drivers/net/virtio/virtio_user/virtio_user_dev.c

   1 /* SPDX-License-Identifier: BSD-3-Clause
   2  * Copyright(c) 2010-2016 Intel Corporation
   3  */
   4
   5 #include <stdint.h>
   6 #include <stdio.h>
   7 #include <fcntl.h>
   8 #include <string.h>
   9 #include <errno.h>
  10 #include <sys/mman.h>
  11 #include <unistd.h>
  12 #include <sys/eventfd.h>
  13 #include <sys/types.h>
  14 #include <sys/stat.h>
  15
  16 #include <rte_eal_memconfig.h>
  17
  18 #include "vhost.h"
  19 #include "virtio_user_dev.h"
  20 #include "../virtio_ethdev.h"
  21
  22 #define VIRTIO_USER_MEM_EVENT_CLB_NAME "virtio_user_mem_event_clb"
  23
  24 static int
  25 virtio_user_create_queue(struct virtio_user_dev *dev, uint32_t queue_sel)
  26 {
  27         /* Of all per virtqueue MSGs, make sure VHOST_SET_VRING_CALL come
  28          * firstly because vhost depends on this msg to allocate virtqueue
  29          * pair.
  30          */
  31         struct vhost_vring_file file;
  32
  33         file.index = queue_sel;
  34         file.fd = dev->callfds[queue_sel];
  35         dev->ops->send_request(dev, VHOST_USER_SET_VRING_CALL, &file);
  36
  37         return 0;
  38 }
  39
  40 static int
  41 virtio_user_kick_queue(struct virtio_user_dev *dev, uint32_t queue_sel)
  42 {
  43         struct vhost_vring_file file;
  44         struct vhost_vring_state state;
  45         struct vring *vring = &dev->vrings[queue_sel];
  46         struct vhost_vring_addr addr = {
  47                 .index = queue_sel,
  48                 .desc_user_addr = (uint64_t)(uintptr_t)vring->desc,
  49                 .avail_user_addr = (uint64_t)(uintptr_t)vring->avail,
  50                 .used_user_addr = (uint64_t)(uintptr_t)vring->used,
  51                 .log_guest_addr = 0,
  52                 .flags = 0, /* disable log */
  53         };
  54
  55         state.index = queue_sel;
  56         state.num = vring->num;
  57         dev->ops->send_request(dev, VHOST_USER_SET_VRING_NUM, &state);
  58
  59         state.index = queue_sel;
  60         state.num = 0; /* no reservation */
  61         dev->ops->send_request(dev, VHOST_USER_SET_VRING_BASE, &state);
  62
  63         dev->ops->send_request(dev, VHOST_USER_SET_VRING_ADDR, &addr);
  64
  65         /* Of all per virtqueue MSGs, make sure VHOST_USER_SET_VRING_KICK comes
  66          * lastly because vhost depends on this msg to judge if
  67          * virtio is ready.
  68          */
  69         file.index = queue_sel;
  70         file.fd = dev->kickfds[queue_sel];
  71         dev->ops->send_request(dev, VHOST_USER_SET_VRING_KICK, &file);
  72
  73         return 0;
  74 }
  75
  76 static int
  77 virtio_user_queue_setup(struct virtio_user_dev *dev,
  78                         int (*fn)(struct virtio_user_dev *, uint32_t))
  79 {
  80         uint32_t i, queue_sel;
  81
  82         for (i = 0; i < dev->max_queue_pairs; ++i) {
  83                 queue_sel = 2 * i + VTNET_SQ_RQ_QUEUE_IDX;
  84                 if (fn(dev, queue_sel) < 0) {
  85                         PMD_DRV_LOG(INFO, "setup rx vq fails: %u", i);
  86                         return -1;
  87                 }
  88         }
  89         for (i = 0; i < dev->max_queue_pairs; ++i) {
  90                 queue_sel = 2 * i + VTNET_SQ_TQ_QUEUE_IDX;
  91                 if (fn(dev, queue_sel) < 0) {
  92                         PMD_DRV_LOG(INFO, "setup tx vq fails: %u", i);
  93                         return -1;
  94                 }
  95         }
  96
  97         return 0;
  98 }
  99
 100 int
 101 is_vhost_user_by_type(const char *path)
 102 {
 103         struct stat sb;
 104
 105         if (stat(path, &sb) == -1)
 106                 return 0;
 107
 108         return S_ISSOCK(sb.st_mode);
 109 }
 110
 111 int
 112 virtio_user_start_device(struct virtio_user_dev *dev)
 113 {
 114         struct rte_mem_config *mcfg = rte_eal_get_configuration()->mem_config;
 115         uint64_t features;
 116         int ret;
 117
 118         /*
 119          * XXX workaround!
