]>
Commit | Line | Data |
---|---|---|
fd534e9b | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
f7f510ec RR |
2 | /* |
3 | * Randomness driver for virtio | |
4 | * Copyright (C) 2007, 2008 Rusty Russell IBM Corporation | |
f7f510ec | 5 | */ |
bb347d98 | 6 | |
f7f510ec RR |
7 | #include <linux/err.h> |
8 | #include <linux/hw_random.h> | |
9 | #include <linux/scatterlist.h> | |
10 | #include <linux/spinlock.h> | |
11 | #include <linux/virtio.h> | |
12 | #include <linux/virtio_rng.h> | |
c22405c9 | 13 | #include <linux/module.h> |
b69df6cd | 14 | #include <linux/slab.h> |
f7f510ec | 15 | |
a17597d3 | 16 | static DEFINE_IDA(rng_index_ida); |
08e53fbd AK |
17 | |
18 | struct virtrng_info { | |
08e53fbd AK |
19 | struct hwrng hwrng; |
20 | struct virtqueue *vq; | |
08e53fbd | 21 | struct completion have_data; |
a17597d3 | 22 | char name[25]; |
6062829f | 23 | unsigned int data_avail; |
a17597d3 | 24 | int index; |
6062829f | 25 | bool busy; |
5c062734 | 26 | bool hwrng_register_done; |
f4981956 | 27 | bool hwrng_removed; |
08e53fbd | 28 | }; |
f7f510ec RR |
29 | |
30 | static void random_recv_done(struct virtqueue *vq) | |
31 | { | |
08e53fbd AK |
32 | struct virtrng_info *vi = vq->vdev->priv; |
33 | ||
e5b89542 | 34 | /* We can get spurious callbacks, e.g. shared IRQs + virtio_pci. */ |
08e53fbd | 35 | if (!virtqueue_get_buf(vi->vq, &vi->data_avail)) |
e5b89542 | 36 | return; |
f7f510ec | 37 | |
08e53fbd | 38 | complete(&vi->have_data); |
f7f510ec RR |
39 | } |
40 | ||
bb347d98 | 41 | /* The host will fill any buffer we give it with sweet, sweet randomness. */ |
08e53fbd | 42 | static void register_buffer(struct virtrng_info *vi, u8 *buf, size_t size) |
f7f510ec RR |
43 | { |
44 | struct scatterlist sg; | |
45 | ||
bb347d98 IM |
46 | sg_init_one(&sg, buf, size); |
47 | ||
f7f510ec | 48 | /* There should always be room for one buffer. */ |
08e53fbd | 49 | virtqueue_add_inbuf(vi->vq, &sg, 1, buf, GFP_KERNEL); |
bb347d98 | 50 | |
08e53fbd | 51 | virtqueue_kick(vi->vq); |
f7f510ec RR |
52 | } |
53 | ||
bb347d98 | 54 | static int virtio_read(struct hwrng *rng, void *buf, size_t size, bool wait) |
f7f510ec | 55 | { |
cc8744e1 | 56 | int ret; |
08e53fbd | 57 | struct virtrng_info *vi = (struct virtrng_info *)rng->priv; |
f7f510ec | 58 | |
f4981956 AK |
59 | if (vi->hwrng_removed) |
60 | return -ENODEV; | |
61 | ||
08e53fbd AK |
62 | if (!vi->busy) { |
63 | vi->busy = true; | |
aef027db | 64 | reinit_completion(&vi->have_data); |
08e53fbd | 65 | register_buffer(vi, buf, size); |
bb347d98 IM |
66 | } |
67 | ||
f7f510ec RR |
68 | if (!wait) |
69 | return 0; | |
70 | ||
08e53fbd | 71 | ret = wait_for_completion_killable(&vi->have_data); |
cc8744e1 AS |
72 | if (ret < 0) |
73 | return ret; | |
594de1dd | 74 | |
08e53fbd | 75 | vi->busy = false; |
594de1dd | 76 | |
08e53fbd | 77 | return vi->data_avail; |
f7f510ec RR |
78 | } |
79 | ||
bb347d98 | 80 | static void virtio_cleanup(struct hwrng *rng) |
f7f510ec | 81 | { |
08e53fbd | 82 | struct virtrng_info *vi = (struct virtrng_info *)rng->priv; |
bb347d98 | 83 | |
08e53fbd AK |
84 | if (vi->busy) |
85 | wait_for_completion(&vi->have_data); | |
86 | } | |
f7f510ec | 87 | |
178d855e | 88 | static int probe_common(struct virtio_device *vdev) |
f7f510ec | 89 | { |
a17597d3 | 90 | int err, index; |
08e53fbd AK |
91 | struct virtrng_info *vi = NULL; |
92 | ||
e5d23a8c | 93 | vi = kzalloc(sizeof(struct virtrng_info), GFP_KERNEL); |
a17597d3 SL |
94 | if (!vi) |
95 | return -ENOMEM; | |
96 | ||
97 | vi->index = index = ida_simple_get(&rng_index_ida, 0, 0, GFP_KERNEL); | |
98 | if (index < 0) { | |
1bbc2606 MT |
99 | err = index; |
100 | goto err_ida; | |
a17597d3 SL |
101 | } |
102 | sprintf(vi->name, "virtio_rng.%d", index); | |
08e53fbd AK |
103 | init_completion(&vi->have_data); |
