contrib/libvhost-user/libvhost-user.h

   1 /*
   2  * Vhost User library
   3  *
   4  * Copyright (c) 2016 Red Hat, Inc.
   5  *
   6  * Authors:
   7  *  Victor Kaplansky <victork@redhat.com>
   8  *  Marc-André Lureau <mlureau@redhat.com>
   9  *
  10  * This work is licensed under the terms of the GNU GPL, version 2 or
  11  * later.  See the COPYING file in the top-level directory.
  12  */
  13
  14 #ifndef LIBVHOST_USER_H
  15 #define LIBVHOST_USER_H
  16
  17 #include <stdint.h>
  18 #include <stdbool.h>
  19 #include <stddef.h>
  20 #include <sys/poll.h>
  21 #include <linux/vhost.h>
  22 #include <pthread.h>
  23 #include "standard-headers/linux/virtio_ring.h"
  24
  25 /* Based on qemu/hw/virtio/vhost-user.c */
  26 #define VHOST_USER_F_PROTOCOL_FEATURES 30
  27 #define VHOST_LOG_PAGE 4096
  28
  29 #define VIRTQUEUE_MAX_SIZE 1024
  30
  31 #define VHOST_MEMORY_MAX_NREGIONS 8
  32
  33 typedef enum VhostSetConfigType {
  34     VHOST_SET_CONFIG_TYPE_MASTER = 0,
  35     VHOST_SET_CONFIG_TYPE_MIGRATION = 1,
  36 } VhostSetConfigType;
  37
  38 /*
  39  * Maximum size of virtio device config space
  40  */
  41 #define VHOST_USER_MAX_CONFIG_SIZE 256
  42
  43 enum VhostUserProtocolFeature {
  44     VHOST_USER_PROTOCOL_F_MQ = 0,
  45     VHOST_USER_PROTOCOL_F_LOG_SHMFD = 1,
  46     VHOST_USER_PROTOCOL_F_RARP = 2,
  47     VHOST_USER_PROTOCOL_F_REPLY_ACK = 3,
  48     VHOST_USER_PROTOCOL_F_NET_MTU = 4,
  49     VHOST_USER_PROTOCOL_F_SLAVE_REQ = 5,
  50     VHOST_USER_PROTOCOL_F_CROSS_ENDIAN = 6,
  51     VHOST_USER_PROTOCOL_F_CRYPTO_SESSION = 7,
  52     VHOST_USER_PROTOCOL_F_PAGEFAULT = 8,
  53     VHOST_USER_PROTOCOL_F_CONFIG = 9,
  54     VHOST_USER_PROTOCOL_F_SLAVE_SEND_FD = 10,
  55     VHOST_USER_PROTOCOL_F_HOST_NOTIFIER = 11,
  56     VHOST_USER_PROTOCOL_F_INFLIGHT_SHMFD = 12,
  57     VHOST_USER_PROTOCOL_F_INBAND_NOTIFICATIONS = 14,
  58
  59     VHOST_USER_PROTOCOL_F_MAX
  60 };
  61
  62 #define VHOST_USER_PROTOCOL_FEATURE_MASK ((1 << VHOST_USER_PROTOCOL_F_MAX) - 1)
  63
  64 typedef enum VhostUserRequest {
  65     VHOST_USER_NONE = 0,
  66     VHOST_USER_GET_FEATURES = 1,
  67     VHOST_USER_SET_FEATURES = 2,
  68     VHOST_USER_SET_OWNER = 3,
  69     VHOST_USER_RESET_OWNER = 4,
  70     VHOST_USER_SET_MEM_TABLE = 5,
  71     VHOST_USER_SET_LOG_BASE = 6,
  72     VHOST_USER_SET_LOG_FD = 7,
  73     VHOST_USER_SET_VRING_NUM = 8,
  74     VHOST_USER_SET_VRING_ADDR = 9,
  75     VHOST_USER_SET_VRING_BASE = 10,
  76     VHOST_USER_GET_VRING_BASE = 11,
  77     VHOST_USER_SET_VRING_KICK = 12,
  78     VHOST_USER_SET_VRING_CALL = 13,
  79     VHOST_USER_SET_VRING_ERR = 14,
  80     VHOST_USER_GET_PROTOCOL_FEATURES = 15,
  81     VHOST_USER_SET_PROTOCOL_FEATURES = 16,
  82     VHOST_USER_GET_QUEUE_NUM = 17,
  83     VHOST_USER_SET_VRING_ENABLE = 18,
  84     VHOST_USER_SEND_RARP = 19,
  85     VHOST_USER_NET_SET_MTU = 20,
  86     VHOST_USER_SET_SLAVE_REQ_FD = 21,
  87     VHOST_USER_IOTLB_MSG = 22,
  88     VHOST_USER_SET_VRING_ENDIAN = 23,
  89     VHOST_USER_GET_CONFIG = 24,
  90     VHOST_USER_SET_CONFIG = 25,
  91     VHOST_USER_CREATE_CRYPTO_SESSION = 26,
  92     VHOST_USER_CLOSE_CRYPTO_SESSION = 27,
  93     VHOST_USER_POSTCOPY_ADVISE  = 28,
  94     VHOST_USER_POSTCOPY_LISTEN  = 29,
