drivers/vhost/vhost.h

   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
  15 struct vhost_device;
  16
  17 struct vhost_work;
  18 typedef void (*vhost_work_fn_t)(struct vhost_work *work);
  19
  20 struct 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. */
  31 struct 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
  40 void vhost_work_init(struct vhost_work *work, vhost_work_fn_t fn);
  41 void vhost_work_queue(struct vhost_dev *dev, struct vhost_work *work);
  42
  43 void vhost_poll_init(struct vhost_poll *poll, vhost_work_fn_t fn,
  44                      unsigned long mask, struct vhost_dev *dev);
  45 int vhost_poll_start(struct vhost_poll *poll, struct file *file);
  46 void vhost_poll_stop(struct vhost_poll *poll);
  47 void vhost_poll_flush(struct vhost_poll *poll);
  48 void vhost_poll_queue(struct vhost_poll *poll);
  49
  50 struct vhost_log {
  51         u64 addr;
  52         u64 len;
  53 };
  54
  55 struct vhost_virtqueue;
  56
  57 /* The virtqueue structure describes a queue attached to a device. */
  58 struct 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
 117 struct 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
 134 long vhost_dev_init(struct vhost_dev *, struct vhost_virtqueue **vqs, int nvqs);
 135 long vhost_dev_set_owner(struct vhost_dev *dev);
 136 bool vhost_dev_has_owner(struct vhost_dev *dev);
 137 long vhost_dev_check_owner(struct vhost_dev *);
 138 struct vhost_memory *vhost_dev_reset_owner_prepare(void);
 139 void vhost_dev_reset_owner(struct vhost_dev *, struct vhost_memory *);
 140 void vhost_dev_cleanup(struct vhost_dev *, bool locked);
 141 void vhost_dev_stop(struct vhost_dev *);
 142 long vhost_dev_ioctl(struct vhost_dev *, unsigned int ioctl, void __user *argp);
 143 long vhost_vring_ioctl(struct vhost_dev *d, int ioctl, void __user *argp);
 144 int vhost_vq_access_ok(struct vhost_virtqueue *vq);
 145 int vhost_log_access_ok(struct vhost_dev *);
 146
 147 int 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);
 151 void vhost_discard_vq_desc(struct vhost_virtqueue *, int n);
 152
 153 int vhost_init_used(struct vhost_virtqueue *);
 154 int vhost_add_used(struct vhost_virtqueue *, unsigned int head, int len);
 155 int vhost_add_used_n(struct vhost_virtqueue *, struct vring_used_elem *heads,
 156                      unsigned count);
 157 void vhost_add_used_and_signal(struct vhost_dev *, struct vhost_virtqueue *,
 158                                unsigned int id, int len);
 159 void vhost_add_used_and_signal_n(struct vhost_dev *, struct vhost_virtqueue *,
 160                                struct vring_used_elem *heads, unsigned count);
 161 void vhost_signal(struct vhost_dev *, struct vhost_virtqueue *);
 162 void vhost_disable_notify(struct vhost_dev *, struct vhost_virtqueue *);
 163 bool vhost_enable_notify(struct vhost_dev *, struct vhost_virtqueue *);
 164
 165 int 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
 174 enum {
 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
 181 static 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