vhost.h revision c4fcb586c337f8b8de3a3d7ba8514eed03695f6e 
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/*
17 * For transmit, used buffer len is unused; we override it to track buffer
18 * status internally; used for zerocopy tx only.
19 */
20/* Lower device DMA failed */
21#define VHOST_DMA_FAILED_LEN	3
22/* Lower device DMA done */
23#define VHOST_DMA_DONE_LEN	2
24/* Lower device DMA in progress */
25#define VHOST_DMA_IN_PROGRESS	1
26/* Buffer unused */
27#define VHOST_DMA_CLEAR_LEN	0
28
29#define VHOST_DMA_IS_DONE(len) ((len) >= VHOST_DMA_DONE_LEN)
30
31struct vhost_device;
32
33struct vhost_work;
34typedef void (*vhost_work_fn_t)(struct vhost_work *work);
35
36struct vhost_work {
37	struct list_head	  node;
38	vhost_work_fn_t		  fn;
39	wait_queue_head_t	  done;
40	int			  flushing;
41	unsigned		  queue_seq;
42	unsigned		  done_seq;
43};
44
45/* Poll a file (eventfd or socket) */
46/* Note: there's nothing vhost specific about this structure. */
47struct vhost_poll {
48	poll_table                table;
49	wait_queue_head_t        *wqh;
50	wait_queue_t              wait;
51	struct vhost_work	  work;
52	unsigned long		  mask;
53	struct vhost_dev	 *dev;
54};
55
56void vhost_work_init(struct vhost_work *work, vhost_work_fn_t fn);
57void vhost_work_queue(struct vhost_dev *dev, struct vhost_work *work);
58
59void vhost_poll_init(struct vhost_poll *poll, vhost_work_fn_t fn,
60		     unsigned long mask, struct vhost_dev *dev);
61void vhost_poll_start(struct vhost_poll *poll, struct file *file);
62void vhost_poll_stop(struct vhost_poll *poll);
63void vhost_poll_flush(struct vhost_poll *poll);
64void vhost_poll_queue(struct vhost_poll *poll);
65
66struct vhost_log {
67	u64 addr;
68	u64 len;
69};
70
71struct vhost_virtqueue;
72
73struct vhost_ubuf_ref {
74	struct kref kref;
75	wait_queue_head_t wait;
76	struct vhost_virtqueue *vq;
77};
78
79struct vhost_ubuf_ref *vhost_ubuf_alloc(struct vhost_virtqueue *, bool zcopy);
80void vhost_ubuf_put(struct vhost_ubuf_ref *);
81void vhost_ubuf_put_and_wait(struct vhost_ubuf_ref *);
82
83/* The virtqueue structure describes a queue attached to a device. */
84struct vhost_virtqueue {
85	struct vhost_dev *dev;
86
87	/* The actual ring of buffers. */
88	struct mutex mutex;
89	unsigned int num;
90	struct vring_desc __user *desc;
91	struct vring_avail __user *avail;
92	struct vring_used __user *used;
93	struct file *kick;
94	struct file *call;
95	struct file *error;
96	struct eventfd_ctx *call_ctx;
97	struct eventfd_ctx *error_ctx;
98	struct eventfd_ctx *log_ctx;
99
100	struct vhost_poll poll;
101
102	/* The routine to call when the Guest pings us, or timeout. */
103	vhost_work_fn_t handle_kick;
104
105	/* Last available index we saw. */
106	u16 last_avail_idx;
107
108	/* Caches available index value from user. */
109	u16 avail_idx;
110
111	/* Last index we used. */
112	u16 last_used_idx;
113
114	/* Used flags */
115	u16 used_flags;
116
117	/* Last used index value we have signalled on */
118	u16 signalled_used;
119
120	/* Last used index value we have signalled on */
121	bool signalled_used_valid;
122
123	/* Log writes to used structure. */
124	bool log_used;
125	u64 log_addr;
126
127	struct iovec iov[UIO_MAXIOV];
128	/* hdr is used to store the virtio header.
129	 * Since each iovec has >= 1 byte length, we never need more than
130	 * header length entries to store the header. */
131	struct iovec hdr[sizeof(struct virtio_net_hdr_mrg_rxbuf)];
132	struct iovec *indirect;
133	size_t vhost_hlen;
134	size_t sock_hlen;
135	struct vring_used_elem *heads;
136	/* We use a kind of RCU to access private pointer.
137	 * All readers access it from worker, which makes it possible to
138	 * flush the vhost_work instead of synchronize_rcu. Therefore readers do
139	 * not need to call rcu_read_lock/rcu_read_unlock: the beginning of
140	 * vhost_work execution acts instead of rcu_read_lock() and the end of
141	 * vhost_work execution acts instead of rcu_read_unlock().
