Merge remote-tracking branch 'remotes/stefanha/tags/tracing-pull-request' into staging
[qemu.git] / hw / virtio / virtio-rng.c
1 /*
2 * A virtio device implementing a hardware random number generator.
3 *
4 * Copyright 2012 Red Hat, Inc.
5 * Copyright 2012 Amit Shah <amit.shah@redhat.com>
6 *
7 * This work is licensed under the terms of the GNU GPL, version 2 or
8 * (at your option) any later version. See the COPYING file in the
9 * top-level directory.
10 */
11
12 #include "qemu/osdep.h"
13 #include "qapi/error.h"
14 #include "qemu/iov.h"
15 #include "hw/qdev.h"
16 #include "hw/virtio/virtio.h"
17 #include "hw/virtio/virtio-rng.h"
18 #include "sysemu/rng.h"
19 #include "qom/object_interfaces.h"
20 #include "trace.h"
21
22 static bool is_guest_ready(VirtIORNG *vrng)
23 {
24 VirtIODevice *vdev = VIRTIO_DEVICE(vrng);
25 if (virtio_queue_ready(vrng->vq)
26 && (vdev->status & VIRTIO_CONFIG_S_DRIVER_OK)) {
27 return true;
28 }
29 trace_virtio_rng_guest_not_ready(vrng);
30 return false;
31 }
32
33 static size_t get_request_size(VirtQueue *vq, unsigned quota)
34 {
35 unsigned int in, out;
36
37 virtqueue_get_avail_bytes(vq, &in, &out, quota, 0);
38 return in;
39 }
40
41 static void virtio_rng_process(VirtIORNG *vrng);
42
43 /* Send data from a char device over to the guest */
44 static void chr_read(void *opaque, const void *buf, size_t size)
45 {
46 VirtIORNG *vrng = opaque;
47 VirtIODevice *vdev = VIRTIO_DEVICE(vrng);
48 VirtQueueElement *elem;
49 size_t len;
50 int offset;
51
52 if (!is_guest_ready(vrng)) {
53 return;
54 }
55
56 vrng->quota_remaining -= size;
57
58 offset = 0;
59 while (offset < size) {
60 elem = virtqueue_pop(vrng->vq, sizeof(VirtQueueElement));
61 if (!elem) {
62 break;
63 }
64 len = iov_from_buf(elem->in_sg, elem->in_num,
65 0, buf + offset, size - offset);
66 offset += len;
67
68 virtqueue_push(vrng->vq, elem, len);
69 trace_virtio_rng_pushed(vrng, len);
70 g_free(elem);
71 }
72 virtio_notify(vdev, vrng->vq);
73
74 if (!virtio_queue_empty(vrng->vq)) {
75 /* If we didn't drain the queue, call virtio_rng_process
76 * to take care of asking for more data as appropriate.
77 */
78 virtio_rng_process(vrng);
79 }
80 }
81
82 static void virtio_rng_process(VirtIORNG *vrng)
83 {
84 size_t size;
85 unsigned quota;
86
87 if (!is_guest_ready(vrng)) {
88 return;
89 }
90
91 if (vrng->activate_timer) {
92 timer_mod(vrng->rate_limit_timer,
93 qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL) + vrng->conf.period_ms);
94 vrng->activate_timer = false;
95 }
96
97 if (vrng->quota_remaining < 0) {
98 quota = 0;
99 } else {
100 quota = MIN((uint64_t)vrng->quota_remaining, (uint64_t)UINT32_MAX);
101 }
102 size = get_request_size(vrng->vq, quota);
103
104 trace_virtio_rng_request(vrng, size, quota);
105
106 size = MIN(vrng->quota_remaining, size);
107 if (size) {
108 rng_backend_request_entropy(vrng->rng, size, chr_read, vrng);
109 }
110 }
111
112 static void handle_input(VirtIODevice *vdev, VirtQueue *vq)
113 {
114 VirtIORNG *vrng = VIRTIO_RNG(vdev);
115 virtio_rng_process(vrng);
116 }
117
118 static uint64_t get_features(VirtIODevice *vdev, uint64_t f, Error **errp)
119 {
120 return f;
121 }
122
123 static int virtio_rng_post_load(void *opaque, int version_id)
124 {
125 VirtIORNG *vrng = opaque;
126
127 /* We may have an element ready but couldn't process it due to a quota
128 * limit. Make sure to try again after live migration when the quota may
129 * have been reset.