 120          *
 121          * We need to make sure that the locks will be
 122          * taken in the correct order to avoid deadlocks.
 123          *
 124          * Before releasing this lock, this thread should
 125          * not trigger any memory hotplug events.
 126          *
 127          * This is a temporary workaround, and should be
 128          * replaced when we get proper supports from the
 129          * memory subsystem in the future.
 130          */
 131         rte_rwlock_read_lock(&mcfg->memory_hotplug_lock);
 132         pthread_mutex_lock(&dev->mutex);
 133
 134         if (is_vhost_user_by_type(dev->path) && dev->vhostfd < 0)
 135                 goto error;
 136
 137         /* Do not check return as already done in init, or reset in stop */
 138         dev->ops->send_request(dev, VHOST_USER_SET_OWNER, NULL);
 139
 140         /* Step 0: tell vhost to create queues */
 141         if (virtio_user_queue_setup(dev, virtio_user_create_queue) < 0)
 142                 goto error;
 143
 144         /* Step 1: set features */
 145         features = dev->features;
 146         /* Strip VIRTIO_NET_F_MAC, as MAC address is handled in vdev init */
 147         features &= ~(1ull << VIRTIO_NET_F_MAC);
 148         /* Strip VIRTIO_NET_F_CTRL_VQ, as devices do not really need to know */
 149         features &= ~(1ull << VIRTIO_NET_F_CTRL_VQ);
 150         features &= ~(1ull << VIRTIO_NET_F_STATUS);
 151         ret = dev->ops->send_request(dev, VHOST_USER_SET_FEATURES, &features);
 152         if (ret < 0)
 153                 goto error;
 154         PMD_DRV_LOG(INFO, "set features: %" PRIx64, features);
 155
 156         /* Step 2: share memory regions */
 157         ret = dev->ops->send_request(dev, VHOST_USER_SET_MEM_TABLE, NULL);
 158         if (ret < 0)
 159                 goto error;
 160
 161         /* Step 3: kick queues */
 162         if (virtio_user_queue_setup(dev, virtio_user_kick_queue) < 0)
 163                 goto error;
 164
 165         /* Step 4: enable queues
 166          * we enable the 1st queue pair by default.
 167          */
 168         dev->ops->enable_qp(dev, 0, 1);
 169
 170         dev->started = true;
 171         pthread_mutex_unlock(&dev->mutex);
 172         rte_rwlock_read_unlock(&mcfg->memory_hotplug_lock);
 173
 174         return 0;
 175 error:
 176         pthread_mutex_unlock(&dev->mutex);
 177         rte_rwlock_read_unlock(&mcfg->memory_hotplug_lock);
 178         /* TODO: free resource here or caller to check */
 179         return -1;
 180 }
 181
 182 int virtio_user_stop_device(struct virtio_user_dev *dev)
 183 {
 184         uint32_t i;
 185
 186         pthread_mutex_lock(&dev->mutex);
 187         for (i = 0; i < dev->max_queue_pairs; ++i)
 188                 dev->ops->enable_qp(dev, i, 0);
 189
 190         if (dev->ops->send_request(dev, VHOST_USER_RESET_OWNER, NULL) < 0) {
 191                 PMD_DRV_LOG(INFO, "Failed to reset the device\n");
 192                 pthread_mutex_unlock(&dev->mutex);
 193                 return -1;
 194         }
 195         dev->started = false;
 196         pthread_mutex_unlock(&dev->mutex);
 197
 198         return 0;
 199 }
 200
 201 static inline void
 202 parse_mac(struct virtio_user_dev *dev, const char *mac)
 203 {
 204         int i, r;
 205         uint32_t tmp[ETHER_ADDR_LEN];
 206
 207         if (!mac)
 208                 return;
 209
 210         r = sscanf(mac, "%x:%x:%x:%x:%x:%x", &tmp[0],
 211                         &tmp[1], &tmp[2], &tmp[3], &tmp[4], &tmp[5]);
 212         if (r == ETHER_ADDR_LEN) {
 213                 for (i = 0; i < ETHER_ADDR_LEN; ++i)
 214                         dev->mac_addr[i] = (uint8_t)tmp[i];
 215                 dev->mac_specified = 1;
 216         } else {
 217                 /* ignore the wrong mac, use random mac */
 218                 PMD_DRV_LOG(ERR, "wrong format of mac: %s", mac);
 219         }
 220 }
 221
 222 static int
 223 virtio_user_dev_init_notify(struct virtio_user_dev *dev)
 224 {
 225         uint32_t i, j;
 226         int callfd;
 227         int kickfd;
 228
 229         for (i = 0; i < VIRTIO_MAX_VIRTQUEUES; ++i) {
 230                 if (i >= dev->max_queue_pairs * 2) {
 231                         dev->kickfds[i] = -1;
 232                         dev->callfds[i] = -1;
 233                         continue;
 234                 }
 235
 236                 /* May use invalid flag, but some backend uses kickfd and
 237                  * callfd as criteria to judge if dev is alive. so finally we
 238                  * use real event_fd.