  95     VHOST_USER_POSTCOPY_END     = 30,
  96     VHOST_USER_GET_INFLIGHT_FD = 31,
  97     VHOST_USER_SET_INFLIGHT_FD = 32,
  98     VHOST_USER_GPU_SET_SOCKET = 33,
  99     VHOST_USER_VRING_KICK = 35,
 100     VHOST_USER_MAX
 101 } VhostUserRequest;
 102
 103 typedef enum VhostUserSlaveRequest {
 104     VHOST_USER_SLAVE_NONE = 0,
 105     VHOST_USER_SLAVE_IOTLB_MSG = 1,
 106     VHOST_USER_SLAVE_CONFIG_CHANGE_MSG = 2,
 107     VHOST_USER_SLAVE_VRING_HOST_NOTIFIER_MSG = 3,
 108     VHOST_USER_SLAVE_VRING_CALL = 4,
 109     VHOST_USER_SLAVE_VRING_ERR = 5,
 110     VHOST_USER_SLAVE_MAX
 111 }  VhostUserSlaveRequest;
 112
 113 typedef struct VhostUserMemoryRegion {
 114     uint64_t guest_phys_addr;
 115     uint64_t memory_size;
 116     uint64_t userspace_addr;
 117     uint64_t mmap_offset;
 118 } VhostUserMemoryRegion;
 119
 120 typedef struct VhostUserMemory {
 121     uint32_t nregions;
 122     uint32_t padding;
 123     VhostUserMemoryRegion regions[VHOST_MEMORY_MAX_NREGIONS];
 124 } VhostUserMemory;
 125
 126 typedef struct VhostUserLog {
 127     uint64_t mmap_size;
 128     uint64_t mmap_offset;
 129 } VhostUserLog;
 130
 131 typedef struct VhostUserConfig {
 132     uint32_t offset;
 133     uint32_t size;
 134     uint32_t flags;
 135     uint8_t region[VHOST_USER_MAX_CONFIG_SIZE];
 136 } VhostUserConfig;
 137
 138 static VhostUserConfig c __attribute__ ((unused));
 139 #define VHOST_USER_CONFIG_HDR_SIZE (sizeof(c.offset) \
 140                                    + sizeof(c.size) \
 141                                    + sizeof(c.flags))
 142
 143 typedef struct VhostUserVringArea {
 144     uint64_t u64;
 145     uint64_t size;
 146     uint64_t offset;
 147 } VhostUserVringArea;
 148
 149 typedef struct VhostUserInflight {
 150     uint64_t mmap_size;
 151     uint64_t mmap_offset;
 152     uint16_t num_queues;
 153     uint16_t queue_size;
 154 } VhostUserInflight;
 155
 156 #if defined(_WIN32) && (defined(__x86_64__) || defined(__i386__))
 157 # define VU_PACKED __attribute__((gcc_struct, packed))
 158 #else
 159 # define VU_PACKED __attribute__((packed))
 160 #endif
 161
 162 typedef struct VhostUserMsg {
 163     int request;
 164
 165 #define VHOST_USER_VERSION_MASK     (0x3)
 166 #define VHOST_USER_REPLY_MASK       (0x1 << 2)
 167 #define VHOST_USER_NEED_REPLY_MASK  (0x1 << 3)
 168     uint32_t flags;
 169     uint32_t size; /* the following payload size */
 170
 171     union {
 172 #define VHOST_USER_VRING_IDX_MASK   (0xff)
 173 #define VHOST_USER_VRING_NOFD_MASK  (0x1 << 8)
 174         uint64_t u64;
 175         struct vhost_vring_state state;
 176         struct vhost_vring_addr addr;
 177         VhostUserMemory memory;
 178         VhostUserLog log;
 179         VhostUserConfig config;
 180         VhostUserVringArea area;
 181         VhostUserInflight inflight;
 182     } payload;
 183
 184     int fds[VHOST_MEMORY_MAX_NREGIONS];
 185     int fd_num;
 186     uint8_t *data;
 187 } VU_PACKED VhostUserMsg;
 188
 189 typedef struct VuDevRegion {
 190     /* Guest Physical address. */
 191     uint64_t gpa;
 192     /* Memory region size. */
 193     uint64_t size;
 194     /* QEMU virtual address (userspace). */
 195     uint64_t qva;
 196     /* Starting offset in our mmaped space. */
