net/vmw_vsock/virtio_transport.c

   1 /*
   2  * virtio transport for vsock
   3  *
   4  * Copyright (C) 2013-2015 Red Hat, Inc.
   5  * Author: Asias He <asias@redhat.com>
   6  *         Stefan Hajnoczi <stefanha@redhat.com>
   7  *
   8  * Some of the code is take from Gerd Hoffmann <kraxel@redhat.com>'s
   9  * early virtio-vsock proof-of-concept bits.
  10  *
  11  * This work is licensed under the terms of the GNU GPL, version 2.
  12  */
  13 #include <linux/spinlock.h>
  14 #include <linux/module.h>
  15 #include <linux/list.h>
  16 #include <linux/atomic.h>
  17 #include <linux/virtio.h>
  18 #include <linux/virtio_ids.h>
  19 #include <linux/virtio_config.h>
  20 #include <linux/virtio_vsock.h>
  21 #include <net/sock.h>
  22 #include <linux/mutex.h>
  23 #include <net/af_vsock.h>
  24
  25 static struct workqueue_struct *virtio_vsock_workqueue;
  26 static struct virtio_vsock *the_virtio_vsock;
  27 static DEFINE_MUTEX(the_virtio_vsock_mutex); /* protects the_virtio_vsock */
  28
  29 struct virtio_vsock {
  30         struct virtio_device *vdev;
  31         struct virtqueue *vqs[VSOCK_VQ_MAX];
  32
  33         /* Virtqueue processing is deferred to a workqueue */
  34         struct work_struct tx_work;
  35         struct work_struct rx_work;
  36         struct work_struct event_work;
  37
  38         /* The following fields are protected by tx_lock.  vqs[VSOCK_VQ_TX]
  39          * must be accessed with tx_lock held.
  40          */
  41         struct mutex tx_lock;
  42
  43         struct work_struct send_pkt_work;
  44         spinlock_t send_pkt_list_lock;
  45         struct list_head send_pkt_list;
  46
  47         atomic_t queued_replies;
  48
  49         /* The following fields are protected by rx_lock.  vqs[VSOCK_VQ_RX]
  50          * must be accessed with rx_lock held.
  51          */
  52         struct mutex rx_lock;
  53         int rx_buf_nr;
  54         int rx_buf_max_nr;
  55
  56         /* The following fields are protected by event_lock.
  57          * vqs[VSOCK_VQ_EVENT] must be accessed with event_lock held.
  58          */
  59         struct mutex event_lock;
  60         struct virtio_vsock_event event_list[8];
  61
  62         u32 guest_cid;
  63 };
  64
  65 static struct virtio_vsock *virtio_vsock_get(void)
  66 {
  67         return the_virtio_vsock;
  68 }
  69
  70 static u32 virtio_transport_get_local_cid(void)
  71 {
  72         struct virtio_vsock *vsock = virtio_vsock_get();
  73
  74         return vsock->guest_cid;
  75 }
  76
  77 static void
  78 virtio_transport_send_pkt_work(struct work_struct *work)
  79 {
  80         struct virtio_vsock *vsock =
  81                 container_of(work, struct virtio_vsock, send_pkt_work);
  82         struct virtqueue *vq;
  83         bool added = false;
  84         bool restart_rx = false;
  85
  86         mutex_lock(&vsock->tx_lock);
  87
  88         vq = vsock->vqs[VSOCK_VQ_TX];
  89
  90         for (;;) {
  91                 struct virtio_vsock_pkt *pkt;
  92                 struct scatterlist hdr, buf, *sgs[2];
  93                 int ret, in_sg = 0, out_sg = 0;
  94                 bool reply;
  95
  96                 spin_lock_bh(&vsock->send_pkt_list_lock);
  97                 if (list_empty(&vsock->send_pkt_list)) {
  98                         spin_unlock_bh(&vsock->send_pkt_list_lock);
  99                         break;
 100                 }
 101
 102                 pkt = list_first_entry(&vsock->send_pkt_list,
 103                                        struct virtio_vsock_pkt, list);
 104                 list_del_init(&pkt->list);
 105                 spin_unlock_bh(&vsock->send_pkt_list_lock);
 106
 107                 reply = pkt->reply;
 108
 109                 sg_init_one(&hdr, &pkt->hdr, sizeof(pkt->hdr));
 110                 sgs[out_sg++] = &hdr;
