity check */
 644         *len = init_iov_iter(vq, &msg->msg_iter, nvq->vhost_hlen, *out);
 645         if (*len == 0) {
 646                 vq_err(vq, "Unexpected header len for TX: %zd expected %zd\n",
 647                         *len, nvq->vhost_hlen);
 648                 return -EFAULT;
 649         }
 650
 651         return ret;
 652 }
 653
 654 static bool tx_can_batch(struct vhost_virtqueue *vq, size_t total_len)
 655 {
 656         return total_len < VHOST_NET_WEIGHT &&
 657                !vhost_vq_avail_empty(vq->dev, vq);
 658 }
 659
 660 #define VHOST_NET_RX_PAD (NET_IP_ALIGN + NET_SKB_PAD)
 661
 662 static int vhost_net_build_xdp(struct vhost_net_virtqueue *nvq,
 663                                struct iov_iter *from)
 664 {
 665         struct vhost_virtqueue *vq = &nvq->vq;
 666         struct vhost_net *net = container_of(vq->dev, struct vhost_net,
 667                                              dev);
 668         struct socket *sock = vhost_vq_get_backend(vq);
 669         struct virtio_net_hdr *gso;
 670         struct xdp_buff *xdp = &nvq->xdp[nvq->batched_xdp];
 671         struct tun_xdp_hdr *hdr;
 672         size_t len = iov_iter_count(from);
 673         int headroom = vhost_sock_xdp(sock) ? XDP_PACKET_HEADROOM : 0;
 674         int buflen = SKB_DATA_ALIGN(sizeof(struct skb_shared_info));
 675         int pad = SKB_DATA_ALIGN(VHOST_NET_RX_PAD + headroom + nvq->sock_hlen);
 676         int sock_hlen = nvq->sock_hlen;
 677         void *buf;
 678         int copied;
 679         int ret;
 680
 681         if (unlikely(len < nvq->sock_hlen))
 682                 return -EFAULT;
 683
 684         if (SKB_DATA_ALIGN(len + pad) +
 685             SKB_DATA_ALIGN(sizeof(struct skb_shared_info)) > PAGE_SIZE)
 686                 return -ENOSPC;
 687
 688         buflen += SKB_DATA_ALIGN(len + pad);
 689         buf = page_frag_alloc_align(&net->pf_cache, buflen, GFP_KERNEL,
 690                                     SMP_CACHE_BYTES);
 691         if (unlikely(!buf))
 692                 return -ENOMEM;
 693
 694         copied = copy_from_iter(buf + offsetof(struct tun_xdp_hdr, gso),
 695                                 sock_hlen, from);
 696         if (copied != sock_hlen) {
 697                 ret = -EFAULT;
 698                 goto err;
 699         }
 700
 701         hdr = buf;
 702         gso = &hdr->gso;
 703
 704         if (!sock_hlen)
 705                 memset(buf, 0, pad);
 706
 707         if ((gso->flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) &&
 708             vhost16_to_cpu(vq, gso->csum_start) +
 709             vhost16_to_cpu(vq, gso->csum_offset) + 2 >
 710             vhost16_to_cpu(vq, gso->hdr_len)) {
 711                 gso->hdr_len = cpu_to_vhost16(vq,
 712                                vhost16_to_cpu(vq, gso->csum_start) +
 713                                vhost16_to_cpu(vq, gso->csum_offset) + 2);
 714
 715                 if (vhost16_to_cpu(vq, gso->hdr_len) > len) {
 716                         ret = -EINVAL;
 717                         goto err;
 718                 }
 719         }
 720
 721         len -= sock_hlen;
 722         copied = copy_from_iter(buf + pad, len, from);
 723         if (copied != len) {
 724                 ret = -EFAULT;
 725                 goto err;
 726         }
 727
 728         xdp_init_buff(xdp, buflen, NULL);
 729         xdp_prepare_buff(xdp, buf, pad, len, true);
 730         hdr->buflen = buflen;
 731
 732         ++nvq->batched_xdp;
 733
 734         return 0;
 735
 736 err:
 737         page_frag_free(buf);
 738         return ret;
 739 }
 740
 741 static void handle_tx_copy(struct vhost_net *net, struct socket *sock)
 742 {
 743         struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_TX];
 744         struct vhost_virtqueue *vq = &nvq->vq;
 745         unsigned out, in;
 746         int head;
 747         struct msghdr msg = {
 748                 .msg_name = NULL,
 749                 .msg_namelen = 0,
 750                 .msg_control = NULL,
 751                 .msg_controllen = 0,
 752                 .msg_flags = MSG_DONTWAIT,
 753         };
 754         size_t len, total_len = 0;
 755         int err;
 756         int sent_pkts = 0;
 757         bool sock_can_batch = (sock->sk->sk_sndbuf == INT_MAX);
 758         bool busyloop_intr;
 759
 760         do {
 761                 busyloop_intr = false;
 762                 if (nvq->done_idx == VHOST_NET_BATCH)
 763                         vhost_tx_batch(net, nvq, sock, &msg);
 764
 765                 head = get_tx_bufs(net, nvq, &msg, &out, &in, &len,
 766                                    &busyloop_intr);
 767                 /* On error, stop handling until the next kick. */
 768                 if (unlikely(head < 0))
 769                         break;
 770                 /* Nothing new?  Wait for eventfd to tell us they refilled. */
 771                 if (head == vq->num) {
 772                         /* Kicks are disabled at this point, break loop and
 773                          * process any remaining batched packets. Queue will
 774                          * be re-enabled afterwards.
 775                          */
 776                         break;
 777                 }
 778
 779                 total_len += len;
 780
 781                 /* For simplicity, TX batching is only enabled if
 782                  * sndbuf is unlimited.
