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* Copyright (c) 2016 Red Hat, Inc.
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* Victor Kaplansky <victork@redhat.com>
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* Marc-André Lureau <mlureau@redhat.com>
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* This work is licensed under the terms of the GNU GPL, version 2 or
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* later. See the COPYING file in the top-level directory.
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#ifndef LIBVHOST_USER_H
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#define LIBVHOST_USER_H
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#include <linux/vhost.h>
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#include "standard-headers/linux/virtio_ring.h"
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/* Based on qemu/hw/virtio/vhost-user.c */
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#define VHOST_USER_F_PROTOCOL_FEATURES 30
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#define VHOST_LOG_PAGE 4096
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#define VHOST_MAX_NR_VIRTQUEUE 8
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#define VIRTQUEUE_MAX_SIZE 1024
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#define VHOST_MEMORY_MAX_NREGIONS 8
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enum VhostUserProtocolFeature {
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VHOST_USER_PROTOCOL_F_MQ = 0,
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VHOST_USER_PROTOCOL_F_LOG_SHMFD = 1,
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VHOST_USER_PROTOCOL_F_RARP = 2,
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VHOST_USER_PROTOCOL_F_MAX
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#define VHOST_USER_PROTOCOL_FEATURE_MASK ((1 << VHOST_USER_PROTOCOL_F_MAX) - 1)
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typedef enum VhostUserRequest {
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VHOST_USER_GET_FEATURES = 1,
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VHOST_USER_SET_FEATURES = 2,
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VHOST_USER_SET_OWNER = 3,
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VHOST_USER_RESET_OWNER = 4,
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VHOST_USER_SET_MEM_TABLE = 5,
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VHOST_USER_SET_LOG_BASE = 6,
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VHOST_USER_SET_LOG_FD = 7,
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VHOST_USER_SET_VRING_NUM = 8,
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VHOST_USER_SET_VRING_ADDR = 9,
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VHOST_USER_SET_VRING_BASE = 10,
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VHOST_USER_GET_VRING_BASE = 11,
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VHOST_USER_SET_VRING_KICK = 12,
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VHOST_USER_SET_VRING_CALL = 13,
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VHOST_USER_SET_VRING_ERR = 14,
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VHOST_USER_GET_PROTOCOL_FEATURES = 15,
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VHOST_USER_SET_PROTOCOL_FEATURES = 16,
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VHOST_USER_GET_QUEUE_NUM = 17,
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VHOST_USER_SET_VRING_ENABLE = 18,
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VHOST_USER_SEND_RARP = 19,
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VHOST_USER_INPUT_GET_CONFIG = 20,
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typedef struct VhostUserMemoryRegion {
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uint64_t guest_phys_addr;
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uint64_t userspace_addr;
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} VhostUserMemoryRegion;
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typedef struct VhostUserMemory {
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VhostUserMemoryRegion regions[VHOST_MEMORY_MAX_NREGIONS];
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typedef struct VhostUserLog {
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# define VU_PACKED __attribute__((gcc_struct, packed))
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# define VU_PACKED __attribute__((packed))
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typedef struct VhostUserMsg {
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VhostUserRequest request;
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#define VHOST_USER_VERSION_MASK (0x3)
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#define VHOST_USER_REPLY_MASK (0x1 << 2)
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uint32_t size; /* the following payload size */
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#define VHOST_USER_VRING_IDX_MASK (0xff)
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#define VHOST_USER_VRING_NOFD_MASK (0x1 << 8)
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struct vhost_vring_state state;
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struct vhost_vring_addr addr;
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VhostUserMemory memory;
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int fds[VHOST_MEMORY_MAX_NREGIONS];
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} VU_PACKED VhostUserMsg;
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typedef struct VuDevRegion {
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/* Guest Physical address. */
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/* Memory region size. */
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/* QEMU virtual address (userspace). */
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/* Starting offset in our mmaped space. */
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uint64_t mmap_offset;
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/* Start address of mmaped space. */
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typedef struct VuDev VuDev;
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typedef uint64_t (*vu_get_features_cb) (VuDev *dev);
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typedef void (*vu_set_features_cb) (VuDev *dev, uint64_t features);
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typedef int (*vu_process_msg_cb) (VuDev *dev, VhostUserMsg *vmsg,
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typedef void (*vu_queue_set_started_cb) (VuDev *dev, int qidx, bool started);
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typedef struct VuDevIface {
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/* called by VHOST_USER_GET_FEATURES to get the features bitmask */