104 | ||
a17597d3 SL |
105 | vi->hwrng = (struct hwrng) { |
106 | .read = virtio_read, | |
107 | .cleanup = virtio_cleanup, | |
108 | .priv = (unsigned long)vi, | |
109 | .name = vi->name, | |
34679ec7 | 110 | .quality = 1000, |
a17597d3 | 111 | }; |
08e53fbd | 112 | vdev->priv = vi; |
f7f510ec RR |
113 | |
114 | /* We expect a single virtqueue. */ | |
08e53fbd AK |
115 | vi->vq = virtio_find_single_vq(vdev, random_recv_done, "input"); |
116 | if (IS_ERR(vi->vq)) { | |
117 | err = PTR_ERR(vi->vq); | |
1bbc2606 | 118 | goto err_find; |
e84e7a56 | 119 | } |
f7f510ec | 120 | |
f7f510ec | 121 | return 0; |
1bbc2606 MT |
122 | |
123 | err_find: | |
124 | ida_simple_remove(&rng_index_ida, index); | |
125 | err_ida: | |
126 | kfree(vi); | |
127 | return err; | |
f7f510ec RR |
128 | } |
129 | ||
178d855e | 130 | static void remove_common(struct virtio_device *vdev) |
f7f510ec | 131 | { |
08e53fbd | 132 | struct virtrng_info *vi = vdev->priv; |
5c062734 | 133 | |
f4981956 | 134 | vi->hwrng_removed = true; |
3856e548 AK |
135 | vi->data_avail = 0; |
136 | complete(&vi->have_data); | |
f7f510ec | 137 | vdev->config->reset(vdev); |
08e53fbd | 138 | vi->busy = false; |
5c062734 AS |
139 | if (vi->hwrng_register_done) |
140 | hwrng_unregister(&vi->hwrng); | |
d2a7ddda | 141 | vdev->config->del_vqs(vdev); |
a17597d3 | 142 | ida_simple_remove(&rng_index_ida, vi->index); |
08e53fbd | 143 | kfree(vi); |
f7f510ec RR |
144 | } |
145 | ||
178d855e AS |
146 | static int virtrng_probe(struct virtio_device *vdev) |
147 | { | |
148 | return probe_common(vdev); | |
149 | } | |
150 | ||
39af33fc | 151 | static void virtrng_remove(struct virtio_device *vdev) |
178d855e AS |
152 | { |
153 | remove_common(vdev); | |
154 | } | |
155 | ||
5c062734 AS |
156 | static void virtrng_scan(struct virtio_device *vdev) |
157 | { | |
158 | struct virtrng_info *vi = vdev->priv; | |
159 | int err; | |
160 | ||
161 | err = hwrng_register(&vi->hwrng); | |
162 | if (!err) | |
163 | vi->hwrng_register_done = true; | |
164 | } | |
165 | ||
89107000 | 166 | #ifdef CONFIG_PM_SLEEP |
0bc1a2ef AS |
167 | static int virtrng_freeze(struct virtio_device *vdev) |
168 | { | |
169 | remove_common(vdev); | |
170 | return 0; | |
171 | } | |
172 | ||
173 | static int virtrng_restore(struct virtio_device *vdev) | |
174 | { | |
e5cc6e79 JQ |
175 | int err; |
176 | ||
177 | err = probe_common(vdev); | |
178 | if (!err) { | |
179 | struct virtrng_info *vi = vdev->priv; | |
180 | ||
181 | /* | |
182 | * Set hwrng_removed to ensure that virtio_read() | |
183 | * does not block waiting for data before the | |
184 | * registration is complete. | |
185 | */ | |
186 | vi->hwrng_removed = true; | |
187 | err = hwrng_register(&vi->hwrng); | |
188 | if (!err) { | |
189 | vi->hwrng_register_done = true; | |
190 | vi->hwrng_removed = false; | |
191 | } | |
192 | } | |
193 | ||
194 | return err; | |
0bc1a2ef AS |
195 | } |
196 | #endif | |
197 | ||
f7f510ec RR |
198 | static struct virtio_device_id id_table[] = { |
199 | { VIRTIO_ID_RNG, VIRTIO_DEV_ANY_ID }, | |
200 | { 0 }, | |
201 | }; | |
202 | ||
d817cd52 | 203 | static struct virtio_driver virtio_rng_driver = { |
f7f510ec RR |
204 | .driver.name = KBUILD_MODNAME, |
205 | .driver.owner = THIS_MODULE, | |
206 | .id_table = id_table, | |
207 | .probe = virtrng_probe, | |
bcd2982a | 208 | .remove = virtrng_remove, |
5c062734 | 209 | .scan = virtrng_scan, |
89107000 | 210 | #ifdef CONFIG_PM_SLEEP |
0bc1a2ef AS |
211 | .freeze = virtrng_freeze, |
212 | .restore = virtrng_restore, | |
213 | #endif | |
f7f510ec RR |
214 | }; |
215 | ||
b2a17029 | 216 | module_virtio_driver(virtio_rng_driver); |
f7f510ec RR |
217 | MODULE_DEVICE_TABLE(virtio, id_table); |
218 | MODULE_DESCRIPTION("Virtio random number driver"); | |
219 | MODULE_LICENSE("GPL"); |