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_poll_init(struct vhost_poll *poll, vhost_work_fn_t fn,
  47                      unsigned long mask, struct vhost_dev *dev);
  48 void vhost_poll_start(struct vhost_poll *poll, struct file *file);
  49 void vhost_poll_stop(struct vhost_poll *poll);
  50 void vhost_poll_flush(struct vhost_poll *poll);
  51 void vhost_poll_queue(struct vhost_poll *poll);
  52
  53 struct vhost_log {
  54         u64 addr;
  55         u64 len;
  56 };
  57
  58 struct vhost_virtqueue;
  59
  60 struct vhost_ubuf_ref {
  61         struct kref kref;
  62         wait_queue_head_t wait;
  63         struct vhost_virtqueue *vq;
  64 };
  65
  66 struct vhost_ubuf_ref *vhost_ubuf_alloc(struct vhost_virtqueue *, bool zcopy);
  67 void vhost_ubuf_put(struct vhost_ubuf_ref *);
  68 void vhost_ubuf_put_and_wait(struct vhost_ubuf_ref *);
  69
  70 /* The virtqueue structure describes a queue attached to a device. */
  71 struct vhost_virtqueue {
  72         struct vhost_dev *dev;
  73
  74         /* The actual ring of buffers. */
  75         struct mutex mutex;
  76         unsigned int num;
  77         struct vring_desc __user *desc;
  78         struct vring_avail __user *avail;
  79         struct vring_used __user *used;
  80         struct file *kick;
  81         struct file *call;
  82         struct file *error;
  83         struct eventfd_ctx *call_ctx;
  84         struct eventfd_ctx *error_ctx;
  85         struct eventfd_ctx *log_ctx;
  86
  87         struct vhost_poll poll;
  88
  89         /* The routine to call when the Guest pings us, or timeout. */
  90         vhost_work_fn_t handle_kick;
  91
  92         /* Last available index we saw. */
  93         u16 last_avail_idx;
  94
  95         /* Caches available index value from user. */
  96         u16 avail_idx;
  97
  98         /* Last index we used. */
  99         u16 last_used_idx;
 100
 101         /* Used flags */
 102         u16 used_flags;
 103
 104         /* Last used index value we have signalled on */
 105         u16 signalled_used;
 106
 107         /* Last used index value we have signalled on */
 108         bool signalled_used_valid;
 109
 110         /* Log writes to used structure. */
 111         bool log_used;
 112         u64 log_addr;
 113
 114         struct iovec iov[UIO_MAXIOV];
 115         /* hdr is used to store the virtio header.
 116          * Since each iovec has >= 1 byte length, we never need more than
 117          * header length entries to store the header. */
 118         struct iovec hdr[sizeof(struct virtio_net_hdr_mrg_rxbuf)];
 119         struct iovec *indirect;
 120         size_t vhost_hlen;
 121         size_t sock_hlen;
 122         struct vring_used_elem *heads;
 123         /* We use a kind of RCU to access private pointer.
 124          * All readers access it from worker, which makes it possible to
 125          * flush the vhost_work instead of synchronize_rcu. Therefore readers do
 126          * not need to call rcu_read_lock/rcu_read_unlock: the beginning of
 127          * vhost_work execution acts instead of rcu_read_lock() and the end of
 128          * vhost_work execution acts instead of rcu_read_unlock().
 129          * Writers use virtqueue mutex. */
 130         void __rcu *private_data;
 131         /* Log write descriptors */
 132         void __user *log_base;
 133         struct vhost_log *log;
 134         /* vhost zerocopy support fields below: */
 135         /* last used idx for outstanding DMA zerocopy buffers */
 136         int upend_idx;
 137         /* first used idx for DMA done zerocopy buffers */
 138         int done_idx;
 139         /* an array of userspace buffers info */
 140         struct ubuf_info *ubuf_info;
 141         /* Reference counting for outstanding ubufs.
 142          * Protected by vq mutex. Writers must also take device mutex. */
 143         struct vhost_ubuf_ref *ubufs;
 144 };
 145
 146 struct vhost_dev {
 147         /* Readers use RCU to access memory table pointer
 148          * log base pointer and features.
 149          * Writers use mutex below.*/
 150         struct vhost_memory __rcu *memory;
 151         struct mm_struct *mm;
 152         struct mutex mutex;
 153         unsigned acked_features;
 154         struct vhost_virtqueue *vqs;
 155         int nvqs;
 156         struct file *log_file;
 157         struct eventfd_ctx *log_ctx;
 158         spinlock_t work_lock;
 159         struct list_head work_list;
 160         struct task_struct *worker;
 161 };
 162
 163 long vhost_dev_init(struct vhost_dev *, struct vhost_virtqueue *vqs, int nvqs);
 164 long vhost_dev_check_owner(struct vhost_dev *);
 165 long vhost_dev_reset_owner(struct vhost_dev *);
 166 void vhost_dev_cleanup(struct vhost_dev *);
 167 long vhost_dev_ioctl(struct vhost_dev *, unsigned int ioctl, unsigned long arg);
 168 int vhost_vq_access_ok(struct vhost_virtqueue *vq);
 169 int vhost_log_access_ok(struct vhost_dev *);
 170
 171 int vhost_get_vq_desc(struct vhost_dev *, struct vhost_virtqueue *,
 172                       struct iovec iov[], unsigned int iov_count,
 173                       unsigned int *out_num, unsigned int *in_num,
 174                       struct vhost_log *log, unsigned int *log_num);
 175 void vhost_discard_vq_desc(struct vhost_virtqueue *, int n);
 176
 177 int vhost_init_used(struct vhost_virtqueue *);
 178 int vhost_add_used(struct vhost_virtqueue *, unsigned int head, int len);
 179 int vhost_add_used_n(struct vhost_virtqueue *, struct vring_used_elem *heads,
 180                      unsigned count);
 181 void vhost_add_used_and_signal(struct vhost_dev *, struct vhost_virtqueue *,
 182                                unsigned int id, int len);
 183 void vhost_add_used_and_signal_n(struct vhost_dev *, struct vhost_virtqueue *,
 184                                struct vring_used_elem *heads, unsigned count);
 185 void vhost_signal(struct vhost_dev *, struct vhost_virtqueue *);
 186 void vhost_disable_notify(struct vhost_dev *, struct vhost_virtqueue *);
 187 bool vhost_enable_notify(struct vhost_dev *, struct vhost_virtqueue *);
 188
 189 int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log,
 190                     unsigned int log_num, u64 len);
 191 void vhost_zerocopy_callback(void *arg);
 192 int vhost_zerocopy_signal_used(struct vhost_virtqueue *vq);
 193
 194 #define vq_err(vq, fmt, ...) do {                                  \
 195                 pr_debug(pr_fmt(fmt), ##__VA_ARGS__);       \
 196                 if ((vq)->error_ctx)                               \
 197                                 eventfd_signal((vq)->error_ctx, 1);\
 198         } while (0)
 199
 200 enum {
 201         VHOST_FEATURES = (1ULL << VIRTIO_F_NOTIFY_ON_EMPTY) |
 202                          (1ULL << VIRTIO_RING_F_INDIRECT_DESC) |
 203                          (1ULL << VIRTIO_RING_F_EVENT_IDX) |
 204                          (1ULL << VHOST_F_LOG_ALL) |
 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