2 * A virtio device implementing a hardware random number generator.
4 * Copyright 2012 Red Hat, Inc.
5 * Copyright 2012 Amit Shah <amit.shah@redhat.com>
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
14 #include "hw/virtio/virtio.h"
15 #include "hw/virtio/virtio-rng.h"
16 #include "sysemu/rng.h"
17 #include "qom/object_interfaces.h"
20 static bool is_guest_ready(VirtIORNG
*vrng
)
22 VirtIODevice
*vdev
= VIRTIO_DEVICE(vrng
);
23 if (virtio_queue_ready(vrng
->vq
)
24 && (vdev
->status
& VIRTIO_CONFIG_S_DRIVER_OK
)) {
27 trace_virtio_rng_guest_not_ready(vrng
);
31 static size_t get_request_size(VirtQueue
*vq
, unsigned quota
)
35 virtqueue_get_avail_bytes(vq
, &in
, &out
, quota
, 0);
39 static void virtio_rng_process(VirtIORNG
*vrng
);
41 /* Send data from a char device over to the guest */
42 static void chr_read(void *opaque
, const void *buf
, size_t size
)
44 VirtIORNG
*vrng
= opaque
;
45 VirtIODevice
*vdev
= VIRTIO_DEVICE(vrng
);
46 VirtQueueElement elem
;
50 if (!is_guest_ready(vrng
)) {
54 vrng
->quota_remaining
-= size
;
57 while (offset
< size
) {
58 if (!virtqueue_pop(vrng
->vq
, &elem
)) {
61 len
= iov_from_buf(elem
.in_sg
, elem
.in_num
,
62 0, buf
+ offset
, size
- offset
);
65 virtqueue_push(vrng
->vq
, &elem
, len
);
66 trace_virtio_rng_pushed(vrng
, len
);
68 virtio_notify(vdev
, vrng
->vq
);
71 static void virtio_rng_process(VirtIORNG
*vrng
)
76 if (!is_guest_ready(vrng
)) {
80 if (vrng
->activate_timer
) {
81 timer_mod(vrng
->rate_limit_timer
,
82 qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL
) + vrng
->conf
.period_ms
);
83 vrng
->activate_timer
= false;
86 if (vrng
->quota_remaining
< 0) {
89 quota
= MIN((uint64_t)vrng
->quota_remaining
, (uint64_t)UINT32_MAX
);
91 size
= get_request_size(vrng
->vq
, quota
);
93 trace_virtio_rng_request(vrng
, size
, quota
);
95 size
= MIN(vrng
->quota_remaining
, size
);
97 rng_backend_request_entropy(vrng
->rng
, size
, chr_read
, vrng
);
101 static void handle_input(VirtIODevice
*vdev
, VirtQueue
*vq
)
103 VirtIORNG
*vrng
= VIRTIO_RNG(vdev
);
104 virtio_rng_process(vrng
);
107 static uint64_t get_features(VirtIODevice
*vdev
, uint64_t f
, Error
**errp
)
112 static void virtio_rng_save(QEMUFile
*f
, void *opaque
)
114 VirtIODevice
*vdev
= opaque
;
116 virtio_save(vdev
, f
);
119 static int virtio_rng_load(QEMUFile
*f
, void *opaque
, int version_id
)
121 VirtIORNG
*vrng
= opaque
;
124 if (version_id
!= 1) {
127 ret
= virtio_load(VIRTIO_DEVICE(vrng
), f
, version_id
);
132 /* We may have an element ready but couldn't process it due to a quota
133 * limit. Make sure to try again after live migration when the quota may
136 virtio_rng_process(vrng
);
141 static void check_rate_limit(void *opaque
)
143 VirtIORNG
*vrng
= opaque
;
145 vrng
->quota_remaining
= vrng
->conf
.max_bytes
;
146 virtio_rng_process(vrng
);
147 vrng
->activate_timer
= true;
150 static void virtio_rng_device_realize(DeviceState
*dev
, Error
**errp
)
152 VirtIODevice
*vdev
= VIRTIO_DEVICE(dev
);
153 VirtIORNG
*vrng
= VIRTIO_RNG(dev
);
154 Error
*local_err
= NULL
;
156 if (vrng
->conf
.period_ms
<= 0) {
157 error_setg(errp
, "'period' parameter expects a positive integer");
161 /* Workaround: Property parsing does not enforce unsigned integers,
