vhost.h revision 2839400f8fe28ce216eeeba3fb97bdf90977f7ad 
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/uio.h>
11#include <linux/virtio_config.h>
12#include <linux/virtio_ring.h>
13#include <linux/atomic.h>
14
15struct vhost_device;
16
17struct vhost_work;
18typedef void (*vhost_work_fn_t)(struct vhost_work *work);
19
20struct vhost_work {
21	struct list_head	  node;
22	vhost_work_fn_t		  fn;
23	wait_queue_head_t	  done;
24	int			  flushing;
25	unsigned		  queue_seq;
26	unsigned		  done_seq;
27};
28
29/* Poll a file (eventfd or socket) */
30/* Note: there's nothing vhost specific about this structure. */
31struct vhost_poll {
32	poll_table                table;
33	wait_queue_head_t        *wqh;
34	wait_queue_t              wait;
35	struct vhost_work	  work;
36	unsigned long		  mask;
37	struct vhost_dev	 *dev;
38};
39
40void vhost_work_init(struct vhost_work *work, vhost_work_fn_t fn);
41void vhost_work_queue(struct vhost_dev *dev, struct vhost_work *work);
42
43void vhost_poll_init(struct vhost_poll *poll, vhost_work_fn_t fn,
44		     unsigned long mask, struct vhost_dev *dev);
45int vhost_poll_start(struct vhost_poll *poll, struct file *file);
46void vhost_poll_stop(struct vhost_poll *poll);
47void vhost_poll_flush(struct vhost_poll *poll);
48void vhost_poll_queue(struct vhost_poll *poll);
49
50struct vhost_log {
51	u64 addr;
52	u64 len;
53};
54
55struct vhost_virtqueue;
56
57/* The virtqueue structure describes a queue attached to a device. */
58struct vhost_virtqueue {
59	struct vhost_dev *dev;
60
61	/* The actual ring of buffers. */
62	struct mutex mutex;
63	unsigned int num;
64	struct vring_desc __user *desc;
65	struct vring_avail __user *avail;
66	struct vring_used __user *used;
67	struct file *kick;
68	struct file *call;
69	struct file *error;
70	struct eventfd_ctx *call_ctx;
71	struct eventfd_ctx *error_ctx;
72	struct eventfd_ctx *log_ctx;
73
74	struct vhost_poll poll;
75
76	/* The routine to call when the Guest pings us, or timeout. */
77	vhost_work_fn_t handle_kick;
78
79	/* Last available index we saw. */
80	u16 last_avail_idx;
81
82	/* Caches available index value from user. */
83	u16 avail_idx;
84
85	/* Last index we used. */
86	u16 last_used_idx;
87
88	/* Used flags */
89	u16 used_flags;
90
91	/* Last used index value we have signalled on */
92	u16 signalled_used;
93
94	/* Last used index value we have signalled on */
95	bool signalled_used_valid;
96
97	/* Log writes to used structure. */
98	bool log_used;
99	u64 log_addr;
100
101	struct iovec iov[UIO_MAXIOV];
102	/* hdr is used to store the virtio header.
103	 * Since each iovec has >= 1 byte length, we never need more than
104	 * header length entries to store the header. */
105	struct iovec hdr[sizeof(struct virtio_net_hdr_mrg_rxbuf)];
106	struct iovec *indirect;
107	size_t vhost_hlen;
108	size_t sock_hlen;
109	struct vring_used_elem *heads;
110	/* We use a kind of RCU to access private pointer.
111	 * All readers access it from worker, which makes it possible to
112	 * flush the vhost_work instead of synchronize_rcu. Therefore readers do
113	 * not need to call rcu_read_lock/rcu_read_unlock: the beginning of
114	 * vhost_work execution acts instead of rcu_read_lock() and the end of
115	 * vhost_work execution acts instead of rcu_read_unlock().