 239                  */
 240                 callfd = eventfd(0, EFD_CLOEXEC | EFD_NONBLOCK);
 241                 if (callfd < 0) {
 242                         PMD_DRV_LOG(ERR, "callfd error, %s", strerror(errno));
 243                         break;
 244                 }
 245                 kickfd = eventfd(0, EFD_CLOEXEC | EFD_NONBLOCK);
 246                 if (kickfd < 0) {
 247                         PMD_DRV_LOG(ERR, "kickfd error, %s", strerror(errno));
 248                         break;
 249                 }
 250                 dev->callfds[i] = callfd;
 251                 dev->kickfds[i] = kickfd;
 252         }
 253
 254         if (i < VIRTIO_MAX_VIRTQUEUES) {
 255                 for (j = 0; j <= i; ++j) {
 256                         close(dev->callfds[j]);
 257                         close(dev->kickfds[j]);
 258                 }
 259
 260                 return -1;
 261         }
 262
 263         return 0;
 264 }
 265
 266 static int
 267 virtio_user_fill_intr_handle(struct virtio_user_dev *dev)
 268 {
 269         uint32_t i;
 270         struct rte_eth_dev *eth_dev = &rte_eth_devices[dev->port_id];
 271
 272         if (!eth_dev->intr_handle) {
 273                 eth_dev->intr_handle = malloc(sizeof(*eth_dev->intr_handle));
 274                 if (!eth_dev->intr_handle) {
 275                         PMD_DRV_LOG(ERR, "fail to allocate intr_handle");
 276                         return -1;
 277                 }
 278                 memset(eth_dev->intr_handle, 0, sizeof(*eth_dev->intr_handle));
 279         }
 280
 281         for (i = 0; i < dev->max_queue_pairs; ++i)
 282                 eth_dev->intr_handle->efds[i] = dev->callfds[i];
 283         eth_dev->intr_handle->nb_efd = dev->max_queue_pairs;
 284         eth_dev->intr_handle->max_intr = dev->max_queue_pairs + 1;
 285         eth_dev->intr_handle->type = RTE_INTR_HANDLE_VDEV;
 286         /* For virtio vdev, no need to read counter for clean */
 287         eth_dev->intr_handle->efd_counter_size = 0;
 288         eth_dev->intr_handle->fd = -1;
 289         if (dev->vhostfd >= 0)
 290                 eth_dev->intr_handle->fd = dev->vhostfd;
 291         else if (dev->is_server)
 292                 eth_dev->intr_handle->fd = dev->listenfd;
 293
 294         return 0;
 295 }
 296
 297 static void
 298 virtio_user_mem_event_cb(enum rte_mem_event type __rte_unused,
 299                                                  const void *addr __rte_unused,
 300                                                  size_t len __rte_unused,
 301                                                  void *arg)
 302 {
 303         struct virtio_user_dev *dev = arg;
 304         uint16_t i;
 305
 306         pthread_mutex_lock(&dev->mutex);
 307
 308         if (dev->started == false)
 309                 goto exit;
 310
 311         /* Step 1: pause the active queues */
 312         for (i = 0; i < dev->queue_pairs; i++)
 313                 dev->ops->enable_qp(dev, i, 0);
 314
 315         /* Step 2: update memory regions */
 316         dev->ops->send_request(dev, VHOST_USER_SET_MEM_TABLE, NULL);
 317
 318         /* Step 3: resume the active queues */
 319         for (i = 0; i < dev->queue_pairs; i++)
 320                 dev->ops->enable_qp(dev, i, 1);
 321
 322 exit:
 323         pthread_mutex_unlock(&dev->mutex);
 324 }
 325
 326 static int
 327 virtio_user_dev_setup(struct virtio_user_dev *dev)
 328 {
 329         uint32_t q;
 330
 331         dev->vhostfd = -1;
 332         dev->vhostfds = NULL;
 333         dev->tapfds = NULL;
 334
 335         if (dev->is_server) {
 336                 if (access(dev->path, F_OK) == 0 &&
 337                     !is_vhost_user_by_type(dev->path)) {
 338                         PMD_DRV_LOG(ERR, "Server mode doesn't support vhost-kernel!");
 339                         return -1;
 340                 }
 341                 dev->ops = &ops_user;
 342         } else {
 343                 if (is_vhost_user_by_type(dev->path)) {
 344                         dev->ops = &ops_user;
 345                 } else {