 111                 if (pkt->buf) {
 112                         sg_init_one(&buf, pkt->buf, pkt->len);
 113                         sgs[out_sg++] = &buf;
 114                 }
 115
 116                 ret = virtqueue_add_sgs(vq, sgs, out_sg, in_sg, pkt, GFP_KERNEL);
 117                 /* Usually this means that there is no more space available in
 118                  * the vq
 119                  */
 120                 if (ret < 0) {
 121                         spin_lock_bh(&vsock->send_pkt_list_lock);
 122                         list_add(&pkt->list, &vsock->send_pkt_list);
 123                         spin_unlock_bh(&vsock->send_pkt_list_lock);
 124                         break;
 125                 }
 126
 127                 if (reply) {
 128                         struct virtqueue *rx_vq = vsock->vqs[VSOCK_VQ_RX];
 129                         int val;
 130
 131                         val = atomic_dec_return(&vsock->queued_replies);
 132
 133                         /* Do we now have resources to resume rx processing? */
 134                         if (val + 1 == virtqueue_get_vring_size(rx_vq))
 135                                 restart_rx = true;
 136                 }
 137
 138                 added = true;
 139         }
 140
 141         if (added)
 142                 virtqueue_kick(vq);
 143
 144         mutex_unlock(&vsock->tx_lock);
 145
 146         if (restart_rx)
 147                 queue_work(virtio_vsock_workqueue, &vsock->rx_work);
 148 }
 149
 150 static int
 151 virtio_transport_send_pkt(struct virtio_vsock_pkt *pkt)
 152 {
 153         struct virtio_vsock *vsock;
 154         int len = pkt->len;
 155
 156         vsock = virtio_vsock_get();
 157         if (!vsock) {
 158                 virtio_transport_free_pkt(pkt);
 159                 return -ENODEV;
 160         }
 161
 162         if (pkt->reply)
 163                 atomic_inc(&vsock->queued_replies);
 164
 165         spin_lock_bh(&vsock->send_pkt_list_lock);
 166         list_add_tail(&pkt->list, &vsock->send_pkt_list);
 167         spin_unlock_bh(&vsock->send_pkt_list_lock);
 168
 169         queue_work(virtio_vsock_workqueue, &vsock->send_pkt_work);
 170         return len;
 171 }
 172
 173 static void virtio_vsock_rx_fill(struct virtio_vsock *vsock)
 174 {
 175         int buf_len = VIRTIO_VSOCK_DEFAULT_RX_BUF_SIZE;
 176         struct virtio_vsock_pkt *pkt;
 177         struct scatterlist hdr, buf, *sgs[2];
 178         struct virtqueue *vq;
 179         int ret;
 180
 181         vq = vsock->vqs[VSOCK_VQ_RX];
 182
 183         do {
 184                 pkt = kzalloc(sizeof(*pkt), GFP_KERNEL);
 185                 if (!pkt)
 186                         break;
 187
 188                 pkt->buf = kmalloc(buf_len, GFP_KERNEL);
 189                 if (!pkt->buf) {
 190                         virtio_transport_free_pkt(pkt);
 191                         break;
 192                 }
 193
 194                 pkt->len = buf_len;
 195
 196                 sg_init_one(&hdr, &pkt->hdr, sizeof(pkt->hdr));
 197                 sgs[0] = &hdr;
 198
 199                 sg_init_one(&buf, pkt->buf, buf_len);
 200                 sgs[1] = &buf;
 201                 ret = virtqueue_add_sgs(vq, sgs, 0, 2, pkt, GFP_KERNEL);
 202                 if (ret) {
 203                         virtio_transport_free_pkt(pkt);
 204                         break;
 205                 }
 206                 vsock->rx_buf_nr++;
 207         } while (vq->num_free);
 208         if (vsock->rx_buf_nr > vsock->rx_buf_max_nr)
 209                 vsock->rx_buf_max_nr = vsock->rx_buf_nr;
 210         virtqueue_kick(vq);
 211 }
 212
 213 static void virtio_transport_tx_work(struct work_struct *work)
 214 {
 215         struct virtio_vsock *vsock =
 216                 container_of(work, struct virtio_vsock, tx_work);
 217         struct virtqueue *vq;
