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* Virtio RNG Support
* Copyright Red Hat, Inc. 2012
* Copyright Amit Shah <>
* This work is licensed under the terms of the GNU GPL, version 2 or
* (at your option) any later version. See the COPYING file in the
* top-level directory.
#include "sysemu/rng.h"
#include "sysemu/rng-random.h"
#define TYPE_VIRTIO_RNG "virtio-rng-device"
#define VIRTIO_RNG(obj) \
/* The Virtio ID for the virtio rng device */
#define VIRTIO_ID_RNG 4
struct VirtIORNGConf {
RngBackend *rng;
uint64_t max_bytes;
uint32_t period_ms;
RndRandom *default_backend;
typedef struct VirtIORNG {
VirtIODevice parent_obj;
/* Only one vq - guest puts buffer(s) on it when it needs entropy */
VirtQueue *vq;
VirtIORNGConf conf;
RngBackend *rng;
/* We purposefully don't migrate this state. The quota will reset on the
* destination as a result. Rate limiting is host state, not guest state.
QEMUTimer *rate_limit_timer;
int64_t quota_remaining;
} VirtIORNG;
/* Set a default rate limit of 2^47 bytes per minute or roughly 2TB/s. If
you have an entropy source capable of generating more entropy than this
and you can pass it through via virtio-rng, then hats off to you. Until
then, this is unlimited for all practical purposes.
#define DEFINE_VIRTIO_RNG_PROPERTIES(_state, _conf_field) \
DEFINE_PROP_UINT64("max-bytes", _state, _conf_field.max_bytes, \
INT64_MAX), \
DEFINE_PROP_UINT32("period", _state, _conf_field.period_ms, 1 << 16)