 346                         dev->ops = &ops_kernel;
 347
 348                         dev->vhostfds = malloc(dev->max_queue_pairs *
 349                                                sizeof(int));
 350                         dev->tapfds = malloc(dev->max_queue_pairs *
 351                                              sizeof(int));
 352                         if (!dev->vhostfds || !dev->tapfds) {
 353                                 PMD_INIT_LOG(ERR, "Failed to malloc");
 354                                 return -1;
 355                         }
 356
 357                         for (q = 0; q < dev->max_queue_pairs; ++q) {
 358                                 dev->vhostfds[q] = -1;
 359                                 dev->tapfds[q] = -1;
 360                         }
 361                 }
 362         }
 363
 364         if (dev->ops->setup(dev) < 0)
 365                 return -1;
 366
 367         if (virtio_user_dev_init_notify(dev) < 0)
 368                 return -1;
 369
 370         if (virtio_user_fill_intr_handle(dev) < 0)
 371                 return -1;
 372
 373         return 0;
 374 }
 375
 376 /* Use below macro to filter features from vhost backend */
 377 #define VIRTIO_USER_SUPPORTED_FEATURES                  \
 378         (1ULL << VIRTIO_NET_F_MAC               |       \
 379          1ULL << VIRTIO_NET_F_STATUS            |       \
 380          1ULL << VIRTIO_NET_F_MQ                |       \
 381          1ULL << VIRTIO_NET_F_CTRL_MAC_ADDR     |       \
 382          1ULL << VIRTIO_NET_F_CTRL_VQ           |       \
 383          1ULL << VIRTIO_NET_F_CTRL_RX           |       \
 384          1ULL << VIRTIO_NET_F_CTRL_VLAN         |       \
 385          1ULL << VIRTIO_NET_F_CSUM              |       \
 386          1ULL << VIRTIO_NET_F_HOST_TSO4         |       \
 387          1ULL << VIRTIO_NET_F_HOST_TSO6         |       \
 388          1ULL << VIRTIO_NET_F_MRG_RXBUF         |       \
 389          1ULL << VIRTIO_RING_F_INDIRECT_DESC    |       \
 390          1ULL << VIRTIO_NET_F_GUEST_CSUM        |       \
 391          1ULL << VIRTIO_NET_F_GUEST_TSO4        |       \
 392          1ULL << VIRTIO_NET_F_GUEST_TSO6        |       \
 393          1ULL << VIRTIO_F_IN_ORDER              |       \
 394          1ULL << VIRTIO_F_VERSION_1)
 395
 396 int
 397 virtio_user_dev_init(struct virtio_user_dev *dev, char *path, int queues,
 398                      int cq, int queue_size, const char *mac, char **ifname,
 399                      int mrg_rxbuf, int in_order)
 400 {
 401         pthread_mutex_init(&dev->mutex, NULL);
 402         snprintf(dev->path, PATH_MAX, "%s", path);
 403         dev->started = 0;
 404         dev->max_queue_pairs = queues;
 405         dev->queue_pairs = 1; /* mq disabled by default */
 406         dev->queue_size = queue_size;
 407         dev->mac_specified = 0;
 408         dev->unsupported_features = 0;
 409         parse_mac(dev, mac);
 410
 411         if (*ifname) {
 412                 dev->ifname = *ifname;
 413                 *ifname = NULL;
 414         }
 415
 416         if (virtio_user_dev_setup(dev) < 0) {
 417                 PMD_INIT_LOG(ERR, "backend set up fails");
 418                 return -1;
 419         }
 420
 421         if (!dev->is_server) {
 422                 if (dev->ops->send_request(dev, VHOST_USER_SET_OWNER,
 423                                            NULL) < 0) {
 424                         PMD_INIT_LOG(ERR, "set_owner fails: %s",
 425                                      strerror(errno));
 426                         return -1;
 427                 }
 428
 429                 if (dev->ops->send_request(dev, VHOST_USER_GET_FEATURES,
 430                                            &dev->device_features) < 0) {
 431                         PMD_INIT_LOG(ERR, "get_features failed: %s",
 432                                      strerror(errno));
 433                         return -1;
 434                 }
 435         } else {
 436                 /* We just pretend vhost-user can support all these features.