 197     uint64_t mmap_offset;
 198     /* Start address of mmaped space. */
 199     uint64_t mmap_addr;
 200 } VuDevRegion;
 201
 202 typedef struct VuDev VuDev;
 203
 204 typedef uint64_t (*vu_get_features_cb) (VuDev *dev);
 205 typedef void (*vu_set_features_cb) (VuDev *dev, uint64_t features);
 206 typedef int (*vu_process_msg_cb) (VuDev *dev, VhostUserMsg *vmsg,
 207                                   int *do_reply);
 208 typedef void (*vu_queue_set_started_cb) (VuDev *dev, int qidx, bool started);
 209 typedef bool (*vu_queue_is_processed_in_order_cb) (VuDev *dev, int qidx);
 210 typedef int (*vu_get_config_cb) (VuDev *dev, uint8_t *config, uint32_t len);
 211 typedef int (*vu_set_config_cb) (VuDev *dev, const uint8_t *data,
 212                                  uint32_t offset, uint32_t size,
 213                                  uint32_t flags);
 214
 215 typedef struct VuDevIface {
 216     /* called by VHOST_USER_GET_FEATURES to get the features bitmask */
 217     vu_get_features_cb get_features;
 218     /* enable vhost implementation features */
 219     vu_set_features_cb set_features;
 220     /* get the protocol feature bitmask from the underlying vhost
 221      * implementation */
 222     vu_get_features_cb get_protocol_features;
 223     /* enable protocol features in the underlying vhost implementation. */
 224     vu_set_features_cb set_protocol_features;
 225     /* process_msg is called for each vhost-user message received */
 226     /* skip libvhost-user processing if return value != 0 */
 227     vu_process_msg_cb process_msg;
 228     /* tells when queues can be processed */
 229     vu_queue_set_started_cb queue_set_started;
 230     /*
 231      * If the queue is processed in order, in which case it will be
 232      * resumed to vring.used->idx. This can help to support resuming
 233      * on unmanaged exit/crash.
 234      */
 235     vu_queue_is_processed_in_order_cb queue_is_processed_in_order;
 236     /* get the config space of the device */
 237     vu_get_config_cb get_config;
 238     /* set the config space of the device */
 239     vu_set_config_cb set_config;
 240 } VuDevIface;
 241
 242 typedef void (*vu_queue_handler_cb) (VuDev *dev, int qidx);
 243
 244 typedef struct VuRing {
 245     unsigned int num;
 246     struct vring_desc *desc;
 247     struct vring_avail *avail;
 248     struct vring_used *used;
 249     uint64_t log_guest_addr;
 250     uint32_t flags;
 251 } VuRing;
 252
 253 typedef struct VuDescStateSplit {
 254     /* Indicate whether this descriptor is inflight or not.
 255      * Only available for head-descriptor. */
 256     uint8_t inflight;
 257
 258     /* Padding */
 259     uint8_t padding[5];
 260
 261     /* Maintain a list for the last batch of used descriptors.
 262      * Only available when batching is used for submitting */
 263     uint16_t next;
 264
 265     /* Used to preserve the order of fetching available descriptors.
 266      * Only available for head-descriptor. */
 267     uint64_t counter;
 268 } VuDescStateSplit;
 269
 270 typedef struct VuVirtqInflight {
 271     /* The feature flags of this region. Now it's initialized to 0. */
 272     uint64_t features;
 273
 274     /* The version of this region. It's 1 currently.