 218         bool added = false;
 219
 220         vq = vsock->vqs[VSOCK_VQ_TX];
 221         mutex_lock(&vsock->tx_lock);
 222         do {
 223                 struct virtio_vsock_pkt *pkt;
 224                 unsigned int len;
 225
 226                 virtqueue_disable_cb(vq);
 227                 while ((pkt = virtqueue_get_buf(vq, &len)) != NULL) {
 228                         virtio_transport_free_pkt(pkt);
 229                         added = true;
 230                 }
 231         } while (!virtqueue_enable_cb(vq));
 232         mutex_unlock(&vsock->tx_lock);
 233
 234         if (added)
 235                 queue_work(virtio_vsock_workqueue, &vsock->send_pkt_work);
 236 }
 237
 238 /* Is there space left for replies to rx packets? */
 239 static bool virtio_transport_more_replies(struct virtio_vsock *vsock)
 240 {
 241         struct virtqueue *vq = vsock->vqs[VSOCK_VQ_RX];
 242         int val;
 243
 244         smp_rmb(); /* paired with atomic_inc() and atomic_dec_return() */
 245         val = atomic_read(&vsock->queued_replies);
 246
 247         return val < virtqueue_get_vring_size(vq);
 248 }
 249
 250 static void virtio_transport_rx_work(struct work_struct *work)
 251 {
 252         struct virtio_vsock *vsock =
 253                 container_of(work, struct virtio_vsock, rx_work);
 254         struct virtqueue *vq;
 255
 256         vq = vsock->vqs[VSOCK_VQ_RX];
 257
 258         mutex_lock(&vsock->rx_lock);
 259
 260         do {
 261                 virtqueue_disable_cb(vq);
 262                 for (;;) {
 263                         struct virtio_vsock_pkt *pkt;
 264                         unsigned int len;
 265
 266                         if (!virtio_transport_more_replies(vsock)) {
 267                                 /* Stop rx until the device processes already
 268                                  * pending replies.  Leave rx virtqueue
 269                                  * callbacks disabled.
 270                                  */
 271                                 goto out;
 272                         }
 273
 274                         pkt = virtqueue_get_buf(vq, &len);
 275                         if (!pkt) {
 276                                 break;
 277                         }
 278
 279                         vsock->rx_buf_nr--;
 280
 281                         /* Drop short/long packets */
 282                         if (unlikely(len < sizeof(pkt->hdr) ||
 283                                      len > sizeof(pkt->hdr) + pkt->len)) {
 284                                 virtio_transport_free_pkt(pkt);
 285                                 continue;
 286                         }
 287
 288                         pkt->len = len - sizeof(pkt->hdr);
 289                         virtio_transport_recv_pkt(pkt);
 290                 }
 291         } while (!virtqueue_enable_cb(vq));
 292
 293 out:
 294         if (vsock->rx_buf_nr < vsock->rx_buf_max_nr / 2)
 295                 virtio_vsock_rx_fill(vsock);
 296         mutex_unlock(&vsock->rx_lock);
 297 }
 298
 299 /* event_lock must be held */
 300 static int virtio_vsock_event_fill_one(struct virtio_vsock *vsock,
 301                                        struct virtio_vsock_event *event)
 302 {
 303         struct scatterlist sg;
 304         struct virtqueue *vq;
 305
 306         vq = vsock->vqs[VSOCK_VQ_EVENT];
 307
 308         sg_init_one(&sg, event, sizeof(*event));
 309
 310         return virtqueue_add_inbuf(vq, &sg, 1, event, GFP_KERNEL);
 311 }
 312
 313 /* event_lock must be held */
 314 static void virtio_vsock_event_fill(struct virtio_vsock *vsock)
 315 {
 316         size_t i;
 317
 318         for (i = 0; i < ARRAY_SIZE(vsock->event_list); i++) {
 319                 struct virtio_vsock_event *event = &vsock->event_list[i];
 320
 321                 virtio_vsock_event_fill_one(vsock, event);
