projects/linux·blob assoc-array-fixes · refs

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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 <[email protected]>
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/spinlock.h>
18#if IS_REACHABLE(CONFIG_VHOST_IOTLB)
19#include <linux/dma-direction.h>
20#include <linux/vhost_iotlb.h>
21#endif
22#include <asm/barrier.h>
23
24/* virtio_ring with information needed for host access. */
25struct vringh {
26 /* Everything is little endian */
27 bool little_endian;
28
29 /* Guest publishes used event idx (note: we always do). */
30 bool event_indices;
31
32 /* Can we get away with weak barriers? */
33 bool weak_barriers;
34
35 /* Use user's VA */
36 bool use_va;
37
38 /* Last available index we saw (ie. where we're up to). */
39 u16 last_avail_idx;
40
41 /* Last index we used. */
42 u16 last_used_idx;
43
44 /* How many descriptors we've completed since last need_notify(). */
45 u32 completed;
46
47 /* The vring (note: it may contain user pointers!) */
48 struct vring vring;
49
50 /* IOTLB for this vring */
51 struct vhost_iotlb *iotlb;
52
53 /* spinlock to synchronize IOTLB accesses */
54 spinlock_t *iotlb_lock;
55
56 /* The function to call to notify the guest about added buffers */
57 void (*notify)(struct vringh *);
58};
59
60struct virtio_device;
61typedef void vrh_callback_t(struct virtio_device *, struct vringh *);
62
63/**
64 * struct vringh_config_ops - ops for creating a host vring from a virtio driver
65 * @find_vrhs: find the host vrings and instantiate them
66 * vdev: the virtio_device
67 * nhvrs: the number of host vrings to find
68 * hvrs: on success, includes new host vrings
69 * callbacks: array of driver callbacks, for each host vring
70 * include a NULL entry for vqs that do not need a callback
71 * Returns 0 on success or error status
72 * @del_vrhs: free the host vrings found by find_vrhs().
73 */
74struct vringh_config_ops {
75 int (*find_vrhs)(struct virtio_device *vdev, unsigned nhvrs,
76 struct vringh *vrhs[], vrh_callback_t *callbacks[]);
77 void (*del_vrhs)(struct virtio_device *vdev);
78};
79
80/* The memory the vring can access, and what offset to apply. */
81struct vringh_range {
82 u64 start, end_incl;
83 u64 offset;
84};
85
86/**
87 * struct vringh_iov - iovec mangler.
88 * @iov: array of iovecs to operate on
89 * @consumed: number of bytes consumed within iov[i]
90 * @i: index of current iovec
91 * @used: number of iovecs present in @iov
92 * @max_num: maximum number of iovecs.
93 * corresponds to allocated memory of @iov
94 *
95 * Mangles iovec in place, and restores it.
96 * Remaining data is iov + i, of used - i elements.
97 */
98struct vringh_iov {
99 struct iovec *iov;
100 size_t consumed; /* Within iov[i] */
101 unsigned i, used, max_num;
102};
103
104/**
105 * struct vringh_kiov - kvec mangler.
106 * @iov: array of iovecs to operate on
107 * @consumed: number of bytes consumed within iov[i]
108 * @i: index of current iovec
109 * @used: number of iovecs present in @iov
110 * @max_num: maximum number of iovecs.
111 * corresponds to allocated memory of @iov
112 *
113 * Mangles kvec in place, and restores it.
114 * Remaining data is iov + i, of used - i elements.
115 */
116struct vringh_kiov {
117 struct kvec *iov;
118 size_t consumed; /* Within iov[i] */
119 unsigned i, used, max_num;
120};
121
122/* Flag on max_num to indicate we're kmalloced. */
123#define VRINGH_IOV_ALLOCATED 0x8000000
124
125/* Helpers for userspace vrings. */
126int vringh_init_user(struct vringh *vrh, u64 features,
127 unsigned int num, bool weak_barriers,
128 vring_desc_t __user *desc,
129 vring_avail_t __user *avail,
130 vring_used_t __user *used);
131
132static inline void vringh_iov_init(struct vringh_iov *iov,
133 struct iovec *iovec, unsigned num)
134{
135 iov->used = iov->i = 0;
136 iov->consumed = 0;
137 iov->max_num = num;
138 iov->iov = iovec;
139}
140
141static inline void vringh_iov_reset(struct vringh_iov *iov)
142{
143 iov->iov[iov->i].iov_len += iov->consumed;
144 iov->iov[iov->i].iov_base -= iov->consumed;
145 iov->consumed = 0;
146 iov->i = 0;
147}
148
149static inline void vringh_iov_cleanup(struct vringh_iov *iov)
150{
151 if (iov->max_num & VRINGH_IOV_ALLOCATED)
152 kfree(iov->iov);
153 iov->max_num = iov->used = iov->i = iov->consumed = 0;
154 iov->iov = NULL;
155}
156
157/* Convert a descriptor into iovecs. */
158int vringh_getdesc_user(struct vringh *vrh,
159 struct vringh_iov *riov,
160 struct vringh_iov *wiov,
161 bool (*getrange)(struct vringh *vrh,
162 u64 addr, struct vringh_range *r),
163 u16 *head);
164
165/* Copy bytes from readable vsg, consuming it (and incrementing wiov->i). */
