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 <linux/atomic.h>
  15
  16 /* This is for zerocopy, used buffer len is set to 1 when lower device DMA
  17  * done */
  18 #define VHOST_DMA_DONE_LEN      1
  19 #define VHOST_DMA_CLEAR_LEN     0
  20
  21 struct vhost_device;
  22
  23 struct vhost_work;
  24 typedef void (*vhost_work_fn_t)(struct vhost_work *work);
  25
  26 struct vhost_work {
  27         struct list_head          node;
  28         vhost_work_fn_t           fn;
  29         wait_queue_head_t         done;
  30         int                       flushing;
  31         unsigned                  queue_seq;
  32         unsigned                  done_seq;
  33 };
  34
  35 /* Poll a file (eventfd or socket) */
  36 /* Note: there's nothing vhost specific about this structure. */
  37 struct vhost_poll {
  38         poll_table                table;
  39         wait_queue_head_t        *wqh;
  40         wait_queue_t              wait;
  41         struct vhost_work         work;
  42         unsigned long             mask;
  43         struct vhost_dev         *dev;
  44 };
  45
  46 void vhost_work_init(struct vhost_work *work, vhost_work_fn_t fn);
  47 void vhost_work_queue(struct vhost_dev *dev, struct vhost_work *work);
  48
  49 void vhost_poll_init(struct vhost_poll *poll, vhost_work_fn_t fn,
  50                      unsigned long mask, struct vhost_dev *dev);
  51 void vhost_poll_start(struct vhost_poll *poll, struct file *file);
  52 void vhost_poll_stop(struct vhost_poll *poll);
  53 void vhost_poll_flush(struct vhost_poll *poll);
  54 void vhost_poll_queue(struct vhost_poll *poll);
  55
  56 struct vhost_log {
  57         u64 addr;
  58         u64 len;
  59 };
  60
  61 struct vhost_virtqueue;
  62
  63 struct vhost_ubuf_ref {
  64         struct kref kref;
  65         wait_queue_head_t wait;
  66         struct vhost_virtqueue *vq;
  67 };
  68
  69 struct vhost_ubuf_ref *vhost_ubuf_alloc(struct vhost_virtqueue *, bool zcopy);
  70 void vhost_ubuf_put(struct vhost_ubuf_ref *);
  71 void vhost_ubuf_put_and_wait(struct vhost_ubuf_ref *);
  72
  73 /* The virtqueue structure describes a queue attached to a device. */
  74 struct vhost_virtqueue {
  75         struct vhost_dev *dev;
  76
  77         /* The actual ring of buffers. */
  78         struct mutex mutex;
  79         unsigned int num;
  80         struct vring_desc __user *desc;
  81         struct vring_avail __user *avail;
  82         struct vring_used __user *used;
  83         struct file *kick;
  84         struct file *call;
  85         struct file *error;
  86         struct eventfd_ctx *call_ctx;
  87         struct eventfd_ctx *error_ctx;
  88         struct eventfd_ctx *log_ctx;
  89
  90         struct vhost_poll poll;
  91
  92         /* The routine to call when the Guest pings us, or timeout. */
  93         vhost_work_fn_t handle_kick;
  94
  95         /* Last available index we saw. */
  96         u16 last_avail_idx;
  97
  98         /* Caches available index value from user. */
  99         u16 avail_idx;
 100
 101         /* Last index we used. */
 102         u16 last_used_idx;
 103
 104         /* Used flags */
 105         u16 used_flags;
 106
 107         /* Last used index value we have signalled on */
 108         u16 signalled_used;
 109
 110         /* Last used index value we have signalled on */
 111         bool signalled_used_valid;
 112
 113         /* Log writes to used structure. */
 114         bool log_used;
 115         u64 log_addr;
 116
 117         struct iovec iov[UIO_MAXIOV];
 118         /* hdr is used to store the virtio header.
 119          * Since each iovec has >= 1 byte length, we never need more than
 120          * header length entries to store the header. */
 121         struct iovec hdr[sizeof(struct virtio_net_hdr_mrg_rxbuf)];
 122         struct iovec *indirect;
 123         size_t vhost_hlen;
 124         size_t sock_hlen;
 125         struct vring_used_elem *heads;
 126         /* We use a kind of RCU to access private pointer.
 127          * All readers access it from worker, which makes it possible to
 128          * flush the vhost_work instead of synchronize_rcu. Therefore readers do
 129          * not need to call rcu_read_lock/rcu_read_unlock: the beginning of
 130          * vhost_work execution acts instead of rcu_read_lock() and the end of
 131          * vhost_work execution acts instead of rcu_read_unlock().
