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
  57struct vhost_ubuf_ref {
  58        struct kref kref;
  59        wait_queue_head_t wait;
  60        struct vhost_virtqueue *vq;
  61};
  62
  63struct vhost_ubuf_ref *vhost_ubuf_alloc(struct vhost_virtqueue *, bool zcopy);
  64void vhost_ubuf_put(struct vhost_ubuf_ref *);
  65void vhost_ubuf_put_and_wait(struct vhost_ubuf_ref *);
  66
  67struct ubuf_info;
  68
  69/* The virtqueue structure describes a queue attached to a device. */
  70struct vhost_virtqueue {
  71        struct vhost_dev *dev;
  72
  73        /* The actual ring of buffers. */
  74        struct mutex mutex;
  75        unsigned int num;
  76        struct vring_desc __user *desc;
  77        struct vring_avail __user *avail;
  78        struct vring_used __user *used;
  79        struct file *kick;
  80        struct file *call;
  81        struct file *error;
  82        struct eventfd_ctx *call_ctx;
  83        struct eventfd_ctx *error_ctx;
  84        struct eventfd_ctx *log_ctx;
  85
  86        struct vhost_poll poll;
  87
  88        /* The routine to call when the Guest pings us, or timeout. */
  89        vhost_work_fn_t handle_kick;
  90
  91        /* Last available index we saw. */
  92        u16 last_avail_idx;
  93
  94        /* Caches available index value from user. */
  95        u16 avail_idx;
  96
  97        /* Last index we used. */
  98        u16 last_used_idx;
  99
 100        /* Used flags */
 101        u16 used_flags;
 102
 103        /* Last used index value we have signalled on */
 104        u16 signalled_used;
 105
 106        /* Last used index value we have signalled on */
 107        bool signalled_used_valid;
 108
 109        /* Log writes to used structure. */
 110        bool log_used;
 111        u64 log_addr;
 112
 113        struct iovec iov[UIO_MAXIOV];
 114        /* hdr is used to store the virtio header.
 115         * Since each iovec has >= 1 byte length, we never need more than
 116         * header length entries to store the header. */
 117        struct iovec hdr[sizeof(struct virtio_net_hdr_mrg_rxbuf)];
 118        struct iovec *indirect;
 119        size_t vhost_hlen;
 120        size_t sock_hlen;
 121        struct vring_used_elem *heads;
 122        /* We use a kind of RCU to access private pointer.
 123         * All readers access it from worker, which makes it possible to
 124         * flush the vhost_work instead of synchronize_rcu. Therefore readers do
 125         * not need to call rcu_read_lock/rcu_read_unlock: the beginning of
 126         * vhost_work execution acts instead of rcu_read_lock() and the end of
 127         * vhost_work execution acts instead of rcu_read_unlock().
 128         * Writers use virtqueue mutex. */
 129        void __rcu *private_data;
 130        /* Log write descriptors */
 131        void __user *log_base;
 132        struct vhost_log *log;
 133        /* vhost zerocopy support fields below: */
 134        /* last used idx for outstanding DMA zerocopy buffers */
 135        int upend_idx;
 136        /* first used idx for DMA done zerocopy buffers */
 137        int done_idx;
 138        /* an array of userspace buffers info */
 139        struct ubuf_info *ubuf_info;
 140        /* Reference counting for outstanding ubufs.
 141         * Protected by vq mutex. Writers must also take device mutex. */
 142        struct vhost_ubuf_ref *ubufs;
 143};
 144
 145struct vhost_dev {
 146        /* Readers use RCU to access memory table pointer
 147         * log base pointer and features.
 148         * Writers use mutex below.*/
 149        struct vhost_memory __rcu *memory;
 150        struct mm_struct *mm;
 151        struct mutex mutex;
 152        unsigned acked_features;
 153        struct vhost_virtqueue *vqs;
 154        int nvqs;
 155        struct file *log_file;
 156        struct eventfd_ctx *log_ctx;
 157        spinlock_t work_lock;
 158        struct list_head work_list;
 159        struct task_struct *worker;
 160};
 161
 162long vhost_dev_init(struct vhost_dev *, struct vhost_virtqueue *vqs, int nvqs);
 163long vhost_dev_check_owner(struct vhost_dev *);
 164long vhost_dev_reset_owner(struct vhost_dev *);
 165void vhost_dev_cleanup(struct vhost_dev *, bool locked);
 166void vhost_dev_stop(struct vhost_dev *);
 167long vhost_dev_ioctl(struct vhost_dev *, unsigned int ioctl, void __user *argp);
 168long vhost_vring_ioctl(struct vhost_dev *d, int ioctl, void __user *argp);
 169int vhost_vq_access_ok(struct vhost_virtqueue *vq);
 170int vhost_log_access_ok(struct vhost_dev *);
 171
 172int vhost_get_vq_desc(struct vhost_dev *, struct vhost_virtqueue *,
 173                      struct iovec iov[], unsigned int iov_count,
 174                      unsigned int *out_num, unsigned int *in_num,
 175                      struct vhost_log *log, unsigned int *log_num);
 176void vhost_discard_vq_desc(struct vhost_virtqueue *, int n);
 177
 178int vhost_init_used(struct vhost_virtqueue *);
 179int vhost_add_used(struct vhost_virtqueue *, unsigned int head, int len);
 180int vhost_add_used_n(struct vhost_virtqueue *, struct vring_used_elem *heads,
 181                     unsigned count);
 182void vhost_add_used_and_signal(struct vhost_dev *, struct vhost_virtqueue *,
 183                               unsigned int id, int len);
 184void vhost_add_used_and_signal_n(struct vhost_dev *, struct vhost_virtqueue *,
 185                               struct vring_used_elem *heads, unsigned count);
 186void vhost_signal(struct vhost_dev *, struct vhost_virtqueue *);
 187void vhost_disable_notify(struct vhost_dev *, struct vhost_virtqueue *);
 188bool vhost_enable_notify(struct vhost_dev *, struct vhost_virtqueue *);
 189
 190int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log,
 191                    unsigned int log_num, u64 len);
 192
 193#define vq_err(vq, fmt, ...) do {                                  \
 194                pr_debug(pr_fmt(fmt), ##__VA_ARGS__);       \
 195                if ((vq)->error_ctx)                               \
 196                                eventfd_signal((vq)->error_ctx, 1);\
 197        } while (0)
 198
 199enum {
 200        VHOST_FEATURES = (1ULL << VIRTIO_F_NOTIFY_ON_EMPTY) |
 201                         (1ULL << VIRTIO_RING_F_INDIRECT_DESC) |
 202                         (1ULL << VIRTIO_RING_F_EVENT_IDX) |
 203                         (1ULL << VHOST_F_LOG_ALL),
 204        VHOST_NET_FEATURES = VHOST_FEATURES |
 205                         (1ULL << VHOST_NET_F_VIRTIO_NET_HDR) |
 206                         (1ULL << VIRTIO_NET_F_MRG_RXBUF),
 207};
 208
 209static inline int vhost_has_feature(struct vhost_dev *dev, int bit)
 210{
 211        unsigned acked_features;
 212
 213        /* TODO: check that we are running from vhost_worker or dev mutex is
 214         * held? */
 215        acked_features = rcu_dereference_index_check(dev->acked_features, 1);
 216        return acked_features & (1 << bit);
 217}
 218
 219void vhost_enable_zcopy(int vq);
 220
 221#endif
 222
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