 275      * Zero value indicates a vm reset happened. */
 276     uint16_t version;
 277
 278     /* The size of VuDescStateSplit array. It's equal to the virtqueue
 279      * size. Slave could get it from queue size field of VhostUserInflight. */
 280     uint16_t desc_num;
 281
 282     /* The head of list that track the last batch of used descriptors. */
 283     uint16_t last_batch_head;
 284
 285     /* Storing the idx value of used ring */
 286     uint16_t used_idx;
 287
 288     /* Used to track the state of each descriptor in descriptor table */
 289     VuDescStateSplit desc[];
 290 } VuVirtqInflight;
 291
 292 typedef struct VuVirtqInflightDesc {
 293     uint16_t index;
 294     uint64_t counter;
 295 } VuVirtqInflightDesc;
 296
 297 typedef struct VuVirtq {
 298     VuRing vring;
 299
 300     VuVirtqInflight *inflight;
 301
 302     VuVirtqInflightDesc *resubmit_list;
 303
 304     uint16_t resubmit_num;
 305
 306     uint64_t counter;
 307
 308     /* Next head to pop */
 309     uint16_t last_avail_idx;
 310
 311     /* Last avail_idx read from VQ. */
 312     uint16_t shadow_avail_idx;
 313
 314     uint16_t used_idx;
 315
 316     /* Last used index value we have signalled on */
 317     uint16_t signalled_used;
 318
 319     /* Last used index value we have signalled on */
 320     bool signalled_used_valid;
 321
 322     /* Notification enabled? */
 323     bool notification;
 324
 325     int inuse;
 326
 327     vu_queue_handler_cb handler;
 328
 329     int call_fd;
 330     int kick_fd;
 331     int err_fd;
 332     unsigned int enable;
 333     bool started;
 334
 335     /* Guest addresses of our ring */
 336     struct vhost_vring_addr vra;
 337 } VuVirtq;
 338
 339 enum VuWatchCondtion {
 340     VU_WATCH_IN = POLLIN,
 341     VU_WATCH_OUT = POLLOUT,
 342     VU_WATCH_PRI = POLLPRI,
 343     VU_WATCH_ERR = POLLERR,
 344     VU_WATCH_HUP = POLLHUP,
 345 };
 346
 347 typedef void (*vu_panic_cb) (VuDev *dev, const char *err);
 348 typedef void (*vu_watch_cb) (VuDev *dev, int condition, void *data);
 349 typedef void (*vu_set_watch_cb) (VuDev *dev, int fd, int condition,
 350                                  vu_watch_cb cb, void *data);
 351 typedef void (*vu_remove_watch_cb) (VuDev *dev, int fd);
 352
 353 typedef struct VuDevInflightInfo {
 354     int fd;
 355     void *addr;
 356     uint64_t size;
 357 } VuDevInflightInfo;
 358
 359 struct VuDev {
 360     int sock;
 361     uint32_t nregions;
 362     VuDevRegion regions[VHOST_MEMORY_MAX_NREGIONS];
 363     VuVirtq *vq;
 364     VuDevInflightInfo inflight_info;
 365     int log_call_fd;
 366     /* Must be held while using slave_fd */
 367     pthread_mutex_t slave_mutex;
 368     int slave_fd;
 369     uint64_t log_size;
 370     uint8_t *log_table;
 371     uint64_t features;
 372     uint64_t protocol_features;
 373     bool broken;
 374     uint16_t max_queues;
 375
 376     /* @set_watch: add or update the given fd to the watch set,
 377      * call cb when condition is met */
 378     vu_set_watch_cb set_watch;
 379
 380     /* @remove_watch: remove the given fd from the watch set */
 381     vu_remove_watch_cb remove_watch;
 382
 383     /* @panic: encountered an unrecoverable error, you may try to
 384      * re-initialize */
 385     vu_panic_cb panic;
 386     const VuDevIface *iface;
 387
 388     /* Postcopy data */
 389     int postcopy_ufd;
 390     bool postcopy_listening;
 391 };
 392
 393 typedef struct VuVirtqElement {
 394     unsigned int index;
 395     unsigned int out_num;
 396     unsigned int in_num;
 397     struct iovec *in_sg;
 398     struct iovec *out_sg;
 399 } VuVirtqElement;
 400
 401 /**
 402  * vu_init:
 403  * @dev: a VuDev context
 404  * @max_queues: maximum number of virtqueues
 405  * @socket: the socket connected to vhost-user master
 406  * @panic: a panic callback
 407  * @set_watch: a set_watch callback
 408  * @remove_watch: a remove_watch callback
 409  * @iface: a VuDevIface structure with vhost-user device callbacks
 410  *
 411  * Intializes a VuDev vhost-user context.
