subprojects/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 <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_BASELINE_NREGIONS 8
  32
  33 /*
  34  * Set a reasonable maximum number of ram slots, which will be supported by
  35  * any architecture.
  36  */
  37 #define VHOST_USER_MAX_RAM_SLOTS 32
  38
  39 #define VHOST_USER_HDR_SIZE offsetof(VhostUserMsg, payload.u64)
  40
  41 typedef enum VhostSetConfigType {
  42     VHOST_SET_CONFIG_TYPE_MASTER = 0,
  43     VHOST_SET_CONFIG_TYPE_MIGRATION = 1,
  44 } VhostSetConfigType;
  45
  46 /*
  47  * Maximum size of virtio device config space
  48  */
  49 #define VHOST_USER_MAX_CONFIG_SIZE 256
  50
  51 enum VhostUserProtocolFeature {
  52     VHOST_USER_PROTOCOL_F_MQ = 0,
  53     VHOST_USER_PROTOCOL_F_LOG_SHMFD = 1,
  54     VHOST_USER_PROTOCOL_F_RARP = 2,
  55     VHOST_USER_PROTOCOL_F_REPLY_ACK = 3,
  56     VHOST_USER_PROTOCOL_F_NET_MTU = 4,
  57     VHOST_USER_PROTOCOL_F_SLAVE_REQ = 5,
  58     VHOST_USER_PROTOCOL_F_CROSS_ENDIAN = 6,
  59     VHOST_USER_PROTOCOL_F_CRYPTO_SESSION = 7,
  60     VHOST_USER_PROTOCOL_F_PAGEFAULT = 8,
  61     VHOST_USER_PROTOCOL_F_CONFIG = 9,
  62     VHOST_USER_PROTOCOL_F_SLAVE_SEND_FD = 10,
  63     VHOST_USER_PROTOCOL_F_HOST_NOTIFIER = 11,
  64     VHOST_USER_PROTOCOL_F_INFLIGHT_SHMFD = 12,
  65     VHOST_USER_PROTOCOL_F_INBAND_NOTIFICATIONS = 14,
  66     VHOST_USER_PROTOCOL_F_CONFIGURE_MEM_SLOTS = 15,
  67
  68     VHOST_USER_PROTOCOL_F_MAX
  69 };
  70
  71 #define VHOST_USER_PROTOCOL_FEATURE_MASK ((1 << VHOST_USER_PROTOCOL_F_MAX) - 1)
  72
  73 typedef enum VhostUserRequest {
  74     VHOST_USER_NONE = 0,
  75     VHOST_USER_GET_FEATURES = 1,
  76     VHOST_USER_SET_FEATURES = 2,
  77     VHOST_USER_SET_OWNER = 3,
  78     VHOST_USER_RESET_OWNER = 4,
  79     VHOST_USER_SET_MEM_TABLE = 5,
  80     VHOST_USER_SET_LOG_BASE = 6,
  81     VHOST_USER_SET_LOG_FD = 7,
  82     VHOST_USER_SET_VRING_NUM = 8,
  83     VHOST_USER_SET_VRING_ADDR = 9,
  84     VHOST_USER_SET_VRING_BASE = 10,
  85     VHOST_USER_GET_VRING_BASE = 11,
  86     VHOST_USER_SET_VRING_KICK = 12,
  87     VHOST_USER_SET_VRING_CALL = 13,
  88     VHOST_USER_SET_VRING_ERR = 14,
  89     VHOST_USER_GET_PROTOCOL_FEATURES = 15,
  90     VHOST_USER_SET_PROTOCOL_FEATURES = 16,
  91     VHOST_USER_GET_QUEUE_NUM = 17,
  92     VHOST_USER_SET_VRING_ENABLE = 18,
  93     VHOST_USER_SEND_RARP = 19,
  94     VHOST_USER_NET_SET_MTU = 20,
  95     VHOST_USER_SET_SLAVE_REQ_FD = 21,
  96     VHOST_USER_IOTLB_MSG = 22,
  97     VHOST_USER_SET_VRING_ENDIAN = 23,
  98     VHOST_USER_GET_CONFIG = 24,
  99     VHOST_USER_SET_CONFIG = 25,
 100     VHOST_USER_CREATE_CRYPTO_SESSION = 26,
 101     VHOST_USER_CLOSE_CRYPTO_SESSION = 27,
 102     VHOST_USER_POSTCOPY_ADVISE  = 28,
 103     VHOST_USER_POSTCOPY_LISTEN  = 29,
