2 * Linux host-side vring helpers; for when the kernel needs to access
3 * someone else's vring.
5 * Copyright IBM Corporation, 2013.
6 * Parts taken from drivers/vhost/vhost.c Copyright 2009 Red Hat, Inc.
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation; either version 2 of the License, or
11 * (at your option) any later version.
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 * GNU General Public License for more details.
18 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, write to the Free Software
20 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
22 * Written by: Rusty Russell <rusty@rustcorp.com.au>
24 #ifndef _LINUX_VRINGH_H
25 #define _LINUX_VRINGH_H
26 #include <uapi/linux/virtio_ring.h>
27 #include <linux/uio.h>
28 #include <linux/slab.h>
29 #include <asm/barrier.h>
31 /* virtio_ring with information needed for host access. */
33 /* Guest publishes used event idx (note: we always do). */
36 /* Can we get away with weak barriers? */
39 /* Last available index we saw (ie. where we're up to). */
42 /* Last index we used. */
45 /* How many descriptors we've completed since last need_notify(). */
48 /* The vring (note: it may contain user pointers!) */
51 /* The function to call to notify the guest about added buffers */
52 void (*notify
)(struct vringh
*);
56 * struct vringh_config_ops - ops for creating a host vring from a virtio driver
57 * @find_vrhs: find the host vrings and instantiate them
58 * vdev: the virtio_device
59 * nhvrs: the number of host vrings to find
60 * hvrs: on success, includes new host vrings
61 * callbacks: array of driver callbacks, for each host vring
62 * include a NULL entry for vqs that do not need a callback
63 * Returns 0 on success or error status
64 * @del_vrhs: free the host vrings found by find_vrhs().
67 typedef void vrh_callback_t(struct virtio_device
*, struct vringh
*);
68 struct vringh_config_ops
{
69 int (*find_vrhs
)(struct virtio_device
*vdev
, unsigned nhvrs
,
70 struct vringh
*vrhs
[], vrh_callback_t
*callbacks
[]);
71 void (*del_vrhs
)(struct virtio_device
*vdev
);
74 /* The memory the vring can access, and what offset to apply. */
81 * struct vringh_iov - iovec mangler.
83 * Mangles iovec in place, and restores it.
84 * Remaining data is iov + i, of used - i elements.
88 size_t consumed
; /* Within iov[i] */
89 unsigned i
, used
, max_num
;
93 * struct vringh_iov - kvec mangler.
95 * Mangles kvec in place, and restores it.
96 * Remaining data is iov + i, of used - i elements.
100 size_t consumed
; /* Within iov[i] */
101 unsigned i
, used
, max_num
;
104 /* Flag on max_num to indicate we're kmalloced. */
105 #define VRINGH_IOV_ALLOCATED 0x8000000
107 /* Helpers for userspace vrings. */
108 int vringh_init_user(struct vringh
*vrh
, u32 features
,
109 unsigned int num
, bool weak_barriers
,
110 struct vring_desc __user
*desc
,
111 struct vring_avail __user
*avail
,
112 struct vring_used __user
*used
);
114 static inline void vringh_iov_init(struct vringh_iov
*iov
,
115 struct iovec
*iovec
, unsigned num
)
117 iov
->used
= iov
->i
= 0;
123 static inline void vringh_iov_reset(struct vringh_iov
*iov
)
125 iov
->iov
[iov
->i
].iov_len
+= iov
->consumed
;
126 iov
->iov
[iov
->i
].iov_base
-= iov
->consumed
;
131 static inline void vringh_iov_cleanup(struct vringh_iov
*iov
)
133 if (iov
->max_num
& VRINGH_IOV_ALLOCATED
)
135 iov
->max_num
= iov
->used
= iov
->i
= iov
->consumed
= 0;
139 /* Convert a descriptor into iovecs. */
140 int vringh_getdesc_user(struct vringh
*vrh
,
141 struct vringh_iov
*riov
,
142 struct vringh_iov
*wiov
,
143 bool (*getrange
)(struct vringh
*vrh
,
144 u64 addr
, struct vringh_range
*r
),
147 /* Copy bytes from readable vsg, consuming it (and incrementing wiov->i). */
148 ssize_t
vringh_iov_pull_user(struct vringh_iov
*riov
, void *dst
, size_t len
);
150 /* Copy bytes into writable vsg, consuming it (and incrementing wiov->i). */
151 ssize_t
vringh_iov_push_user(struct vringh_iov
*wiov
,
152 const void *src
, size_t len
);
154 /* Mark a descriptor as used. */
155 int vringh_complete_user(struct vringh
*vrh
, u16 head
, u32 len
);
156 int vringh_complete_multi_user(struct vringh
*vrh
,
157 const struct vring_used_elem used
[],
160 /* Pretend we've never seen descriptor (for easy error handling). */
161 void vringh_abandon_user(struct vringh
*vrh
, unsigned int num
);
163 /* Do we need to fire the eventfd to notify the other side? */
164 int vringh_need_notify_user(struct vringh
*vrh
);
166 bool vringh_notify_enable_user(struct vringh
*vrh
);
167 void vringh_notify_disable_user(struct vringh
*vrh
);
169 /* Helpers for kernelspace vrings. */
170 int vringh_init_kern(struct vringh
*vrh
, u32 features
,
171 unsigned int num
, bool weak_barriers
,
172 struct vring_desc
*desc
,
173 struct vring_avail
*avail
,
174 struct vring_used
*used
);
176 static inline void vringh_kiov_init(struct vringh_kiov
*kiov
,
177 struct kvec
*kvec
, unsigned num
)
179 kiov
->used
= kiov
->i
= 0;
185 static inline void vringh_kiov_reset(struct vringh_kiov
*kiov
)
187 kiov
->iov
[kiov
->i
].iov_len
+= kiov
->consumed
;
188 kiov
->iov
[kiov
->i
].iov_base
-= kiov
->consumed
;
193 static inline void vringh_kiov_cleanup(struct vringh_kiov
*kiov
)
195 if (kiov
->max_num
& VRINGH_IOV_ALLOCATED
)
197 kiov
->max_num
= kiov
->used
= kiov
->i
= kiov
->consumed
= 0;
201 int vringh_getdesc_kern(struct vringh
*vrh
,
202 struct vringh_kiov
*riov
,
203 struct vringh_kiov
*wiov
,
207 ssize_t
vringh_iov_pull_kern(struct vringh_kiov
*riov
, void *dst
, size_t len
);
208 ssize_t
vringh_iov_push_kern(struct vringh_kiov
*wiov
,
209 const void *src
, size_t len
);
210 void vringh_abandon_kern(struct vringh
*vrh
, unsigned int num
);
211 int vringh_complete_kern(struct vringh
*vrh
, u16 head
, u32 len
);
213 bool vringh_notify_enable_kern(struct vringh
*vrh
);
214 void vringh_notify_disable_kern(struct vringh
*vrh
);
216 int vringh_need_notify_kern(struct vringh
*vrh
);
218 /* Notify the guest about buffers added to the used ring */
219 static inline void vringh_notify(struct vringh
*vrh
)
225 #endif /* _LINUX_VRINGH_H */
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