vhost.h revision 8dd014adfea6f173c1ef6378f7e5e7924866c923 
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
16struct vhost_device;
17
18enum {
19	/* Enough place for all fragments, head, and virtio net header. */
20	VHOST_NET_MAX_SG = MAX_SKB_FRAGS + 2,
21};
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_poll_init(struct vhost_poll *poll, vhost_work_fn_t fn,
47		     unsigned long mask, struct vhost_dev *dev);
48void vhost_poll_start(struct vhost_poll *poll, struct file *file);
49void vhost_poll_stop(struct vhost_poll *poll);
50void vhost_poll_flush(struct vhost_poll *poll);
51void vhost_poll_queue(struct vhost_poll *poll);
52
53struct vhost_log {
54	u64 addr;
55	u64 len;
56};
57
58/* The virtqueue structure describes a queue attached to a device. */
59struct vhost_virtqueue {
60	struct vhost_dev *dev;
61
62	/* The actual ring of buffers. */
63	struct mutex mutex;
64	unsigned int num;
65	struct vring_desc __user *desc;
66	struct vring_avail __user *avail;
67	struct vring_used __user *used;
68	struct file *kick;
69	struct file *call;
70	struct file *error;
71	struct eventfd_ctx *call_ctx;
72	struct eventfd_ctx *error_ctx;
73	struct eventfd_ctx *log_ctx;
74
75	struct vhost_poll poll;
76
77	/* The routine to call when the Guest pings us, or timeout. */
78	vhost_work_fn_t handle_kick;
79
80	/* Last available index we saw. */
81	u16 last_avail_idx;
82
83	/* Caches available index value from user. */
84	u16 avail_idx;
85
86	/* Last index we used. */
87	u16 last_used_idx;
88
89	/* Used flags */
90	u16 used_flags;
91
92	/* Log writes to used structure. */
93	bool log_used;
94	u64 log_addr;
95
96	struct iovec indirect[VHOST_NET_MAX_SG];
97	struct iovec iov[VHOST_NET_MAX_SG];
98	struct iovec hdr[VHOST_NET_MAX_SG];
99	size_t vhost_hlen;
100	size_t sock_hlen;
101	struct vring_used_elem heads[VHOST_NET_MAX_SG];
102	/* We use a kind of RCU to access private pointer.
103	 * All readers access it from worker, which makes it possible to
104	 * flush the vhost_work instead of synchronize_rcu. Therefore readers do
105	 * not need to call rcu_read_lock/rcu_read_unlock: the beginning of
106	 * vhost_work execution acts instead of rcu_read_lock() and the end of
107	 * vhost_work execution acts instead of rcu_read_lock().
108	 * Writers use virtqueue mutex. */
109	void *private_data;
110	/* Log write descriptors */
111	void __user *log_base;
112	struct vhost_log log[VHOST_NET_MAX_SG];
113};
114
115struct vhost_dev {
116	/* Readers use RCU to access memory table pointer
117	 * log base pointer and features.
118	 * Writers use mutex below.*/
119	struct vhost_memory *memory;
120	struct mm_struct *mm;
121	struct mutex mutex;
122	unsigned acked_features;
123	struct vhost_virtqueue *vqs;
124	int nvqs;
125	struct file *log_file;
126	struct eventfd_ctx *log_ctx;
127	spinlock_t work_lock;
128	struct list_head work_list;
129	struct task_struct *worker;
130};
131
132long vhost_dev_init(struct vhost_dev *, struct vhost_virtqueue *vqs, int nvqs);
133long vhost_dev_check_owner(struct vhost_dev *);
134long vhost_dev_reset_owner(struct vhost_dev *);
135void vhost_dev_cleanup(struct vhost_dev *);
136long vhost_dev_ioctl(struct vhost_dev *, unsigned int ioctl, unsigned long arg);
137int vhost_vq_access_ok(struct vhost_virtqueue *vq);
138int vhost_log_access_ok(struct vhost_dev *);
139
140int vhost_get_vq_desc(struct vhost_dev *, struct vhost_virtqueue *,
141		      struct iovec iov[], unsigned int iov_count,
142		      unsigned int *out_num, unsigned int *in_num,
143		      struct vhost_log *log, unsigned int *log_num);
144void vhost_discard_vq_desc(struct vhost_virtqueue *, int n);
145
146int vhost_add_used(struct vhost_virtqueue *, unsigned int head, int len);
147int vhost_add_used_n(struct vhost_virtqueue *, struct vring_used_elem *heads,
148		     unsigned count);
149void vhost_add_used_and_signal(struct vhost_dev *, struct vhost_virtqueue *,
150			       unsigned int id, int len);
151void vhost_add_used_and_signal_n(struct vhost_dev *, struct vhost_virtqueue *,
152			       struct vring_used_elem *heads, unsigned count);
153void vhost_signal(struct vhost_dev *, struct vhost_virtqueue *);
154void vhost_disable_notify(struct vhost_virtqueue *);
155bool vhost_enable_notify(struct vhost_virtqueue *);
156
157int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log,
158		    unsigned int log_num, u64 len);
159
160#define vq_err(vq, fmt, ...) do {                                  \
161		pr_debug(pr_fmt(fmt), ##__VA_ARGS__);       \
162		if ((vq)->error_ctx)                               \
163				eventfd_signal((vq)->error_ctx, 1);\
164	} while (0)
165
166enum {
167	VHOST_FEATURES = (1 << VIRTIO_F_NOTIFY_ON_EMPTY) |
168			 (1 << VIRTIO_RING_F_INDIRECT_DESC) |
169			 (1 << VHOST_F_LOG_ALL) |
170			 (1 << VHOST_NET_F_VIRTIO_NET_HDR) |
171			 (1 << VIRTIO_NET_F_MRG_RXBUF),
172};
173
174static inline int vhost_has_feature(struct vhost_dev *dev, int bit)
175{
176	unsigned acked_features = rcu_dereference(dev->acked_features);
177	return acked_features & (1 << bit);
178}
179
180#endif
181