 104     VHOST_USER_POSTCOPY_END     = 30,
 105     VHOST_USER_GET_INFLIGHT_FD = 31,
 106     VHOST_USER_SET_INFLIGHT_FD = 32,
 107     VHOST_USER_GPU_SET_SOCKET = 33,
 108     VHOST_USER_VRING_KICK = 35,
 109     VHOST_USER_GET_MAX_MEM_SLOTS = 36,
 110     VHOST_USER_ADD_MEM_REG = 37,
 111     VHOST_USER_REM_MEM_REG = 38,
 112     VHOST_USER_MAX
 113 } VhostUserRequest;
 114
 115 typedef enum VhostUserSlaveRequest {
 116     VHOST_USER_SLAVE_NONE = 0,
 117     VHOST_USER_SLAVE_IOTLB_MSG = 1,
 118     VHOST_USER_SLAVE_CONFIG_CHANGE_MSG = 2,
 119     VHOST_USER_SLAVE_VRING_HOST_NOTIFIER_MSG = 3,
 120     VHOST_USER_SLAVE_VRING_CALL = 4,
 121     VHOST_USER_SLAVE_VRING_ERR = 5,
 122     VHOST_USER_SLAVE_MAX
 123 }  VhostUserSlaveRequest;
 124
 125 typedef struct VhostUserMemoryRegion {
 126     uint64_t guest_phys_addr;
 127     uint64_t memory_size;
 128     uint64_t userspace_addr;
 129     uint64_t mmap_offset;
 130 } VhostUserMemoryRegion;
 131
 132 #define VHOST_USER_MEM_REG_SIZE (sizeof(VhostUserMemoryRegion))
 133
 134 typedef struct VhostUserMemory {
 135     uint32_t nregions;
 136     uint32_t padding;
 137     VhostUserMemoryRegion regions[VHOST_MEMORY_BASELINE_NREGIONS];
 138 } VhostUserMemory;
 139
 140 typedef struct VhostUserMemRegMsg {
 141     uint64_t padding;
 142     VhostUserMemoryRegion region;
 143 } VhostUserMemRegMsg;
 144
 145 typedef struct VhostUserLog {
 146     uint64_t mmap_size;
 147     uint64_t mmap_offset;
 148 } VhostUserLog;
 149
 150 typedef struct VhostUserConfig {
 151     uint32_t offset;
 152     uint32_t size;
 153     uint32_t flags;
 154     uint8_t region[VHOST_USER_MAX_CONFIG_SIZE];
 155 } VhostUserConfig;
 156
 157 static VhostUserConfig c __attribute__ ((unused));
 158 #define VHOST_USER_CONFIG_HDR_SIZE (sizeof(c.offset) \
 159                                    + sizeof(c.size) \
 160                                    + sizeof(c.flags))
 161
 162 typedef struct VhostUserVringArea {
 163     uint64_t u64;
 164     uint64_t size;
 165     uint64_t offset;
 166 } VhostUserVringArea;
 167
 168 typedef struct VhostUserInflight {
 169     uint64_t mmap_size;
 170     uint64_t mmap_offset;
 171     uint16_t num_queues;
 172     uint16_t queue_size;
 173 } VhostUserInflight;
 174
 175 #if defined(_WIN32) && (defined(__x86_64__) || defined(__i386__))
 176 # define VU_PACKED __attribute__((gcc_struct, packed))
 177 #else
 178 # define VU_PACKED __attribute__((packed))
 179 #endif
 180
 181 typedef struct VhostUserMsg {
 182     int request;
 183
 184 #define VHOST_USER_VERSION_MASK     (0x3)
 185 #define VHOST_USER_REPLY_MASK       (0x1 << 2)
 186 #define VHOST_USER_NEED_REPLY_MASK  (0x1 << 3)
 187     uint32_t flags;
 188     uint32_t size; /* the following payload size */
 189
 190     union {