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vu_get_features_cb get_features;
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/* enable vhost implementation features */
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vu_set_features_cb set_features;
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/* get the protocol feature bitmask from the underlying vhost
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vu_get_features_cb get_protocol_features;
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/* enable protocol features in the underlying vhost implementation. */
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vu_set_features_cb set_protocol_features;
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/* process_msg is called for each vhost-user message received */
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/* skip libvhost-user processing if return value != 0 */
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vu_process_msg_cb process_msg;
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/* tells when queues can be processed */
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vu_queue_set_started_cb queue_set_started;
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typedef void (*vu_queue_handler_cb) (VuDev *dev, int qidx);
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typedef struct VuRing {
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struct vring_desc *desc;
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struct vring_avail *avail;
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struct vring_used *used;
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uint64_t log_guest_addr;
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typedef struct VuVirtq {
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/* Next head to pop */
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uint16_t last_avail_idx;
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/* Last avail_idx read from VQ. */
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uint16_t shadow_avail_idx;
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/* Last used index value we have signalled on */
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uint16_t signalled_used;
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/* Last used index value we have signalled on */
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bool signalled_used_valid;
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/* Notification enabled? */
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vu_queue_handler_cb handler;
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enum VuWatchCondtion {
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VU_WATCH_IN = 1 << 0,
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VU_WATCH_OUT = 1 << 1,
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VU_WATCH_PRI = 1 << 2,
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VU_WATCH_ERR = 1 << 3,
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VU_WATCH_HUP = 1 << 4,
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typedef void (*vu_panic_cb) (VuDev *dev, const char *err);
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typedef void (*vu_watch_cb) (VuDev *dev, int condition, void *data);
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typedef void (*vu_set_watch_cb) (VuDev *dev, int fd, int condition,
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vu_watch_cb cb, void *data);
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typedef void (*vu_remove_watch_cb) (VuDev *dev, int fd);
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VuDevRegion regions[VHOST_MEMORY_MAX_NREGIONS];
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VuVirtq vq[VHOST_MAX_NR_VIRTQUEUE];
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uint64_t protocol_features;
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/* @set_watch: add or update the given fd to the watch set,
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* call cb when condition is met */
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vu_set_watch_cb set_watch;
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/* @remove_watch: remove the given fd from the watch set */
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vu_remove_watch_cb remove_watch;
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/* @panic: encountered an unrecoverable error, you may try to
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const VuDevIface *iface;
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typedef struct VuVirtqElement {
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unsigned int out_num;
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struct iovec *out_sg;
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* @dev: a VuDev context
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* @socket: the socket connected to vhost-user master
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* @panic: a panic callback
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* @set_watch: a set_watch callback
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* @remove_watch: a remove_watch callback
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* @iface: a VuDevIface structure with vhost-user device callbacks
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* Intializes a VuDev vhost-user context.
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void vu_init(VuDev *dev,
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vu_set_watch_cb set_watch,
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vu_remove_watch_cb remove_watch,
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const VuDevIface *iface);
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* @dev: a VuDev context
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* Cleans up the VuDev context
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void vu_deinit(VuDev *dev);
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* @dev: a VuDev context
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* Process one vhost-user message.
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* Returns: TRUE on success, FALSE on failure.
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bool vu_dispatch(VuDev *dev);
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* @dev: a VuDev context
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* @guest_addr: guest address
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* Translate a guest address to a pointer. Returns NULL on failure.
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void *vu_gpa_to_va(VuDev *dev, uint64_t guest_addr);
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* @dev: a VuDev context
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* Returns the queue number @qidx.
