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 struct vhost_ubuf_ref {
  58         struct kref kref;
  59         wait_queue_head_t wait;
  60         struct vhost_virtqueue *vq;
  61 };
  62
  63 struct vhost_ubuf_ref *vhost_ubuf_alloc(struct vhost_virtqueue *, bool zcopy);
  64 void vhost_ubuf_put(struct vhost_ubuf_ref *);
  65 void vhost_ubuf_put_and_wait(struct vhost_ubuf_ref *);
  66
  67 struct ubuf_info;
  68
  69 /* The virtqueue structure describes a queue attached to a device. */
  70 struct 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
 145 struct 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
 162 long vhost_dev_init(struct vhost_dev *, struct vhost_virtqueue *vqs, int nvqs);
 163 long vhost_dev_check_owner(struct vhost_dev *);
 164 long vhost_dev_reset_owner(struct vhost_dev *);
 165 void vhost_dev_cleanup(struct vhost_dev *, bool locked);
 166 void vhost_dev_stop(struct vhost_dev *);
 167 long vhost_dev_ioctl(struct vhost_dev *, unsigned int ioctl, void __user *argp);
 168 long vhost_vring_ioctl(struct vhost_dev *d, int ioctl, void __user *argp);
 169 int vhost_vq_access_ok(struct vhost_virtqueue *vq);
 170 int vhost_log_access_ok(struct vhost_dev *);
 171
 172 int 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);
 176 void vhost_discard_vq_desc(struct vhost_virtqueue *, int n);
 177
 178 int vhost_init_used(struct vhost_virtqueue *);
 179 int vhost_add_used(struct vhost_virtqueue *, unsigned int head, int len);
 180 int vhost_add_used_n(struct vhost_virtqueue *, struct vring_used_elem *heads,
 181                      unsigned count);
 182 void vhost_add_used_and_signal(struct vhost_dev *, struct vhost_virtqueue *,
 183                                unsigned int id, int len);
 184 void vhost_add_used_and_signal_n(struct vhost_dev *, struct vhost_virtqueue *,
 185                                struct vring_used_elem *heads, unsigned count);
 186 void vhost_signal(struct vhost_dev *, struct vhost_virtqueue *);
 187 void vhost_disable_notify(struct vhost_dev *, struct vhost_virtqueue *);
 188 bool vhost_enable_notify(struct vhost_dev *, struct vhost_virtqueue *);
 189
 190 int 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
 199 enum {
 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
 209 static 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
 219 void vhost_enable_zcopy(int vq);
 220
 221 #endif