vhost-user-rng: Add vhost-user-rng implementation

Introduce a random number generator (RNG) backend that communicates
with a vhost-user server to retrieve entropy.  That way other VMM
that comply with the vhost user protocl can use the same vhost-user
daemon without having to write yet another RNG driver.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Message-Id: <20211012205904.4106769-2-mathieu.poirier@linaro.org>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Mathieu Poirier 2021-10-12 14:59:02 -06:00 committed by Michael S. Tsirkin
parent 6889eb2d43
commit 821d28b88f
4 changed files with 328 additions and 0 deletions

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@ -63,3 +63,8 @@ config VHOST_USER_I2C
bool
default y
depends on VIRTIO && VHOST_USER
config VHOST_USER_RNG
bool
default y
depends on VIRTIO && VHOST_USER

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@ -27,6 +27,7 @@ virtio_ss.add(when: 'CONFIG_VIRTIO_IOMMU', if_true: files('virtio-iommu.c'))
virtio_ss.add(when: 'CONFIG_VIRTIO_MEM', if_true: files('virtio-mem.c'))
virtio_ss.add(when: 'CONFIG_VHOST_USER_I2C', if_true: files('vhost-user-i2c.c'))
virtio_ss.add(when: ['CONFIG_VIRTIO_PCI', 'CONFIG_VHOST_USER_I2C'], if_true: files('vhost-user-i2c-pci.c'))
virtio_ss.add(when: 'CONFIG_VHOST_USER_RNG', if_true: files('vhost-user-rng.c'))
virtio_pci_ss = ss.source_set()
virtio_pci_ss.add(when: 'CONFIG_VHOST_VSOCK', if_true: files('vhost-vsock-pci.c'))