 191 #define VHOST_USER_VRING_IDX_MASK   (0xff)
 192 #define VHOST_USER_VRING_NOFD_MASK  (0x1 << 8)
 193         uint64_t u64;
 194         struct vhost_vring_state state;
 195         struct vhost_vring_addr addr;
 196         VhostUserMemory memory;
 197         VhostUserMemRegMsg memreg;
 198         VhostUserLog log;
 199         VhostUserConfig config;
 200         VhostUserVringArea area;
 201         VhostUserInflight inflight;
 202     } payload;
 203
 204     int fds[VHOST_MEMORY_BASELINE_NREGIONS];
 205     int fd_num;
 206     uint8_t *data;
 207 } VU_PACKED VhostUserMsg;
 208
 209 typedef struct VuDevRegion {
 210     /* Guest Physical address. */
 211     uint64_t gpa;
 212     /* Memory region size. */
 213     uint64_t size;
 214     /* QEMU virtual address (userspace). */
 215     uint64_t qva;
 216     /* Starting offset in our mmaped space. */
 217     uint64_t mmap_offset;
 218     /* Start address of mmaped space. */
 219     uint64_t mmap_addr;
 220 } VuDevRegion;
 221
 222 typedef struct VuDev VuDev;
 223
 224 typedef uint64_t (*vu_get_features_cb) (VuDev *dev);
 225 typedef void (*vu_set_features_cb) (VuDev *dev, uint64_t features);
 226 typedef int (*vu_process_msg_cb) (VuDev *dev, VhostUserMsg *vmsg,
 227                                   int *do_reply);
 228 typedef bool (*vu_read_msg_cb) (VuDev *dev, int sock, VhostUserMsg *vmsg);
 229 typedef void (*vu_queue_set_started_cb) (VuDev *dev, int qidx, bool started);
 230 typedef bool (*vu_queue_is_processed_in_order_cb) (VuDev *dev, int qidx);
 231 typedef int (*vu_get_config_cb) (VuDev *dev, uint8_t *config, uint32_t len);
 232 typedef int (*vu_set_config_cb) (VuDev *dev, const uint8_t *data,
 233                                  uint32_t offset, uint32_t size,
 234                                  uint32_t flags);
 235
 236 typedef struct VuDevIface {
 237     /* called by VHOST_USER_GET_FEATURES to get the features bitmask */
 238     vu_get_features_cb get_features;
 239     /* enable vhost implementation features */
 240     vu_set_features_cb set_features;
 241     /* get the protocol feature bitmask from the underlying vhost
 242      * implementation */
 243     vu_get_features_cb get_protocol_features;
 244     /* enable protocol features in the underlying vhost implementation. */
 245     vu_set_features_cb set_protocol_features;
 246     /* process_msg is called for each vhost-user message received */
 247     /* skip libvhost-user processing if return value != 0 */
 248     vu_process_msg_cb process_msg;
 249     /* tells when queues can be processed */
 250     vu_queue_set_started_cb queue_set_started;
 251     /*
 252      * If the queue is processed in order, in which case it will be
 253      * resumed to vring.used->idx. This can help to support resuming
 254      * on unmanaged exit/crash.
