linux/drivers/vhost/vhost.h
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   1#ifndef _VHOST_H
   2#define _VHOST_H
   3
   4#include <linux/eventfd.h>
   5#include <linux/vhost.h>
   6#include <linux/mm.h>
   7#include <linux/mutex.h>
   8#include <linux/poll.h>
   9#include <linux/file.h>
  10#include <linux/uio.h>
  11#include <linux/virtio_config.h>
  12#include <linux/virtio_ring.h>
  13#include <linux/atomic.h>
  14
  15struct vhost_device;
  16
  17struct vhost_work;
  18typedef void (*vhost_work_fn_t)(struct vhost_work *work);
  19
  20struct vhost_work {
  21        struct list_head          node;
  22        vhost_work_fn_t           fn;
  23        wait_queue_head_t         done;
  24        int                       flushing;
  25        unsigned                  queue_seq;
  26        unsigned                  done_seq;
  27};
  28
  29/* Poll a file (eventfd or socket) */
  30/* Note: there's nothing vhost specific about this structure. */
  31struct vhost_poll {
  32        poll_table                table;
  33        wait_queue_head_t        *wqh;
  34        wait_queue_t              wait;
  35        struct vhost_work         work;
  36        unsigned long             mask;
  37        struct vhost_dev         *dev;
  38};
  39
  40void vhost_work_init(struct vhost_work *work, vhost_work_fn_t fn);
  41void vhost_work_queue(struct vhost_dev *dev, struct vhost_work *work);
  42
  43void vhost_poll_init(struct vhost_poll *poll, vhost_work_fn_t fn,
  44                     unsigned long mask, struct vhost_dev *dev);
  45int vhost_poll_start(struct vhost_poll *poll, struct file *file);
  46void vhost_poll_stop(struct vhost_poll *poll);
  47void vhost_poll_flush(struct vhost_poll *poll);
  48void vhost_poll_queue(struct vhost_poll *poll);
  49
  50struct vhost_log {
  51        u64 addr;
  52        u64 len;
  53};
  54
  55struct vhost_virtqueue;
  56
  57/* The virtqueue structure describes a queue attached to a device. */
  58struct vhost_virtqueue {
  59        struct vhost_dev *dev;
  60
  61        /* The actual ring of buffers. */
  62        struct mutex mutex;
  63        unsigned int num;
  64        struct vring_desc __user *desc;
  65        struct vring_avail __user *avail;
  66        struct vring_used __user *used;
  67        struct file *kick;
  68        struct file *call;
  69        struct file *error;
  70        struct eventfd_ctx *call_ctx;
  71        struct eventfd_ctx *error_ctx;
  72        struct eventfd_ctx *log_ctx;
  73
  74        struct vhost_poll poll;
  75
  76        /* The routine to call when the Guest pings us, or timeout. */
  77        vhost_work_fn_t handle_kick;
  78
  79        /* Last available index we saw. */
  80        u16 last_avail_idx;
  81
  82        /* Caches available index value from user. */
  83        u16 avail_idx;
  84
  85        /* Last index we used. */
  86        u16 last_used_idx;
  87
  88        /* Used flags */
  89        u16 used_flags;
  90
  91        /* Last used index value we have signalled on */
  92        u16 signalled_used;
  93
  94        /* Last used index value we have signalled on */
  95        bool signalled_used_valid;
  96
  97        /* Log writes to used structure. */
  98        bool log_used;
  99        u64 log_addr;
 100
 101        struct iovec iov[UIO_MAXIOV];
 102        struct iovec *indirect;
 103        struct vring_used_elem *heads;
 104        /* We use a kind of RCU to access private pointer.
 105         * All readers access it from worker, which makes it possible to
 106         * flush the vhost_work instead of synchronize_rcu. Therefore readers do
 107         * not need to call rcu_read_lock/rcu_read_unlock: the beginning of
 108         * vhost_work execution acts instead of rcu_read_lock() and the end of
 109         * vhost_work execution acts instead of rcu_read_unlock().
