Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
1/* SPDX-License-Identifier: GPL-2.0-or-later */
2/*
3 * Linux host-side vring helpers; for when the kernel needs to access
4 * someone else's vring.
5 *
6 * Copyright IBM Corporation, 2013.
7 * Parts taken from drivers/vhost/vhost.c Copyright 2009 Red Hat, Inc.
8 *
9 * Written by: Rusty Russell <rusty@rustcorp.com.au>
10 */
11#ifndef _LINUX_VRINGH_H
12#define _LINUX_VRINGH_H
13#include <uapi/linux/virtio_ring.h>
14#include <linux/virtio_byteorder.h>
15#include <linux/uio.h>
16#include <linux/slab.h>
17#include <linux/dma-direction.h>
18#include <linux/vhost_iotlb.h>
19#include <asm/barrier.h>
20
21/* virtio_ring with information needed for host access. */
22struct vringh {
23 /* Everything is little endian */
24 bool little_endian;
25
26 /* Guest publishes used event idx (note: we always do). */
27 bool event_indices;
28
29 /* Can we get away with weak barriers? */
30 bool weak_barriers;
31
32 /* Last available index we saw (ie. where we're up to). */
33 u16 last_avail_idx;
34
35 /* Last index we used. */
36 u16 last_used_idx;
37
38 /* How many descriptors we've completed since last need_notify(). */
39 u32 completed;
40
41 /* The vring (note: it may contain user pointers!) */
42 struct vring vring;
43
44 /* IOTLB for this vring */
45 struct vhost_iotlb *iotlb;
46
47 /* The function to call to notify the guest about added buffers */
48 void (*notify)(struct vringh *);
49};
50
51/**
52 * struct vringh_config_ops - ops for creating a host vring from a virtio driver
53 * @find_vrhs: find the host vrings and instantiate them
54 * vdev: the virtio_device
55 * nhvrs: the number of host vrings to find
56 * hvrs: on success, includes new host vrings
57 * callbacks: array of driver callbacks, for each host vring
58 * include a NULL entry for vqs that do not need a callback
59 * Returns 0 on success or error status
60 * @del_vrhs: free the host vrings found by find_vrhs().
61 */
62struct virtio_device;
63typedef void vrh_callback_t(struct virtio_device *, struct vringh *);
64struct vringh_config_ops {
65 int (*find_vrhs)(struct virtio_device *vdev, unsigned nhvrs,
66 struct vringh *vrhs[], vrh_callback_t *callbacks[]);
67 void (*del_vrhs)(struct virtio_device *vdev);
68};
69
70/* The memory the vring can access, and what offset to apply. */
71struct vringh_range {
72 u64 start, end_incl;
73 u64 offset;
74};
75
76/**
77 * struct vringh_iov - iovec mangler.
78 *
79 * Mangles iovec in place, and restores it.
80 * Remaining data is iov + i, of used - i elements.
81 */
82struct vringh_iov {
83 struct iovec *iov;
84 size_t consumed; /* Within iov[i] */
85 unsigned i, used, max_num;
86};
87
88/**
89 * struct vringh_iov - kvec mangler.
90 *
91 * Mangles kvec in place, and restores it.
92 * Remaining data is iov + i, of used - i elements.
93 */
94struct vringh_kiov {
95 struct kvec *iov;
96 size_t consumed; /* Within iov[i] */
97 unsigned i, used, max_num;
98};
99
100/* Flag on max_num to indicate we're kmalloced. */
101#define VRINGH_IOV_ALLOCATED 0x8000000
102
103/* Helpers for userspace vrings. */
104int vringh_init_user(struct vringh *vrh, u64 features,
105 unsigned int num, bool weak_barriers,
106 struct vring_desc __user *desc,
107 struct vring_avail __user *avail,
108 struct vring_used __user *used);
109
110static inline void vringh_iov_init(struct vringh_iov *iov,
111 struct iovec *iovec, unsigned num)
112{
113 iov->used = iov->i = 0;
114 iov->consumed = 0;
115 iov->max_num = num;
116 iov->iov = iovec;
117}
118
119static inline void vringh_iov_reset(struct vringh_iov *iov)
120{
121 iov->iov[iov->i].iov_len += iov->consumed;
122 iov->iov[iov->i].iov_base -= iov->consumed;
123 iov->consumed = 0;
124 iov->i = 0;
125}
126
127static inline void vringh_iov_cleanup(struct vringh_iov *iov)
128{
129 if (iov->max_num & VRINGH_IOV_ALLOCATED)
130 kfree(iov->iov);
131 iov->max_num = iov->used = iov->i = iov->consumed = 0;
132 iov->iov = NULL;
133}
134
135/* Convert a descriptor into iovecs. */
136int vringh_getdesc_user(struct vringh *vrh,
137 struct vringh_iov *riov,
138 struct vringh_iov *wiov,
139 bool (*getrange)(struct vringh *vrh,
140 u64 addr, struct vringh_range *r),
141 u16 *head);
142
143/* Copy bytes from readable vsg, consuming it (and incrementing wiov->i). */
144ssize_t vringh_iov_pull_user(struct vringh_iov *riov, void *dst, size_t len);
145
146/* Copy bytes into writable vsg, consuming it (and incrementing wiov->i). */
147ssize_t vringh_iov_push_user(struct vringh_iov *wiov,