289
hw/virtio/vhost-user-rng.c Normal file
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@ -0,0 +1,289 @@
/*
* Vhost-user RNG virtio device
*
* Copyright (c) 2021 Mathieu Poirier <mathieu.poirier@linaro.org>
*
* Implementation seriously tailored on vhost-user-i2c.c
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
#include "qemu/osdep.h"
#include "qapi/error.h"
#include "hw/qdev-properties.h"
#include "hw/virtio/virtio-bus.h"
#include "hw/virtio/vhost-user-rng.h"
#include "qemu/error-report.h"
#include "standard-headers/linux/virtio_ids.h"
static void vu_rng_start(VirtIODevice *vdev)
{
VHostUserRNG *rng = VHOST_USER_RNG(vdev);
BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(vdev)));
VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
int ret;
int i;
if (!k->set_guest_notifiers) {
error_report("binding does not support guest notifiers");
return;
}
ret = vhost_dev_enable_notifiers(&rng->vhost_dev, vdev);
if (ret < 0) {
error_report("Error enabling host notifiers: %d", -ret);
return;
}
ret = k->set_guest_notifiers(qbus->parent, rng->vhost_dev.nvqs, true);
if (ret < 0) {
error_report("Error binding guest notifier: %d", -ret);
goto err_host_notifiers;
}
rng->vhost_dev.acked_features = vdev->guest_features;
ret = vhost_dev_start(&rng->vhost_dev, vdev);
if (ret < 0) {
error_report("Error starting vhost-user-rng: %d", -ret);
goto err_guest_notifiers;
}
/*
* guest_notifier_mask/pending not used yet, so just unmask
* everything here. virtio-pci will do the right thing by
* enabling/disabling irqfd.
*/
for (i = 0; i < rng->vhost_dev.nvqs; i++) {
vhost_virtqueue_mask(&rng->vhost_dev, vdev, i, false);
}
return;
err_guest_notifiers:
k->set_guest_notifiers(qbus->parent, rng->vhost_dev.nvqs, false);
err_host_notifiers:
vhost_dev_disable_notifiers(&rng->vhost_dev, vdev);
}
static void vu_rng_stop(VirtIODevice *vdev)
{
VHostUserRNG *rng = VHOST_USER_RNG(vdev);
BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(vdev)));
VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(qbus);
int ret;
if (!k->set_guest_notifiers) {
return;
}
vhost_dev_stop(&rng->vhost_dev, vdev);
ret = k->set_guest_notifiers(qbus->parent, rng->vhost_dev.nvqs, false);
if (ret < 0) {
error_report("vhost guest notifier cleanup failed: %d", ret);
return;
}
vhost_dev_disable_notifiers(&rng->vhost_dev, vdev);
}
static void vu_rng_set_status(VirtIODevice *vdev, uint8_t status)
{
VHostUserRNG *rng = VHOST_USER_RNG(vdev);
bool should_start = status & VIRTIO_CONFIG_S_DRIVER_OK;
if (!vdev->vm_running) {
should_start = false;
}
if (rng->vhost_dev.started == should_start) {
return;
}
if (should_start) {
vu_rng_start(vdev);
} else {
vu_rng_stop(vdev);
}
}
static uint64_t vu_rng_get_features(VirtIODevice *vdev,
uint64_t requested_features, Error **errp)
{
/* No feature bits used yet */
return requested_features;
}
static void vu_rng_handle_output(VirtIODevice *vdev, VirtQueue *vq)
{
/*
* Not normally called; it's the daemon that handles the queue;
* however virtio's cleanup path can call this.
*/
}
static void vu_rng_guest_notifier_mask(VirtIODevice *vdev, int idx, bool mask)
{
VHostUserRNG *rng = VHOST_USER_RNG(vdev);
vhost_virtqueue_mask(&rng->vhost_dev, vdev, idx, mask);
}
static bool vu_rng_guest_notifier_pending(VirtIODevice *vdev, int idx)
{
VHostUserRNG *rng = VHOST_USER_RNG(vdev);
return vhost_virtqueue_pending(&rng->vhost_dev, idx);
}
static void vu_rng_connect(DeviceState *dev)
{
VirtIODevice *vdev = VIRTIO_DEVICE(dev);
VHostUserRNG *rng = VHOST_USER_RNG(vdev);
if (rng->connected) {
return;
}
rng->connected = true;
/* restore vhost state */
if (virtio_device_started(vdev, vdev->status)) {
vu_rng_start(vdev);
}
}
static void vu_rng_disconnect(DeviceState *dev)
{