 322         }
 323
 324         virtqueue_kick(vsock->vqs[VSOCK_VQ_EVENT]);
 325 }
 326
 327 static void virtio_vsock_reset_sock(struct sock *sk)
 328 {
 329         lock_sock(sk);
 330         sk->sk_state = SS_UNCONNECTED;
 331         sk->sk_err = ECONNRESET;
 332         sk->sk_error_report(sk);
 333         release_sock(sk);
 334 }
 335
 336 static void virtio_vsock_update_guest_cid(struct virtio_vsock *vsock)
 337 {
 338         struct virtio_device *vdev = vsock->vdev;
 339         u64 guest_cid;
 340
 341         vdev->config->get(vdev, offsetof(struct virtio_vsock_config, guest_cid),
 342                           &guest_cid, sizeof(guest_cid));
 343         vsock->guest_cid = le64_to_cpu(guest_cid);
 344 }
 345
 346 /* event_lock must be held */
 347 static void virtio_vsock_event_handle(struct virtio_vsock *vsock,
 348                                       struct virtio_vsock_event *event)
 349 {
 350         switch (le32_to_cpu(event->id)) {
 351         case VIRTIO_VSOCK_EVENT_TRANSPORT_RESET:
 352                 virtio_vsock_update_guest_cid(vsock);
 353                 vsock_for_each_connected_socket(virtio_vsock_reset_sock);
 354                 break;
 355         }
 356 }
 357
 358 static void virtio_transport_event_work(struct work_struct *work)
 359 {
 360         struct virtio_vsock *vsock =
 361                 container_of(work, struct virtio_vsock, event_work);
 362         struct virtqueue *vq;
 363
 364         vq = vsock->vqs[VSOCK_VQ_EVENT];
 365
 366         mutex_lock(&vsock->event_lock);
 367
 368         do {
 369                 struct virtio_vsock_event *event;
 370                 unsigned int len;
 371
 372                 virtqueue_disable_cb(vq);
 373                 while ((event = virtqueue_get_buf(vq, &len)) != NULL) {
 374                         if (len == sizeof(*event))
 375                                 virtio_vsock_event_handle(vsock, event);
 376
 377                         virtio_vsock_event_fill_one(vsock, event);
 378                 }
 379         } while (!virtqueue_enable_cb(vq));
 380
 381         virtqueue_kick(vsock->vqs[VSOCK_VQ_EVENT]);
 382
 383         mutex_unlock(&vsock->event_lock);
 384 }
 385
 386 static void virtio_vsock_event_done(struct virtqueue *vq)
 387 {
 388         struct virtio_vsock *vsock = vq->vdev->priv;
 389
 390         if (!vsock)
 391                 return;
 392         queue_work(virtio_vsock_workqueue, &vsock->event_work);
 393 }
 394
 395 static void virtio_vsock_tx_done(struct virtqueue *vq)
 396 {
 397         struct virtio_vsock *vsock = vq->vdev->priv;
 398
 399         if (!vsock)
 400                 return;
 401         queue_work(virtio_vsock_workqueue, &vsock->tx_work);
 402 }
 403
 404 static void virtio_vsock_rx_done(struct virtqueue *vq)
 405 {
 406         struct virtio_vsock *vsock = vq->vdev->priv;
 407
 408         if (!vsock)
 409                 return;
 410         queue_work(virtio_vsock_workqueue, &vsock->rx_work);
 411 }
 412
 413 static struct virtio_transport virtio_transport = {
 414         .transport = {
 415                 .get_local_cid            = virtio_transport_get_local_cid,
 416
 417                 .init                     = virtio_transport_do_socket_init,
 418                 .destruct                 = virtio_transport_destruct,
 419                 .release                  = virtio_transport_release,
 420                 .connect                  = virtio_transport_connect,
 421                 .shutdown                 = virtio_transport_shutdown,
 422
 423                 .dgram_bind               = virtio_transport_dgram_bind,
 424                 .dgram_dequeue            = virtio_transport_dgram_dequeue,
 425                 .dgram_enqueue            = virtio_transport_dgram_enqueue,
 426                 .dgram_allow              = virtio_transport_dgram_allow,
