GNU Linux-libre 4.4.289-gnu1
[releases.git] / drivers / hv / hv_utils_transport.c
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 {
30         mutex_lock(&hvt->outmsg_lock);
31         kfree(hvt->outmsg);
32         hvt->outmsg = NULL;
33         hvt->outmsg_len = 0;
34         mutex_unlock(&hvt->outmsg_lock);
35         if (hvt->on_reset)
36                 hvt->on_reset();
37 }
38
39 static ssize_t hvt_op_read(struct file *file, char __user *buf,
40                            size_t count, loff_t *ppos)
41 {
42         struct hvutil_transport *hvt;
43         int ret;
44
45         hvt = container_of(file->f_op, struct hvutil_transport, fops);
46
47         if (wait_event_interruptible(hvt->outmsg_q, hvt->outmsg_len > 0))
48                 return -EINTR;
49
50         mutex_lock(&hvt->outmsg_lock);
51         if (!hvt->outmsg) {
52                 ret = -EAGAIN;
53                 goto out_unlock;
54         }
55
56         if (count < hvt->outmsg_len) {
57                 ret = -EINVAL;
58                 goto out_unlock;
59         }
60
61         if (!copy_to_user(buf, hvt->outmsg, hvt->outmsg_len))
62                 ret = hvt->outmsg_len;
63         else
64                 ret = -EFAULT;
65
66         kfree(hvt->outmsg);
67         hvt->outmsg = NULL;
68         hvt->outmsg_len = 0;
69
70 out_unlock:
71         mutex_unlock(&hvt->outmsg_lock);
72         return ret;
73 }
74
75 static ssize_t hvt_op_write(struct file *file, const char __user *buf,
76                             size_t count, loff_t *ppos)
77 {
78         struct hvutil_transport *hvt;
79         u8 *inmsg;
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->on_msg(inmsg, count))
88                 return -EFAULT;
89         kfree(inmsg);
90
91         return count;
92 }
93
94 static unsigned int hvt_op_poll(struct file *file, poll_table *wait)
95 {
96         struct hvutil_transport *hvt;
97
98         hvt = container_of(file->f_op, struct hvutil_transport, fops);
99
100         poll_wait(file, &hvt->outmsg_q, wait);
101         if (hvt->outmsg_len > 0)
102                 return POLLIN | POLLRDNORM;
103
104         return 0;
105 }
106
107 static int hvt_op_open(struct inode *inode, struct file *file)
108 {
109         struct hvutil_transport *hvt;
110
111         hvt = container_of(file->f_op, struct hvutil_transport, fops);
112
113         /*
114          * Switching to CHARDEV mode. We switch bach to INIT when device
115          * gets released.
116          */
117         if (hvt->mode == HVUTIL_TRANSPORT_INIT)
118                 hvt->mode = HVUTIL_TRANSPORT_CHARDEV;
119         else if (hvt->mode == HVUTIL_TRANSPORT_NETLINK) {
120                 /*
121                  * We're switching from netlink communication to using char
122                  * device. Issue the reset first.
123                  */
124                 hvt_reset(hvt);
125                 hvt->mode = HVUTIL_TRANSPORT_CHARDEV;
126         } else
127                 return -EBUSY;
128
129         return 0;
130 }
131
132 static int hvt_op_release(struct inode *inode, struct file *file)
133 {
134         struct hvutil_transport *hvt;
135
136         hvt = container_of(file->f_op, struct hvutil_transport, fops);
137
138         hvt->mode = HVUTIL_TRANSPORT_INIT;
139         /*
140          * Cleanup message buffers to avoid spurious messages when the daemon
141          * connects back.
142          */
143         hvt_reset(hvt);
144
145         return 0;
146 }
147
148 static void hvt_cn_callback(struct cn_msg *msg, struct netlink_skb_parms *nsp)
149 {
150         struct hvutil_transport *hvt, *hvt_found = NULL;
151
152         spin_lock(&hvt_list_lock);
153         list_for_each_entry(hvt, &hvt_list, list) {
154                 if (hvt->cn_id.idx == msg->id.idx &&
155                     hvt->cn_id.val == msg->id.val) {
156                         hvt_found = hvt;
157                         break;
158                 }
159         }
160         spin_unlock(&hvt_list_lock);
161         if (!hvt_found) {
162                 pr_warn("hvt_cn_callback: spurious message received!\n");
163                 return;
164         }
165
166         /*
167          * Switching to NETLINK mode. Switching to CHARDEV happens when someone
168          * opens the device.
