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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Kernel/userspace transport abstraction for Hyper-V util driver.
4 *
5 * Copyright (C) 2015, Vitaly Kuznetsov <vkuznets@redhat.com>
6 */
7
8#include <linux/slab.h>
9#include <linux/fs.h>
10#include <linux/poll.h>
11
12#include "hyperv_vmbus.h"
13#include "hv_utils_transport.h"
14
15static DEFINE_SPINLOCK(hvt_list_lock);
16static LIST_HEAD(hvt_list);
17
18static void hvt_reset(struct hvutil_transport *hvt)
19{
20 kfree(hvt->outmsg);
21 hvt->outmsg = NULL;
22 hvt->outmsg_len = 0;
23 if (hvt->on_reset)
24 hvt->on_reset();
25}
26
27static ssize_t hvt_op_read(struct file *file, char __user *buf,
28 size_t count, loff_t *ppos)
29{
30 struct hvutil_transport *hvt;
31 int ret;
32
33 hvt = container_of(file->f_op, struct hvutil_transport, fops);
34
35 if (wait_event_interruptible(hvt->outmsg_q, hvt->outmsg_len > 0 ||
36 hvt->mode != HVUTIL_TRANSPORT_CHARDEV))
37 return -EINTR;
38
39 mutex_lock(&hvt->lock);
40
41 if (hvt->mode == HVUTIL_TRANSPORT_DESTROY) {
42 ret = -EBADF;
43 goto out_unlock;
44 }
45
46 if (!hvt->outmsg) {
47 ret = -EAGAIN;
48 goto out_unlock;
49 }
50
51 if (count < hvt->outmsg_len) {
52 ret = -EINVAL;
53 goto out_unlock;
54 }
55
56 if (!copy_to_user(buf, hvt->outmsg, hvt->outmsg_len))
57 ret = hvt->outmsg_len;
58 else
59 ret = -EFAULT;
60
61 kfree(hvt->outmsg);
62 hvt->outmsg = NULL;
63 hvt->outmsg_len = 0;
64
65 if (hvt->on_read)
66 hvt->on_read();
67 hvt->on_read = NULL;
68
69out_unlock:
70 mutex_unlock(&hvt->lock);
71 return ret;
72}
73
74static ssize_t hvt_op_write(struct file *file, const char __user *buf,
75 size_t count, loff_t *ppos)
76{
77 struct hvutil_transport *hvt;
78 u8 *inmsg;
79 int ret;
80
81 hvt = container_of(file->f_op, struct hvutil_transport, fops);
82
83 inmsg = memdup_user(buf, count);
84 if (IS_ERR(inmsg))
85 return PTR_ERR(inmsg);
86
87 if (hvt->mode == HVUTIL_TRANSPORT_DESTROY)
88 ret = -EBADF;
89 else
90 ret = hvt->on_msg(inmsg, count);
91
92 kfree(inmsg);
93
94 return ret ? ret : count;
95}
96
97static __poll_t hvt_op_poll(struct file *file, poll_table *wait)
98{
99 struct hvutil_transport *hvt;
100
101 hvt = container_of(file->f_op, struct hvutil_transport, fops);
102
103 poll_wait(file, &hvt->outmsg_q, wait);
104
105 if (hvt->mode == HVUTIL_TRANSPORT_DESTROY)
106 return EPOLLERR | EPOLLHUP;
107
108 if (hvt->outmsg_len > 0)
109 return EPOLLIN | EPOLLRDNORM;
110
111 return 0;
112}
113
114static int hvt_op_open(struct inode *inode, struct file *file)
115{
116 struct hvutil_transport *hvt;
117 int ret = 0;
118 bool issue_reset = false;
119
120 hvt = container_of(file->f_op, struct hvutil_transport, fops);
121
122 mutex_lock(&hvt->lock);
123
124 if (hvt->mode == HVUTIL_TRANSPORT_DESTROY) {
125 ret = -EBADF;
126 } else if (hvt->mode == HVUTIL_TRANSPORT_INIT) {
127 /*
128 * Switching to CHARDEV mode. We switch bach to INIT when
129 * device gets released.
