summaryrefslogtreecommitdiffstats
path: root/drivers/vhost/vhost.h
blob: af3c11ded5fd4910ed0dccea161a801298036731 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
#ifndef _VHOST_H
#define _VHOST_H

#include <linux/eventfd.h>
#include <linux/vhost.h>
#include <linux/mm.h>
#include <linux/mutex.h>
#include <linux/poll.h>
#include <linux/file.h>
#include <linux/skbuff.h>
#include <linux/uio.h>
#include <linux/virtio_config.h>
#include <linux/virtio_ring.h>
#include <asm/atomic.h>

struct vhost_device;

enum {
	/* Enough place for all fragments, head, and virtio net header. */
	VHOST_NET_MAX_SG = MAX_SKB_FRAGS + 2,
};

struct vhost_work;
typedef void (*vhost_work_fn_t)(struct vhost_work *work);

struct vhost_work {
	struct list_head	  node;
	vhost_work_fn_t		  fn;
	wait_queue_head_t	  done;
	int			  flushing;
	unsigned		  queue_seq;
	unsigned		  done_seq;
};

/* Poll a file (eventfd or socket) */
/* Note: there's nothing vhost specific about this structure. */
struct vhost_poll {
	poll_table                table;
	wait_queue_head_t        *wqh;
	wait_queue_t              wait;
	struct vhost_work	  work;
	unsigned long		  mask;
	struct vhost_dev	 *dev;
};

void vhost_poll_init(struct vhost_poll *poll, vhost_work_fn_t fn,
		     unsigned long mask, struct vhost_dev *dev);
void vhost_poll_start(struct vhost_poll *poll, struct file *file);
void vhost_poll_stop(struct vhost_poll *poll);
void vhost_poll_flush(struct vhost_poll *poll);
void vhost_poll_queue(struct vhost_poll *poll);

struct vhost_log {
	u64 addr;
	u64 len;
};

/* The virtqueue structure describes a queue attached to a device. */
struct vhost_virtqueue {
	struct vhost_dev *dev;

	/* The actual ring of buffers. */
	struct mutex mutex;
	unsigned int num;
	struct vring_desc __user *desc;
	struct vring_avail __user *avail;
	struct vring_used __user *used;
	struct file *kick;
	struct file *call;
	struct file *error;
	struct eventfd_ctx *call_ctx;
	struct eventfd_ctx *error_ctx;
	struct eventfd_ctx *log_ctx;

	struct vhost_poll poll;

	/* The routine to call when the Guest pings us, or timeout. */
	vhost_work_fn_t handle_kick;

	/* Last available index we saw. */
	u16 last_avail_idx;

	/* Caches available index value from user. */
	u16 avail_idx;

	/* Last index we used. */
	u16 last_used_idx;

	/* Used flags */
	u16 used_flags;

	/* Log writes to used structure. */
	bool log_used;
	u64 log_addr;

	struct iovec indirect[VHOST_NET_MAX_SG];
	struct iovec iov[VHOST_NET_MAX_SG];
	struct iovec hdr[VHOST_NET_MAX_SG];
	size_t vhost_hlen;
	size_t sock_hlen;
	struct vring_used_elem heads[VHOST_NET_MAX_SG];
	/* We use a kind of RCU to access private pointer.
	 * All readers access it from worker, which makes it possible to
	 * flush the vhost_work instead of synchronize_rcu. Therefore readers do
	 * not need to call rcu_read_lock/rcu_read_unlock: the beginning of
	 * vhost_work execution acts instead of rcu_read_lock() and the end of
	 * vhost_work execution acts instead of rcu_read_lock().
	 * Writers use virtqueue mutex. */
	void __rcu *private_data;
	/* Log write descriptors */
	void __user *log_base;
	struct vhost_log log[VHOST_NET_MAX_SG];
};

struct vhost_dev {
	/* Readers use RCU to access memory table pointer
	 * log base pointer and features.
	 * Writers use mutex below.*/
	struct vhost_memory __rcu *memory;
	struct mm_struct *mm;
	struct mutex mutex;
	unsigned acked_features;
	struct vhost_virtqueue *vqs;
	int nvqs;
	struct file *log_file;
	struct eventfd_ctx *log_ctx;
	spinlock_t work_lock;
	struct list_head work_list;
	struct task_struct *worker;
};

long vhost_dev_init(struct vhost_dev *, struct vhost_virtqueue *vqs, int nvqs);
long vhost_dev_check_owner(struct vhost_dev *);
long vhost_dev_reset_owner(struct vhost_dev *);
void vhost_dev_cleanup(struct vhost_dev *);
long vhost_dev_ioctl(struct vhost_dev *, unsigned int ioctl, unsigned long arg);
int vhost_vq_access_ok(struct vhost_virtqueue *vq);
int vhost_log_access_ok(struct vhost_dev *);

int vhost_get_vq_desc(struct vhost_dev *, struct vhost_virtqueue *,
		      struct iovec iov[], unsigned int iov_count,
		      unsigned int *out_num, unsigned int *in_num,
		      struct vhost_log *log, unsigned int *log_num);
void vhost_discard_vq_desc(struct vhost_virtqueue *, int n);

int vhost_add_used(struct vhost_virtqueue *, unsigned int head, int len);
int vhost_add_used_n(struct vhost_virtqueue *, struct vring_used_elem *heads,
		     unsigned count);
void vhost_add_used_and_signal(struct vhost_dev *, struct vhost_virtqueue *,
			       unsigned int id, int len);
void vhost_add_used_and_signal_n(struct vhost_dev *, struct vhost_virtqueue *,
			       struct vring_used_elem *heads, unsigned count);
void vhost_signal(struct vhost_dev *, struct vhost_virtqueue *);
void vhost_disable_notify(struct vhost_virtqueue *);
bool vhost_enable_notify(struct vhost_virtqueue *);

int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log,
		    unsigned int log_num, u64 len);

#define vq_err(vq, fmt, ...) do {                                  \
		pr_debug(pr_fmt(fmt), ##__VA_ARGS__);       \
		if ((vq)->error_ctx)                               \
				eventfd_signal((vq)->error_ctx, 1);\
	} while (0)

enum {
	VHOST_FEATURES = (1 << VIRTIO_F_NOTIFY_ON_EMPTY) |
			 (1 << VIRTIO_RING_F_INDIRECT_DESC) |
			 (1 << VHOST_F_LOG_ALL) |
			 (1 << VHOST_NET_F_VIRTIO_NET_HDR) |
			 (1 << VIRTIO_NET_F_MRG_RXBUF),
};

static inline int vhost_has_feature(struct vhost_dev *dev, int bit)
{
	unsigned acked_features;

	acked_features =
		rcu_dereference_index_check(dev->acked_features,
					    lockdep_is_held(&dev->mutex));
	return acked_features & (1 << bit);
}

#endif