 132          * Writers use virtqueue mutex. */
 133         void __rcu *private_data;
 134         /* Log write descriptors */
 135         void __user *log_base;
 136         struct vhost_log *log;
 137         /* vhost zerocopy support fields below: */
 138         /* last used idx for outstanding DMA zerocopy buffers */
 139         int upend_idx;
 140         /* first used idx for DMA done zerocopy buffers */
 141         int done_idx;
 142         /* an array of userspace buffers info */
 143         struct ubuf_info *ubuf_info;
 144         /* Reference counting for outstanding ubufs.
 145          * Protected by vq mutex. Writers must also take device mutex. */
 146         struct vhost_ubuf_ref *ubufs;
 147 };
 148
 149 struct vhost_dev {
 150         /* Readers use RCU to access memory table pointer
 151          * log base pointer and features.
 152          * Writers use mutex below.*/
 153         struct vhost_memory __rcu *memory;
 154         struct mm_struct *mm;
 155         struct mutex mutex;
 156         unsigned acked_features;
 157         struct vhost_virtqueue *vqs;
 158         int nvqs;
 159         struct file *log_file;
 160         struct eventfd_ctx *log_ctx;
 161         spinlock_t work_lock;
 162         struct list_head work_list;
 163         struct task_struct *worker;
 164 };
 165
 166 long vhost_dev_init(struct vhost_dev *, struct vhost_virtqueue *vqs, int nvqs);
 167 long vhost_dev_check_owner(struct vhost_dev *);
 168 long vhost_dev_reset_owner(struct vhost_dev *);
 169 void vhost_dev_cleanup(struct vhost_dev *, bool locked);
 170 long vhost_dev_ioctl(struct vhost_dev *, unsigned int ioctl, unsigned long arg);
 171 int vhost_vq_access_ok(struct vhost_virtqueue *vq);
 172 int vhost_log_access_ok(struct vhost_dev *);
 173
 174 int vhost_get_vq_desc(struct vhost_dev *, struct vhost_virtqueue *,
 175                       struct iovec iov[], unsigned int iov_count,
 176                       unsigned int *out_num, unsigned int *in_num,
 177                       struct vhost_log *log, unsigned int *log_num);
 178 void vhost_discard_vq_desc(struct vhost_virtqueue *, int n);
 179
 180 int vhost_init_used(struct vhost_virtqueue *);
 181 int vhost_add_used(struct vhost_virtqueue *, unsigned int head, int len);
 182 int vhost_add_used_n(struct vhost_virtqueue *, struct vring_used_elem *heads,
 183                      unsigned count);
 184 void vhost_add_used_and_signal(struct vhost_dev *, struct vhost_virtqueue *,
 185                                unsigned int id, int len);
 186 void vhost_add_used_and_signal_n(struct vhost_dev *, struct vhost_virtqueue *,
 187                                struct vring_used_elem *heads, unsigned count);
 188 void vhost_signal(struct vhost_dev *, struct vhost_virtqueue *);
 189 void vhost_disable_notify(struct vhost_dev *, struct vhost_virtqueue *);
 190 bool vhost_enable_notify(struct vhost_dev *, struct vhost_virtqueue *);
 191
 192 int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log,
 193                     unsigned int log_num, u64 len);
 194 void vhost_zerocopy_callback(struct ubuf_info *);
 195 int vhost_zerocopy_signal_used(struct vhost_virtqueue *vq);
 196
 197 #define vq_err(vq, fmt, ...) do {                                  \
 198                 pr_debug(pr_fmt(fmt), ##__VA_ARGS__);       \
 199                 if ((vq)->error_ctx)                               \
 200                                 eventfd_signal((vq)->error_ctx, 1);\
 201         } while (0)
 202
 203 enum {
 204         VHOST_FEATURES = (1ULL << VIRTIO_F_NOTIFY_ON_EMPTY) |
 205                          (1ULL << VIRTIO_RING_F_INDIRECT_DESC) |
 206                          (1ULL << VIRTIO_RING_F_EVENT_IDX) |
 207                          (1ULL << VHOST_F_LOG_ALL),
 208         VHOST_NET_FEATURES = VHOST_FEATURES |
 209                          (1ULL << VHOST_NET_F_VIRTIO_NET_HDR) |
 210                          (1ULL << VIRTIO_NET_F_MRG_RXBUF),
 211 };
 212
 213 static inline int vhost_has_feature(struct vhost_dev *dev, int bit)
 214 {
 215         unsigned acked_features;
 216
 217         /* TODO: check that we are running from vhost_worker or dev mutex is
 218          * held? */
 219         acked_features = rcu_dereference_index_check(dev->acked_features, 1);
 220         return acked_features & (1 << bit);
 221 }
 222
 223 void vhost_enable_zcopy(int vq);
 224
 225 #endif