130 */
131 hvt->mode = HVUTIL_TRANSPORT_CHARDEV;
132 }
133 else if (hvt->mode == HVUTIL_TRANSPORT_NETLINK) {
134 /*
135 * We're switching from netlink communication to using char
136 * device. Issue the reset first.
137 */
138 issue_reset = true;
139 hvt->mode = HVUTIL_TRANSPORT_CHARDEV;
140 } else {
141 ret = -EBUSY;
142 }
143
144 if (issue_reset)
145 hvt_reset(hvt);
146
147 mutex_unlock(&hvt->lock);
148
149 return ret;
150}
151
152static void hvt_transport_free(struct hvutil_transport *hvt)
153{
154 misc_deregister(&hvt->mdev);
155 kfree(hvt->outmsg);
156 kfree(hvt);
157}
158
159static int hvt_op_release(struct inode *inode, struct file *file)
160{
161 struct hvutil_transport *hvt;
162 int mode_old;
163
164 hvt = container_of(file->f_op, struct hvutil_transport, fops);
165
166 mutex_lock(&hvt->lock);
167 mode_old = hvt->mode;
168 if (hvt->mode != HVUTIL_TRANSPORT_DESTROY)
169 hvt->mode = HVUTIL_TRANSPORT_INIT;
170 /*
171 * Cleanup message buffers to avoid spurious messages when the daemon
172 * connects back.
173 */
174 hvt_reset(hvt);
175
176 if (mode_old == HVUTIL_TRANSPORT_DESTROY)
177 complete(&hvt->release);
178
179 mutex_unlock(&hvt->lock);
180
181 return 0;
182}
183
184static void hvt_cn_callback(struct cn_msg *msg, struct netlink_skb_parms *nsp)
185{
186 struct hvutil_transport *hvt, *hvt_found = NULL;
187
188 spin_lock(&hvt_list_lock);
189 list_for_each_entry(hvt, &hvt_list, list) {
190 if (hvt->cn_id.idx == msg->id.idx &&
191 hvt->cn_id.val == msg->id.val) {
192 hvt_found = hvt;
193 break;
194 }
195 }
196 spin_unlock(&hvt_list_lock);
197 if (!hvt_found) {
198 pr_warn("hvt_cn_callback: spurious message received!\n");
199 return;
200 }
201
202 /*
203 * Switching to NETLINK mode. Switching to CHARDEV happens when someone
204 * opens the device.
205 */
206 mutex_lock(&hvt->lock);
207 if (hvt->mode == HVUTIL_TRANSPORT_INIT)
208 hvt->mode = HVUTIL_TRANSPORT_NETLINK;
209
210 if (hvt->mode == HVUTIL_TRANSPORT_NETLINK)
211 hvt_found->on_msg(msg->data, msg->len);
212 else
213 pr_warn("hvt_cn_callback: unexpected netlink message!\n");
214 mutex_unlock(&hvt->lock);
215}
216
217int hvutil_transport_send(struct hvutil_transport *hvt, void *msg, int len,
218 void (*on_read_cb)(void))
219{
220 struct cn_msg *cn_msg;
221 int ret = 0;
222
223 if (hvt->mode == HVUTIL_TRANSPORT_INIT ||
224 hvt->mode == HVUTIL_TRANSPORT_DESTROY) {
225 return -EINVAL;
226 } else if (hvt->mode == HVUTIL_TRANSPORT_NETLINK) {
227 cn_msg = kzalloc(sizeof(*cn_msg) + len, GFP_ATOMIC);
228 if (!cn_msg)
229 return -ENOMEM;
230 cn_msg->id.idx = hvt->cn_id.idx;
231 cn_msg->id.val = hvt->cn_id.val;
232 cn_msg->len = len;
233 memcpy(cn_msg->data, msg, len);
234 ret = cn_netlink_send(cn_msg, 0, 0, GFP_ATOMIC);
235 kfree(cn_msg);
236 /*
237 * We don't know when netlink messages are delivered but unlike
238 * in CHARDEV mode we're not blocked and we can send next
239 * messages right away.