 437                  * Note that this could be problematic that if some feature is
 438                  * negotiated but not supported by the vhost-user which comes
 439                  * later.
 440                  */
 441                 dev->device_features = VIRTIO_USER_SUPPORTED_FEATURES;
 442         }
 443
 444         if (!mrg_rxbuf) {
 445                 dev->device_features &= ~(1ull << VIRTIO_NET_F_MRG_RXBUF);
 446                 dev->unsupported_features |= (1ull << VIRTIO_NET_F_MRG_RXBUF);
 447         }
 448
 449         if (!in_order) {
 450                 dev->device_features &= ~(1ull << VIRTIO_F_IN_ORDER);
 451                 dev->unsupported_features |= (1ull << VIRTIO_F_IN_ORDER);
 452         }
 453
 454         if (dev->mac_specified) {
 455                 dev->device_features |= (1ull << VIRTIO_NET_F_MAC);
 456         } else {
 457                 dev->device_features &= ~(1ull << VIRTIO_NET_F_MAC);
 458                 dev->unsupported_features |= (1ull << VIRTIO_NET_F_MAC);
 459         }
 460
 461         if (cq) {
 462                 /* device does not really need to know anything about CQ,
 463                  * so if necessary, we just claim to support CQ
 464                  */
 465                 dev->device_features |= (1ull << VIRTIO_NET_F_CTRL_VQ);
 466         } else {
 467                 dev->device_features &= ~(1ull << VIRTIO_NET_F_CTRL_VQ);
 468                 /* Also disable features depends on VIRTIO_NET_F_CTRL_VQ */
 469                 dev->device_features &= ~(1ull << VIRTIO_NET_F_CTRL_RX);
 470                 dev->device_features &= ~(1ull << VIRTIO_NET_F_CTRL_VLAN);
 471                 dev->device_features &= ~(1ull << VIRTIO_NET_F_GUEST_ANNOUNCE);
 472                 dev->device_features &= ~(1ull << VIRTIO_NET_F_MQ);
 473                 dev->device_features &= ~(1ull << VIRTIO_NET_F_CTRL_MAC_ADDR);
 474                 dev->unsupported_features |= (1ull << VIRTIO_NET_F_CTRL_VQ);
 475                 dev->unsupported_features |= (1ull << VIRTIO_NET_F_CTRL_RX);
 476                 dev->unsupported_features |= (1ull << VIRTIO_NET_F_CTRL_VLAN);
 477                 dev->unsupported_features |=
 478                         (1ull << VIRTIO_NET_F_GUEST_ANNOUNCE);
 479                 dev->unsupported_features |= (1ull << VIRTIO_NET_F_MQ);
 480                 dev->unsupported_features |=
 481                         (1ull << VIRTIO_NET_F_CTRL_MAC_ADDR);
 482         }
 483
 484         /* The backend will not report this feature, we add it explicitly */
 485         if (is_vhost_user_by_type(dev->path))
 486                 dev->device_features |= (1ull << VIRTIO_NET_F_STATUS);
 487
 488         dev->device_features &= VIRTIO_USER_SUPPORTED_FEATURES;
 489         dev->unsupported_features |= ~VIRTIO_USER_SUPPORTED_FEATURES;
 490
 491         if (rte_mem_event_callback_register(VIRTIO_USER_MEM_EVENT_CLB_NAME,
 492                                 virtio_user_mem_event_cb, dev)) {
 493                 if (rte_errno != ENOTSUP) {
 494                         PMD_INIT_LOG(ERR, "Failed to register mem event"
 495                                         " callback\n");
 496                         return -1;
 497                 }
 498         }
 499
 500         return 0;
 501 }
 502
 503 void
 504 virtio_user_dev_uninit(struct virtio_user_dev *dev)
 505 {
 506         uint32_t i;
 507
 508         virtio_user_stop_device(dev);
 509
 510         rte_mem_event_callback_unregister(VIRTIO_USER_MEM_EVENT_CLB_NAME, dev);
 511
 512         for (i = 0; i < dev->max_queue_pairs * 2; ++i) {
 513                 close(dev->callfds[i]);
 514                 close(dev->kickfds[i]);
 515         }
 516
 517         close(dev->vhostfd);
