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/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
  21struct vhost_device;
  22
  23struct vhost_work;
  24typedef void (*vhost_work_fn_t)(struct vhost_work *work);
  25
  26struct 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. */
  37struct 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
  46void vhost_work_init(struct vhost_work *work, vhost_work_fn_t fn);
  47void vhost_work_queue(struct vhost_dev *dev, struct vhost_work *work);
  48
  49void vhost_poll_init(struct vhost_poll *poll, vhost_work_fn_t fn,
  50                     unsigned long mask, struct vhost_dev *dev);
  51void vhost_poll_start(struct vhost_poll *poll, struct file *file);
  52void vhost_poll_stop(struct vhost_poll *poll);
  53void vhost_poll_flush(struct vhost_poll *poll);
  54void vhost_poll_queue(struct vhost_poll *poll);
  55
  56struct vhost_log {
  57        u64 addr;
  58        u64 len;
  59};
  60
  61struct vhost_virtqueue;
  62
  63struct vhost_ubuf_ref {
  64        struct kref kref;
  65        wait_queue_head_t wait;
  66        struct vhost_virtqueue *vq;
  67};
  68
  69struct vhost_ubuf_ref *vhost_ubuf_alloc(struct vhost_virtqueue *, bool zcopy);
  70void vhost_ubuf_put(struct vhost_ubuf_ref *);
  71void vhost_ubuf_put_and_wait(struct vhost_ubuf_ref *);
  72
  73/* The virtqueue structure describes a queue attached to a device. */
  74struct 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
 149struct 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
 166long vhost_dev_init(struct vhost_dev *, struct vhost_virtqueue *vqs, int nvqs);
 167long vhost_dev_check_owner(struct vhost_dev *);
 168long vhost_dev_reset_owner(struct vhost_dev *);
 169void vhost_dev_cleanup(struct vhost_dev *, bool locked);
 170long vhost_dev_ioctl(struct vhost_dev *, unsigned int ioctl, unsigned long arg);
 171int vhost_vq_access_ok(struct vhost_virtqueue *vq);
 172int vhost_log_access_ok(struct vhost_dev *);
 173
 174int 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);
 178void vhost_discard_vq_desc(struct vhost_virtqueue *, int n);
 179
 180int vhost_init_used(struct vhost_virtqueue *);
 181int vhost_add_used(struct vhost_virtqueue *, unsigned int head, int len);
 182int vhost_add_used_n(struct vhost_virtqueue *, struct vring_used_elem *heads,
 183                     unsigned count);
 184void vhost_add_used_and_signal(struct vhost_dev *, struct vhost_virtqueue *,
 185                               unsigned int id, int len);
 186void vhost_add_used_and_signal_n(struct vhost_dev *, struct vhost_virtqueue *,
 187                               struct vring_used_elem *heads, unsigned count);
 188void vhost_signal(struct vhost_dev *, struct vhost_virtqueue *);
 189void vhost_disable_notify(struct vhost_dev *, struct vhost_virtqueue *);
 190bool vhost_enable_notify(struct vhost_dev *, struct vhost_virtqueue *);
 191
 192int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log,
 193                    unsigned int log_num, u64 len);
 194void vhost_zerocopy_callback(struct ubuf_info *);
 195int 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
 203enum {
 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
 213static 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
 223void vhost_enable_zcopy(int vq);
 224
 225#endif
 226
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