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VuVirtq *vu_get_queue(VuDev *dev, int qidx);
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* vu_set_queue_handler:
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* @dev: a VuDev context
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* @vq: a VuVirtq queue
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* @handler: the queue handler callback
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* Set the queue handler. This function may be called several times
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* for the same queue. If called with NULL @handler, the handler is
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void vu_set_queue_handler(VuDev *dev, VuVirtq *vq,
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vu_queue_handler_cb handler);
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* vu_queue_set_notification:
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* @dev: a VuDev context
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* @vq: a VuVirtq queue
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* Set whether the queue notifies (via event index or interrupt)
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void vu_queue_set_notification(VuDev *dev, VuVirtq *vq, int enable);
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* @dev: a VuDev context
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* @vq: a VuVirtq queue
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* Returns: whether the queue is enabled.
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bool vu_queue_enabled(VuDev *dev, VuVirtq *vq);
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* @dev: a VuDev context
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* @vq: a VuVirtq queue
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* Returns: whether the queue is empty.
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int vu_queue_empty(VuDev *dev, VuVirtq *vq);
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* @dev: a VuDev context
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* @vq: a VuVirtq queue
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* Request to notify the queue via callfd (skipped if unnecessary)
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void vu_queue_notify(VuDev *dev, VuVirtq *vq);
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* @dev: a VuDev context
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* @vq: a VuVirtq queue
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* @sz: the size of struct to return (must be >= VuVirtqElement)
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* Returns: a VuVirtqElement filled from the queue or NULL.
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void *vu_queue_pop(VuDev *dev, VuVirtq *vq, size_t sz);
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* @dev: a VuDev context
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* @vq: a VuVirtq queue
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* @num: number of elements to push back
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* Pretend that elements weren't popped from the virtqueue. The next
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* virtqueue_pop() will refetch the oldest element.
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* Returns: true on success, false if @num is greater than the number of in use
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bool vu_queue_rewind(VuDev *dev, VuVirtq *vq, unsigned int num);
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* @dev: a VuDev context
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* @vq: a VuVirtq queue
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* @elem: a VuVirtqElement
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* @len: length in bytes to write
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* @idx: optional offset for the used ring index (0 in general)
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* Fill the used ring with @elem element.
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void vu_queue_fill(VuDev *dev, VuVirtq *vq,
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const VuVirtqElement *elem,
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unsigned int len, unsigned int idx);
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* @dev: a VuDev context
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* @vq: a VuVirtq queue
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* @elem: a VuVirtqElement
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* @len: length in bytes to write
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* Helper that combines vu_queue_fill() with a vu_queue_flush().
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void vu_queue_push(VuDev *dev, VuVirtq *vq,
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const VuVirtqElement *elem, unsigned int len);
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* @dev: a VuDev context
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* @vq: a VuVirtq queue
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* @num: number of elements to flush
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* Mark the last number of elements as done (used.idx is updated by
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void vu_queue_flush(VuDev *dev, VuVirtq *vq, unsigned int num);
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* vu_queue_get_avail_bytes:
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* @dev: a VuDev context
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* @vq: a VuVirtq queue
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* @in_bytes: in bytes
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* @out_bytes: out bytes
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* @max_in_bytes: stop counting after max_in_bytes
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* @max_out_bytes: stop counting after max_out_bytes
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* Count the number of available bytes, up to max_in_bytes/max_out_bytes.
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void vu_queue_get_avail_bytes(VuDev *vdev, VuVirtq *vq, unsigned int *in_bytes,
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unsigned int *out_bytes,
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unsigned max_in_bytes, unsigned max_out_bytes);
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* vu_queue_avail_bytes:
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* @dev: a VuDev context
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* @vq: a VuVirtq queue
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* @in_bytes: expected in bytes
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* @out_bytes: expected out bytes
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* Returns: true if in_bytes <= in_total && out_bytes <= out_total
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bool vu_queue_avail_bytes(VuDev *dev, VuVirtq *vq, unsigned int in_bytes,
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unsigned int out_bytes);
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#endif /* LIBVHOST_USER_H */