 518
 519         if (dev->is_server && dev->listenfd >= 0) {
 520                 close(dev->listenfd);
 521                 dev->listenfd = -1;
 522         }
 523
 524         if (dev->vhostfds) {
 525                 for (i = 0; i < dev->max_queue_pairs; ++i)
 526                         close(dev->vhostfds[i]);
 527                 free(dev->vhostfds);
 528                 free(dev->tapfds);
 529         }
 530
 531         free(dev->ifname);
 532
 533         if (dev->is_server)
 534                 unlink(dev->path);
 535 }
 536
 537 uint8_t
 538 virtio_user_handle_mq(struct virtio_user_dev *dev, uint16_t q_pairs)
 539 {
 540         uint16_t i;
 541         uint8_t ret = 0;
 542
 543         if (q_pairs > dev->max_queue_pairs) {
 544                 PMD_INIT_LOG(ERR, "multi-q config %u, but only %u supported",
 545                              q_pairs, dev->max_queue_pairs);
 546                 return -1;
 547         }
 548
 549         /* Server mode can't enable queue pairs if vhostfd is invalid,
 550          * always return 0 in this case.
 551          */
 552         if (!dev->is_server || dev->vhostfd >= 0) {
 553                 for (i = 0; i < q_pairs; ++i)
 554                         ret |= dev->ops->enable_qp(dev, i, 1);
 555                 for (i = q_pairs; i < dev->max_queue_pairs; ++i)
 556                         ret |= dev->ops->enable_qp(dev, i, 0);
 557         }
 558         dev->queue_pairs = q_pairs;
 559
 560         return ret;
 561 }
 562
 563 static uint32_t
 564 virtio_user_handle_ctrl_msg(struct virtio_user_dev *dev, struct vring *vring,
 565                             uint16_t idx_hdr)
 566 {
 567         struct virtio_net_ctrl_hdr *hdr;
 568         virtio_net_ctrl_ack status = ~0;
 569         uint16_t i, idx_data, idx_status;
 570         uint32_t n_descs = 0;
 571
 572         /* locate desc for header, data, and status */
 573         idx_data = vring->desc[idx_hdr].next;
 574         n_descs++;
 575
 576         i = idx_data;
 577         while (vring->desc[i].flags == VRING_DESC_F_NEXT) {
 578                 i = vring->desc[i].next;
 579                 n_descs++;
 580         }
 581
 582         /* locate desc for status */
 583         idx_status = i;
 584         n_descs++;
 585
 586         hdr = (void *)(uintptr_t)vring->desc[idx_hdr].addr;
 587         if (hdr->class == VIRTIO_NET_CTRL_MQ &&
 588             hdr->cmd == VIRTIO_NET_CTRL_MQ_VQ_PAIRS_SET) {
 589                 uint16_t queues;
 590
 591                 queues = *(uint16_t *)(uintptr_t)vring->desc[idx_data].addr;
 592                 status = virtio_user_handle_mq(dev, queues);
 593         }
 594
 595         /* Update status */
 596         *(virtio_net_ctrl_ack *)(uintptr_t)vring->desc[idx_status].addr = status;
 597
 598         return n_descs;
 599 }
 600
 601 void
 602 virtio_user_handle_cq(struct virtio_user_dev *dev, uint16_t queue_idx)
 603 {
 604         uint16_t avail_idx, desc_idx;
 605         struct vring_used_elem *uep;
 606         uint32_t n_descs;
 607         struct vring *vring = &dev->vrings[queue_idx];
 608
 609         /* Consume avail ring, using used ring idx as first one */
 610         while (vring->used->idx != vring->avail->idx) {
 611                 avail_idx = (vring->used->idx) & (vring->num - 1);
 612                 desc_idx = vring->avail->ring[avail_idx];
 613
 614                 n_descs = virtio_user_handle_ctrl_msg(dev, vring, desc_idx);
 615
 616                 /* Update used ring */
 617                 uep = &vring->used->ring[avail_idx];
 618                 uep->id = avail_idx;
 619                 uep->len = n_descs;
 620
 621                 vring->used->idx++;
 622         }
 623 }