162 * So this is a hack to reject such numbers. */
163 if (vrng
->conf
.max_bytes
> INT64_MAX
) {
164 error_setg(errp
, "'max-bytes' parameter must be non-negative, "
165 "and less than 2^63");
169 if (vrng
->conf
.rng
== NULL
) {
170 vrng
->conf
.default_backend
= RNG_RANDOM(object_new(TYPE_RNG_RANDOM
));
172 user_creatable_complete(OBJECT(vrng
->conf
.default_backend
),
175 error_propagate(errp
, local_err
);
176 object_unref(OBJECT(vrng
->conf
.default_backend
));
180 object_property_add_child(OBJECT(dev
),
182 OBJECT(vrng
->conf
.default_backend
),
185 /* The child property took a reference, we can safely drop ours now */
186 object_unref(OBJECT(vrng
->conf
.default_backend
));
188 object_property_set_link(OBJECT(dev
),
189 OBJECT(vrng
->conf
.default_backend
),
193 vrng
->rng
= vrng
->conf
.rng
;
194 if (vrng
->rng
== NULL
) {
195 error_setg(errp
, "'rng' parameter expects a valid object");
199 virtio_init(vdev
, "virtio-rng", VIRTIO_ID_RNG
, 0);
201 vrng
->vq
= virtio_add_queue(vdev
, 8, handle_input
);
202 vrng
->quota_remaining
= vrng
->conf
.max_bytes
;
203 vrng
->rate_limit_timer
= timer_new_ms(QEMU_CLOCK_VIRTUAL
,
204 check_rate_limit
, vrng
);
205 vrng
->activate_timer
= true;
206 register_savevm(dev
, "virtio-rng", -1, 1, virtio_rng_save
,
207 virtio_rng_load
, vrng
);
210 static void virtio_rng_device_unrealize(DeviceState
*dev
, Error
**errp
)
212 VirtIODevice
*vdev
= VIRTIO_DEVICE(dev
);
213 VirtIORNG
*vrng
= VIRTIO_RNG(dev
);
215 timer_del(vrng
->rate_limit_timer
);
216 timer_free(vrng
->rate_limit_timer
);
217 unregister_savevm(dev
, "virtio-rng", vrng
);
218 virtio_cleanup(vdev
);
221 static Property virtio_rng_properties
[] = {
222 /* Set a default rate limit of 2^47 bytes per minute or roughly 2TB/s. If
223 * you have an entropy source capable of generating more entropy than this
224 * and you can pass it through via virtio-rng, then hats off to you. Until
225 * then, this is unlimited for all practical purposes.
227 DEFINE_PROP_UINT64("max-bytes", VirtIORNG
, conf
.max_bytes
, INT64_MAX
),
228 DEFINE_PROP_UINT32("period", VirtIORNG
, conf
.period_ms
, 1 << 16),
229 DEFINE_PROP_END_OF_LIST(),
232 static void virtio_rng_class_init(ObjectClass
*klass
, void *data
)
234 DeviceClass
*dc
= DEVICE_CLASS(klass
);
235 VirtioDeviceClass
*vdc
= VIRTIO_DEVICE_CLASS(klass
);
237 dc
->props
= virtio_rng_properties
;
238 set_bit(DEVICE_CATEGORY_MISC
, dc
->categories
);
239 vdc
->realize
= virtio_rng_device_realize
;
240 vdc
->unrealize
= virtio_rng_device_unrealize
;
241 vdc
->get_features
= get_features
;
244 static void virtio_rng_initfn(Object
*obj
)
246 VirtIORNG
*vrng
= VIRTIO_RNG(obj
);
248 object_property_add_link(obj
, "rng", TYPE_RNG_BACKEND
,
249 (Object
**)&vrng
->conf
.rng
,
250 qdev_prop_allow_set_link_before_realize
,
251 OBJ_PROP_LINK_UNREF_ON_RELEASE
, NULL
);
254 static const TypeInfo virtio_rng_info
= {
255 .name
= TYPE_VIRTIO_RNG
,
256 .parent
= TYPE_VIRTIO_DEVICE
,
257 .instance_size
= sizeof(VirtIORNG
),
258 .instance_init
= virtio_rng_initfn
,
259 .class_init
= virtio_rng_class_init
,
262 static void virtio_register_types(void)
264 type_register_static(&virtio_rng_info
);
267 type_init(virtio_register_types
)