169          */
170         if (hvt->mode == HVUTIL_TRANSPORT_INIT)
171                 hvt->mode = HVUTIL_TRANSPORT_NETLINK;
172
173         if (hvt->mode == HVUTIL_TRANSPORT_NETLINK)
174                 hvt_found->on_msg(msg->data, msg->len);
175         else
176                 pr_warn("hvt_cn_callback: unexpected netlink message!\n");
177 }
178
179 int hvutil_transport_send(struct hvutil_transport *hvt, void *msg, int len)
180 {
181         struct cn_msg *cn_msg;
182         int ret = 0;
183
184         if (hvt->mode == HVUTIL_TRANSPORT_INIT) {
185                 return -EINVAL;
186         } else if (hvt->mode == HVUTIL_TRANSPORT_NETLINK) {
187                 cn_msg = kzalloc(sizeof(*cn_msg) + len, GFP_ATOMIC);
188                 if (!cn_msg)
189                         return -ENOMEM;
190                 cn_msg->id.idx = hvt->cn_id.idx;
191                 cn_msg->id.val = hvt->cn_id.val;
192                 cn_msg->len = len;
193                 memcpy(cn_msg->data, msg, len);
194                 ret = cn_netlink_send(cn_msg, 0, 0, GFP_ATOMIC);
195                 kfree(cn_msg);
196                 return ret;
197         }
198         /* HVUTIL_TRANSPORT_CHARDEV */
199         mutex_lock(&hvt->outmsg_lock);
200         if (hvt->outmsg) {
201                 /* Previous message wasn't received */
202                 ret = -EFAULT;
203                 goto out_unlock;
204         }
205         hvt->outmsg = kzalloc(len, GFP_KERNEL);
206         if (hvt->outmsg) {
207                 memcpy(hvt->outmsg, msg, len);
208                 hvt->outmsg_len = len;
209                 wake_up_interruptible(&hvt->outmsg_q);
210         } else
211                 ret = -ENOMEM;
212 out_unlock:
213         mutex_unlock(&hvt->outmsg_lock);
214         return ret;
215 }
216
217 struct hvutil_transport *hvutil_transport_init(const char *name,
218                                                u32 cn_idx, u32 cn_val,
219                                                int (*on_msg)(void *, int),
220                                                void (*on_reset)(void))
221 {
222         struct hvutil_transport *hvt;
223
224         hvt = kzalloc(sizeof(*hvt), GFP_KERNEL);
225         if (!hvt)
226                 return NULL;
227
228         hvt->cn_id.idx = cn_idx;
229         hvt->cn_id.val = cn_val;
230
231         hvt->mdev.minor = MISC_DYNAMIC_MINOR;
232         hvt->mdev.name = name;
233
234         hvt->fops.owner = THIS_MODULE;
235         hvt->fops.read = hvt_op_read;
236         hvt->fops.write = hvt_op_write;
237         hvt->fops.poll = hvt_op_poll;
238         hvt->fops.open = hvt_op_open;
239         hvt->fops.release = hvt_op_release;
240
241         hvt->mdev.fops = &hvt->fops;
242
243         init_waitqueue_head(&hvt->outmsg_q);
244         mutex_init(&hvt->outmsg_lock);
245
246         spin_lock(&hvt_list_lock);
247         list_add(&hvt->list, &hvt_list);
248         spin_unlock(&hvt_list_lock);
249
250         hvt->on_msg = on_msg;
251         hvt->on_reset = on_reset;
252
253         if (misc_register(&hvt->mdev))
254                 goto err_free_hvt;
255
256         /* Use cn_id.idx/cn_id.val to determine if we need to setup netlink */
257         if (hvt->cn_id.idx > 0 && hvt->cn_id.val > 0 &&
258             cn_add_callback(&hvt->cn_id, name, hvt_cn_callback))
259                 goto err_free_hvt;
260
261         return hvt;
262
263 err_free_hvt:
264         kfree(hvt);
265         return NULL;
266 }
267
268 void hvutil_transport_destroy(struct hvutil_transport *hvt)
269 {
270         spin_lock(&hvt_list_lock);
271         list_del(&hvt->list);
272         spin_unlock(&hvt_list_lock);
273         if (hvt->cn_id.idx > 0 && hvt->cn_id.val > 0)
274                 cn_del_callback(&hvt->cn_id);
275         misc_deregister(&hvt->mdev);
276         kfree(hvt->outmsg);
277         kfree(hvt);
278 }