 255      */
 256     vu_queue_is_processed_in_order_cb queue_is_processed_in_order;
 257     /* get the config space of the device */
 258     vu_get_config_cb get_config;
 259     /* set the config space of the device */
 260     vu_set_config_cb set_config;
 261 } VuDevIface;
 262
 263 typedef void (*vu_queue_handler_cb) (VuDev *dev, int qidx);
 264
 265 typedef struct VuRing {
 266     unsigned int num;
 267     struct vring_desc *desc;
 268     struct vring_avail *avail;
 269     struct vring_used *used;
 270     uint64_t log_guest_addr;
 271     uint32_t flags;
 272 } VuRing;
 273
 274 typedef struct VuDescStateSplit {
 275     /* Indicate whether this descriptor is inflight or not.
 276      * Only available for head-descriptor. */
 277     uint8_t inflight;
 278
 279     /* Padding */
 280     uint8_t padding[5];
 281
 282     /* Maintain a list for the last batch of used descriptors.
 283      * Only available when batching is used for submitting */
 284     uint16_t next;
 285
 286     /* Used to preserve the order of fetching available descriptors.
 287      * Only available for head-descriptor. */
 288     uint64_t counter;
 289 } VuDescStateSplit;
 290
 291 typedef struct VuVirtqInflight {
 292     /* The feature flags of this region. Now it's initialized to 0. */
 293     uint64_t features;
 294
 295     /* The version of this region. It's 1 currently.
 296      * Zero value indicates a vm reset happened. */
 297     uint16_t version;
 298
 299     /* The size of VuDescStateSplit array. It's equal to the virtqueue
 300      * size. Slave could get it from queue size field of VhostUserInflight. */
 301     uint16_t desc_num;
 302
 303     /* The head of list that track the last batch of used descriptors. */
 304     uint16_t last_batch_head;
 305
 306     /* Storing the idx value of used ring */
 307     uint16_t used_idx;
 308
 309     /* Used to track the state of each descriptor in descriptor table */
 310     VuDescStateSplit desc[];
 311 } VuVirtqInflight;
 312
 313 typedef struct VuVirtqInflightDesc {
 314     uint16_t index;
 315     uint64_t counter;
 316 } VuVirtqInflightDesc;
 317
 318 typedef struct VuVirtq {
 319     VuRing vring;
 320
 321     VuVirtqInflight *inflight;
 322
 323     VuVirtqInflightDesc *resubmit_list;
 324
 325     uint16_t resubmit_num;
 326
 327     uint64_t counter;
 328
 329     /* Next head to pop */
 330     uint16_t last_avail_idx;
 331
 332     /* Last avail_idx read from VQ. */
 333     uint16_t shadow_avail_idx;
 334
 335     uint16_t used_idx;
 336
 337     /* Last used index value we have signalled on */
 338     uint16_t signalled_used;
 339
 340     /* Last used index value we have signalled on */
 341     bool signalled_used_valid;
 342
 343     /* Notification enabled? */
 344     bool notification;
 345
 346     unsigned int inuse;
 347
 348     vu_queue_handler_cb handler;
 349
 350     int call_fd;
 351     int kick_fd;
 352     int err_fd;
 353     unsigned int enable;
 354     bool started;
 355
 356     /* Guest addresses of our ring */
 357     struct vhost_vring_addr vra;
 358 } VuVirtq;
 359
 360 enum VuWatchCondtion {
 361     VU_WATCH_IN = POLLIN,
 362     VU_WATCH_OUT = POLLOUT,
 363     VU_WATCH_PRI = POLLPRI,
 364     VU_WATCH_ERR = POLLERR,
 365     VU_WATCH_HUP = POLLHUP,
 366 };
 367
 368 typedef void (*vu_panic_cb) (VuDev *dev, const char *err);
 369 typedef void (*vu_watch_cb) (VuDev *dev, int condition, void *data);
 370 typedef void (*vu_set_watch_cb) (VuDev *dev, int fd, int condition,
 371                                  vu_watch_cb cb, void *data);
 372 typedef void (*vu_remove_watch_cb) (VuDev *dev, int fd);
 373
 374 typedef struct VuDevInflightInfo {
 375     int fd;
 376     void *addr;
 377     uint64_t size;
 378 } VuDevInflightInfo;
 379
 380 struct VuDev {
 381     int sock;
 382     uint32_t nregions;
 383     VuDevRegion regions[VHOST_USER_MAX_RAM_SLOTS];
 384     VuVirtq *vq;
 385     VuDevInflightInfo inflight_info;
 386     int log_call_fd;
 387     /* Must be held while using slave_fd */
 388     pthread_mutex_t slave_mutex;
 389     int slave_fd;
 390     uint64_t log_size;
 391     uint8_t *log_table;
 392     uint64_t features;
 393     uint64_t protocol_features;
 394     bool broken;
 395     uint16_t max_queues;
 396
 397     /*
 398      * @read_msg: custom method to read vhost-user message
 399      *
 400      * Read data from vhost_user socket fd and fill up
 401      * the passed VhostUserMsg *vmsg struct.
