qemu-e2k/hw/virtio/virtio-rng.c

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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/osdep.h"
2016-03-14 09:01:28 +01:00
#include "qapi/error.h"
#include "qemu/iov.h"
#include "hw/qdev.h"
#include "hw/virtio/virtio.h"
#include "hw/virtio/virtio-rng.h"
#include "sysemu/rng.h"
#include "qom/object_interfaces.h"
#include "trace.h"
static bool is_guest_ready(VirtIORNG *vrng)
{
VirtIODevice *vdev = VIRTIO_DEVICE(vrng);
if (virtio_queue_ready(vrng->vq)
&& (vdev->status & VIRTIO_CONFIG_S_DRIVER_OK)) {
return true;
}
trace_virtio_rng_guest_not_ready(vrng);
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;
VirtIODevice *vdev = VIRTIO_DEVICE(vrng);
VirtQueueElement *elem;
size_t len;
int offset;
if (!is_guest_ready(vrng)) {
return;
}
/* we can't modify the virtqueue until
* our state is fully synced
*/
if (!runstate_check(RUN_STATE_RUNNING)) {
trace_virtio_rng_cpu_is_stopped(vrng, size);
return;
}
vrng->quota_remaining -= size;
offset = 0;
while (offset < size) {
elem = virtqueue_pop(vrng->vq, sizeof(VirtQueueElement));
if (!elem) {
break;
}
trace_virtio_rng_popped(vrng);
len = iov_from_buf(elem->in_sg, elem->in_num,
0, buf + offset, size - offset);
offset += len;
virtqueue_push(vrng->vq, elem, len);
trace_virtio_rng_pushed(vrng, len);
g_free(elem);
}
virtio_notify(vdev, vrng->vq);
if (!virtio_queue_empty(vrng->vq)) {
/* If we didn't drain the queue, call virtio_rng_process
* to take care of asking for more data as appropriate.
*/
virtio_rng_process(vrng);
}
}
static void virtio_rng_process(VirtIORNG *vrng)
{
size_t size;
unsigned quota;
if (!is_guest_ready(vrng)) {
return;
}
if (vrng->activate_timer) {
timer_mod(vrng->rate_limit_timer,
qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL) + vrng->conf.period_ms);
vrng->activate_timer = false;
}
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);
trace_virtio_rng_request(vrng, size, 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 = VIRTIO_RNG(vdev);
virtio_rng_process(vrng);
}
static uint64_t get_features(VirtIODevice *vdev, uint64_t f, Error **errp)
{
return f;
}
static void virtio_rng_vm_state_change(void *opaque, int running,
RunState state)
{
Fix for crash after migration in virtio-rng on bi-endian targets VirtIO devices now remember which endianness they're operating in in order to support targets which may have guests of either endianness, such as powerpc. This endianness state is transferred in a subsection of the virtio device's information. With virtio-rng this can lead to an abort after a loadvm hitting the assert() in virtio_is_big_endian(). This can be reproduced by doing a migrate and load from file on a bi-endian target with a virtio-rng device. The actual guest state isn't particularly important to triggering this. The cause is that virtio_rng_load_device() calls virtio_rng_process() which accesses the ring and thus needs the endianness. However, virtio_rng_process() is called via virtio_load() before it loads the subsections. Essentially the ->load callback in VirtioDeviceClass should only be used for actually reading the device state from the stream, not for post-load re-initialization. This patch fixes the bug by moving the virtio_rng_process() after the call to virtio_load(). Better yet would be to convert virtio to use vmsd and have the virtio_rng_process() as a post_load callback, but that's a bigger project for another day. This is bugfix, and should be considered for the 2.2 branch. Signed-off-by: David Gibson <david@gibson.dropbear.id.au> Reviewed-by: Greg Kurz <gkurz@linux.vnet.ibm.com> Message-id: 1417067290-20715-1-git-send-email-david@gibson.dropbear.id.au Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
2014-11-27 06:48:10 +01:00
VirtIORNG *vrng = opaque;
trace_virtio_rng_vm_state_change(vrng, running, state);
/* We may have an element ready but couldn't process it due to a quota
* limit or because CPU was stopped. Make sure to try again when the
* CPU restart.
