linux/include/linux/vhost.h
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   1#ifndef _LINUX_VHOST_H
   2#define _LINUX_VHOST_H
   3/* Userspace interface for in-kernel virtio accelerators. */
   4
   5/* vhost is used to reduce the number of system calls involved in virtio.
   6 *
   7 * Existing virtio net code is used in the guest without modification.
   8 *
   9 * This header includes interface used by userspace hypervisor for
  10 * device configuration.
  11 */
  12
  13#include <linux/types.h>
  14#include <linux/compiler.h>
  15#include <linux/ioctl.h>
  16#include <linux/virtio_config.h>
  17#include <linux/virtio_ring.h>
  18
  19struct vhost_vring_state {
  20        unsigned int index;
  21        unsigned int num;
  22};
  23
  24struct vhost_vring_file {
  25        unsigned int index;
  26        int fd; /* Pass -1 to unbind from file. */
  27
  28};
  29
  30struct vhost_vring_addr {
  31        unsigned int index;
  32        /* Option flags. */
  33        unsigned int flags;
  34        /* Flag values: */
  35        /* Whether log address is valid. If set enables logging. */
  36#define VHOST_VRING_F_LOG 0
  37
  38        /* Start of array of descriptors (virtually contiguous) */
  39        __u64 desc_user_addr;
  40        /* Used structure address. Must be 32 bit aligned */
  41        __u64 used_user_addr;
  42        /* Available structure address. Must be 16 bit aligned */
  43        __u64 avail_user_addr;
  44        /* Logging support. */
  45        /* Log writes to used structure, at offset calculated from specified
  46         * address. Address must be 32 bit aligned. */
  47        __u64 log_guest_addr;
  48};
  49
  50struct vhost_memory_region {
  51        __u64 guest_phys_addr;
  52        __u64 memory_size; /* bytes */
  53        __u64 userspace_addr;
  54        __u64 flags_padding; /* No flags are currently specified. */
  55};
  56
  57/* All region addresses and sizes must be 4K aligned. */
  58#define VHOST_PAGE_SIZE 0x1000
  59
  60struct vhost_memory {
  61        __u32 nregions;
  62        __u32 padding;
  63        struct vhost_memory_region regions[0];
  64};
  65
  66/* ioctls */
  67
  68#define VHOST_VIRTIO 0xAF
  69
  70/* Features bitmask for forward compatibility.  Transport bits are used for
  71 * vhost specific features. */
  72#define VHOST_GET_FEATURES      _IOR(VHOST_VIRTIO, 0x00, __u64)
  73#define VHOST_SET_FEATURES      _IOW(VHOST_VIRTIO, 0x00, __u64)
  74
  75/* Set current process as the (exclusive) owner of this file descriptor.  This
  76 * must be called before any other vhost command.  Further calls to
  77 * VHOST_OWNER_SET fail until VHOST_OWNER_RESET is called. */
  78#define VHOST_SET_OWNER _IO(VHOST_VIRTIO, 0x01)
  79/* Give up ownership, and reset the device to default values.
  80 * Allows subsequent call to VHOST_OWNER_SET to succeed. */
  81#define VHOST_RESET_OWNER _IO(VHOST_VIRTIO, 0x02)
  82
  83/* Set up/modify memory layout */
  84#define VHOST_SET_MEM_TABLE     _IOW(VHOST_VIRTIO, 0x03, struct vhost_memory)
  85
  86/* Write logging setup. */
  87/* Memory writes can optionally be logged by setting bit at an offset
  88 * (calculated from the physical address) from specified log base.
  89 * The bit is set using an atomic 32 bit operation. */
  90/* Set base address for logging. */
  91#define VHOST_SET_LOG_BASE _IOW(VHOST_VIRTIO, 0x04, __u64)
  92/* Specify an eventfd file descriptor to signal on log write. */
  93#define VHOST_SET_LOG_FD _IOW(VHOST_VIRTIO, 0x07, int)
  94
  95/* Ring setup. */
  96/* Set number of descriptors in ring. This parameter can not
  97 * be modified while ring is running (bound to a device). */
  98#define VHOST_SET_VRING_NUM _IOW(VHOST_VIRTIO, 0x10, struct vhost_vring_state)
  99/* Set addresses for the ring. */
 100#define VHOST_SET_VRING_ADDR _IOW(VHOST_VIRTIO, 0x11, struct vhost_vring_addr)
 101/* Base value where queue looks for available descriptors */
 102#define VHOST_SET_VRING_BASE _IOW(VHOST_VIRTIO, 0x12, struct vhost_vring_state)
 103/* Get accessor: reads index, writes value in num */
 104#define VHOST_GET_VRING_BASE _IOWR(VHOST_VIRTIO, 0x12, struct vhost_vring_state)
 105
 106/* The following ioctls use eventfd file descriptors to signal and poll
 107 * for events. */
 108
 109/* Set eventfd to poll for added buffers */
 110#define VHOST_SET_VRING_KICK _IOW(VHOST_VIRTIO, 0x20, struct vhost_vring_file)
 111/* Set eventfd to signal when buffers have beed used */
 112#define VHOST_SET_VRING_CALL _IOW(VHOST_VIRTIO, 0x21, struct vhost_vring_file)
 113/* Set eventfd to signal an error */
 114#define VHOST_SET_VRING_ERR _IOW(VHOST_VIRTIO, 0x22, struct vhost_vring_file)
 115
 116/* VHOST_NET specific defines */
 117
 118/* Attach virtio net ring to a raw socket, or tap device.
 119 * The socket must be already bound to an ethernet device, this device will be
 120 * used for transmit.  Pass fd -1 to unbind from the socket and the transmit
 121 * device.  This can be used to stop the ring (e.g. for migration). */
 122#define VHOST_NET_SET_BACKEND _IOW(VHOST_VIRTIO, 0x30, struct vhost_vring_file)
 123
 124/* Feature bits */
 125/* Log all write descriptors. Can be changed while device is active. */
 126#define VHOST_F_LOG_ALL 26
 127/* vhost-net should add virtio_net_hdr for RX, and strip for TX packets. */
 128#define VHOST_NET_F_VIRTIO_NET_HDR 27
 129
 130#endif
 131
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