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14b50f80 VK |
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 | ||
25 | static DEFINE_SPINLOCK(hvt_list_lock); | |
26 | static struct list_head hvt_list = LIST_HEAD_INIT(hvt_list); | |
27 | ||
28 | static void hvt_reset(struct hvutil_transport *hvt) | |
29 | { | |
14b50f80 VK |
30 | kfree(hvt->outmsg); |
31 | hvt->outmsg = NULL; | |
32 | hvt->outmsg_len = 0; | |
14b50f80 VK |
33 | if (hvt->on_reset) |
34 | hvt->on_reset(); | |
35 | } | |
36 | ||
37 | static 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 | ||
a1502566 VK |
45 | if (wait_event_interruptible(hvt->outmsg_q, hvt->outmsg_len > 0 || |
46 | hvt->mode != HVUTIL_TRANSPORT_CHARDEV)) | |
14b50f80 VK |
47 | return -EINTR; |
48 | ||
a72f3a4c | 49 | mutex_lock(&hvt->lock); |
a1502566 VK |
50 | |
51 | if (hvt->mode == HVUTIL_TRANSPORT_DESTROY) { | |
52 | ret = -EBADF; | |
53 | goto out_unlock; | |
54 | } | |
55 | ||
14b50f80 VK |
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 | ||
e0fa3e5e VK |
75 | if (hvt->on_read) |
76 | hvt->on_read(); | |
77 | hvt->on_read = NULL; | |
78 | ||
14b50f80 | 79 | out_unlock: |
a72f3a4c | 80 | mutex_unlock(&hvt->lock); |
14b50f80 VK |
81 | return ret; |
82 | } | |
83 | ||
84 | static 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; | |
1f75338b | 89 | int ret; |
14b50f80 VK |
90 | |
91 | hvt = container_of(file->f_op, struct hvutil_transport, fops); | |
92 | ||
b0035964 OH |
93 | inmsg = memdup_user(buf, count); |
94 | if (IS_ERR(inmsg)) | |
95 | return PTR_ERR(inmsg); | |
96 | ||
a1502566 VK |
97 | if (hvt->mode == HVUTIL_TRANSPORT_DESTROY) |
98 | ret = -EBADF; | |
99 | else | |
100 | ret = hvt->on_msg(inmsg, count); | |
1f75338b | 101 | |
14b50f80 VK |
102 | kfree(inmsg); |
103 | ||
1f75338b | 104 | return ret ? ret : count; |
14b50f80 VK |
105 | } |
106 | ||
afc9a42b | 107 | static __poll_t hvt_op_poll(struct file *file, poll_table *wait) |
14b50f80 VK |
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); | |
a1502566 VK |
114 | |
115 | if (hvt->mode == HVUTIL_TRANSPORT_DESTROY) | |
77b744a5 | 116 | return POLLERR | POLLHUP; |
a1502566 | 117 | |
14b50f80 VK |
118 | if (hvt->outmsg_len > 0) |
119 | return POLLIN | POLLRDNORM; | |
120 | ||
121 | return 0; | |
122 | } | |
123 | ||
124 | static int hvt_op_open(struct inode *inode, struct file *file) | |
125 | { | |
126 | struct hvutil_transport *hvt; | |
a1502566 VK |
127 | int ret = 0; |
128 | bool issue_reset = false; | |
14b50f80 VK |
129 | |
130 | hvt = container_of(file->f_op, struct hvutil_transport, fops); | |
131 | ||
a1502566 VK |
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 | */ | |
14b50f80 | 141 | hvt->mode = HVUTIL_TRANSPORT_CHARDEV; |
a1502566 | 142 | } |
14b50f80 VK |
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 | */ | |
a1502566 | 148 | issue_reset = true; |
14b50f80 | 149 | hvt->mode = HVUTIL_TRANSPORT_CHARDEV; |
a1502566 VK |
150 | } else { |
151 | ret = -EBUSY; | |
152 | } | |
14b50f80 | 153 | |
a1502566 VK |
154 | if (issue_reset) |
155 | hvt_reset(hvt); | |
156 | ||
157 | mutex_unlock(&hvt->lock); | |
158 | ||
159 | return ret; | |
14b50f80 VK |
160 | } |
161 | ||
9420098a VK |
162 | static void hvt_transport_free(struct hvutil_transport *hvt) |
163 | { | |
164 | misc_deregister(&hvt->mdev); | |
165 | kfree(hvt->outmsg); | |
166 | kfree(hvt); | |