 402      *
 403      * If reading fails, it should close the received set of file
 404      * descriptors as socket message's auxiliary data.
 405      *
 406      * For the details, please refer to vu_message_read in libvhost-user.c
 407      * which will be used by default if not custom method is provided when
 408      * calling vu_init
 409      *
 410      * Returns: true if vhost-user message successfully received,
 411      *          otherwise return false.
 412      *
 413      */
 414     vu_read_msg_cb read_msg;
 415
 416     /*
 417      * @set_watch: add or update the given fd to the watch set,
 418      * call cb when condition is met.
 419      */
 420     vu_set_watch_cb set_watch;
 421
 422     /* @remove_watch: remove the given fd from the watch set */
 423     vu_remove_watch_cb remove_watch;
 424
 425     /*
 426      * @panic: encountered an unrecoverable error, you may try to re-initialize
 427      */
 428     vu_panic_cb panic;
 429     const VuDevIface *iface;
 430
 431     /* Postcopy data */
 432     int postcopy_ufd;
 433     bool postcopy_listening;
 434 };
 435
 436 typedef struct VuVirtqElement {
 437     unsigned int index;
 438     unsigned int out_num;
 439     unsigned int in_num;
 440     struct iovec *in_sg;
 441     struct iovec *out_sg;
 442 } VuVirtqElement;
 443
 444 /**
 445  * vu_init:
 446  * @dev: a VuDev context
 447  * @max_queues: maximum number of virtqueues
 448  * @socket: the socket connected to vhost-user master
 449  * @panic: a panic callback
 450  * @set_watch: a set_watch callback
 451  * @remove_watch: a remove_watch callback
 452  * @iface: a VuDevIface structure with vhost-user device callbacks
 453  *
 454  * Initializes a VuDev vhost-user context.
 455  *
 456  * Returns: true on success, false on failure.
 457  **/
 458 bool vu_init(VuDev *dev,
 459              uint16_t max_queues,
 460              int socket,
 461              vu_panic_cb panic,
 462              vu_read_msg_cb read_msg,
 463              vu_set_watch_cb set_watch,
 464              vu_remove_watch_cb remove_watch,
 465              const VuDevIface *iface);
 466
 467
 468 /**
 469  * vu_deinit:
 470  * @dev: a VuDev context
 471  *
 472  * Cleans up the VuDev context
 473  */
 474 void vu_deinit(VuDev *dev);
 475
 476
 477 /**
 478  * vu_request_to_string: return string for vhost message request
 479  * @req: VhostUserMsg request
 480  *
 481  * Returns a const string, do not free.
 482  */
 483 const char *vu_request_to_string(unsigned int req);
 484
 485 /**
 486  * vu_dispatch:
 487  * @dev: a VuDev context
 488  *
 489  * Process one vhost-user message.
 490  *
 491  * Returns: TRUE on success, FALSE on failure.