VirtIODevice *vdev = VIRTIO_DEVICE(dev);
VHostUserRNG *rng = VHOST_USER_RNG(vdev);
if (!rng->connected) {
return;
}
rng->connected = false;
if (rng->vhost_dev.started) {
vu_rng_stop(vdev);
}
}
static void vu_rng_event(void *opaque, QEMUChrEvent event)
{
DeviceState *dev = opaque;
switch (event) {
case CHR_EVENT_OPENED:
vu_rng_connect(dev);
break;
case CHR_EVENT_CLOSED:
vu_rng_disconnect(dev);
break;
case CHR_EVENT_BREAK:
case CHR_EVENT_MUX_IN:
case CHR_EVENT_MUX_OUT:
/* Ignore */
break;
}
}
static void vu_rng_device_realize(DeviceState *dev, Error **errp)
{
VirtIODevice *vdev = VIRTIO_DEVICE(dev);
VHostUserRNG *rng = VHOST_USER_RNG(dev);
int ret;
if (!rng->chardev.chr) {
error_setg(errp, "missing chardev");
return;
}
if (!vhost_user_init(&rng->vhost_user, &rng->chardev, errp)) {
return;
}
virtio_init(vdev, "vhost-user-rng", VIRTIO_ID_RNG, 0);
rng->req_vq = virtio_add_queue(vdev, 4, vu_rng_handle_output);
if (!rng->req_vq) {
error_setg_errno(errp, -1, "virtio_add_queue() failed");
goto virtio_add_queue_failed;
}
rng->vhost_dev.nvqs = 1;
rng->vhost_dev.vqs = g_new0(struct vhost_virtqueue, rng->vhost_dev.nvqs);
ret = vhost_dev_init(&rng->vhost_dev, &rng->vhost_user,
VHOST_BACKEND_TYPE_USER, 0, errp);
if (ret < 0) {
error_setg_errno(errp, -ret, "vhost_dev_init() failed");
goto vhost_dev_init_failed;
}
qemu_chr_fe_set_handlers(&rng->chardev, NULL, NULL, vu_rng_event, NULL,
dev, NULL, true);
return;
vhost_dev_init_failed:
virtio_delete_queue(rng->req_vq);
virtio_add_queue_failed:
virtio_cleanup(vdev);
vhost_user_cleanup(&rng->vhost_user);
}
static void vu_rng_device_unrealize(DeviceState *dev)
{
VirtIODevice *vdev = VIRTIO_DEVICE(dev);
VHostUserRNG *rng = VHOST_USER_RNG(dev);
vu_rng_set_status(vdev, 0);
vhost_dev_cleanup(&rng->vhost_dev);
g_free(rng->vhost_dev.vqs);
rng->vhost_dev.vqs = NULL;
virtio_delete_queue(rng->req_vq);
virtio_cleanup(vdev);
vhost_user_cleanup(&rng->vhost_user);
}
static const VMStateDescription vu_rng_vmstate = {
.name = "vhost-user-rng",
.unmigratable = 1,
};
static Property vu_rng_properties[] = {
DEFINE_PROP_CHR("chardev", VHostUserRNG, chardev),
DEFINE_PROP_END_OF_LIST(),
};
static void vu_rng_class_init(ObjectClass *klass, void *data)
{
DeviceClass *dc = DEVICE_CLASS(klass);
VirtioDeviceClass *vdc = VIRTIO_DEVICE_CLASS(klass);
device_class_set_props(dc, vu_rng_properties);
dc->vmsd = &vu_rng_vmstate;
set_bit(DEVICE_CATEGORY_INPUT, dc->categories);
vdc->realize = vu_rng_device_realize;
vdc->unrealize = vu_rng_device_unrealize;
vdc->get_features = vu_rng_get_features;
vdc->set_status = vu_rng_set_status;
vdc->guest_notifier_mask = vu_rng_guest_notifier_mask;
vdc->guest_notifier_pending = vu_rng_guest_notifier_pending;
}
static const TypeInfo vu_rng_info = {
.name = TYPE_VHOST_USER_RNG,
.parent = TYPE_VIRTIO_DEVICE,
.instance_size = sizeof(VHostUserRNG),
.class_init = vu_rng_class_init,
};
static void vu_rng_register_types(void)
{
type_register_static(&vu_rng_info);
}
type_init(vu_rng_register_types)

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@ -0,0 +1,33 @@
/*
* Vhost-user RNG virtio device
*
* Copyright (c) 2021 Mathieu Poirier <mathieu.poirier@linaro.org>
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
#ifndef _QEMU_VHOST_USER_RNG_H
#define _QEMU_VHOST_USER_RNG_H
#include "hw/virtio/virtio.h"
#include "hw/virtio/vhost.h"
#include "hw/virtio/vhost-user.h"
#include "chardev/char-fe.h"
#define TYPE_VHOST_USER_RNG "vhost-user-rng"
OBJECT_DECLARE_SIMPLE_TYPE(VHostUserRNG, VHOST_USER_RNG)
struct VHostUserRNG {
/*< private >*/
VirtIODevice parent;
CharBackend chardev;
struct vhost_virtqueue *vhost_vq;
struct vhost_dev vhost_dev;
VhostUserState vhost_user;
VirtQueue *req_vq;
bool connected;
/*< public >*/
};
#endif /* _QEMU_VHOST_USER_RNG_H */