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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 "iov.h"
#include "qdev.h"
#include "virtio.h"
#include "virtio-rng.h"
#include "qemu/rng.h"
typedef struct VirtIORNG {
VirtIODevice vdev;
DeviceState *qdev;
/* Only one vq - guest puts buffer(s) on it when it needs entropy */
VirtQueue *vq;
VirtQueueElement elem;
/* Config data for the device -- currently only chardev */
VirtIORNGConf *conf;
/* Whether we've popped a vq element into 'elem' above */
bool popped;
RngBackend *rng;
} VirtIORNG;
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 pop_an_elem(VirtIORNG *vrng)
{
size_t size;
if (!vrng->popped && !virtqueue_pop(vrng->vq, &vrng->elem)) {
return 0;
}
vrng->popped = true;
size = iov_size(vrng->elem.in_sg, vrng->elem.in_num);
return size;
}
/* 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;
size_t len;
int offset;
if (!is_guest_ready(vrng)) {
return;
}
offset = 0;
while (offset < size) {
if (!pop_an_elem(vrng)) {
break;
}
len = iov_from_buf(vrng->elem.in_sg, vrng->elem.in_num,
0, buf + offset, size - offset);
offset += len;
virtqueue_push(vrng->vq, &vrng->elem, len);
vrng->popped = false;
}
virtio_notify(&vrng->vdev, vrng->vq);
/*
* Lastly, if we had multiple elems queued by the guest, and we
* didn't have enough data to fill them all, indicate we want more
* data.
*/
len = pop_an_elem(vrng);
if (len) {
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);
size_t size;
size = pop_an_elem(vrng);
if (size) {
rng_backend_request_entropy(vrng->rng, size, chr_read, 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);
qemu_put_byte(f, vrng->popped);
if (vrng->popped) {
int i;
qemu_put_be32(f, vrng->elem.index);
qemu_put_be32(f, vrng->elem.in_num);
for (i = 0; i < vrng->elem.in_num; i++) {
qemu_put_be64(f, vrng->elem.in_addr[i]);
}
qemu_put_be32(f, vrng->elem.out_num);
for (i = 0; i < vrng->elem.out_num; i++) {
qemu_put_be64(f, vrng->elem.out_addr[i]);
}
}
}
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);
vrng->popped = qemu_get_byte(f);
if (vrng->popped) {
int i;
vrng->elem.index = qemu_get_be32(f);
vrng->elem.in_num = qemu_get_be32(f);
g_assert(vrng->elem.in_num < VIRTQUEUE_MAX_SIZE);
for (i = 0; i < vrng->elem.in_num; i++) {
vrng->elem.in_addr[i] = qemu_get_be64(f);
}
vrng->elem.out_num = qemu_get_be32(f);
g_assert(vrng->elem.out_num < VIRTQUEUE_MAX_SIZE);
for (i = 0; i < vrng->elem.out_num; i++) {
vrng->elem.out_addr[i] = qemu_get_be64(f);
}
virtqueue_map_sg(vrng->elem.in_sg, vrng->elem.in_addr,
vrng->elem.in_num, 1);
virtqueue_map_sg(vrng->elem.out_sg, vrng->elem.out_addr,
vrng->elem.out_num, 0);
}
return 0;
}
VirtIODevice *virtio_rng_init(DeviceState *dev, VirtIORNGConf *conf)
{
VirtIORNG *vrng;
VirtIODevice *vdev;
Error *local_err = NULL;
vdev = virtio_common_init("virtio-rng", VIRTIO_ID_RNG, 0,
sizeof(VirtIORNG));
vrng = DO_UPCAST(VirtIORNG, vdev, vdev);
vrng->rng = conf->rng;
if (vrng->rng == NULL) {
qerror_report(QERR_INVALID_PARAMETER_VALUE, "rng", "a valid object");
return NULL;
}
rng_backend_open(vrng->rng, &local_err);
if (local_err) {
qerror_report_err(local_err);
error_free(local_err);
return NULL;
}
vrng->vq = virtio_add_queue(vdev, 8, handle_input);
vrng->vdev.get_features = get_features;
vrng->qdev = dev;
vrng->conf = conf;
vrng->popped = false;
register_savevm(dev, "virtio-rng", -1, 1, virtio_rng_save,
virtio_rng_load, vrng);
return vdev;
}
void virtio_rng_exit(VirtIODevice *vdev)
{
VirtIORNG *vrng = DO_UPCAST(VirtIORNG, vdev, vdev);
unregister_savevm(vrng->qdev, "virtio-rng", vrng);
virtio_cleanup(vdev);
}
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