 427
 428                 .stream_dequeue           = virtio_transport_stream_dequeue,
 429                 .stream_enqueue           = virtio_transport_stream_enqueue,
 430                 .stream_has_data          = virtio_transport_stream_has_data,
 431                 .stream_has_space         = virtio_transport_stream_has_space,
 432                 .stream_rcvhiwat          = virtio_transport_stream_rcvhiwat,
 433                 .stream_is_active         = virtio_transport_stream_is_active,
 434                 .stream_allow             = virtio_transport_stream_allow,
 435
 436                 .notify_poll_in           = virtio_transport_notify_poll_in,
 437                 .notify_poll_out          = virtio_transport_notify_poll_out,
 438                 .notify_recv_init         = virtio_transport_notify_recv_init,
 439                 .notify_recv_pre_block    = virtio_transport_notify_recv_pre_block,
 440                 .notify_recv_pre_dequeue  = virtio_transport_notify_recv_pre_dequeue,
 441                 .notify_recv_post_dequeue = virtio_transport_notify_recv_post_dequeue,
 442                 .notify_send_init         = virtio_transport_notify_send_init,
 443                 .notify_send_pre_block    = virtio_transport_notify_send_pre_block,
 444                 .notify_send_pre_enqueue  = virtio_transport_notify_send_pre_enqueue,
 445                 .notify_send_post_enqueue = virtio_transport_notify_send_post_enqueue,
 446
 447                 .set_buffer_size          = virtio_transport_set_buffer_size,
 448                 .set_min_buffer_size      = virtio_transport_set_min_buffer_size,
 449                 .set_max_buffer_size      = virtio_transport_set_max_buffer_size,
 450                 .get_buffer_size          = virtio_transport_get_buffer_size,
 451                 .get_min_buffer_size      = virtio_transport_get_min_buffer_size,
 452                 .get_max_buffer_size      = virtio_transport_get_max_buffer_size,
 453         },
 454
 455         .send_pkt = virtio_transport_send_pkt,
 456 };
 457
 458 static int virtio_vsock_probe(struct virtio_device *vdev)
 459 {
 460         vq_callback_t *callbacks[] = {
 461                 virtio_vsock_rx_done,
 462                 virtio_vsock_tx_done,
 463                 virtio_vsock_event_done,
 464         };
 465         static const char * const names[] = {
 466                 "rx",
 467                 "tx",
 468                 "event",
 469         };
 470         struct virtio_vsock *vsock = NULL;
 471         int ret;
 472
 473         ret = mutex_lock_interruptible(&the_virtio_vsock_mutex);
 474         if (ret)
 475                 return ret;
 476
 477         /* Only one virtio-vsock device per guest is supported */
 478         if (the_virtio_vsock) {
 479                 ret = -EBUSY;
 480                 goto out;
 481         }
 482
 483         vsock = kzalloc(sizeof(*vsock), GFP_KERNEL);
 484         if (!vsock) {
 485                 ret = -ENOMEM;
 486                 goto out;
 487         }
 488
 489         vsock->vdev = vdev;
 490
 491         ret = vsock->vdev->config->find_vqs(vsock->vdev, VSOCK_VQ_MAX,
 492                                             vsock->vqs, callbacks, names);
 493         if (ret < 0)
 494                 goto out;
 495
 496         virtio_vsock_update_guest_cid(vsock);
 497
 498         ret = vsock_core_init(&virtio_transport.transport);
 499         if (ret < 0)
 500                 goto out_vqs;
 501
 502         vsock->rx_buf_nr = 0;
 503         vsock->rx_buf_max_nr = 0;
 504         atomic_set(&vsock->queued_replies, 0);
 505
 506         vdev->priv = vsock;
 507         the_virtio_vsock = vsock;
 508         mutex_init(&vsock->tx_lock);
 509         mutex_init(&vsock->rx_lock);
 510         mutex_init(&vsock->event_lock);
 511         spin_lock_init(&vsock->send_pkt_list_lock);
