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/skbuff.h>
  11 #include <linux/uio.h>
  12 #include <linux/virtio_config.h>
  13 #include <linux/virtio_ring.h>
  14 #include <asm/atomic.h>
  15
  16 struct vhost_device;
  17
  18 struct vhost_work;
  19 typedef void (*vhost_work_fn_t)(struct vhost_work *work);
  20
  21 struct vhost_work {
  22         struct list_head          node;
  23         vhost_work_fn_t           fn;
  24         wait_queue_head_t         done;
  25         int                       flushing;
  26         unsigned                  queue_seq;
  27         unsigned                  done_seq;
  28 };
  29
  30 /* Poll a file (eventfd or socket) */
  31 /* Note: there's nothing vhost specific about this structure. */
  32 struct vhost_poll {
  33         poll_table                table;
  34         wait_queue_head_t        *wqh;
  35         wait_queue_t              wait;
  36         struct vhost_work         work;
  37         unsigned long             mask;
  38         struct vhost_dev         *dev;
  39 };
  40
  41 void vhost_poll_init(struct vhost_poll *poll, vhost_work_fn_t fn,
  42                      unsigned long mask, struct vhost_dev *dev);
  43 void vhost_poll_start(struct vhost_poll *poll, struct file *file);
  44 void vhost_poll_stop(struct vhost_poll *poll);
  45 void vhost_poll_flush(struct vhost_poll *poll);
  46 void vhost_poll_queue(struct vhost_poll *poll);
  47
  48 struct vhost_log {
  49         u64 addr;
  50         u64 len;
  51 };
  52
  53 /* The virtqueue structure describes a queue attached to a device. */
  54 struct vhost_virtqueue {
  55         struct vhost_dev *dev;
  56
  57         /* The actual ring of buffers. */
  58         struct mutex mutex;
  59         unsigned int num;
  60         struct vring_desc __user *desc;
  61         struct vring_avail __user *avail;
  62         struct vring_used __user *used;
  63         struct file *kick;
  64         struct file *call;
  65         struct file *error;
  66         struct eventfd_ctx *call_ctx;
  67         struct eventfd_ctx *error_ctx;
  68         struct eventfd_ctx *log_ctx;
  69
  70         struct vhost_poll poll;
  71
  72         /* The routine to call when the Guest pings us, or timeout. */
  73         vhost_work_fn_t handle_kick;
  74
  75         /* Last available index we saw. */
  76         u16 last_avail_idx;
  77
  78         /* Caches available index value from user. */
  79         u16 avail_idx;
  80
  81         /* Last index we used. */
  82         u16 last_used_idx;
  83
  84         /* Used flags */
  85         u16 used_flags;
  86
  87         /* Last used index value we have signalled on */
  88         u16 signalled_used;
  89
  90         /* Last used index value we have signalled on */
  91         bool signalled_used_valid;
  92
  93         /* Log writes to used structure. */
  94         bool log_used;
  95         u64 log_addr;
  96
  97         struct iovec iov[UIO_MAXIOV];
  98         /* hdr is used to store the virtio header.
  99          * Since each iovec has >= 1 byte length, we never need more than
 100          * header length entries to store the header. */
 101         struct iovec hdr[sizeof(struct virtio_net_hdr_mrg_rxbuf)];
 102         struct iovec *indirect;
 103         size_t vhost_hlen;
 104         size_t sock_hlen;
 105         struct vring_used_elem *heads;
 106         /* We use a kind of RCU to access private pointer.
 107          * All readers access it from worker, which makes it possible to
 108          * flush the vhost_work instead of synchronize_rcu. Therefore readers do
 109          * not need to call rcu_read_lock/rcu_read_unlock: the beginning of
 110          * vhost_work execution acts instead of rcu_read_lock() and the end of
 111          * vhost_work execution acts instead of rcu_read_unlock().