*/
if (running && is_guest_ready(vrng)) {
virtio_rng_process(vrng);
}
}
static void check_rate_limit(void *opaque)
{
VirtIORNG *vrng = opaque;
vrng->quota_remaining = vrng->conf.max_bytes;
virtio_rng_process(vrng);
vrng->activate_timer = true;
}
static void virtio_rng_device_realize(DeviceState *dev, Error **errp)
{
VirtIODevice *vdev = VIRTIO_DEVICE(dev);
VirtIORNG *vrng = VIRTIO_RNG(dev);
Error *local_err = NULL;
if (vrng->conf.period_ms <= 0) {
error_setg(errp, "'period' parameter expects a positive integer");
return;
}
/* Workaround: Property parsing does not enforce unsigned integers,
* So this is a hack to reject such numbers. */
if (vrng->conf.max_bytes > INT64_MAX) {
error_setg(errp, "'max-bytes' parameter must be non-negative, "
"and less than 2^63");
return;
}
if (vrng->conf.rng == NULL) {
vrng->conf.default_backend = RNG_RANDOM(object_new(TYPE_RNG_RANDOM));
user_creatable_complete(OBJECT(vrng->conf.default_backend),
&local_err);
if (local_err) {
error_propagate(errp, local_err);
object_unref(OBJECT(vrng->conf.default_backend));
return;
}
object_property_add_child(OBJECT(dev),
"default-backend",
OBJECT(vrng->conf.default_backend),
NULL);
/* The child property took a reference, we can safely drop ours now */
object_unref(OBJECT(vrng->conf.default_backend));
object_property_set_link(OBJECT(dev),
OBJECT(vrng->conf.default_backend),
"rng", NULL);
}
vrng->rng = vrng->conf.rng;
if (vrng->rng == NULL) {
error_setg(errp, "'rng' parameter expects a valid object");
return;
}
virtio_init(vdev, "virtio-rng", VIRTIO_ID_RNG, 0);
vrng->vq = virtio_add_queue(vdev, 8, handle_input);
vrng->quota_remaining = vrng->conf.max_bytes;
vrng->rate_limit_timer = timer_new_ms(QEMU_CLOCK_VIRTUAL,
check_rate_limit, vrng);
vrng->activate_timer = true;
vrng->vmstate = qemu_add_vm_change_state_handler(virtio_rng_vm_state_change,
vrng);
}
static void virtio_rng_device_unrealize(DeviceState *dev, Error **errp)
{
VirtIODevice *vdev = VIRTIO_DEVICE(dev);
VirtIORNG *vrng = VIRTIO_RNG(dev);
qemu_del_vm_change_state_handler(vrng->vmstate);
timer_del(vrng->rate_limit_timer);
timer_free(vrng->rate_limit_timer);
virtio_cleanup(vdev);
}
static const VMStateDescription vmstate_virtio_rng = {
.name = "virtio-rng",
.minimum_version_id = 1,
.version_id = 1,
.fields = (VMStateField[]) {
VMSTATE_VIRTIO_DEVICE,
VMSTATE_END_OF_LIST()
},
};
static Property virtio_rng_properties[] = {
/* 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_PROP_UINT64("max-bytes", VirtIORNG, conf.max_bytes, INT64_MAX),
DEFINE_PROP_UINT32("period", VirtIORNG, conf.period_ms, 1 << 16),
DEFINE_PROP_LINK("rng", VirtIORNG, conf.rng, TYPE_RNG_BACKEND, RngBackend *),
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->props = virtio_rng_properties;
dc->vmsd = &vmstate_virtio_rng;
set_bit(DEVICE_CATEGORY_MISC, dc->categories);
vdc->realize = virtio_rng_device_realize;
vdc->unrealize = virtio_rng_device_unrealize;
vdc->get_features = get_features;
}
static const TypeInfo virtio_rng_info = {
.name = TYPE_VIRTIO_RNG,
.parent = TYPE_VIRTIO_DEVICE,
.instance_size = sizeof(VirtIORNG),
.class_init = virtio_rng_class_init,
};
static void virtio_register_types(void)
{
type_register_static(&virtio_rng_info);
}
type_init(virtio_register_types)