 110         * Writers use virtqueue mutex. */
 111        void __rcu *private_data;
 112        /* Log write descriptors */
 113        void __user *log_base;
 114        struct vhost_log *log;
 115};
 116
 117struct vhost_dev {
 118        /* Readers use RCU to access memory table pointer
 119         * log base pointer and features.
 120         * Writers use mutex below.*/
 121        struct vhost_memory __rcu *memory;
 122        struct mm_struct *mm;
 123        struct mutex mutex;
 124        unsigned acked_features;
 125        struct vhost_virtqueue **vqs;
 126        int nvqs;
 127        struct file *log_file;
 128        struct eventfd_ctx *log_ctx;
 129        spinlock_t work_lock;
 130        struct list_head work_list;
 131        struct task_struct *worker;
 132};
 133
 134long vhost_dev_init(struct vhost_dev *, struct vhost_virtqueue **vqs, int nvqs);
 135long vhost_dev_set_owner(struct vhost_dev *dev);
 136bool vhost_dev_has_owner(struct vhost_dev *dev);
 137long vhost_dev_check_owner(struct vhost_dev *);
 138struct vhost_memory *vhost_dev_reset_owner_prepare(void);
 139void vhost_dev_reset_owner(struct vhost_dev *, struct vhost_memory *);
 140void vhost_dev_cleanup(struct vhost_dev *, bool locked);
 141void vhost_dev_stop(struct vhost_dev *);
 142long vhost_dev_ioctl(struct vhost_dev *, unsigned int ioctl, void __user *argp);
 143long vhost_vring_ioctl(struct vhost_dev *d, int ioctl, void __user *argp);
 144int vhost_vq_access_ok(struct vhost_virtqueue *vq);
 145int vhost_log_access_ok(struct vhost_dev *);
 146
 147int vhost_get_vq_desc(struct vhost_dev *, struct vhost_virtqueue *,
 148                      struct iovec iov[], unsigned int iov_count,
 149                      unsigned int *out_num, unsigned int *in_num,
 150                      struct vhost_log *log, unsigned int *log_num);
 151void vhost_discard_vq_desc(struct vhost_virtqueue *, int n);
 152
 153int vhost_init_used(struct vhost_virtqueue *);
 154int vhost_add_used(struct vhost_virtqueue *, unsigned int head, int len);
 155int vhost_add_used_n(struct vhost_virtqueue *, struct vring_used_elem *heads,
 156                     unsigned count);
 157void vhost_add_used_and_signal(struct vhost_dev *, struct vhost_virtqueue *,
 158                               unsigned int id, int len);
 159void vhost_add_used_and_signal_n(struct vhost_dev *, struct vhost_virtqueue *,
 160                               struct vring_used_elem *heads, unsigned count);
 161void vhost_signal(struct vhost_dev *, struct vhost_virtqueue *);
 162void vhost_disable_notify(struct vhost_dev *, struct vhost_virtqueue *);
 163bool vhost_enable_notify(struct vhost_dev *, struct vhost_virtqueue *);
 164
 165int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log,
 166                    unsigned int log_num, u64 len);
 167
 168#define vq_err(vq, fmt, ...) do {                                  \
 169                pr_debug(pr_fmt(fmt), ##__VA_ARGS__);       \
 170                if ((vq)->error_ctx)                               \
 171                                eventfd_signal((vq)->error_ctx, 1);\
 172        } while (0)
 173
 174enum {
 175        VHOST_FEATURES = (1ULL << VIRTIO_F_NOTIFY_ON_EMPTY) |
 176                         (1ULL << VIRTIO_RING_F_INDIRECT_DESC) |
 177                         (1ULL << VIRTIO_RING_F_EVENT_IDX) |
 178                         (1ULL << VHOST_F_LOG_ALL),
 179};
 180
 181static inline int vhost_has_feature(struct vhost_dev *dev, int bit)
 182{
 183        unsigned acked_features;
 184
 185        /* TODO: check that we are running from vhost_worker or dev mutex is
 186         * held? */
 187        acked_features = rcu_dereference_index_check(dev->acked_features, 1);
 188        return acked_features & (1 << bit);
 189}
 190#endif
 191
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