142	 * Writers use virtqueue mutex. */
143	void __rcu *private_data;
144	/* Log write descriptors */
145	void __user *log_base;
146	struct vhost_log *log;
147	/* vhost zerocopy support fields below: */
148	/* last used idx for outstanding DMA zerocopy buffers */
149	int upend_idx;
150	/* first used idx for DMA done zerocopy buffers */
151	int done_idx;
152	/* an array of userspace buffers info */
153	struct ubuf_info *ubuf_info;
154	/* Reference counting for outstanding ubufs.
155	 * Protected by vq mutex. Writers must also take device mutex. */
156	struct vhost_ubuf_ref *ubufs;
157};
158
159struct vhost_dev {
160	/* Readers use RCU to access memory table pointer
161	 * log base pointer and features.
162	 * Writers use mutex below.*/
163	struct vhost_memory __rcu *memory;
164	struct mm_struct *mm;
165	struct mutex mutex;
166	unsigned acked_features;
167	struct vhost_virtqueue *vqs;
168	int nvqs;
169	struct file *log_file;
170	struct eventfd_ctx *log_ctx;
171	spinlock_t work_lock;
172	struct list_head work_list;
173	struct task_struct *worker;
174};
175
176long vhost_dev_init(struct vhost_dev *, struct vhost_virtqueue *vqs, int nvqs);
177long vhost_dev_check_owner(struct vhost_dev *);
178long vhost_dev_reset_owner(struct vhost_dev *);
179void vhost_dev_cleanup(struct vhost_dev *, bool locked);
180long vhost_dev_ioctl(struct vhost_dev *, unsigned int ioctl, unsigned long arg);
181int vhost_vq_access_ok(struct vhost_virtqueue *vq);
182int vhost_log_access_ok(struct vhost_dev *);
183
184int vhost_get_vq_desc(struct vhost_dev *, struct vhost_virtqueue *,
185		      struct iovec iov[], unsigned int iov_count,
186		      unsigned int *out_num, unsigned int *in_num,
187		      struct vhost_log *log, unsigned int *log_num);
188void vhost_discard_vq_desc(struct vhost_virtqueue *, int n);
189
190int vhost_init_used(struct vhost_virtqueue *);
191int vhost_add_used(struct vhost_virtqueue *, unsigned int head, int len);
192int vhost_add_used_n(struct vhost_virtqueue *, struct vring_used_elem *heads,
193		     unsigned count);
194void vhost_add_used_and_signal(struct vhost_dev *, struct vhost_virtqueue *,
195			       unsigned int id, int len);
196void vhost_add_used_and_signal_n(struct vhost_dev *, struct vhost_virtqueue *,
197			       struct vring_used_elem *heads, unsigned count);
198void vhost_signal(struct vhost_dev *, struct vhost_virtqueue *);
199void vhost_disable_notify(struct vhost_dev *, struct vhost_virtqueue *);
200bool vhost_enable_notify(struct vhost_dev *, struct vhost_virtqueue *);
201
202int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log,
203		    unsigned int log_num, u64 len);
204void vhost_zerocopy_callback(struct ubuf_info *, bool);
205int vhost_zerocopy_signal_used(struct vhost_virtqueue *vq);
206
207#define vq_err(vq, fmt, ...) do {                                  \
208		pr_debug(pr_fmt(fmt), ##__VA_ARGS__);       \
209		if ((vq)->error_ctx)                               \
210				eventfd_signal((vq)->error_ctx, 1);\
211	} while (0)
212
213enum {
214	VHOST_FEATURES = (1ULL << VIRTIO_F_NOTIFY_ON_EMPTY) |
215			 (1ULL << VIRTIO_RING_F_INDIRECT_DESC) |
216			 (1ULL << VIRTIO_RING_F_EVENT_IDX) |
217			 (1ULL << VHOST_F_LOG_ALL),
218	VHOST_NET_FEATURES = VHOST_FEATURES |
219			 (1ULL << VHOST_NET_F_VIRTIO_NET_HDR) |
220			 (1ULL << VIRTIO_NET_F_MRG_RXBUF),
221};
222
223static inline int vhost_has_feature(struct vhost_dev *dev, int bit)
224{
225	unsigned acked_features;
226
227	/* TODO: check that we are running from vhost_worker or dev mutex is
228	 * held? */
229	acked_features = rcu_dereference_index_check(dev->acked_features, 1);
230	return acked_features & (1 << bit);
231}
232
233void vhost_enable_zcopy(int vq);
234
235#endif
236