1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
|
/*
* Randomness driver for virtio
* Copyright (C) 2007, 2008 Rusty Russell IBM Corporation
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <linux/err.h>
#include <linux/hw_random.h>
#include <linux/scatterlist.h>
#include <linux/spinlock.h>
#include <linux/virtio.h>
#include <linux/virtio_rng.h>
#include <linux/module.h>
static DEFINE_IDA(rng_index_ida);
struct virtrng_info {
struct hwrng hwrng;
struct virtqueue *vq;
struct completion have_data;
char name[25];
unsigned int data_avail;
int index;
bool busy;
bool hwrng_register_done;
};
static void random_recv_done(struct virtqueue *vq)
{
struct virtrng_info *vi = vq->vdev->priv;
/* We can get spurious callbacks, e.g. shared IRQs + virtio_pci. */
if (!virtqueue_get_buf(vi->vq, &vi->data_avail))
return;
complete(&vi->have_data);
}
/* The host will fill any buffer we give it with sweet, sweet randomness. */
static void register_buffer(struct virtrng_info *vi, u8 *buf, size_t size)
{
struct scatterlist sg;
sg_init_one(&sg, buf, size);
/* There should always be room for one buffer. */
virtqueue_add_inbuf(vi->vq, &sg, 1, buf, GFP_KERNEL);
virtqueue_kick(vi->vq);
}
static int virtio_read(struct hwrng *rng, void *buf, size_t size, bool wait)
{
int ret;
struct virtrng_info *vi = (struct virtrng_info *)rng->priv;
if (!vi->busy) {
vi->busy = true;
init_completion(&vi->have_data);
register_buffer(vi, buf, size);
}
if (!wait)
return 0;
ret = wait_for_completion_killable(&vi->have_data);
if (ret < 0)
return ret;
vi->busy = false;
return vi->data_avail;
}
static void virtio_cleanup(struct hwrng *rng)
{
struct virtrng_info *vi = (struct virtrng_info *)rng->priv;
if (vi->busy)
wait_for_completion(&vi->have_data);
}
static int probe_common(struct virtio_device *vdev)
{
int err, index;
struct virtrng_info *vi = NULL;
vi = kzalloc(sizeof(struct virtrng_info), GFP_KERNEL);
if (!vi)
return -ENOMEM;
vi->index = index = ida_simple_get(&rng_index_ida, 0, 0, GFP_KERNEL);
if (index < 0) {
kfree(vi);
return index;
}
sprintf(vi->name, "virtio_rng.%d", index);
init_completion(&vi->have_data);
vi->hwrng = (struct hwrng) {
.read = virtio_read,
.cleanup = virtio_cleanup,
.priv = (unsigned long)vi,
.name = vi->name,
};
vdev->priv = vi;
/* We expect a single virtqueue. */
vi->vq = virtio_find_single_vq(vdev, random_recv_done, "input");
if (IS_ERR(vi->vq)) {
err = PTR_ERR(vi->vq);
vi->vq = NULL;
kfree(vi);
ida_simple_remove(&rng_index_ida, index);
return err;
}
return 0;
}
static void remove_common(struct virtio_device *vdev)
{
struct virtrng_info *vi = vdev->priv;
vdev->config->reset(vdev);
vi->busy = false;
if (vi->hwrng_register_done)
hwrng_unregister(&vi->hwrng);
vdev->config->del_vqs(vdev);
ida_simple_remove(&rng_index_ida, vi->index);
kfree(vi);
}
static int virtrng_probe(struct virtio_device *vdev)
{
return probe_common(vdev);
}
static void virtrng_remove(struct virtio_device *vdev)
{
remove_common(vdev);
}
static void virtrng_scan(struct virtio_device *vdev)
{
struct virtrng_info *vi = vdev->priv;
int err;
err = hwrng_register(&vi->hwrng);
if (!err)
vi->hwrng_register_done = true;
}
#ifdef CONFIG_PM_SLEEP
static int virtrng_freeze(struct virtio_device *vdev)
{
remove_common(vdev);
return 0;
}
static int virtrng_restore(struct virtio_device *vdev)
{
return probe_common(vdev);
}
#endif
static struct virtio_device_id id_table[] = {
{ VIRTIO_ID_RNG, VIRTIO_DEV_ANY_ID },
{ 0 },
};
static struct virtio_driver virtio_rng_driver = {
.driver.name = KBUILD_MODNAME,
.driver.owner = THIS_MODULE,
.id_table = id_table,
.probe = virtrng_probe,
.remove = virtrng_remove,
.scan = virtrng_scan,
#ifdef CONFIG_PM_SLEEP
.freeze = virtrng_freeze,
.restore = virtrng_restore,
#endif
};
module_virtio_driver(virtio_rng_driver);
MODULE_DEVICE_TABLE(virtio, id_table);
MODULE_DESCRIPTION("Virtio random number driver");
MODULE_LICENSE("GPL");
|