 783                  */
 784                 if (sock_can_batch) {
 785                         err = vhost_net_build_xdp(nvq, &msg.msg_iter);
 786                         if (!err) {
 787                                 goto done;
 788                         } else if (unlikely(err != -ENOSPC)) {
 789                                 vhost_tx_batch(net, nvq, sock, &msg);
 790                                 vhost_discard_vq_desc(vq, 1);
 791                                 vhost_net_enable_vq(net, vq);
 792                                 break;
 793                         }
 794
 795                         /* We can't build XDP buff, go for single
 796                          * packet path but let's flush batched
 797                          * packets.
 798                          */
 799                         vhost_tx_batch(net, nvq, sock, &msg);
 800                         msg.msg_control = NULL;
 801                 } else {
 802                         if (tx_can_batch(vq, total_len))
 803                                 msg.msg_flags |= MSG_MORE;
 804                         else
 805                                 msg.msg_flags &= ~MSG_MORE;
 806                 }
 807
 808                 err = sock->ops->sendmsg(sock, &msg, len);
 809                 if (unlikely(err < 0)) {
 810                         if (err == -EAGAIN || err == -ENOMEM || err == -ENOBUFS) {
 811                                 vhost_discard_vq_desc(vq, 1);
 812                                 vhost_net_enable_vq(net, vq);
 813                                 break;
 814                         }
 815                         pr_debug("Fail to send packet: err %d", err);
 816                 } else if (unlikely(err != len))
 817                         pr_debug("Truncated TX packet: len %d != %zd\n",
 818                                  err, len);
 819 done:
 820                 vq->heads[nvq->done_idx].id = cpu_to_vhost32(vq, head);
 821                 vq->heads[nvq->done_idx].len = 0;
 822                 ++nvq->done_idx;
 823         } while (likely(!vhost_exceeds_weight(vq, ++sent_pkts, total_len)));
 824
 825         /* Kicks are still disabled, dispatch any remaining batched msgs. */
 826         vhost_tx_batch(net, nvq, sock, &msg);
 827
 828         if (unlikely(busyloop_intr))
 829                 /* If interrupted while doing busy polling, requeue the
 830                  * handler to be fair handle_rx as well as other tasks
 831                  * waiting on cpu.
 832                  */
 833                 vhost_poll_queue(&vq->poll);
 834         else
 835                 /* All of our work has been completed; however, before
 836                  * leaving the TX handler, do one last check for work,
 837                  * and requeue handler if necessary. If there is no work,
 838                  * queue will be reenabled.
 839                  */
 840                 vhost_net_busy_poll_try_queue(net, vq);
 841 }
 842
 843 static void handle_tx_zerocopy(struct vhost_net *net, struct socket *sock)
 844 {
 845         struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_TX];
 846         struct vhost_virtqueue *vq = &nvq->vq;
 847         unsigned out, in;
 848         int head;
 849         struct msghdr msg = {
 850                 .msg_name = NULL,
 851                 .msg_namelen = 0,
 852                 .msg_control = NULL,
 853                 .msg_controllen = 0,
 854                 .msg_flags = MSG_DONTWAIT,
 855         };
 856         struct tun_msg_ctl ctl;
 857         size_t len, total_len = 0;
 858         int err;
 859         struct vhost_net_ubuf_ref *ubufs;
 860         struct ubuf_info_msgzc *ubuf;
 861         bool zcopy_used;
 862         int sent_pkts = 0;
 863
 864         do {
 865                 bool busyloop_intr;
 866
 867                 /* Release DMAs done buffers first */
 868                 vhost_zerocopy_signal_used(net, vq);
 869
 870                 busyloop_intr = false;
 871                 head = get_tx_bufs(net, nvq, &msg, &out, &in, &len,
 872                                    &busyloop_intr);
 873                 /* On error, stop handling until the next kick. */
 874                 if (unlikely(head < 0))
 875                         break;
 876                 /* Nothing new?  Wait for eventfd to tell us they refilled. */
 877                 if (head == vq->num) {
 878                         if (unlikely(busyloop_intr)) {
 879                                 vhost_poll_queue(&vq->poll);
 880                         } else if (unlikely(vhost_enable_notify(&net->dev, vq))) {
 881                                 vhost_disable_notify(&net->dev, vq);
 882                                 continue;
 883                         }
 884                         break;
 885                 }
 886
 887                 zcopy_used = len >= VHOST_GOODCOPY_LEN
 888                              && !vhost_exceeds_maxpend(net)
 889                              && vhost_net_tx_select_zcopy(net);
 890
 891                 /* use msg_control to pass vhost zerocopy ubuf info to skb */
 892                 if (zcopy_used) {
 893                         ubuf = nvq->ubuf_info + nvq->upend_idx;
 894                         vq->heads[nvq->upend_idx].id = cpu_to_vhost32(vq, head);
 895                         vq->heads[nvq->upend_idx].len = VHOST_DMA_IN_PROGRESS;
 896                         ubuf->ctx = nvq->ubufs;
 897                         ubuf->desc = nvq->upend_idx;
 898                         ubuf->ubuf.ops = &vhost_ubuf_ops;
 899                         ubuf->ubuf.flags = SKBFL_ZEROCOPY_FRAG;
 900                         refcount_set(&ubuf->ubuf.refcnt, 1);
 901                         msg.msg_control = &ctl;
 902                         ctl.type = TUN_MSG_UBUF;
 903                         ctl.ptr = &ubuf->ubuf;
 904                         msg.msg_controllen = sizeof(ctl);
