xref: /openbmc/qemu/include/hw/virtio/virtio-rng.h (revision 2c9b15ca)
1 /*
2  * Virtio RNG Support
3  *
4  * Copyright Red Hat, Inc. 2012
5  * Copyright 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 #ifndef _QEMU_VIRTIO_RNG_H
13 #define _QEMU_VIRTIO_RNG_H
14 
15 #include "sysemu/rng.h"
16 #include "sysemu/rng-random.h"
17 
18 #define TYPE_VIRTIO_RNG "virtio-rng-device"
19 #define VIRTIO_RNG(obj) \
20         OBJECT_CHECK(VirtIORNG, (obj), TYPE_VIRTIO_RNG)
21 
22 /* The Virtio ID for the virtio rng device */
23 #define VIRTIO_ID_RNG    4
24 
25 struct VirtIORNGConf {
26     RngBackend *rng;
27     uint64_t max_bytes;
28     uint32_t period_ms;
29     RndRandom *default_backend;
30 };
31 
32 typedef struct VirtIORNG {
33     VirtIODevice parent_obj;
34 
35     /* Only one vq - guest puts buffer(s) on it when it needs entropy */
36     VirtQueue *vq;
37 
38     VirtIORNGConf conf;
39 
40     RngBackend *rng;
41 
42     /* We purposefully don't migrate this state.  The quota will reset on the
43      * destination as a result.  Rate limiting is host state, not guest state.
44      */
45     QEMUTimer *rate_limit_timer;
46     int64_t quota_remaining;
47 } VirtIORNG;
48 
49 /* Set a default rate limit of 2^47 bytes per minute or roughly 2TB/s.  If
50    you have an entropy source capable of generating more entropy than this
51    and you can pass it through via virtio-rng, then hats off to you.  Until
52    then, this is unlimited for all practical purposes.
53 */
54 #define DEFINE_VIRTIO_RNG_PROPERTIES(_state, _conf_field)                    \
55         DEFINE_PROP_UINT64("max-bytes", _state, _conf_field.max_bytes,       \
56                            INT64_MAX),                                       \
57         DEFINE_PROP_UINT32("period", _state, _conf_field.period_ms, 1 << 16)
58 
59 #endif
60