 412  *
 413  * Returns: true on success, false on failure.
 414  **/
 415 bool vu_init(VuDev *dev,
 416              uint16_t max_queues,
 417              int socket,
 418              vu_panic_cb panic,
 419              vu_set_watch_cb set_watch,
 420              vu_remove_watch_cb remove_watch,
 421              const VuDevIface *iface);
 422
 423
 424 /**
 425  * vu_deinit:
 426  * @dev: a VuDev context
 427  *
 428  * Cleans up the VuDev context
 429  */
 430 void vu_deinit(VuDev *dev);
 431
 432 /**
 433  * vu_dispatch:
 434  * @dev: a VuDev context
 435  *
 436  * Process one vhost-user message.
 437  *
 438  * Returns: TRUE on success, FALSE on failure.
 439  */
 440 bool vu_dispatch(VuDev *dev);
 441
 442 /**
 443  * vu_gpa_to_va:
 444  * @dev: a VuDev context
 445  * @plen: guest memory size
 446  * @guest_addr: guest address
 447  *
 448  * Translate a guest address to a pointer. Returns NULL on failure.
 449  */
 450 void *vu_gpa_to_va(VuDev *dev, uint64_t *plen, uint64_t guest_addr);
 451
 452 /**
 453  * vu_get_queue:
 454  * @dev: a VuDev context
 455  * @qidx: queue index
 456  *
 457  * Returns the queue number @qidx.
 458  */
 459 VuVirtq *vu_get_queue(VuDev *dev, int qidx);
 460
 461 /**
 462  * vu_set_queue_handler:
 463  * @dev: a VuDev context
 464  * @vq: a VuVirtq queue
 465  * @handler: the queue handler callback
 466  *
 467  * Set the queue handler. This function may be called several times
 468  * for the same queue. If called with NULL @handler, the handler is
 469  * removed.
 470  */
 471 void vu_set_queue_handler(VuDev *dev, VuVirtq *vq,
 472                           vu_queue_handler_cb handler);
 473
 474 /**
 475  * vu_set_queue_host_notifier:
 476  * @dev: a VuDev context
 477  * @vq: a VuVirtq queue
 478  * @fd: a file descriptor
 479  * @size: host page size
 480  * @offset: notifier offset in @fd file
 481  *
 482  * Set queue's host notifier. This function may be called several
 483  * times for the same queue. If called with -1 @fd, the notifier
 484  * is removed.
 485  */
 486 bool vu_set_queue_host_notifier(VuDev *dev, VuVirtq *vq, int fd,
 487                                 int size, int offset);
 488
 489 /**
 490  * vu_queue_set_notification:
 491  * @dev: a VuDev context
 492  * @vq: a VuVirtq queue
 493  * @enable: state
 494  *
 495  * Set whether the queue notifies (via event index or interrupt)
 496  */
 497 void vu_queue_set_notification(VuDev *dev, VuVirtq *vq, int enable);
 498
 499 /**
 500  * vu_queue_enabled:
 501  * @dev: a VuDev context
 502  * @vq: a VuVirtq queue
 503  *
 504  * Returns: whether the queue is enabled.
 505  */
 506 bool vu_queue_enabled(VuDev *dev, VuVirtq *vq);
 507
 508 /**
 509  * vu_queue_started:
 510  * @dev: a VuDev context
 511  * @vq: a VuVirtq queue
 512  *
 513  * Returns: whether the queue is started.
 514  */
 515 bool vu_queue_started(const VuDev *dev, const VuVirtq *vq);
 516
 517 /**
 518  * vu_queue_empty:
 519  * @dev: a VuDev context
 520  * @vq: a VuVirtq queue
 521  *
 522  * Returns: true if the queue is empty or not ready.
 523  */
 524 bool vu_queue_empty(VuDev *dev, VuVirtq *vq);
 525
 526 /**
 527  * vu_queue_notify:
 528  * @dev: a VuDev context
 529  * @vq: a VuVirtq queue
 530  *
 531  * Request to notify the queue via callfd (skipped if unnecessary)
 532  */
 533 void vu_queue_notify(VuDev *dev, VuVirtq *vq);
 534
 535 /**
 536  * vu_queue_notify_sync:
 537  * @dev: a VuDev context
 538  * @vq: a VuVirtq queue
 539  *
 540  * Request to notify the queue via callfd (skipped if unnecessary)
 541  * or sync message if possible.