 905                         ubufs = nvq->ubufs;
 906                         atomic_inc(&ubufs->refcount);
 907                         nvq->upend_idx = (nvq->upend_idx + 1) % UIO_MAXIOV;
 908                 } else {
 909                         msg.msg_control = NULL;
 910                         ubufs = NULL;
 911                 }
 912                 total_len += len;
 913                 if (tx_can_batch(vq, total_len) &&
 914                     likely(!vhost_exceeds_maxpend(net))) {
 915                         msg.msg_flags |= MSG_MORE;
 916                 } else {
 917                         msg.msg_flags &= ~MSG_MORE;
 918                 }
 919
 920                 err = sock->ops->sendmsg(sock, &msg, len);
 921                 if (unlikely(err < 0)) {
 922                         bool retry = err == -EAGAIN || err == -ENOMEM || err == -ENOBUFS;
 923
 924                         if (zcopy_used) {
 925                                 if (vq->heads[ubuf->desc].len == VHOST_DMA_IN_PROGRESS)
 926                                         vhost_net_ubuf_put(ubufs);
 927                                 if (retry)
 928                                         nvq->upend_idx = ((unsigned)nvq->upend_idx - 1)
 929                                                 % UIO_MAXIOV;
 930                                 else
 931                                         vq->heads[ubuf->desc].len = VHOST_DMA_DONE_LEN;
 932                         }
 933                         if (retry) {
 934                                 vhost_discard_vq_desc(vq, 1);
 935                                 vhost_net_enable_vq(net, vq);
 936                                 break;
 937                         }
 938                         pr_debug("Fail to send packet: err %d", err);
 939                 } else if (unlikely(err != len))
 940                         pr_debug("Truncated TX packet: "
 941                                  " len %d != %zd\n", err, len);
 942                 if (!zcopy_used)
 943                         vhost_add_used_and_signal(&net->dev, vq, head, 0);
 944                 else
 945                         vhost_zerocopy_signal_used(net, vq);
 946                 vhost_net_tx_packet(net);
 947         } while (likely(!vhost_exceeds_weight(vq, ++sent_pkts, total_len)));
 948 }
 949
 950 /* Expects to be always run from workqueue - which acts as
 951  * read-size critical section for our kind of RCU. */
 952 static void handle_tx(struct vhost_net *net)
 953 {
 954         struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_TX];
 955         struct vhost_virtqueue *vq = &nvq->vq;
 956         struct socket *sock;
 957
 958         mutex_lock_nested(&vq->mutex, VHOST_NET_VQ_TX);
 959         sock = vhost_vq_get_backend(vq);
 960         if (!sock)
 961                 goto out;
 962
 963         if (!vq_meta_prefetch(vq))
 964                 goto out;
 965
 966         vhost_disable_notify(&net->dev, vq);
 967         vhost_net_disable_vq(net, vq);
 968
 969         if (vhost_sock_zcopy(sock))
 970                 handle_tx_zerocopy(net, sock);
 971         else
 972                 handle_tx_copy(net, sock);
 973
 974 out:
 975         mutex_unlock(&vq->mutex);
 976 }
 977
 978 static int peek_head_len(struct vhost_net_virtqueue *rvq, struct sock *sk)
 979 {
 980         struct sk_buff *head;
 981         int len = 0;
 982         unsigned long flags;
 983
 984         if (rvq->rx_ring)
 985                 return vhost_net_buf_peek(rvq);
 986
 987         spin_lock_irqsave(&sk->sk_receive_queue.lock, flags);
 988         head = skb_peek(&sk->sk_receive_queue);
 989         if (likely(head)) {
 990                 len = head->len;
 991                 if (skb_vlan_tag_present(head))
 992                         len += VLAN_HLEN;
 993         }
 994
 995         spin_unlock_irqrestore(&sk->sk_receive_queue.lock, flags);
 996         return len;
 997 }
 998
 999 static int vhost_net_rx_peek_head_len(struct vhost_net *net, struct sock *sk,
1000                                       bool *busyloop_intr)
1001 {
1002         struct vhost_net_virtqueue *rnvq = &net->vqs[VHOST_NET_VQ_RX];
1003         struct vhost_net_virtqueue *tnvq = &net->vqs[VHOST_NET_VQ_TX];
1004         struct vhost_virtqueue *rvq = &rnvq->vq;
1005         struct vhost_virtqueue *tvq = &tnvq->vq;
1006         int len = peek_head_len(rnvq, sk);
1007
1008         if (!len && rvq->busyloop_timeout) {
1009                 /* Flush batched heads first */
1010                 vhost_net_signal_used(rnvq);
1011                 /* Both tx vq and rx socket were polled here */
1012                 vhost_net_busy_poll(net, rvq, tvq, busyloop_intr, true);
1013
1014                 len = peek_head_len(rnvq, sk);
1015         }
1016
1017         return len;
1018 }
1019
1020 /* This is a multi-buffer version of vhost_get_desc, that works if
1021  *      vq has read descriptors only.
1022  * @vq          - the relevant virtqueue
1023  * @datalen     - data length we'll be reading
1024  * @iovcount    - returned count of io vectors we fill
1025  * @log         - vhost log
1026  * @log_num     - log offset
1027  * @quota       - headcount quota, 1 for big buffer
1028  *      returns number of buffer heads allocated, negative on error
1029  */
1030 static int get_rx_bufs(struct vhost_virtqueue *vq,
1031                        struct vring_used_elem *heads,
1032                        int datalen,
1033                        unsigned *iovcount,
1034                        struct vhost_log *log,
1035                        unsigned *log_num,
1036                        unsigned int quota)
1037 {
1038         unsigned int out, in;
1039         int seg = 0;
1040         int headcount = 0;
1041         unsigned d;
1042         int r, nlogs = 0;
1043         /* len is always initialized before use since we are always called with
1044          * datalen > 0.
