Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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linux
1/*
2 * Linux host-side vring helpers; for when the kernel needs to access
3 * someone else's vring.
4 *
5 * Copyright IBM Corporation, 2013.
6 * Parts taken from drivers/vhost/vhost.c Copyright 2009 Red Hat, Inc.
7 *
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.
12 *
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.
17 *
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.
21 *
22 * Written by: Rusty Russell <rusty@rustcorp.com.au>
23 */
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>
30
31/* virtio_ring with information needed for host access. */
32struct vringh {
33 /* Guest publishes used event idx (note: we always do). */
34 bool event_indices;
35
36 /* Can we get away with weak barriers? */
37 bool weak_barriers;
38
39 /* Last available index we saw (ie. where we're up to). */
40 u16 last_avail_idx;
41
42 /* Last index we used. */
43 u16 last_used_idx;
44
45 /* How many descriptors we've completed since last need_notify(). */
46 u32 completed;
47
48 /* The vring (note: it may contain user pointers!) */
49 struct vring vring;
50
51 /* The function to call to notify the guest about added buffers */
52 void (*notify)(struct vringh *);
53};
54
55/**
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().
65 */
66struct virtio_device;
67typedef void vrh_callback_t(struct virtio_device *, struct vringh *);
68struct 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);
72};
73
74/* The memory the vring can access, and what offset to apply. */
75struct vringh_range {
76 u64 start, end_incl;
77 u64 offset;
78};
79
80/**
81 * struct vringh_iov - iovec mangler.
82 *
83 * Mangles iovec in place, and restores it.
84 * Remaining data is iov + i, of used - i elements.
85 */
86struct vringh_iov {
87 struct iovec *iov;
88 size_t consumed; /* Within iov[i] */
89 unsigned i, used, max_num;
90};
91
92/**
93 * struct vringh_iov - kvec mangler.
94 *
95 * Mangles kvec in place, and restores it.
96 * Remaining data is iov + i, of used - i elements.
97 */
98struct vringh_kiov {
99 struct kvec *iov;
100 size_t consumed; /* Within iov[i] */
101 unsigned i, used, max_num;
102};
103
104/* Flag on max_num to indicate we're kmalloced. */
105#define VRINGH_IOV_ALLOCATED 0x8000000
106
107/* Helpers for userspace vrings. */
108int 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);
113
114static inline void vringh_iov_init(struct vringh_iov *iov,
115 struct iovec *iovec, unsigned num)
116{
117 iov->used = iov->i = 0;
118 iov->consumed = 0;
119 iov->max_num = num;
120 iov->iov = iovec;
121}
122
123static inline void vringh_iov_reset(struct vringh_iov *iov)
124{
125 iov->iov[iov->i].iov_len += iov->consumed;
126 iov->iov[iov->i].iov_base -= iov->consumed;
127 iov->consumed = 0;
128 iov->i = 0;
129}
130
131static inline void vringh_iov_cleanup(struct vringh_iov *iov)
132{
133 if (iov->max_num & VRINGH_IOV_ALLOCATED)
134 kfree(iov->iov);
135 iov->max_num = iov->used = iov->i = iov->consumed = 0;
136 iov->iov = NULL;
137}
138
139/* Convert a descriptor into iovecs. */
140int 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),
145 u16 *head);
146
147/* Copy bytes from readable vsg, consuming it (and incrementing wiov->i). */
148ssize_t vringh_iov_pull_user(struct vringh_iov *riov, void *dst, size_t len);
149
150/* Copy bytes into writable vsg, consuming it (and incrementing wiov->i). */
151ssize_t vringh_iov_push_user(struct vringh_iov *wiov,
152 const void *src, size_t len);
153
154/* Mark a descriptor as used. */
155int vringh_complete_user(struct vringh *vrh, u16 head, u32 len);
156int vringh_complete_multi_user(struct vringh *vrh,
157 const struct vring_used_elem used[],
158 unsigned num_used);
159
160/* Pretend we've never seen descriptor (for easy error handling). */
161void vringh_abandon_user(struct vringh *vrh, unsigned int num);
162
163/* Do we need to fire the eventfd to notify the other side? */
164int vringh_need_notify_user(struct vringh *vrh);
165
166bool vringh_notify_enable_user(struct vringh *vrh);
167void vringh_notify_disable_user(struct vringh *vrh);
168
169/* Helpers for kernelspace vrings. */
170int 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);
175
176static inline void vringh_kiov_init(struct vringh_kiov *kiov,
177 struct kvec *kvec, unsigned num)
178{
179 kiov->used = kiov->i = 0;
180 kiov->consumed = 0;
181 kiov->max_num = num;
182 kiov->iov = kvec;
183}
184
185static inline void vringh_kiov_reset(struct vringh_kiov *kiov)
186{
187 kiov->iov[kiov->i].iov_len += kiov->consumed;
188 kiov->iov[kiov->i].iov_base -= kiov->consumed;
189 kiov->consumed = 0;
190 kiov->i = 0;
191}
192
193static inline void vringh_kiov_cleanup(struct vringh_kiov *kiov)
194{
195 if (kiov->max_num & VRINGH_IOV_ALLOCATED)
196 kfree(kiov->iov);
197 kiov->max_num = kiov->used = kiov->i = kiov->consumed = 0;
198 kiov->iov = NULL;
199}
200
201int vringh_getdesc_kern(struct vringh *vrh,
202 struct vringh_kiov *riov,
203 struct vringh_kiov *wiov,
204 u16 *head,
205 gfp_t gfp);
206
207ssize_t vringh_iov_pull_kern(struct vringh_kiov *riov, void *dst, size_t len);
208ssize_t vringh_iov_push_kern(struct vringh_kiov *wiov,
209 const void *src, size_t len);
210void vringh_abandon_kern(struct vringh *vrh, unsigned int num);
211int vringh_complete_kern(struct vringh *vrh, u16 head, u32 len);
212
213bool vringh_notify_enable_kern(struct vringh *vrh);
214void vringh_notify_disable_kern(struct vringh *vrh);
215
216int vringh_need_notify_kern(struct vringh *vrh);
217
218/* Notify the guest about buffers added to the used ring */
219static inline void vringh_notify(struct vringh *vrh)
220{
221 if (vrh->notify)
222 vrh->notify(vrh);
223}
224
225#endif /* _LINUX_VRINGH_H */