116	 * Writers use virtqueue mutex. */
117	void __rcu *private_data;
118	/* Log write descriptors */
119	void __user *log_base;
120	struct vhost_log *log;
121};
122
123struct vhost_dev {
124	/* Readers use RCU to access memory table pointer
125	 * log base pointer and features.
126	 * Writers use mutex below.*/
127	struct vhost_memory __rcu *memory;
128	struct mm_struct *mm;
129	struct mutex mutex;
130	unsigned acked_features;
131	struct vhost_virtqueue **vqs;
132	int nvqs;
133	struct file *log_file;
134	struct eventfd_ctx *log_ctx;
135	spinlock_t work_lock;
136	struct list_head work_list;
137	struct task_struct *worker;
138};
139
140long vhost_dev_init(struct vhost_dev *, struct vhost_virtqueue **vqs, int nvqs);
141long vhost_dev_check_owner(struct vhost_dev *);
142long vhost_dev_reset_owner(struct vhost_dev *);
143void vhost_dev_cleanup(struct vhost_dev *, bool locked);
144void vhost_dev_stop(struct vhost_dev *);
145long vhost_dev_ioctl(struct vhost_dev *, unsigned int ioctl, void __user *argp);
146long vhost_vring_ioctl(struct vhost_dev *d, int ioctl, void __user *argp);
147int vhost_vq_access_ok(struct vhost_virtqueue *vq);
148int vhost_log_access_ok(struct vhost_dev *);
149
150int vhost_get_vq_desc(struct vhost_dev *, struct vhost_virtqueue *,
151		      struct iovec iov[], unsigned int iov_count,
152		      unsigned int *out_num, unsigned int *in_num,
153		      struct vhost_log *log, unsigned int *log_num);
154void vhost_discard_vq_desc(struct vhost_virtqueue *, int n);
155
156int vhost_init_used(struct vhost_virtqueue *);
157int vhost_add_used(struct vhost_virtqueue *, unsigned int head, int len);
158int vhost_add_used_n(struct vhost_virtqueue *, struct vring_used_elem *heads,
159		     unsigned count);
160void vhost_add_used_and_signal(struct vhost_dev *, struct vhost_virtqueue *,
161			       unsigned int id, int len);
162void vhost_add_used_and_signal_n(struct vhost_dev *, struct vhost_virtqueue *,
163			       struct vring_used_elem *heads, unsigned count);
164void vhost_signal(struct vhost_dev *, struct vhost_virtqueue *);
165void vhost_disable_notify(struct vhost_dev *, struct vhost_virtqueue *);
166bool vhost_enable_notify(struct vhost_dev *, struct vhost_virtqueue *);
167
168int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log,
169		    unsigned int log_num, u64 len);
170
171#define vq_err(vq, fmt, ...) do {                                  \
172		pr_debug(pr_fmt(fmt), ##__VA_ARGS__);       \
173		if ((vq)->error_ctx)                               \
174				eventfd_signal((vq)->error_ctx, 1);\
175	} while (0)
176
177enum {
178	VHOST_FEATURES = (1ULL << VIRTIO_F_NOTIFY_ON_EMPTY) |
179			 (1ULL << VIRTIO_RING_F_INDIRECT_DESC) |
180			 (1ULL << VIRTIO_RING_F_EVENT_IDX) |
181			 (1ULL << VHOST_F_LOG_ALL),
182	VHOST_NET_FEATURES = VHOST_FEATURES |
183			 (1ULL << VHOST_NET_F_VIRTIO_NET_HDR) |
184			 (1ULL << VIRTIO_NET_F_MRG_RXBUF),
185};
186
187static inline int vhost_has_feature(struct vhost_dev *dev, int bit)
188{
189	unsigned acked_features;
190
191	/* TODO: check that we are running from vhost_worker or dev mutex is
192	 * held? */
193	acked_features = rcu_dereference_index_check(dev->acked_features, 1);
194	return acked_features & (1 << bit);
195}
196
197void vhost_enable_zcopy(int vq);
198
199#endif
200