240 */
241 if (on_read_cb)
242 on_read_cb();
243 return ret;
244 }
245 /* HVUTIL_TRANSPORT_CHARDEV */
246 mutex_lock(&hvt->lock);
247 if (hvt->mode != HVUTIL_TRANSPORT_CHARDEV) {
248 ret = -EINVAL;
249 goto out_unlock;
250 }
251
252 if (hvt->outmsg) {
253 /* Previous message wasn't received */
254 ret = -EFAULT;
255 goto out_unlock;
256 }
257 hvt->outmsg = kzalloc(len, GFP_KERNEL);
258 if (hvt->outmsg) {
259 memcpy(hvt->outmsg, msg, len);
260 hvt->outmsg_len = len;
261 hvt->on_read = on_read_cb;
262 wake_up_interruptible(&hvt->outmsg_q);
263 } else
264 ret = -ENOMEM;
265out_unlock:
266 mutex_unlock(&hvt->lock);
267 return ret;
268}
269
270struct hvutil_transport *hvutil_transport_init(const char *name,
271 u32 cn_idx, u32 cn_val,
272 int (*on_msg)(void *, int),
273 void (*on_reset)(void))
274{
275 struct hvutil_transport *hvt;
276
277 hvt = kzalloc(sizeof(*hvt), GFP_KERNEL);
278 if (!hvt)
279 return NULL;
280
281 hvt->cn_id.idx = cn_idx;
282 hvt->cn_id.val = cn_val;
283
284 hvt->mdev.minor = MISC_DYNAMIC_MINOR;
285 hvt->mdev.name = name;
286
287 hvt->fops.owner = THIS_MODULE;
288 hvt->fops.read = hvt_op_read;
289 hvt->fops.write = hvt_op_write;
290 hvt->fops.poll = hvt_op_poll;
291 hvt->fops.open = hvt_op_open;
292 hvt->fops.release = hvt_op_release;
293
294 hvt->mdev.fops = &hvt->fops;
295
296 init_waitqueue_head(&hvt->outmsg_q);
297 mutex_init(&hvt->lock);
298 init_completion(&hvt->release);
299
300 spin_lock(&hvt_list_lock);
301 list_add(&hvt->list, &hvt_list);
302 spin_unlock(&hvt_list_lock);
303
304 hvt->on_msg = on_msg;
305 hvt->on_reset = on_reset;
306
307 if (misc_register(&hvt->mdev))
308 goto err_free_hvt;
309
310 /* Use cn_id.idx/cn_id.val to determine if we need to setup netlink */
311 if (hvt->cn_id.idx > 0 && hvt->cn_id.val > 0 &&
312 cn_add_callback(&hvt->cn_id, name, hvt_cn_callback))
313 goto err_free_hvt;
314
315 return hvt;
316
317err_free_hvt:
318 spin_lock(&hvt_list_lock);
319 list_del(&hvt->list);
320 spin_unlock(&hvt_list_lock);
321 kfree(hvt);
322 return NULL;
323}
324
325void hvutil_transport_destroy(struct hvutil_transport *hvt)
326{
327 int mode_old;
328
329 mutex_lock(&hvt->lock);
330 mode_old = hvt->mode;
331 hvt->mode = HVUTIL_TRANSPORT_DESTROY;
332 wake_up_interruptible(&hvt->outmsg_q);
333 mutex_unlock(&hvt->lock);
334
335 /*
336 * In case we were in 'chardev' mode we still have an open fd so we
337 * have to defer freeing the device. Netlink interface can be freed
338 * now.
339 */
340 spin_lock(&hvt_list_lock);
341 list_del(&hvt->list);
342 spin_unlock(&hvt_list_lock);
343 if (hvt->cn_id.idx > 0 && hvt->cn_id.val > 0)
344 cn_del_callback(&hvt->cn_id);
345
346 if (mode_old == HVUTIL_TRANSPORT_CHARDEV)
347 wait_for_completion(&hvt->release);
348
349 hvt_transport_free(hvt);
350}
1/*
2 * Kernel/userspace transport abstraction for Hyper-V util driver.