1045          */
1046         u32 len;
1047
1048         while (datalen > 0 && headcount < quota) {
1049                 if (unlikely(seg >= UIO_MAXIOV)) {
1050                         r = -ENOBUFS;
1051                         goto err;
1052                 }
1053                 r = vhost_get_vq_desc(vq, vq->iov + seg,
1054                                       ARRAY_SIZE(vq->iov) - seg, &out,
1055                                       &in, log, log_num);
1056                 if (unlikely(r < 0))
1057                         goto err;
1058
1059                 d = r;
1060                 if (d == vq->num) {
1061                         r = 0;
1062                         goto err;
1063                 }
1064                 if (unlikely(out || in <= 0)) {
1065                         vq_err(vq, "unexpected descriptor format for RX: "
1066                                 "out %d, in %d\n", out, in);
1067                         r = -EINVAL;
1068                         goto err;
1069                 }
1070                 if (unlikely(log)) {
1071                         nlogs += *log_num;
1072                         log += *log_num;
1073                 }
1074                 heads[headcount].id = cpu_to_vhost32(vq, d);
1075                 len = iov_length(vq->iov + seg, in);
1076                 heads[headcount].len = cpu_to_vhost32(vq, len);
1077                 datalen -= len;
1078                 ++headcount;
1079                 seg += in;
1080         }
1081         heads[headcount - 1].len = cpu_to_vhost32(vq, len + datalen);
1082         *iovcount = seg;
1083         if (unlikely(log))
1084                 *log_num = nlogs;
1085
1086         /* Detect overrun */
1087         if (unlikely(datalen > 0)) {
1088                 r = UIO_MAXIOV + 1;
1089                 goto err;
1090         }
1091         return headcount;
1092 err:
1093         vhost_discard_vq_desc(vq, headcount);
1094         return r;
1095 }
1096
1097 /* Expects to be always run from workqueue - which acts as
1098  * read-size critical section for our kind of RCU. */
1099 static void handle_rx(struct vhost_net *net)
1100 {
1101         struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_RX];
1102         struct vhost_virtqueue *vq = &nvq->vq;
1103         unsigned in, log;
1104         struct vhost_log *vq_log;
1105         struct msghdr msg = {
1106                 .msg_name = NULL,
1107                 .msg_namelen = 0,
1108                 .msg_control = NULL, /* FIXME: get and handle RX aux data. */
1109                 .msg_controllen = 0,
1110                 .msg_flags = MSG_DONTWAIT,
1111         };
1112         struct virtio_net_hdr hdr = {
1113                 .flags = 0,
1114                 .gso_type = VIRTIO_NET_HDR_GSO_NONE
1115         };
1116         size_t total_len = 0;
1117         int err, mergeable;
1118         s16 headcount;
1119         size_t vhost_hlen, sock_hlen;
1120         size_t vhost_len, sock_len;
1121         bool busyloop_intr = false;
1122         bool set_num_buffers;
1123         struct socket *sock;
1124         struct iov_iter fixup;
1125         __virtio16 num_buffers;
1126         int recv_pkts = 0;
1127
1128         mutex_lock_nested(&vq->mutex, VHOST_NET_VQ_RX);
1129         sock = vhost_vq_get_backend(vq);
1130         if (!sock)
1131                 goto out;
1132
1133         if (!vq_meta_prefetch(vq))
1134                 goto out;
1135
1136         vhost_disable_notify(&net->dev, vq);
1137         vhost_net_disable_vq(net, vq);
1138
1139         vhost_hlen = nvq->vhost_hlen;
1140         sock_hlen = nvq->sock_hlen;
1141
1142         vq_log = unlikely(vhost_has_feature(vq, VHOST_F_LOG_ALL)) ?
1143                 vq->log : NULL;
1144         mergeable = vhost_has_feature(vq, VIRTIO_NET_F_MRG_RXBUF);
1145         set_num_buffers = mergeable ||
1146                           vhost_has_feature(vq, VIRTIO_F_VERSION_1);
1147
1148         do {
1149                 sock_len = vhost_net_rx_peek_head_len(net, sock->sk,
1150                                                       &busyloop_intr);
1151                 if (!sock_len)
1152                         break;
1153                 sock_len += sock_hlen;
1154                 vhost_len = sock_len + vhost_hlen;
1155                 headcount = get_rx_bufs(vq, vq->heads + nvq->done_idx,
1156                                         vhost_len, &in, vq_log, &log,
1157                                         likely(mergeable) ? UIO_MAXIOV : 1);
1158                 /* On error, stop handling until the next kick. */
1159                 if (unlikely(headcount < 0))
1160                         goto out;
1161                 /* OK, now we need to know about added descriptors. */
1162                 if (!headcount) {
1163                         if (unlikely(busyloop_intr)) {
1164                                 vhost_poll_queue(&vq->poll);
1165                         } else if (unlikely(vhost_enable_notify(&net->dev, vq))) {
1166                                 /* They have slipped one in as we were
1167                                  * doing that: check again. */
1168                                 vhost_disable_notify(&net->dev, vq);
1169                                 continue;
1170                         }
1171                         /* Nothing new?  Wait for eventfd to tell us
1172                          * they refilled. */
1173                         goto out;
1174                 }
1175                 busyloop_intr = false;
1176                 if (nvq->rx_ring)
1177                         msg.msg_control = vhost_net_buf_consume(&nvq->rxq);
1178                 /* On overrun, truncate and discard */
1179                 if (unlikely(headcount > UIO_MAXIOV)) {
1180                         iov_iter_init(&msg.msg_iter, ITER_DEST, vq->iov, 1, 1);
1181                         err = sock->ops->recvmsg(sock, &msg,
1182                                                  1, MSG_DONTWAIT | MSG_TRUNC);
1183                         pr_debug("Discarded rx packet: len %zd\n", sock_len);
1184                         continue;
1185                 }
1186                 /* We don't need to be notified again. */
1187                 iov_iter_init(&msg.msg_iter, ITER_DEST, vq->iov, in, vhost_len);
1188                 fixup = msg.msg_iter;
1189                 if (unlikely((vhost_hlen))) {
1190                         /* We will supply the header ourselves
1191                          * TODO: support TSO.