148 const void *src, size_t len);
149
150/* Mark a descriptor as used. */
151int vringh_complete_user(struct vringh *vrh, u16 head, u32 len);
152int vringh_complete_multi_user(struct vringh *vrh,
153 const struct vring_used_elem used[],
154 unsigned num_used);
155
156/* Pretend we've never seen descriptor (for easy error handling). */
157void vringh_abandon_user(struct vringh *vrh, unsigned int num);
158
159/* Do we need to fire the eventfd to notify the other side? */
160int vringh_need_notify_user(struct vringh *vrh);
161
162bool vringh_notify_enable_user(struct vringh *vrh);
163void vringh_notify_disable_user(struct vringh *vrh);
164
165/* Helpers for kernelspace vrings. */
166int vringh_init_kern(struct vringh *vrh, u64 features,
167 unsigned int num, bool weak_barriers,
168 struct vring_desc *desc,
169 struct vring_avail *avail,
170 struct vring_used *used);
171
172static inline void vringh_kiov_init(struct vringh_kiov *kiov,
173 struct kvec *kvec, unsigned num)
174{
175 kiov->used = kiov->i = 0;
176 kiov->consumed = 0;
177 kiov->max_num = num;
178 kiov->iov = kvec;
179}
180
181static inline void vringh_kiov_reset(struct vringh_kiov *kiov)
182{
183 kiov->iov[kiov->i].iov_len += kiov->consumed;
184 kiov->iov[kiov->i].iov_base -= kiov->consumed;
185 kiov->consumed = 0;
186 kiov->i = 0;
187}
188
189static inline void vringh_kiov_cleanup(struct vringh_kiov *kiov)
190{
191 if (kiov->max_num & VRINGH_IOV_ALLOCATED)
192 kfree(kiov->iov);
193 kiov->max_num = kiov->used = kiov->i = kiov->consumed = 0;
194 kiov->iov = NULL;
195}
196
197int vringh_getdesc_kern(struct vringh *vrh,
198 struct vringh_kiov *riov,
199 struct vringh_kiov *wiov,
200 u16 *head,
201 gfp_t gfp);
202
203ssize_t vringh_iov_pull_kern(struct vringh_kiov *riov, void *dst, size_t len);
204ssize_t vringh_iov_push_kern(struct vringh_kiov *wiov,
205 const void *src, size_t len);
206void vringh_abandon_kern(struct vringh *vrh, unsigned int num);
207int vringh_complete_kern(struct vringh *vrh, u16 head, u32 len);
208
209bool vringh_notify_enable_kern(struct vringh *vrh);
210void vringh_notify_disable_kern(struct vringh *vrh);
211
212int vringh_need_notify_kern(struct vringh *vrh);
213
214/* Notify the guest about buffers added to the used ring */
215static inline void vringh_notify(struct vringh *vrh)
216{
217 if (vrh->notify)
218 vrh->notify(vrh);
219}
220
221static inline bool vringh_is_little_endian(const struct vringh *vrh)
222{
223 return vrh->little_endian ||
224 virtio_legacy_is_little_endian();
225}
226
227static inline u16 vringh16_to_cpu(const struct vringh *vrh, __virtio16 val)
228{
229 return __virtio16_to_cpu(vringh_is_little_endian(vrh), val);
230}
231
232static inline __virtio16 cpu_to_vringh16(const struct vringh *vrh, u16 val)
233{
234 return __cpu_to_virtio16(vringh_is_little_endian(vrh), val);
235}
236
237static inline u32 vringh32_to_cpu(const struct vringh *vrh, __virtio32 val)
238{
239 return __virtio32_to_cpu(vringh_is_little_endian(vrh), val);
240}
241
242static inline __virtio32 cpu_to_vringh32(const struct vringh *vrh, u32 val)
243{
244 return __cpu_to_virtio32(vringh_is_little_endian(vrh), val);
245}
246
247static inline u64 vringh64_to_cpu(const struct vringh *vrh, __virtio64 val)
248{
249 return __virtio64_to_cpu(vringh_is_little_endian(vrh), val);
250}
251
252static inline __virtio64 cpu_to_vringh64(const struct vringh *vrh, u64 val)
253{
254 return __cpu_to_virtio64(vringh_is_little_endian(vrh), val);
255}
256
257void vringh_set_iotlb(struct vringh *vrh, struct vhost_iotlb *iotlb);
258
259int vringh_init_iotlb(struct vringh *vrh, u64 features,
260 unsigned int num, bool weak_barriers,
261 struct vring_desc *desc,
262 struct vring_avail *avail,
263 struct vring_used *used);
264
265int vringh_getdesc_iotlb(struct vringh *vrh,
266 struct vringh_kiov *riov,
267 struct vringh_kiov *wiov,
268 u16 *head,
269 gfp_t gfp);
270
271ssize_t vringh_iov_pull_iotlb(struct vringh *vrh,
272 struct vringh_kiov *riov,
273 void *dst, size_t len);
274ssize_t vringh_iov_push_iotlb(struct vringh *vrh,
275 struct vringh_kiov *wiov,
276 const void *src, size_t len);
277
278void vringh_abandon_iotlb(struct vringh *vrh, unsigned int num);
279
280int vringh_complete_iotlb(struct vringh *vrh, u16 head, u32 len);
281
282bool vringh_notify_enable_iotlb(struct vringh *vrh);
283void vringh_notify_disable_iotlb(struct vringh *vrh);
284
285int vringh_need_notify_iotlb(struct vringh *vrh);
286
287#endif /* _LINUX_VRINGH_H */