3 *
4 * Copyright (C) 2015, Vitaly Kuznetsov <vkuznets@redhat.com>
5 *
6 * This program is free software; you can redistribute it and/or modify it
7 * under the terms of the GNU General Public License version 2 as published
8 * by the Free Software Foundation.
9 *
10 * This program is distributed in the hope that it will be useful, but
11 * WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
13 * NON INFRINGEMENT. See the GNU General Public License for more
14 * details.
15 *
16 */
17
18#include <linux/slab.h>
19#include <linux/fs.h>
20#include <linux/poll.h>
21
22#include "hyperv_vmbus.h"
23#include "hv_utils_transport.h"
24
25static DEFINE_SPINLOCK(hvt_list_lock);
26static struct list_head hvt_list = LIST_HEAD_INIT(hvt_list);
27
28static void hvt_reset(struct hvutil_transport *hvt)
29{
30 kfree(hvt->outmsg);
31 hvt->outmsg = NULL;
32 hvt->outmsg_len = 0;
33 if (hvt->on_reset)
34 hvt->on_reset();
35}
36
37static ssize_t hvt_op_read(struct file *file, char __user *buf,
38 size_t count, loff_t *ppos)
39{
40 struct hvutil_transport *hvt;
41 int ret;
42
43 hvt = container_of(file->f_op, struct hvutil_transport, fops);
44
45 if (wait_event_interruptible(hvt->outmsg_q, hvt->outmsg_len > 0 ||
46 hvt->mode != HVUTIL_TRANSPORT_CHARDEV))
47 return -EINTR;
48
49 mutex_lock(&hvt->lock);
50
51 if (hvt->mode == HVUTIL_TRANSPORT_DESTROY) {
52 ret = -EBADF;
53 goto out_unlock;
54 }
55
56 if (!hvt->outmsg) {
57 ret = -EAGAIN;
58 goto out_unlock;
59 }
60
61 if (count < hvt->outmsg_len) {
62 ret = -EINVAL;
63 goto out_unlock;
64 }
65
66 if (!copy_to_user(buf, hvt->outmsg, hvt->outmsg_len))
67 ret = hvt->outmsg_len;
68 else
69 ret = -EFAULT;
70
71 kfree(hvt->outmsg);
72 hvt->outmsg = NULL;
73 hvt->outmsg_len = 0;
74
75 if (hvt->on_read)
76 hvt->on_read();
77 hvt->on_read = NULL;
78
79out_unlock:
80 mutex_unlock(&hvt->lock);
81 return ret;
82}
83
84static ssize_t hvt_op_write(struct file *file, const char __user *buf,
85 size_t count, loff_t *ppos)
86{
87 struct hvutil_transport *hvt;
88 u8 *inmsg;
89 int ret;
90
91 hvt = container_of(file->f_op, struct hvutil_transport, fops);
92
93 inmsg = memdup_user(buf, count);
94 if (IS_ERR(inmsg))
95 return PTR_ERR(inmsg);
96
97 if (hvt->mode == HVUTIL_TRANSPORT_DESTROY)
98 ret = -EBADF;
99 else
100 ret = hvt->on_msg(inmsg, count);
101
102 kfree(inmsg);
103
104 return ret ? ret : count;
105}
106
107static unsigned int hvt_op_poll(struct file *file, poll_table *wait)
108{
109 struct hvutil_transport *hvt;
110
111 hvt = container_of(file->f_op, struct hvutil_transport, fops);
112
113 poll_wait(file, &hvt->outmsg_q, wait);
114
115 if (hvt->mode == HVUTIL_TRANSPORT_DESTROY)
116 return POLLERR | POLLHUP;
117
118 if (hvt->outmsg_len > 0)
119 return POLLIN | POLLRDNORM;
120
121 return 0;
122}
123
124static int hvt_op_open(struct inode *inode, struct file *file)
125{
126 struct hvutil_transport *hvt;
127 int ret = 0;
128 bool issue_reset = false;
129
130 hvt = container_of(file->f_op, struct hvutil_transport, fops);
131
132 mutex_lock(&hvt->lock);
133
134 if (hvt->mode == HVUTIL_TRANSPORT_DESTROY) {
135 ret = -EBADF;
136 } else if (hvt->mode == HVUTIL_TRANSPORT_INIT) {
137 /*
138 * Switching to CHARDEV mode. We switch bach to INIT when
139 * device gets released.