 112          * Writers use virtqueue mutex. */
 113         void __rcu *private_data;
 114         /* Log write descriptors */
 115         void __user *log_base;
 116         struct vhost_log *log;
 117 };
 118
 119 struct vhost_dev {
 120         /* Readers use RCU to access memory table pointer
 121          * log base pointer and features.
 122          * Writers use mutex below.*/
 123         struct vhost_memory __rcu *memory;
 124         struct mm_struct *mm;
 125         struct mutex mutex;
 126         unsigned acked_features;
 127         struct vhost_virtqueue *vqs;
 128         int nvqs;
 129         struct file *log_file;
 130         struct eventfd_ctx *log_ctx;
 131         spinlock_t work_lock;
 132         struct list_head work_list;
 133         struct task_struct *worker;
 134 };
 135
 136 long vhost_dev_init(struct vhost_dev *, struct vhost_virtqueue *vqs, int nvqs);
 137 long vhost_dev_check_owner(struct vhost_dev *);
 138 long vhost_dev_reset_owner(struct vhost_dev *);
 139 void vhost_dev_cleanup(struct vhost_dev *);
 140 long vhost_dev_ioctl(struct vhost_dev *, unsigned int ioctl, unsigned long arg);
 141 int vhost_vq_access_ok(struct vhost_virtqueue *vq);
 142 int vhost_log_access_ok(struct vhost_dev *);
 143
 144 int vhost_get_vq_desc(struct vhost_dev *, struct vhost_virtqueue *,
 145                       struct iovec iov[], unsigned int iov_count,
 146                       unsigned int *out_num, unsigned int *in_num,
 147                       struct vhost_log *log, unsigned int *log_num);
 148 void vhost_discard_vq_desc(struct vhost_virtqueue *, int n);
 149
 150 int vhost_add_used(struct vhost_virtqueue *, unsigned int head, int len);
 151 int vhost_add_used_n(struct vhost_virtqueue *, struct vring_used_elem *heads,
 152                      unsigned count);
 153 void vhost_add_used_and_signal(struct vhost_dev *, struct vhost_virtqueue *,
 154                                unsigned int id, int len);
 155 void vhost_add_used_and_signal_n(struct vhost_dev *, struct vhost_virtqueue *,
 156                                struct vring_used_elem *heads, unsigned count);
 157 void vhost_signal(struct vhost_dev *, struct vhost_virtqueue *);
 158 void vhost_disable_notify(struct vhost_dev *, struct vhost_virtqueue *);
 159 bool vhost_enable_notify(struct vhost_dev *, struct vhost_virtqueue *);
 160
 161 int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log,
 162                     unsigned int log_num, u64 len);
 163
 164 #define vq_err(vq, fmt, ...) do {                                  \
 165                 pr_debug(pr_fmt(fmt), ##__VA_ARGS__);       \
 166                 if ((vq)->error_ctx)                               \
 167                                 eventfd_signal((vq)->error_ctx, 1);\
 168         } while (0)
 169
 170 enum {
 171         VHOST_FEATURES = (1ULL << VIRTIO_F_NOTIFY_ON_EMPTY) |
 172                          (1ULL << VIRTIO_RING_F_INDIRECT_DESC) |
 173                          (1ULL << VIRTIO_RING_F_EVENT_IDX) |
 174                          (1ULL << VHOST_F_LOG_ALL) |
 175                          (1ULL << VHOST_NET_F_VIRTIO_NET_HDR) |
 176                          (1ULL << VIRTIO_NET_F_MRG_RXBUF),
 177 };
 178
 179 static inline int vhost_has_feature(struct vhost_dev *dev, int bit)
 180 {
 181         unsigned acked_features;
 182
 183         /* TODO: check that we are running from vhost_worker or dev mutex is
 184          * held? */
 185         acked_features = rcu_dereference_index_check(dev->acked_features, 1);
 186         return acked_features & (1 << bit);
 187 }
 188
 189 #endif