 542  */
 543 void vu_queue_notify_sync(VuDev *dev, VuVirtq *vq);
 544
 545 /**
 546  * vu_queue_pop:
 547  * @dev: a VuDev context
 548  * @vq: a VuVirtq queue
 549  * @sz: the size of struct to return (must be >= VuVirtqElement)
 550  *
 551  * Returns: a VuVirtqElement filled from the queue or NULL. The
 552  * returned element must be free()-d by the caller.
 553  */
 554 void *vu_queue_pop(VuDev *dev, VuVirtq *vq, size_t sz);
 555
 556
 557 /**
 558  * vu_queue_unpop:
 559  * @dev: a VuDev context
 560  * @vq: a VuVirtq queue
 561  * @elem: The #VuVirtqElement
 562  * @len: number of bytes written
 563  *
 564  * Pretend the most recent element wasn't popped from the virtqueue.  The next
 565  * call to vu_queue_pop() will refetch the element.
 566  */
 567 void vu_queue_unpop(VuDev *dev, VuVirtq *vq, VuVirtqElement *elem,
 568                     size_t len);
 569
 570 /**
 571  * vu_queue_rewind:
 572  * @dev: a VuDev context
 573  * @vq: a VuVirtq queue
 574  * @num: number of elements to push back
 575  *
 576  * Pretend that elements weren't popped from the virtqueue.  The next
 577  * virtqueue_pop() will refetch the oldest element.
 578  *
 579  * Returns: true on success, false if @num is greater than the number of in use
 580  * elements.
 581  */
 582 bool vu_queue_rewind(VuDev *dev, VuVirtq *vq, unsigned int num);
 583
 584 /**
 585  * vu_queue_fill:
 586  * @dev: a VuDev context
 587  * @vq: a VuVirtq queue
 588  * @elem: a VuVirtqElement
 589  * @len: length in bytes to write
 590  * @idx: optional offset for the used ring index (0 in general)
 591  *
 592  * Fill the used ring with @elem element.
 593  */
 594 void vu_queue_fill(VuDev *dev, VuVirtq *vq,
 595                    const VuVirtqElement *elem,
 596                    unsigned int len, unsigned int idx);
 597
 598 /**
 599  * vu_queue_push:
 600  * @dev: a VuDev context
 601  * @vq: a VuVirtq queue
 602  * @elem: a VuVirtqElement
 603  * @len: length in bytes to write
 604  *
 605  * Helper that combines vu_queue_fill() with a vu_queue_flush().
 606  */
 607 void vu_queue_push(VuDev *dev, VuVirtq *vq,
 608                    const VuVirtqElement *elem, unsigned int len);
 609
 610 /**
 611  * vu_queue_flush:
 612  * @dev: a VuDev context
 613  * @vq: a VuVirtq queue
 614  * @num: number of elements to flush
 615  *
 616  * Mark the last number of elements as done (used.idx is updated by
 617  * num elements).
 618 */
 619 void vu_queue_flush(VuDev *dev, VuVirtq *vq, unsigned int num);
 620
 621 /**
 622  * vu_queue_get_avail_bytes:
 623  * @dev: a VuDev context
 624  * @vq: a VuVirtq queue
 625  * @in_bytes: in bytes
 626  * @out_bytes: out bytes
 627  * @max_in_bytes: stop counting after max_in_bytes
 628  * @max_out_bytes: stop counting after max_out_bytes
 629  *
 630  * Count the number of available bytes, up to max_in_bytes/max_out_bytes.
 631  */
 632 void vu_queue_get_avail_bytes(VuDev *vdev, VuVirtq *vq, unsigned int *in_bytes,
 633                               unsigned int *out_bytes,
 634                               unsigned max_in_bytes, unsigned max_out_bytes);
 635
 636 /**
 637  * vu_queue_avail_bytes:
 638  * @dev: a VuDev context
 639  * @vq: a VuVirtq queue
 640  * @in_bytes: expected in bytes
 641  * @out_bytes: expected out bytes
 642  *
 643  * Returns: true if in_bytes <= in_total && out_bytes <= out_total
 644  */
 645 bool vu_queue_avail_bytes(VuDev *dev, VuVirtq *vq, unsigned int in_bytes,
 646                           unsigned int out_bytes);
 647
 648 #endif /* LIBVHOST_USER_H */