1192                          */
1193                         iov_iter_advance(&msg.msg_iter, vhost_hlen);
1194                 }
1195                 err = sock->ops->recvmsg(sock, &msg,
1196                                          sock_len, MSG_DONTWAIT | MSG_TRUNC);
1197                 /* Userspace might have consumed the packet meanwhile:
1198                  * it's not supposed to do this usually, but might be hard
1199                  * to prevent. Discard data we got (if any) and keep going. */
1200                 if (unlikely(err != sock_len)) {
1201                         pr_debug("Discarded rx packet: "
1202                                  " len %d, expected %zd\n", err, sock_len);
1203                         vhost_discard_vq_desc(vq, headcount);
1204                         continue;
1205                 }
1206                 /* Supply virtio_net_hdr if VHOST_NET_F_VIRTIO_NET_HDR */
1207                 if (unlikely(vhost_hlen)) {
1208                         if (copy_to_iter(&hdr, sizeof(hdr),
1209                                          &fixup) != sizeof(hdr)) {
1210                                 vq_err(vq, "Unable to write vnet_hdr "
1211                                        "at addr %p\n", vq->iov->iov_base);
1212                                 goto out;
1213                         }
1214                 } else {
1215                         /* Header came from socket; we'll need to patch
1216                          * ->num_buffers over if VIRTIO_NET_F_MRG_RXBUF
1217                          */
1218                         iov_iter_advance(&fixup, sizeof(hdr));
1219                 }
1220                 /* TODO: Should check and handle checksum. */
1221
1222                 num_buffers = cpu_to_vhost16(vq, headcount);
1223                 if (likely(set_num_buffers) &&
1224                     copy_to_iter(&num_buffers, sizeof num_buffers,
1225                                  &fixup) != sizeof num_buffers) {
1226                         vq_err(vq, "Failed num_buffers write");
1227                         vhost_discard_vq_desc(vq, headcount);
1228                         goto out;
1229                 }
1230                 nvq->done_idx += headcount;
1231                 if (nvq->done_idx > VHOST_NET_BATCH)
1232                         vhost_net_signal_used(nvq);
1233                 if (unlikely(vq_log))
1234                         vhost_log_write(vq, vq_log, log, vhost_len,
1235                                         vq->iov, in);
1236                 total_len += vhost_len;
1237         } while (likely(!vhost_exceeds_weight(vq, ++recv_pkts, total_len)));
1238
1239         if (unlikely(busyloop_intr))
1240                 vhost_poll_queue(&vq->poll);
1241         else if (!sock_len)
1242                 vhost_net_enable_vq(net, vq);
1243 out:
1244         vhost_net_signal_used(nvq);
1245         mutex_unlock(&vq->mutex);
1246 }
1247
1248 static void handle_tx_kick(struct vhost_work *work)
1249 {
1250         struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
1251                                                   poll.work);
1252         struct vhost_net *net = container_of(vq->dev, struct vhost_net, dev);
1253
1254         handle_tx(net);
1255 }
1256
1257 static void handle_rx_kick(struct vhost_work *work)
1258 {
1259         struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
1260                                                   poll.work);
1261         struct vhost_net *net = container_of(vq->dev, struct vhost_net, dev);
1262
1263         handle_rx(net);
1264 }
1265
1266 static void handle_tx_net(struct vhost_work *work)
1267 {
1268         struct vhost_net *net = container_of(work, struct vhost_net,
1269                                              poll[VHOST_NET_VQ_TX].work);
1270         handle_tx(net);
1271 }
1272
1273 static void handle_rx_net(struct vhost_work *work)
1274 {
1275         struct vhost_net *net = container_of(work, struct vhost_net,
1276                                              poll[VHOST_NET_VQ_RX].work);
1277         handle_rx(net);
1278 }
1279
1280 static int vhost_net_open(struct inode *inode, struct file *f)
1281 {
1282         struct vhost_net *n;
1283         struct vhost_dev *dev;
1284         struct vhost_virtqueue **vqs;
1285         void **queue;
1286         struct xdp_buff *xdp;
1287         int i;
1288
1289         n = kvmalloc(sizeof *n, GFP_KERNEL | __GFP_RETRY_MAYFAIL);
1290         if (!n)
1291                 return -ENOMEM;
1292         vqs = kmalloc_array(VHOST_NET_VQ_MAX, sizeof(*vqs), GFP_KERNEL);
1293         if (!vqs) {
1294                 kvfree(n);
1295                 return -ENOMEM;
1296         }
1297
1298         queue = kmalloc_array(VHOST_NET_BATCH, sizeof(void *),
1299                               GFP_KERNEL);
1300         if (!queue) {
1301                 kfree(vqs);
1302                 kvfree(n);
1303                 return -ENOMEM;
1304         }
1305         n->vqs[VHOST_NET_VQ_RX].rxq.queue = queue;
1306
1307         xdp = kmalloc_array(VHOST_NET_BATCH, sizeof(*xdp), GFP_KERNEL);
1308         if (!xdp) {
1309                 kfree(vqs);
1310                 kvfree(n);
1311                 kfree(queue);
1312                 return -ENOMEM;
1313         }
1314         n->vqs[VHOST_NET_VQ_TX].xdp = xdp;
1315
1316         dev = &n->dev;
1317         vqs[VHOST_NET_VQ_TX] = &n->vqs[VHOST_NET_VQ_TX].vq;
