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/*
* A virtio device implementing a hardware random number generator.
*
* Copyright 2012 Red Hat, Inc.
* Copyright 2012 Amit Shah <amit.shah@redhat.com>
*
* 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 "qemu/iov.h"
#include "hw/qdev.h"
#include "qapi/qmp/qerror.h"
#include "hw/virtio/virtio.h"
#include "hw/virtio/virtio-rng.h"
#include "sysemu/rng.h"
static bool is_guest_ready(VirtIORNG *vrng)
{
if (virtio_queue_ready(vrng->vq)
&& (vrng->vdev.status & VIRTIO_CONFIG_S_DRIVER_OK)) {
return true;
}
return false;
}
static size_t get_request_size(VirtQueue *vq, unsigned quota)
{
unsigned int in, out;
virtqueue_get_avail_bytes(vq, &in, &out, quota, 0);
return in;
}
static void virtio_rng_process(VirtIORNG *vrng);
/* Send data from a char device over to the guest */
static void chr_read(void *opaque, const void *buf, size_t size)
{
VirtIORNG *vrng = opaque;
VirtQueueElement elem;
size_t len;
int offset;
if (!is_guest_ready(vrng)) {
return;
}
vrng->quota_remaining -= size;
offset = 0;
while (offset < size) {
if (!virtqueue_pop(vrng->vq, &elem)) {
break;
}
len = iov_from_buf(elem.in_sg, elem.in_num,
0, buf + offset, size - offset);
offset += len;
virtqueue_push(vrng->vq, &elem, len);
}
virtio_notify(&vrng->vdev, vrng->vq);
}
static void virtio_rng_process(VirtIORNG *vrng)
{
size_t size;
unsigned quota;
if (!is_guest_ready(vrng)) {
return;
}
if (vrng->quota_remaining < 0) {
quota = 0;
} else {
quota = MIN((uint64_t)vrng->quota_remaining, (uint64_t)UINT32_MAX);
}
size = get_request_size(vrng->vq, quota);
size = MIN(vrng->quota_remaining, size);
if (size) {
rng_backend_request_entropy(vrng->rng, size, chr_read, vrng);
}
}
static void handle_input(VirtIODevice *vdev, VirtQueue *vq)
{
VirtIORNG *vrng = DO_UPCAST(VirtIORNG, vdev, vdev);
virtio_rng_process(vrng);
}
static uint32_t get_features(VirtIODevice *vdev, uint32_t f)
{
return f;
}
static void virtio_rng_save(QEMUFile *f, void *opaque)
{
VirtIORNG *vrng = opaque;
virtio_save(&vrng->vdev, f);
}
static int virtio_rng_load(QEMUFile *f, void *opaque, int version_id)
{
VirtIORNG *vrng = opaque;
if (version_id != 1) {
return -EINVAL;
}
virtio_load(&vrng->vdev, f);
/* We may have an element ready but couldn't process it due to a quota
* limit. Make sure to try again after live migration when the quota may
* have been reset.
*/
virtio_rng_process(vrng);
return 0;
}
static void check_rate_limit(void *opaque)
{
VirtIORNG *s = opaque;
s->quota_remaining = s->conf.max_bytes;
virtio_rng_process(s);
qemu_mod_timer(s->rate_limit_timer,
qemu_get_clock_ms(vm_clock) + s->conf.period_ms);
}
static int virtio_rng_device_init(VirtIODevice *vdev)
{
DeviceState *qdev = DEVICE(vdev);
VirtIORNG *vrng = VIRTIO_RNG(vdev);
Error *local_err = NULL;
if (vrng->conf.rng == NULL) {
vrng->conf.default_backend = RNG_RANDOM(object_new(TYPE_RNG_RANDOM));
object_property_add_child(OBJECT(qdev),
"default-backend",
OBJECT(vrng->conf.default_backend),
NULL);
object_property_set_link(OBJECT(qdev),
OBJECT(vrng->conf.default_backend),
"rng", NULL);
}
virtio_init(vdev, "virtio-rng", VIRTIO_ID_RNG, 0);
vrng->rng = vrng->conf.rng;
if (vrng->rng == NULL) {
qerror_report(QERR_INVALID_PARAMETER_VALUE, "rng", "a valid object");
return -1;
}
rng_backend_open(vrng->rng, &local_err);
if (local_err) {
qerror_report_err(local_err);
error_free(local_err);
return -1;
}
vrng->vq = virtio_add_queue(vdev, 8, handle_input);
vrng->vdev.get_features = get_features;
assert(vrng->conf.max_bytes <= INT64_MAX);
vrng->quota_remaining = vrng->conf.max_bytes;
vrng->rate_limit_timer = qemu_new_timer_ms(vm_clock,
check_rate_limit, vrng);
qemu_mod_timer(vrng->rate_limit_timer,
qemu_get_clock_ms(vm_clock) + vrng->conf.period_ms);
register_savevm(qdev, "virtio-rng", -1, 1, virtio_rng_save,
virtio_rng_load, vrng);
return 0;
}
static int virtio_rng_device_exit(DeviceState *qdev)
{
VirtIORNG *vrng = VIRTIO_RNG(qdev);
VirtIODevice *vdev = VIRTIO_DEVICE(qdev);
qemu_del_timer(vrng->rate_limit_timer);
qemu_free_timer(vrng->rate_limit_timer);
unregister_savevm(qdev, "virtio-rng", vrng);
virtio_common_cleanup(vdev);
return 0;
}
static Property virtio_rng_properties[] = {
DEFINE_VIRTIO_RNG_PROPERTIES(VirtIORNG, conf),
DEFINE_PROP_END_OF_LIST(),
};
static void virtio_rng_class_init(ObjectClass *klass, void *data)
{
DeviceClass *dc = DEVICE_CLASS(klass);
VirtioDeviceClass *vdc = VIRTIO_DEVICE_CLASS(klass);
dc->exit = virtio_rng_device_exit;
dc->props = virtio_rng_properties;
vdc->init = virtio_rng_device_init;
vdc->get_features = get_features;
}
static void virtio_rng_initfn(Object *obj)
{
VirtIORNG *vrng = VIRTIO_RNG(obj);
object_property_add_link(obj, "rng", TYPE_RNG_BACKEND,
(Object **)&vrng->conf.rng, NULL);
}
static const TypeInfo virtio_rng_info = {
.name = TYPE_VIRTIO_RNG,
.parent = TYPE_VIRTIO_DEVICE,
.instance_size = sizeof(VirtIORNG),
.instance_init = virtio_rng_initfn,
.class_init = virtio_rng_class_init,
};
static void virtio_register_types(void)
{
type_register_static(&virtio_rng_info);
}
type_init(virtio_register_types)
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