167 | } | |
168 | ||
14b50f80 VK |
169 | static int hvt_op_release(struct inode *inode, struct file *file) |
170 | { | |
171 | struct hvutil_transport *hvt; | |
9420098a | 172 | int mode_old; |
14b50f80 VK |
173 | |
174 | hvt = container_of(file->f_op, struct hvutil_transport, fops); | |
175 | ||
a1502566 | 176 | mutex_lock(&hvt->lock); |
9420098a | 177 | mode_old = hvt->mode; |
a1502566 VK |
178 | if (hvt->mode != HVUTIL_TRANSPORT_DESTROY) |
179 | hvt->mode = HVUTIL_TRANSPORT_INIT; | |
14b50f80 VK |
180 | /* |
181 | * Cleanup message buffers to avoid spurious messages when the daemon | |
182 | * connects back. | |
183 | */ | |
184 | hvt_reset(hvt); | |
185 | ||
9420098a | 186 | if (mode_old == HVUTIL_TRANSPORT_DESTROY) |
e9c18ae6 VK |
187 | complete(&hvt->release); |
188 | ||
189 | mutex_unlock(&hvt->lock); | |
9420098a | 190 | |
14b50f80 VK |
191 | return 0; |
192 | } | |
193 | ||
194 | static void hvt_cn_callback(struct cn_msg *msg, struct netlink_skb_parms *nsp) | |
195 | { | |
196 | struct hvutil_transport *hvt, *hvt_found = NULL; | |
197 | ||
198 | spin_lock(&hvt_list_lock); | |
199 | list_for_each_entry(hvt, &hvt_list, list) { | |
200 | if (hvt->cn_id.idx == msg->id.idx && | |
201 | hvt->cn_id.val == msg->id.val) { | |
202 | hvt_found = hvt; | |
203 | break; | |
204 | } | |
205 | } | |
206 | spin_unlock(&hvt_list_lock); | |
207 | if (!hvt_found) { | |
208 | pr_warn("hvt_cn_callback: spurious message received!\n"); | |
209 | return; | |
210 | } | |
211 | ||
212 | /* | |
213 | * Switching to NETLINK mode. Switching to CHARDEV happens when someone | |
214 | * opens the device. | |
215 | */ | |
a1502566 | 216 | mutex_lock(&hvt->lock); |
14b50f80 VK |
217 | if (hvt->mode == HVUTIL_TRANSPORT_INIT) |
218 | hvt->mode = HVUTIL_TRANSPORT_NETLINK; | |
219 | ||
220 | if (hvt->mode == HVUTIL_TRANSPORT_NETLINK) | |
221 | hvt_found->on_msg(msg->data, msg->len); | |
222 | else | |
223 | pr_warn("hvt_cn_callback: unexpected netlink message!\n"); | |
a1502566 | 224 | mutex_unlock(&hvt->lock); |
14b50f80 VK |
225 | } |
226 | ||
e0fa3e5e VK |
227 | int hvutil_transport_send(struct hvutil_transport *hvt, void *msg, int len, |
228 | void (*on_read_cb)(void)) | |
14b50f80 VK |
229 | { |
230 | struct cn_msg *cn_msg; | |
231 | int ret = 0; | |
232 | ||
a1502566 VK |
233 | if (hvt->mode == HVUTIL_TRANSPORT_INIT || |
234 | hvt->mode == HVUTIL_TRANSPORT_DESTROY) { | |
14b50f80 VK |
235 | return -EINVAL; |
236 | } else if (hvt->mode == HVUTIL_TRANSPORT_NETLINK) { | |
237 | cn_msg = kzalloc(sizeof(*cn_msg) + len, GFP_ATOMIC); | |
9dd6a064 | 238 | if (!cn_msg) |
14b50f80 VK |
239 | return -ENOMEM; |
240 | cn_msg->id.idx = hvt->cn_id.idx; | |
241 | cn_msg->id.val = hvt->cn_id.val; | |
242 | cn_msg->len = len; | |
243 | memcpy(cn_msg->data, msg, len); | |
244 | ret = cn_netlink_send(cn_msg, 0, 0, GFP_ATOMIC); | |
245 | kfree(cn_msg); | |
e0fa3e5e VK |
246 | /* |
247 | * We don't know when netlink messages are delivered but unlike | |
248 | * in CHARDEV mode we're not blocked and we can send next | |
249 | * messages right away. | |
250 | */ | |
251 | if (on_read_cb) | |
252 | on_read_cb(); | |
14b50f80 VK |
253 | return ret; |
254 | } | |
255 | /* HVUTIL_TRANSPORT_CHARDEV */ | |
a72f3a4c | 256 | mutex_lock(&hvt->lock); |
a1502566 VK |
257 | if (hvt->mode != HVUTIL_TRANSPORT_CHARDEV) { |
258 | ret = -EINVAL; | |
259 | goto out_unlock; | |