166ssize_t vringh_iov_pull_user(struct vringh_iov *riov, void *dst, size_t len);
167
168/* Copy bytes into writable vsg, consuming it (and incrementing wiov->i). */
169ssize_t vringh_iov_push_user(struct vringh_iov *wiov,
170 const void *src, size_t len);
171
172/* Mark a descriptor as used. */
173int vringh_complete_user(struct vringh *vrh, u16 head, u32 len);
174int vringh_complete_multi_user(struct vringh *vrh,
175 const struct vring_used_elem used[],
176 unsigned num_used);
177
178/* Do we need to fire the eventfd to notify the other side? */
179int vringh_need_notify_user(struct vringh *vrh);
180
181bool vringh_notify_enable_user(struct vringh *vrh);
182void vringh_notify_disable_user(struct vringh *vrh);
183
184/* Helpers for kernelspace vrings. */
185int vringh_init_kern(struct vringh *vrh, u64 features,
186 unsigned int num, bool weak_barriers,
187 struct vring_desc *desc,
188 struct vring_avail *avail,
189 struct vring_used *used);
190
191static inline void vringh_kiov_init(struct vringh_kiov *kiov,
192 struct kvec *kvec, unsigned num)
193{
194 kiov->used = kiov->i = 0;
195 kiov->consumed = 0;
196 kiov->max_num = num;
197 kiov->iov = kvec;
198}
199
200static inline void vringh_kiov_reset(struct vringh_kiov *kiov)
201{
202 kiov->iov[kiov->i].iov_len += kiov->consumed;
203 kiov->iov[kiov->i].iov_base -= kiov->consumed;
204 kiov->consumed = 0;
205 kiov->i = 0;
206}
207
208static inline void vringh_kiov_cleanup(struct vringh_kiov *kiov)
209{
210 if (kiov->max_num & VRINGH_IOV_ALLOCATED)
211 kfree(kiov->iov);
212 kiov->max_num = kiov->used = kiov->i = kiov->consumed = 0;
213 kiov->iov = NULL;
214}
215
216static inline size_t vringh_kiov_length(struct vringh_kiov *kiov)
217{
218 size_t len = 0;
219 int i;
220
221 for (i = kiov->i; i < kiov->used; i++)
222 len += kiov->iov[i].iov_len;
223
224 return len;
225}
226
227void vringh_kiov_advance(struct vringh_kiov *kiov, size_t len);
228
229int vringh_getdesc_kern(struct vringh *vrh,
230 struct vringh_kiov *riov,
231 struct vringh_kiov *wiov,
232 u16 *head,
233 gfp_t gfp);
234
235int vringh_complete_kern(struct vringh *vrh, u16 head, u32 len);
236
237bool vringh_notify_enable_kern(struct vringh *vrh);
238void vringh_notify_disable_kern(struct vringh *vrh);
239
240int vringh_need_notify_kern(struct vringh *vrh);
241
242/* Notify the guest about buffers added to the used ring */
243static inline void vringh_notify(struct vringh *vrh)
244{
245 if (vrh->notify)
246 vrh->notify(vrh);
247}
248
249static inline bool vringh_is_little_endian(const struct vringh *vrh)
250{
251 return vrh->little_endian ||
252 virtio_legacy_is_little_endian();
253}
254
255static inline u16 vringh16_to_cpu(const struct vringh *vrh, __virtio16 val)
256{
257 return __virtio16_to_cpu(vringh_is_little_endian(vrh), val);
258}
259
260static inline __virtio16 cpu_to_vringh16(const struct vringh *vrh, u16 val)
261{
262 return __cpu_to_virtio16(vringh_is_little_endian(vrh), val);
263}
264
265static inline u32 vringh32_to_cpu(const struct vringh *vrh, __virtio32 val)
266{
267 return __virtio32_to_cpu(vringh_is_little_endian(vrh), val);
268}
269
270static inline __virtio32 cpu_to_vringh32(const struct vringh *vrh, u32 val)
271{
272 return __cpu_to_virtio32(vringh_is_little_endian(vrh), val);
273}
274
275static inline u64 vringh64_to_cpu(const struct vringh *vrh, __virtio64 val)
276{
277 return __virtio64_to_cpu(vringh_is_little_endian(vrh), val);
278}
279
280static inline __virtio64 cpu_to_vringh64(const struct vringh *vrh, u64 val)
281{
282 return __cpu_to_virtio64(vringh_is_little_endian(vrh), val);
283}
284
285#if IS_REACHABLE(CONFIG_VHOST_IOTLB)
286
287void vringh_set_iotlb(struct vringh *vrh, struct vhost_iotlb *iotlb,
288 spinlock_t *iotlb_lock);
289
290int vringh_init_iotlb(struct vringh *vrh, u64 features,
291 unsigned int num, bool weak_barriers,
292 struct vring_desc *desc,
293 struct vring_avail *avail,
294 struct vring_used *used);
295
296int vringh_init_iotlb_va(struct vringh *vrh, u64 features,
297 unsigned int num, bool weak_barriers,
298 struct vring_desc *desc,
299 struct vring_avail *avail,
300 struct vring_used *used);
301
302int vringh_getdesc_iotlb(struct vringh *vrh,
303 struct vringh_kiov *riov,
304 struct vringh_kiov *wiov,
305 u16 *head,
306 gfp_t gfp);
307
308ssize_t vringh_iov_pull_iotlb(struct vringh *vrh,
309 struct vringh_kiov *riov,
310 void *dst, size_t len);
311ssize_t vringh_iov_push_iotlb(struct vringh *vrh,
312 struct vringh_kiov *wiov,
313 const void *src, size_t len);
314
315int vringh_complete_iotlb(struct vringh *vrh, u16 head, u32 len);
316
317int vringh_need_notify_iotlb(struct vringh *vrh);
318
319#endif /* CONFIG_VHOST_IOTLB */
320
321#endif /* _LINUX_VRINGH_H */