140 */
141 hvt->mode = HVUTIL_TRANSPORT_CHARDEV;
142 }
143 else if (hvt->mode == HVUTIL_TRANSPORT_NETLINK) {
144 /*
145 * We're switching from netlink communication to using char
146 * device. Issue the reset first.
147 */
148 issue_reset = true;
149 hvt->mode = HVUTIL_TRANSPORT_CHARDEV;
150 } else {
151 ret = -EBUSY;
152 }
153
154 if (issue_reset)
155 hvt_reset(hvt);
156
157 mutex_unlock(&hvt->lock);
158
159 return ret;
160}
161
162static void hvt_transport_free(struct hvutil_transport *hvt)
163{
164 misc_deregister(&hvt->mdev);
165 kfree(hvt->outmsg);
166 kfree(hvt);
167}
168
169static int hvt_op_release(struct inode *inode, struct file *file)
170{
171 struct hvutil_transport *hvt;
172 int mode_old;
173
174 hvt = container_of(file->f_op, struct hvutil_transport, fops);
175
176 mutex_lock(&hvt->lock);
177 mode_old = hvt->mode;
178 if (hvt->mode != HVUTIL_TRANSPORT_DESTROY)
179 hvt->mode = HVUTIL_TRANSPORT_INIT;
180 /*
181 * Cleanup message buffers to avoid spurious messages when the daemon
182 * connects back.
183 */
184 hvt_reset(hvt);
185 mutex_unlock(&hvt->lock);
186
187 if (mode_old == HVUTIL_TRANSPORT_DESTROY)
188 hvt_transport_free(hvt);
189
190 return 0;
191}
192
193static void hvt_cn_callback(struct cn_msg *msg, struct netlink_skb_parms *nsp)
194{
195 struct hvutil_transport *hvt, *hvt_found = NULL;
196
197 spin_lock(&hvt_list_lock);
198 list_for_each_entry(hvt, &hvt_list, list) {
199 if (hvt->cn_id.idx == msg->id.idx &&
200 hvt->cn_id.val == msg->id.val) {
201 hvt_found = hvt;
202 break;
203 }
204 }
205 spin_unlock(&hvt_list_lock);
206 if (!hvt_found) {
207 pr_warn("hvt_cn_callback: spurious message received!\n");
208 return;
209 }
210
211 /*
212 * Switching to NETLINK mode. Switching to CHARDEV happens when someone
213 * opens the device.
214 */
215 mutex_lock(&hvt->lock);
216 if (hvt->mode == HVUTIL_TRANSPORT_INIT)
217 hvt->mode = HVUTIL_TRANSPORT_NETLINK;
218
219 if (hvt->mode == HVUTIL_TRANSPORT_NETLINK)
220 hvt_found->on_msg(msg->data, msg->len);
221 else
222 pr_warn("hvt_cn_callback: unexpected netlink message!\n");
223 mutex_unlock(&hvt->lock);
224}
225
226int hvutil_transport_send(struct hvutil_transport *hvt, void *msg, int len,
227 void (*on_read_cb)(void))
228{
229 struct cn_msg *cn_msg;
230 int ret = 0;
231
232 if (hvt->mode == HVUTIL_TRANSPORT_INIT ||
233 hvt->mode == HVUTIL_TRANSPORT_DESTROY) {
234 return -EINVAL;
235 } else if (hvt->mode == HVUTIL_TRANSPORT_NETLINK) {
236 cn_msg = kzalloc(sizeof(*cn_msg) + len, GFP_ATOMIC);
237 if (!cn_msg)
238 return -ENOMEM;
239 cn_msg->id.idx = hvt->cn_id.idx;
240 cn_msg->id.val = hvt->cn_id.val;
241 cn_msg->len = len;
242 memcpy(cn_msg->data, msg, len);
243 ret = cn_netlink_send(cn_msg, 0, 0, GFP_ATOMIC);
244 kfree(cn_msg);
245 /*
246 * We don't know when netlink messages are delivered but unlike
247 * in CHARDEV mode we're not blocked and we can send next
248 * messages right away.