260 | } | |
261 | ||
14b50f80 VK |
262 | if (hvt->outmsg) { |
263 | /* Previous message wasn't received */ | |
264 | ret = -EFAULT; | |
265 | goto out_unlock; | |
266 | } | |
267 | hvt->outmsg = kzalloc(len, GFP_KERNEL); | |
cdc0c0c9 OH |
268 | if (hvt->outmsg) { |
269 | memcpy(hvt->outmsg, msg, len); | |
270 | hvt->outmsg_len = len; | |
e0fa3e5e | 271 | hvt->on_read = on_read_cb; |
cdc0c0c9 OH |
272 | wake_up_interruptible(&hvt->outmsg_q); |
273 | } else | |
274 | ret = -ENOMEM; | |
14b50f80 | 275 | out_unlock: |
a72f3a4c | 276 | mutex_unlock(&hvt->lock); |
14b50f80 VK |
277 | return ret; |
278 | } | |
279 | ||
280 | struct hvutil_transport *hvutil_transport_init(const char *name, | |
281 | u32 cn_idx, u32 cn_val, | |
282 | int (*on_msg)(void *, int), | |
283 | void (*on_reset)(void)) | |
284 | { | |
285 | struct hvutil_transport *hvt; | |
286 | ||
287 | hvt = kzalloc(sizeof(*hvt), GFP_KERNEL); | |
288 | if (!hvt) | |
289 | return NULL; | |
290 | ||
291 | hvt->cn_id.idx = cn_idx; | |
292 | hvt->cn_id.val = cn_val; | |
293 | ||
294 | hvt->mdev.minor = MISC_DYNAMIC_MINOR; | |
295 | hvt->mdev.name = name; | |
296 | ||
297 | hvt->fops.owner = THIS_MODULE; | |
298 | hvt->fops.read = hvt_op_read; | |
299 | hvt->fops.write = hvt_op_write; | |
300 | hvt->fops.poll = hvt_op_poll; | |
301 | hvt->fops.open = hvt_op_open; | |
302 | hvt->fops.release = hvt_op_release; | |
303 | ||
304 | hvt->mdev.fops = &hvt->fops; | |
305 | ||
306 | init_waitqueue_head(&hvt->outmsg_q); | |
a72f3a4c | 307 | mutex_init(&hvt->lock); |
e9c18ae6 | 308 | init_completion(&hvt->release); |
14b50f80 VK |
309 | |
310 | spin_lock(&hvt_list_lock); | |
311 | list_add(&hvt->list, &hvt_list); | |
312 | spin_unlock(&hvt_list_lock); | |
313 | ||
314 | hvt->on_msg = on_msg; | |
315 | hvt->on_reset = on_reset; | |
316 | ||
317 | if (misc_register(&hvt->mdev)) | |
318 | goto err_free_hvt; | |
319 | ||
320 | /* Use cn_id.idx/cn_id.val to determine if we need to setup netlink */ | |
321 | if (hvt->cn_id.idx > 0 && hvt->cn_id.val > 0 && | |
322 | cn_add_callback(&hvt->cn_id, name, hvt_cn_callback)) | |
323 | goto err_free_hvt; | |
324 | ||
325 | return hvt; | |
326 | ||
327 | err_free_hvt: | |
e66853b0 AN |
328 | spin_lock(&hvt_list_lock); |
329 | list_del(&hvt->list); | |
330 | spin_unlock(&hvt_list_lock); | |
14b50f80 VK |
331 | kfree(hvt); |
332 | return NULL; | |
333 | } | |
334 | ||
335 | void hvutil_transport_destroy(struct hvutil_transport *hvt) | |
336 | { | |
9420098a VK |
337 | int mode_old; |
338 | ||
a1502566 | 339 | mutex_lock(&hvt->lock); |
9420098a | 340 | mode_old = hvt->mode; |
a1502566 VK |
341 | hvt->mode = HVUTIL_TRANSPORT_DESTROY; |
342 | wake_up_interruptible(&hvt->outmsg_q); | |
343 | mutex_unlock(&hvt->lock); | |
344 | ||
9420098a VK |
345 | /* |
346 | * In case we were in 'chardev' mode we still have an open fd so we | |
347 | * have to defer freeing the device. Netlink interface can be freed | |
348 | * now. | |
349 | */ | |
14b50f80 VK |
350 | spin_lock(&hvt_list_lock); |
351 | list_del(&hvt->list); | |
352 | spin_unlock(&hvt_list_lock); | |
353 | if (hvt->cn_id.idx > 0 && hvt->cn_id.val > 0) | |
354 | cn_del_callback(&hvt->cn_id); | |
9420098a | 355 | |
e9c18ae6 VK |
356 | if (mode_old == HVUTIL_TRANSPORT_CHARDEV) |
357 | wait_for_completion(&hvt->release); | |
358 | ||
359 | hvt_transport_free(hvt); | |
14b50f80 | 360 | } |