 492  */
 493 bool vu_dispatch(VuDev *dev);
 494
 495 /**
 496  * vu_gpa_to_va:
 497  * @dev: a VuDev context
 498  * @plen: guest memory size
 499  * @guest_addr: guest address
 500  *
 501  * Translate a guest address to a pointer. Returns NULL on failure.
 502  */
 503 void *vu_gpa_to_va(VuDev *dev, uint64_t *plen, uint64_t guest_addr);
 504
 505 /**
 506  * vu_get_queue:
 507  * @dev: a VuDev context
 508  * @qidx: queue index
 509  *
 510  * Returns the queue number @qidx.
 511  */
 512 VuVirtq *vu_get_queue(VuDev *dev, int qidx);
 513
 514 /**
 515  * vu_set_queue_handler:
 516  * @dev: a VuDev context
 517  * @vq: a VuVirtq queue
 518  * @handler: the queue handler callback
 519  *
 520  * Set the queue handler. This function may be called several times
 521  * for the same queue. If called with NULL @handler, the handler is
 522  * removed.
 523  */
 524 void vu_set_queue_handler(VuDev *dev, VuVirtq *vq,
 525                           vu_queue_handler_cb handler);
 526
 527 /**
 528  * vu_set_queue_host_notifier:
 529  * @dev: a VuDev context
 530  * @vq: a VuVirtq queue
 531  * @fd: a file descriptor
 532  * @size: host page size
 533  * @offset: notifier offset in @fd file
 534  *
 535  * Set queue's host notifier. This function may be called several
 536  * times for the same queue. If called with -1 @fd, the notifier
 537  * is removed.
 538  */
 539 bool vu_set_queue_host_notifier(VuDev *dev, VuVirtq *vq, int fd,
 540                                 int size, int offset);
 541
 542 /**
 543  * vu_queue_set_notification:
 544  * @dev: a VuDev context
 545  * @vq: a VuVirtq queue
 546  * @enable: state
 547  *
 548  * Set whether the queue notifies (via event index or interrupt)
 549  */
 550 void vu_queue_set_notification(VuDev *dev, VuVirtq *vq, int enable);
 551
 552 /**
 553  * vu_queue_enabled:
 554  * @dev: a VuDev context
 555  * @vq: a VuVirtq queue
 556  *
 557  * Returns: whether the queue is enabled.
 558  */
 559 bool vu_queue_enabled(VuDev *dev, VuVirtq *vq);
 560
 561 /**
 562  * vu_queue_started:
 563  * @dev: a VuDev context
 564  * @vq: a VuVirtq queue
 565  *
 566  * Returns: whether the queue is started.
 567  */
 568 bool vu_queue_started(const VuDev *dev, const VuVirtq *vq);
 569
 570 /**
 571  * vu_queue_empty:
 572  * @dev: a VuDev context
 573  * @vq: a VuVirtq queue
 574  *
 575  * Returns: true if the queue is empty or not ready.
 576  */
 577 bool vu_queue_empty(VuDev *dev, VuVirtq *vq);
 578
 579 /**
 580  * vu_queue_notify:
 581  * @dev: a VuDev context
 582  * @vq: a VuVirtq queue
 583  *
 584  * Request to notify the queue via callfd (skipped if unnecessary)
 585  */
 586 void vu_queue_notify(VuDev *dev, VuVirtq *vq);
 587
 588 /**
 589  * vu_queue_notify_sync:
 590  * @dev: a VuDev context
 591  * @vq: a VuVirtq queue
 592  *
 593  * Request to notify the queue via callfd (skipped if unnecessary)
 594  * or sync message if possible.
 595  */
 596 void vu_queue_notify_sync(VuDev *dev, VuVirtq *vq);
 597
 598 /**
 599  * vu_queue_pop:
 600  * @dev: a VuDev context
 601  * @vq: a VuVirtq queue
 602  * @sz: the size of struct to return (must be >= VuVirtqElement)
 603  *
 604  * Returns: a VuVirtqElement filled from the queue or NULL. The
 605  * returned element must be free()-d by the caller.