249 */
250 if (on_read_cb)
251 on_read_cb();
252 return ret;
253 }
254 /* HVUTIL_TRANSPORT_CHARDEV */
255 mutex_lock(&hvt->lock);
256 if (hvt->mode != HVUTIL_TRANSPORT_CHARDEV) {
257 ret = -EINVAL;
258 goto out_unlock;
259 }
260
261 if (hvt->outmsg) {
262 /* Previous message wasn't received */
263 ret = -EFAULT;
264 goto out_unlock;
265 }
266 hvt->outmsg = kzalloc(len, GFP_KERNEL);
267 if (hvt->outmsg) {
268 memcpy(hvt->outmsg, msg, len);
269 hvt->outmsg_len = len;
270 hvt->on_read = on_read_cb;
271 wake_up_interruptible(&hvt->outmsg_q);
272 } else
273 ret = -ENOMEM;
274out_unlock:
275 mutex_unlock(&hvt->lock);
276 return ret;
277}
278
279struct hvutil_transport *hvutil_transport_init(const char *name,
280 u32 cn_idx, u32 cn_val,
281 int (*on_msg)(void *, int),
282 void (*on_reset)(void))
283{
284 struct hvutil_transport *hvt;
285
286 hvt = kzalloc(sizeof(*hvt), GFP_KERNEL);
287 if (!hvt)
288 return NULL;
289
290 hvt->cn_id.idx = cn_idx;
291 hvt->cn_id.val = cn_val;
292
293 hvt->mdev.minor = MISC_DYNAMIC_MINOR;
294 hvt->mdev.name = name;
295
296 hvt->fops.owner = THIS_MODULE;
297 hvt->fops.read = hvt_op_read;
298 hvt->fops.write = hvt_op_write;
299 hvt->fops.poll = hvt_op_poll;
300 hvt->fops.open = hvt_op_open;
301 hvt->fops.release = hvt_op_release;
302
303 hvt->mdev.fops = &hvt->fops;
304
305 init_waitqueue_head(&hvt->outmsg_q);
306 mutex_init(&hvt->lock);
307
308 spin_lock(&hvt_list_lock);
309 list_add(&hvt->list, &hvt_list);
310 spin_unlock(&hvt_list_lock);
311
312 hvt->on_msg = on_msg;
313 hvt->on_reset = on_reset;
314
315 if (misc_register(&hvt->mdev))
316 goto err_free_hvt;
317
318 /* Use cn_id.idx/cn_id.val to determine if we need to setup netlink */
319 if (hvt->cn_id.idx > 0 && hvt->cn_id.val > 0 &&
320 cn_add_callback(&hvt->cn_id, name, hvt_cn_callback))
321 goto err_free_hvt;
322
323 return hvt;
324
325err_free_hvt:
326 spin_lock(&hvt_list_lock);
327 list_del(&hvt->list);
328 spin_unlock(&hvt_list_lock);
329 kfree(hvt);
330 return NULL;
331}
332
333void hvutil_transport_destroy(struct hvutil_transport *hvt)
334{
335 int mode_old;
336
337 mutex_lock(&hvt->lock);
338 mode_old = hvt->mode;
339 hvt->mode = HVUTIL_TRANSPORT_DESTROY;
340 wake_up_interruptible(&hvt->outmsg_q);
341 mutex_unlock(&hvt->lock);
342
343 /*
344 * In case we were in 'chardev' mode we still have an open fd so we
345 * have to defer freeing the device. Netlink interface can be freed
346 * now.
347 */
348 spin_lock(&hvt_list_lock);
349 list_del(&hvt->list);
350 spin_unlock(&hvt_list_lock);
351 if (hvt->cn_id.idx > 0 && hvt->cn_id.val > 0)
352 cn_del_callback(&hvt->cn_id);
353
354 if (mode_old != HVUTIL_TRANSPORT_CHARDEV)
355 hvt_transport_free(hvt);
356}