 512         INIT_LIST_HEAD(&vsock->send_pkt_list);
 513         INIT_WORK(&vsock->rx_work, virtio_transport_rx_work);
 514         INIT_WORK(&vsock->tx_work, virtio_transport_tx_work);
 515         INIT_WORK(&vsock->event_work, virtio_transport_event_work);
 516         INIT_WORK(&vsock->send_pkt_work, virtio_transport_send_pkt_work);
 517
 518         mutex_lock(&vsock->rx_lock);
 519         virtio_vsock_rx_fill(vsock);
 520         mutex_unlock(&vsock->rx_lock);
 521
 522         mutex_lock(&vsock->event_lock);
 523         virtio_vsock_event_fill(vsock);
 524         mutex_unlock(&vsock->event_lock);
 525
 526         mutex_unlock(&the_virtio_vsock_mutex);
 527         return 0;
 528
 529 out_vqs:
 530         vsock->vdev->config->del_vqs(vsock->vdev);
 531 out:
 532         kfree(vsock);
 533         mutex_unlock(&the_virtio_vsock_mutex);
 534         return ret;
 535 }
 536
 537 static void virtio_vsock_remove(struct virtio_device *vdev)
 538 {
 539         struct virtio_vsock *vsock = vdev->priv;
 540         struct virtio_vsock_pkt *pkt;
 541
 542         flush_work(&vsock->rx_work);
 543         flush_work(&vsock->tx_work);
 544         flush_work(&vsock->event_work);
 545         flush_work(&vsock->send_pkt_work);
 546
 547         vdev->config->reset(vdev);
 548
 549         mutex_lock(&vsock->rx_lock);
 550         while ((pkt = virtqueue_detach_unused_buf(vsock->vqs[VSOCK_VQ_RX])))
 551                 virtio_transport_free_pkt(pkt);
 552         mutex_unlock(&vsock->rx_lock);
 553
 554         mutex_lock(&vsock->tx_lock);
 555         while ((pkt = virtqueue_detach_unused_buf(vsock->vqs[VSOCK_VQ_TX])))
 556                 virtio_transport_free_pkt(pkt);
 557         mutex_unlock(&vsock->tx_lock);
 558
 559         spin_lock_bh(&vsock->send_pkt_list_lock);
 560         while (!list_empty(&vsock->send_pkt_list)) {
 561                 pkt = list_first_entry(&vsock->send_pkt_list,
 562                                        struct virtio_vsock_pkt, list);
 563                 list_del(&pkt->list);
 564                 virtio_transport_free_pkt(pkt);
 565         }
 566         spin_unlock_bh(&vsock->send_pkt_list_lock);
 567
 568         mutex_lock(&the_virtio_vsock_mutex);
 569         the_virtio_vsock = NULL;
 570         vsock_core_exit();
 571         mutex_unlock(&the_virtio_vsock_mutex);
 572
 573         vdev->config->del_vqs(vdev);
 574
 575         kfree(vsock);
 576 }
 577
 578 static struct virtio_device_id id_table[] = {
 579         { VIRTIO_ID_VSOCK, VIRTIO_DEV_ANY_ID },
 580         { 0 },
 581 };
 582
 583 static unsigned int features[] = {
 584 };
 585
 586 static struct virtio_driver virtio_vsock_driver = {
 587         .feature_table = features,
 588         .feature_table_size = ARRAY_SIZE(features),
 589         .driver.name = KBUILD_MODNAME,
 590         .driver.owner = THIS_MODULE,
 591         .id_table = id_table,
 592         .probe = virtio_vsock_probe,
 593         .remove = virtio_vsock_remove,
 594 };
 595
 596 static int __init virtio_vsock_init(void)
 597 {
 598         int ret;
 599
 600         virtio_vsock_workqueue = alloc_workqueue("virtio_vsock", 0, 0);
 601         if (!virtio_vsock_workqueue)
 602                 return -ENOMEM;
 603         ret = register_virtio_driver(&virtio_vsock_driver);
 604         if (ret)
 605                 destroy_workqueue(virtio_vsock_workqueue);
 606         return ret;
 607 }
 608
 609 static void __exit virtio_vsock_exit(void)
 610 {
 611         unregister_virtio_driver(&virtio_vsock_driver);
 612         destroy_workqueue(virtio_vsock_workqueue);
 613 }
 614
 615 module_init(virtio_vsock_init);
 616 module_exit(virtio_vsock_exit);
 617 MODULE_LICENSE("GPL v2");
 618 MODULE_AUTHOR("Asias He");
 619 MODULE_DESCRIPTION("virtio transport for vsock");
 620 MODULE_DEVICE_TABLE(virtio, id_table);