130 */
131 virtio_rng_process(vrng);
132
133 return 0;
134 }
135
136 static void check_rate_limit(void *opaque)
137 {
138 VirtIORNG *vrng = opaque;
139
140 vrng->quota_remaining = vrng->conf.max_bytes;
141 virtio_rng_process(vrng);
142 vrng->activate_timer = true;
143 }
144
145 static void virtio_rng_device_realize(DeviceState *dev, Error **errp)
146 {
147 VirtIODevice *vdev = VIRTIO_DEVICE(dev);
148 VirtIORNG *vrng = VIRTIO_RNG(dev);
149 Error *local_err = NULL;
150
151 if (vrng->conf.period_ms <= 0) {
152 error_setg(errp, "'period' parameter expects a positive integer");
153 return;
154 }
155
156 /* Workaround: Property parsing does not enforce unsigned integers,
157 * So this is a hack to reject such numbers. */
158 if (vrng->conf.max_bytes > INT64_MAX) {
159 error_setg(errp, "'max-bytes' parameter must be non-negative, "
160 "and less than 2^63");
161 return;
162 }
163
164 if (vrng->conf.rng == NULL) {
165 vrng->conf.default_backend = RNG_RANDOM(object_new(TYPE_RNG_RANDOM));
166
167 user_creatable_complete(OBJECT(vrng->conf.default_backend),
168 &local_err);
169 if (local_err) {
170 error_propagate(errp, local_err);
171 object_unref(OBJECT(vrng->conf.default_backend));
172 return;
173 }
174
175 object_property_add_child(OBJECT(dev),
176 "default-backend",
177 OBJECT(vrng->conf.default_backend),
178 NULL);
179
180 /* The child property took a reference, we can safely drop ours now */
181 object_unref(OBJECT(vrng->conf.default_backend));
182
183 object_property_set_link(OBJECT(dev),
184 OBJECT(vrng->conf.default_backend),
185 "rng", NULL);
186 }
187
188 vrng->rng = vrng->conf.rng;
189 if (vrng->rng == NULL) {
190 error_setg(errp, "'rng' parameter expects a valid object");
191 return;
192 }
193
194 virtio_init(vdev, "virtio-rng", VIRTIO_ID_RNG, 0);
195
196 vrng->vq = virtio_add_queue(vdev, 8, handle_input);
197 vrng->quota_remaining = vrng->conf.max_bytes;
198 vrng->rate_limit_timer = timer_new_ms(QEMU_CLOCK_VIRTUAL,
199 check_rate_limit, vrng);
200 vrng->activate_timer = true;
201 }
202
203 static void virtio_rng_device_unrealize(DeviceState *dev, Error **errp)
204 {
205 VirtIODevice *vdev = VIRTIO_DEVICE(dev);
206 VirtIORNG *vrng = VIRTIO_RNG(dev);
207
208 timer_del(vrng->rate_limit_timer);
209 timer_free(vrng->rate_limit_timer);
210 virtio_cleanup(vdev);
211 }
212
213 static const VMStateDescription vmstate_virtio_rng = {
214 .name = "virtio-rng",
215 .minimum_version_id = 1,
216 .version_id = 1,
217 .fields = (VMStateField[]) {
218 VMSTATE_VIRTIO_DEVICE,
219 VMSTATE_END_OF_LIST()
220 },
221 .post_load = virtio_rng_post_load,
222 };
223
224 static Property virtio_rng_properties[] = {
225 /* Set a default rate limit of 2^47 bytes per minute or roughly 2TB/s. If
226 * you have an entropy source capable of generating more entropy than this
227 * and you can pass it through via virtio-rng, then hats off to you. Until
228 * then, this is unlimited for all practical purposes.
229 */
230 DEFINE_PROP_UINT64("max-bytes", VirtIORNG, conf.max_bytes, INT64_MAX),
231 DEFINE_PROP_UINT32("period", VirtIORNG, conf.period_ms, 1 << 16),
232 DEFINE_PROP_END_OF_LIST(),
233 };
234
235 static void virtio_rng_class_init(ObjectClass *klass, void *data)
236 {
237 DeviceClass *dc = DEVICE_CLASS(klass);
238 VirtioDeviceClass *vdc = VIRTIO_DEVICE_CLASS(klass);
239
240 dc->props = virtio_rng_properties;
241 dc->vmsd = &vmstate_virtio_rng;
242 set_bit(DEVICE_CATEGORY_MISC, dc->categories);
243 vdc->realize = virtio_rng_device_realize;
244 vdc->unrealize = virtio_rng_device_unrealize;
245 vdc->get_features = get_features;
246 }
247
248 static void virtio_rng_initfn(Object *obj)
249 {
250 VirtIORNG *vrng = VIRTIO_RNG(obj);
251
252 object_property_add_link(obj, "rng", TYPE_RNG_BACKEND,
253 (Object **)&vrng->conf.rng,
254 qdev_prop_allow_set_link_before_realize,
255 OBJ_PROP_LINK_UNREF_ON_RELEASE, NULL);
256 }
257
258 static const TypeInfo virtio_rng_info = {
259 .name = TYPE_VIRTIO_RNG,
260 .parent = TYPE_VIRTIO_DEVICE,
261 .instance_size = sizeof(VirtIORNG),
262 .instance_init = virtio_rng_initfn,
263 .class_init = virtio_rng_class_init,
264 };
265
266 static void virtio_register_types(void)
267 {
268 type_register_static(&virtio_rng_info);
269 }
270
271 type_init(virtio_register_types)