vhost.h revision e0e9b406470b8dd75a115cf82c4791f41615c4c3 
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
18struct vhost_work;
19typedef void (*vhost_work_fn_t)(struct vhost_work *work);
20
21struct vhost_work {
22	struct list_head	  node;
23	vhost_work_fn_t		  fn;
24	wait_queue_head_t	  done;
25	int			  flushing;
26	unsigned		  queue_seq;
27	unsigned		  done_seq;
28};
29
30/* Poll a file (eventfd or socket) */
31/* Note: there's nothing vhost specific about this structure. */
32struct vhost_poll {
33	poll_table                table;
34	wait_queue_head_t        *wqh;
35	wait_queue_t              wait;
36	struct vhost_work	  work;
37	unsigned long		  mask;
38	struct vhost_dev	 *dev;
39};
40
41void vhost_poll_init(struct vhost_poll *poll, vhost_work_fn_t fn,
42		     unsigned long mask, struct vhost_dev *dev);
43void vhost_poll_start(struct vhost_poll *poll, struct file *file);
44void vhost_poll_stop(struct vhost_poll *poll);
45void vhost_poll_flush(struct vhost_poll *poll);
46void vhost_poll_queue(struct vhost_poll *poll);
47
48struct vhost_log {
49	u64 addr;
50	u64 len;
51};
52
53/* The virtqueue structure describes a queue attached to a device. */
54struct vhost_virtqueue {
55	struct vhost_dev *dev;
56
57	/* The actual ring of buffers. */
58	struct mutex mutex;
59	unsigned int num;
60	struct vring_desc __user *desc;
61	struct vring_avail __user *avail;
62	struct vring_used __user *used;
63	struct file *kick;
64	struct file *call;
65	struct file *error;
66	struct eventfd_ctx *call_ctx;
67	struct eventfd_ctx *error_ctx;
68	struct eventfd_ctx *log_ctx;
69
70	struct vhost_poll poll;
71
72	/* The routine to call when the Guest pings us, or timeout. */
73	vhost_work_fn_t handle_kick;
74
75	/* Last available index we saw. */
76	u16 last_avail_idx;
77
78	/* Caches available index value from user. */
79	u16 avail_idx;
80
81	/* Last index we used. */
82	u16 last_used_idx;
83
84	/* Used flags */
85	u16 used_flags;
86
87	/* Log writes to used structure. */
88	bool log_used;
89	u64 log_addr;
90
91	struct iovec iov[UIO_MAXIOV];
92	/* hdr is used to store the virtio header.
93	 * Since each iovec has >= 1 byte length, we never need more than
94	 * header length entries to store the header. */
95	struct iovec hdr[sizeof(struct virtio_net_hdr_mrg_rxbuf)];
96	struct iovec *indirect;
97	size_t vhost_hlen;
98	size_t sock_hlen;
99	struct vring_used_elem *heads;
100	/* We use a kind of RCU to access private pointer.
101	 * All readers access it from worker, which makes it possible to
102	 * flush the vhost_work instead of synchronize_rcu. Therefore readers do
103	 * not need to call rcu_read_lock/rcu_read_unlock: the beginning of
104	 * vhost_work execution acts instead of rcu_read_lock() and the end of
105	 * vhost_work execution acts instead of rcu_read_lock().
106	 * Writers use virtqueue mutex. */
107	void *private_data;
108	/* Log write descriptors */
109	void __user *log_base;
110	struct vhost_log *log;
111};
112
113struct vhost_dev {
114	/* Readers use RCU to access memory table pointer
115	 * log base pointer and features.
116	 * Writers use mutex below.*/
117	struct vhost_memory *memory;
118	struct mm_struct *mm;
119	struct mutex mutex;
120	unsigned acked_features;
121	struct vhost_virtqueue *vqs;
122	int nvqs;
123	struct file *log_file;
124	struct eventfd_ctx *log_ctx;
125	spinlock_t work_lock;
126	struct list_head work_list;
127	struct task_struct *worker;
128};
129
130long vhost_dev_init(struct vhost_dev *, struct vhost_virtqueue *vqs, int nvqs);
131long vhost_dev_check_owner(struct vhost_dev *);
132long vhost_dev_reset_owner(struct vhost_dev *);
133void vhost_dev_cleanup(struct vhost_dev *);
134long vhost_dev_ioctl(struct vhost_dev *, unsigned int ioctl, unsigned long arg);
135int vhost_vq_access_ok(struct vhost_virtqueue *vq);
136int vhost_log_access_ok(struct vhost_dev *);
137
138int vhost_get_vq_desc(struct vhost_dev *, struct vhost_virtqueue *,
139		      struct iovec iov[], unsigned int iov_count,
140		      unsigned int *out_num, unsigned int *in_num,
141		      struct vhost_log *log, unsigned int *log_num);
142void vhost_discard_vq_desc(struct vhost_virtqueue *, int n);
143
144int vhost_add_used(struct vhost_virtqueue *, unsigned int head, int len);
145int vhost_add_used_n(struct vhost_virtqueue *, struct vring_used_elem *heads,
146		     unsigned count);
147void vhost_add_used_and_signal(struct vhost_dev *, struct vhost_virtqueue *,
148			       unsigned int id, int len);
149void vhost_add_used_and_signal_n(struct vhost_dev *, struct vhost_virtqueue *,
150			       struct vring_used_elem *heads, unsigned count);
151void vhost_signal(struct vhost_dev *, struct vhost_virtqueue *);
152void vhost_disable_notify(struct vhost_virtqueue *);
153bool vhost_enable_notify(struct vhost_virtqueue *);
154
155int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log,
156		    unsigned int log_num, u64 len);
157
158#define vq_err(vq, fmt, ...) do {                                  \
159		pr_debug(pr_fmt(fmt), ##__VA_ARGS__);       \
160		if ((vq)->error_ctx)                               \
161				eventfd_signal((vq)->error_ctx, 1);\
162	} while (0)
163
164enum {
165	VHOST_FEATURES = (1 << VIRTIO_F_NOTIFY_ON_EMPTY) |
166			 (1 << VIRTIO_RING_F_INDIRECT_DESC) |
167			 (1 << VHOST_F_LOG_ALL) |
168			 (1 << VHOST_NET_F_VIRTIO_NET_HDR) |
169			 (1 << VIRTIO_NET_F_MRG_RXBUF),
170};
171
172static inline int vhost_has_feature(struct vhost_dev *dev, int bit)
173{
174	unsigned acked_features = rcu_dereference(dev->acked_features);
175	return acked_features & (1 << bit);
176}
177
178#endif
179