 606  */
 607 void *vu_queue_pop(VuDev *dev, VuVirtq *vq, size_t sz);
 608
 609
 610 /**
 611  * vu_queue_unpop:
 612  * @dev: a VuDev context
 613  * @vq: a VuVirtq queue
 614  * @elem: The #VuVirtqElement
 615  * @len: number of bytes written
 616  *
 617  * Pretend the most recent element wasn't popped from the virtqueue.  The next
 618  * call to vu_queue_pop() will refetch the element.
 619  */
 620 void vu_queue_unpop(VuDev *dev, VuVirtq *vq, VuVirtqElement *elem,
 621                     size_t len);
 622
 623 /**
 624  * vu_queue_rewind:
 625  * @dev: a VuDev context
 626  * @vq: a VuVirtq queue
 627  * @num: number of elements to push back
 628  *
 629  * Pretend that elements weren't popped from the virtqueue.  The next
 630  * virtqueue_pop() will refetch the oldest element.
 631  *
 632  * Returns: true on success, false if @num is greater than the number of in use
 633  * elements.
 634  */
 635 bool vu_queue_rewind(VuDev *dev, VuVirtq *vq, unsigned int num);
 636
 637 /**
 638  * vu_queue_fill:
 639  * @dev: a VuDev context
 640  * @vq: a VuVirtq queue
 641  * @elem: a VuVirtqElement
 642  * @len: length in bytes to write
 643  * @idx: optional offset for the used ring index (0 in general)
 644  *
 645  * Fill the used ring with @elem element.
 646  */
 647 void vu_queue_fill(VuDev *dev, VuVirtq *vq,
 648                    const VuVirtqElement *elem,
 649                    unsigned int len, unsigned int idx);
 650
 651 /**
 652  * vu_queue_push:
 653  * @dev: a VuDev context
 654  * @vq: a VuVirtq queue
 655  * @elem: a VuVirtqElement
 656  * @len: length in bytes to write
 657  *
 658  * Helper that combines vu_queue_fill() with a vu_queue_flush().
 659  */
 660 void vu_queue_push(VuDev *dev, VuVirtq *vq,
 661                    const VuVirtqElement *elem, unsigned int len);
 662
 663 /**
 664  * vu_queue_flush:
 665  * @dev: a VuDev context
 666  * @vq: a VuVirtq queue
 667  * @num: number of elements to flush
 668  *
 669  * Mark the last number of elements as done (used.idx is updated by
 670  * num elements).
 671 */
 672 void vu_queue_flush(VuDev *dev, VuVirtq *vq, unsigned int num);
 673
 674 /**
 675  * vu_queue_get_avail_bytes:
 676  * @dev: a VuDev context
 677  * @vq: a VuVirtq queue
 678  * @in_bytes: in bytes
 679  * @out_bytes: out bytes
 680  * @max_in_bytes: stop counting after max_in_bytes
 681  * @max_out_bytes: stop counting after max_out_bytes
 682  *
 683  * Count the number of available bytes, up to max_in_bytes/max_out_bytes.
 684  */
 685 void vu_queue_get_avail_bytes(VuDev *vdev, VuVirtq *vq, unsigned int *in_bytes,
 686                               unsigned int *out_bytes,
 687                               unsigned max_in_bytes, unsigned max_out_bytes);
 688
 689 /**
 690  * vu_queue_avail_bytes:
 691  * @dev: a VuDev context
 692  * @vq: a VuVirtq queue
 693  * @in_bytes: expected in bytes
 694  * @out_bytes: expected out bytes
 695  *
 696  * Returns: true if in_bytes <= in_total && out_bytes <= out_total
 697  */
 698 bool vu_queue_avail_bytes(VuDev *dev, VuVirtq *vq, unsigned int in_bytes,
 699                           unsigned int out_bytes);
 700
 701 #endif /* LIBVHOST_USER_H */