1318         vqs[VHOST_NET_VQ_RX] = &n->vqs[VHOST_NET_VQ_RX].vq;
1319         n->vqs[VHOST_NET_VQ_TX].vq.handle_kick = handle_tx_kick;
1320         n->vqs[VHOST_NET_VQ_RX].vq.handle_kick = handle_rx_kick;
1321         for (i = 0; i < VHOST_NET_VQ_MAX; i++) {
1322                 n->vqs[i].ubufs = NULL;
1323                 n->vqs[i].ubuf_info = NULL;
1324                 n->vqs[i].upend_idx = 0;
1325                 n->vqs[i].done_idx = 0;
1326                 n->vqs[i].batched_xdp = 0;
1327                 n->vqs[i].vhost_hlen = 0;
1328                 n->vqs[i].sock_hlen = 0;
1329                 n->vqs[i].rx_ring = NULL;
1330                 vhost_net_buf_init(&n->vqs[i].rxq);
1331         }
1332         vhost_dev_init(dev, vqs, VHOST_NET_VQ_MAX,
1333                        UIO_MAXIOV + VHOST_NET_BATCH,
1334                        VHOST_NET_PKT_WEIGHT, VHOST_NET_WEIGHT, true,
1335                        NULL);
1336
1337         vhost_poll_init(n->poll + VHOST_NET_VQ_TX, handle_tx_net, EPOLLOUT, dev,
1338                         vqs[VHOST_NET_VQ_TX]);
1339         vhost_poll_init(n->poll + VHOST_NET_VQ_RX, handle_rx_net, EPOLLIN, dev,
1340                         vqs[VHOST_NET_VQ_RX]);
1341
1342         f->private_data = n;
1343         page_frag_cache_init(&n->pf_cache);
1344
1345         return 0;
1346 }
1347
1348 static struct socket *vhost_net_stop_vq(struct vhost_net *n,
1349                                         struct vhost_virtqueue *vq)
1350 {
1351         struct socket *sock;
1352         struct vhost_net_virtqueue *nvq =
1353                 container_of(vq, struct vhost_net_virtqueue, vq);
1354
1355         mutex_lock(&vq->mutex);
1356         sock = vhost_vq_get_backend(vq);
1357         vhost_net_disable_vq(n, vq);
1358         vhost_vq_set_backend(vq, NULL);
1359         vhost_net_buf_unproduce(nvq);
1360         nvq->rx_ring = NULL;
1361         mutex_unlock(&vq->mutex);
1362         return sock;
1363 }
1364
1365 static void vhost_net_stop(struct vhost_net *n, struct socket **tx_sock,
1366                            struct socket **rx_sock)
1367 {
1368         *tx_sock = vhost_net_stop_vq(n, &n->vqs[VHOST_NET_VQ_TX].vq);
1369         *rx_sock = vhost_net_stop_vq(n, &n->vqs[VHOST_NET_VQ_RX].vq);
1370 }
1371
1372 static void vhost_net_flush(struct vhost_net *n)
1373 {
1374         vhost_dev_flush(&n->dev);
1375         if (n->vqs[VHOST_NET_VQ_TX].ubufs) {
1376                 mutex_lock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
1377                 n->tx_flush = true;
1378                 mutex_unlock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
1379                 /* Wait for all lower device DMAs done. */
1380                 vhost_net_ubuf_put_and_wait(n->vqs[VHOST_NET_VQ_TX].ubufs);
1381                 mutex_lock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
1382                 n->tx_flush = false;
1383                 atomic_set(&n->vqs[VHOST_NET_VQ_TX].ubufs->refcount, 1);
1384                 mutex_unlock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
1385         }
1386 }
1387
1388 static int vhost_net_release(struct inode *inode, struct file *f)
1389 {
1390         struct vhost_net *n = f->private_data;
1391         struct socket *tx_sock;
1392         struct socket *rx_sock;
1393
1394         vhost_net_stop(n, &tx_sock, &rx_sock);
1395         vhost_net_flush(n);
1396         vhost_dev_stop(&n->dev);
1397         vhost_dev_cleanup(&n->dev);
1398         vhost_net_vq_reset(n);
1399         if (tx_sock)
1400                 sockfd_put(tx_sock);
1401         if (rx_sock)
1402                 sockfd_put(rx_sock);
1403         /* Make sure no callbacks are outstanding */
1404         synchronize_rcu();
1405         /* We do an extra flush before freeing memory,
1406          * since jobs can re-queue themselves. */
1407         vhost_net_flush(n);
1408         kfree(n->vqs[VHOST_NET_VQ_RX].rxq.queue);
1409         kfree(n->vqs[VHOST_NET_VQ_TX].xdp);
1410         kfree(n->dev.vqs);
1411         page_frag_cache_drain(&n->pf_cache);
1412         kvfree(n);
1413         return 0;
1414 }
1415
1416 static struct socket *get_raw_socket(int fd)
1417 {
1418         int r;
1419         struct socket *sock = sockfd_lookup(fd, &r);
1420
1421         if (!sock)
1422                 return ERR_PTR(-ENOTSOCK);
1423
1424         /* Parameter checking */
1425         if (sock->sk->sk_type != SOCK_RAW) {
1426                 r = -ESOCKTNOSUPPORT;
1427                 goto err;
1428         }
1429
1430         if (sock->sk->sk_family != AF_PACKET) {
1431                 r = -EPFNOSUPPORT;
1432                 goto err;
1433         }
1434         return sock;
1435 err:
1436         sockfd_put(sock);
1437         return ERR_PTR(r);
1438 }
1439
1440 static struct ptr_ring *get_tap_ptr_ring(struct file *file)
1441 {
1442         struct ptr_ring *ring;
1443         ring = tun_get_tx_ring(file);
1444         if (!IS_ERR(ring))
1445                 goto out;
1446         ring = tap_get_ptr_ring(file);
1447         if (!IS_ERR(ring))
1448                 goto out;
1449         ring = NULL;
1450 out:
1451         return ring;
1452 }
1453
1454 static struct socket *get_tap_socket(int fd)
1455 {
1456         struct file *file = fget(fd);
1457         struct socket *sock;
1458
1459         if (!file)
1460                 return ERR_PTR(-EBADF);
1461         sock = tun_get_socket(file);
1462         if (!IS_ERR(sock))
1463                 return sock;
1464         sock = tap_get_socket(file);
1465         if (IS_ERR(sock))
1466                 fput(file);
1467         return sock;
1468 }
1469
1470 static struct socket *get_socket(int fd)
1471 {
1472         struct socket *sock;
1473
1474         /* special case to disable backend */
1475         if (fd == -1)
1476                 return NULL;
1477         sock = get_raw_socket(fd);
1478         if (!IS_ERR(sock))
1479                 return sock;
1480         sock = get_tap_socket(fd);
1481         if (!IS_ERR(sock))
1482                 return sock;
1483         return ERR_PTR(-ENOTSOCK);
1484 }
1485
1486 static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd)
1487 {
1488         struct socket *sock, *oldsock;
1489         struct vhost_virtqueue *vq;
1490         struct vhost_net_virtqueue *nvq;
1491         struct vhost_net_ubuf_ref *ubufs, *oldubufs = NULL;
1492         int r;
1493
1494         mutex_lock(&n->dev.mutex);
1495         r = vhost_dev_check_owner(&n->dev);
1496         if (r)
1497                 goto err;
1498
1499         if (index >= VHOST_NET_VQ_MAX) {
1500                 r = -ENOBUFS;
1501                 goto err;
1502         }
1503         vq = &n->vqs[index].vq;
1504         nvq = &n->vqs[index];
1505         mutex_lock(&vq->mutex);
1506
1507         if (fd == -1)
1508                 vhost_clear_msg(&n->dev);
1509
1510         /* Verify that ring has been setup correctly. */
1511         if (!vhost_vq_access_ok(vq)) {
1512                 r = -EFAULT;
1513                 goto err_vq;
1514         }
1515         sock = get_socket(fd);
1516         if (IS_ERR(sock)) {
1517                 r = PTR_ERR(sock);
1518                 goto err_vq;
1519         }
1520
1521         /* start polling new socket */
1522         oldsock = vhost_vq_get_backend(vq);
1523         if (sock != oldsock) {
1524                 ubufs = vhost_net_ubuf_alloc(vq,
1525                                              sock && vhost_sock_zcopy(sock));
1526                 if (IS_ERR(ubufs)) {
1527                         r = PTR_ERR(ubufs);
1528                         goto err_ubufs;
1529                 }
1530
1531                 vhost_net_disable_vq(n, vq);
1532                 vhost_vq_set_backend(vq, sock);
1533                 vhost_net_buf_unproduce(nvq);
1534                 r = vhost_vq_init_access(vq);
1535                 if (r)
1536                         goto err_used;
1537                 r = vhost_net_enable_vq(n, vq);
1538                 if (r)
1539                         goto err_used;
1540                 if (index == VHOST_NET_VQ_RX) {
1541                         if (sock)
1542                                 nvq->rx_ring = get_tap_ptr_ring(sock->file);
1543                         else
1544                                 nvq->rx_ring = NULL;
1545                 }
1546
1547                 oldubufs = nvq->ubufs;
1548                 nvq->ubufs = ubufs;
1549
1550                 n->tx_packets = 0;
1551                 n->tx_zcopy_err = 0;
1552                 n->tx_flush = false;
1553         }
1554
1555         mutex_unlock(&vq->mutex);
1556
1557         if (oldubufs) {
1558                 vhost_net_ubuf_put_wait_and_free(oldubufs);
1559                 mutex_lock(&vq->mutex);
1560                 vhost_zerocopy_signal_used(n, vq);
1561                 mutex_unlock(&vq->mutex);
1562         }
1563
1564         if (oldsock) {
1565                 vhost_dev_flush(&n->dev);
1566                 sockfd_put(oldsock);
1567         }
1568
1569         mutex_unlock(&n->dev.mutex);
1570         return 0;
1571
1572 err_used:
1573         vhost_vq_set_backend(vq, oldsock);
1574         vhost_net_enable_vq(n, vq);
1575         if (ubufs)
1576                 vhost_net_ubuf_put_wait_and_free(ubufs);
1577 err_ubufs:
1578         if (sock)
1579                 sockfd_put(sock);
1580 err_vq:
1581         mutex_unlock(&vq->mutex);
1582 err:
1583         mutex_unlock(&n->dev.mutex);
1584         return r;
1585 }
1586
1587 static long vhost_net_reset_owner(struct vhost_net *n)
1588 {
1589         struct socket *tx_sock = NULL;
1590         struct socket *rx_sock = NULL;
1591         long err;
1592         struct vhost_iotlb *umem;
1593
1594         mutex_lock(&n->dev.mutex);
1595         err = vhost_dev_check_owner(&n->dev);
1596         if (err)
1597                 goto done;
1598         umem = vhost_dev_reset_owner_prepare();
1599         if (!umem) {
1600                 err = -ENOMEM;
1601                 goto done;
1602         }
1603         vhost_net_stop(n, &tx_sock, &rx_sock);
1604         vhost_net_flush(n);
1605         vhost_dev_stop(&n->dev);
1606         vhost_dev_reset_owner(&n->dev, umem);
1607         vhost_net_vq_reset(n);
1608 done:
1609         mutex_unlock(&n->dev.mutex);
1610         if (tx_sock)
1611                 sockfd_put(tx_sock);
1612         if (rx_sock)
1613                 sockfd_put(rx_sock);
1614         return err;
1615 }
1616
1617 static int vhost_net_set_features(struct vhost_net *n, u64 features)
1618 {
1619         size_t vhost_hlen, sock_hlen, hdr_len;
1620         int i;
1621
1622         hdr_len = (features & ((1ULL << VIRTIO_NET_F_MRG_RXBUF) |
1623                                (1ULL << VIRTIO_F_VERSION_1))) ?
1624                         sizeof(struct virtio_net_hdr_mrg_rxbuf) :
1625                         sizeof(struct virtio_net_hdr);
1626         if (features & (1 << VHOST_NET_F_VIRTIO_NET_HDR)) {
1627                 /* vhost provides vnet_hdr */
1628                 vhost_hlen = hdr_len;
1629                 sock_hlen = 0;
1630         } else {
1631                 /* socket provides vnet_hdr */
1632                 vhost_hlen = 0;
1633                 sock_hlen = hdr_len;
1634         }
1635         mutex_lock(&n->dev.mutex);
1636         if ((features & (1 << VHOST_F_LOG_ALL)) &&
1637             !vhost_log_access_ok(&n->dev))
1638                 goto out_unlock;
1639
1640         if ((features & (1ULL << VIRTIO_F_ACCESS_PLATFORM))) {
1641                 if (vhost_init_device_iotlb(&n->dev))
1642                         goto out_unlock;
1643         }
1644
1645         for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
1646                 mutex_lock(&n->vqs[i].vq.mutex);
1647                 n->vqs[i].vq.acked_features = features;
1648                 n->vqs[i].vhost_hlen = vhost_hlen;
1649                 n->vqs[i].sock_hlen = sock_hlen;
1650                 mutex_unlock(&n->vqs[i].vq.mutex);
1651         }
1652         mutex_unlock(&n->dev.mutex);
1653         return 0;
1654
1655 out_unlock:
1656         mutex_unlock(&n->dev.mutex);
1657         return -EFAULT;
1658 }
1659
1660 static long vhost_net_set_owner(struct vhost_net *n)
1661 {
1662         int r;
1663
1664         mutex_lock(&n->dev.mutex);
1665         if (vhost_dev_has_owner(&n->dev)) {
1666                 r = -EBUSY;
1667                 goto out;
1668         }
1669         r = vhost_net_set_ubuf_info(n);
1670         if (r)
1671                 goto out;
1672         r = vhost_dev_set_owner(&n->dev);
1673         if (r)
1674                 vhost_net_clear_ubuf_info(n);
1675         vhost_net_flush(n);
1676 out:
1677         mutex_unlock(&n->dev.mutex);
1678         return r;
1679 }
1680
1681 static long vhost_net_ioctl(struct file *f, unsigned int ioctl,
1682                             unsigned long arg)
1683 {
1684         struct vhost_net *n = f->private_data;
1685         void __user *argp = (void __user *)arg;
1686         u64 __user *featurep = argp;
1687         struct vhost_vring_file backend;
1688         u64 features;
1689         int r;
1690
1691         switch (ioctl) {
1692         case VHOST_NET_SET_BACKEND:
1693                 if (copy_from_user(&backend, argp, sizeof backend))
1694                         return -EFAULT;
1695                 return vhost_net_set_backend(n, backend.index, backend.fd);
1696         case VHOST_GET_FEATURES:
1697                 features = VHOST_NET_FEATURES;
1698                 if (copy_to_user(featurep, &features, sizeof features))
1699                         return -EFAULT;
1700                 return 0;
1701         case VHOST_SET_FEATURES:
1702                 if (copy_from_user(&features, featurep, sizeof features))
1703                         return -EFAULT;
1704                 if (features & ~VHOST_NET_FEATURES)
1705                         return -EOPNOTSUPP;
1706                 return vhost_net_set_features(n, features);
1707         case VHOST_GET_BACKEND_FEATURES:
1708                 features = VHOST_NET_BACKEND_FEATURES;
1709                 if (copy_to_user(featurep, &features, sizeof(features)))
1710                         return -EFAULT;
1711                 return 0;
1712         case VHOST_SET_BACKEND_FEATURES:
1713                 if (copy_from_user(&features, featurep, sizeof(features)))
1714                         return -EFAULT;
1715                 if (features & ~VHOST_NET_BACKEND_FEATURES)
1716                         return -EOPNOTSUPP;
1717                 vhost_set_backend_features(&n->dev, features);
1718                 return 0;
1719         case VHOST_RESET_OWNER:
1720                 return vhost_net_reset_owner(n);
1721         case VHOST_SET_OWNER:
1722                 return vhost_net_set_owner(n);
1723         default:
1724                 mutex_lock(&n->dev.mutex);
1725                 r = vhost_dev_ioctl(&n->dev, ioctl, argp);
1726                 if (r == -ENOIOCTLCMD)
1727                         r = vhost_vring_ioctl(&n->dev, ioctl, argp);
1728                 else
1729                         vhost_net_flush(n);
1730                 mutex_unlock(&n->dev.mutex);
1731                 return r;
1732         }
1733 }
1734
1735 static ssize_t vhost_net_chr_read_iter(struct kiocb *iocb, struct iov_iter *to)
1736 {
1737         struct file *file = iocb->ki_filp;
1738         struct vhost_net *n = file->private_data;
1739         struct vhost_dev *dev = &n->dev;
1740         int noblock = file->f_flags & O_NONBLOCK;
1741
1742         return vhost_chr_read_iter(dev, to, noblock);
1743 }
1744
1745 static ssize_t vhost_net_chr_write_iter(struct kiocb *iocb,
1746                                         struct iov_iter *from)
1747 {
1748         struct file *file = iocb->ki_filp;
1749         struct vhost_net *n = file->private_data;
1750         struct vhost_dev *dev = &n->dev;
1751
1752         return vhost_chr_write_iter(dev, from);
1753 }
1754
1755 static __poll_t vhost_net_chr_poll(struct file *file, poll_table *wait)
1756 {
1757         struct vhost_net *n = file->private_data;
1758         struct vhost_dev *dev = &n->dev;
1759
1760         return vhost_chr_poll(file, dev, wait);
1761 }
1762
1763 static const struct file_operations vhost_net_fops = {
1764         .owner          = THIS_MODULE,
1765         .release        = vhost_net_release,
1766         .read_iter      = vhost_net_chr_read_iter,
1767         .write_iter     = vhost_net_chr_write_iter,
1768         .poll           = vhost_net_chr_poll,
1769         .unlocked_ioctl = vhost_net_ioctl,
1770         .compat_ioctl   = compat_ptr_ioctl,
1771         .open           = vhost_net_open,
1772         .llseek         = noop_llseek,
1773 };
1774
1775 static struct miscdevice vhost_net_misc = {
1776         .minor = VHOST_NET_MINOR,
1777         .name = "vhost-net",
1778         .fops = &vhost_net_fops,
1779 };
1780
1781 static int __init vhost_net_init(void)
1782 {
1783         if (experimental_zcopytx)
1784                 vhost_net_enable_zcopy(VHOST_NET_VQ_TX);
1785         return misc_register(&vhost_net_misc);
1786 }
1787 module_init(vhost_net_init);
1788
1789 static void __exit vhost_net_exit(void)
1790 {
1791         misc_deregister(&vhost_net_misc);
1792 }
1793 module_exit(vhost_net_exit);
1794
1795 MODULE_VERSION("0.0.1");
1796 MODULE_LICENSE("GPL v2");
1797 MODULE_AUTHOR("Michael S. Tsirkin");
1798 MODULE_DESCRIPTION("Host kernel accelerator for virtio net");
1799 MODULE_ALIAS_MISCDEV(VHOST_NET_MINOR);
1800 MODULE_ALIAS("devname:vhost-net");