hw/virtio/virtio-rng.c - qemu - Git at Google

 /*
  * 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 VirtIODevice *virtio_rng_common_init(DeviceState *dev,
                                             VirtIORNGConf *conf,
                                             VirtIORNG **pvrng)
 {
     VirtIORNG *vrng = *pvrng;
     VirtIODevice *vdev;
     Error *local_err = NULL;

     /*
      * We have two cases here: the old virtio-rng-x device, and the
      * refactored virtio-rng.
      * This will disappear later in the serie.
      */
     if (vrng == NULL) {
         vdev = virtio_common_init("virtio-rng", VIRTIO_ID_RNG, 0,
                                   sizeof(VirtIORNG));
         vrng = DO_UPCAST(VirtIORNG, vdev, vdev);
     } else {
         vdev = VIRTIO_DEVICE(vrng);
         virtio_init(vdev, "virtio-rng", VIRTIO_ID_RNG, 0);
     }

     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;
     memcpy(&(vrng->conf), conf, sizeof(struct VirtIORNGConf));

     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(dev, "virtio-rng", -1, 1, virtio_rng_save,
                     virtio_rng_load, vrng);

     return vdev;
 }

 /*
  * This two functions will be removed later in the serie.
  */
 VirtIODevice *virtio_rng_init(DeviceState *dev, VirtIORNGConf *conf)
 {
     VirtIORNG *vdev = NULL;
     return virtio_rng_common_init(dev, conf, &vdev);
 }

 void virtio_rng_exit(VirtIODevice *vdev)
 {
     VirtIORNG *vrng = DO_UPCAST(VirtIORNG, vdev, vdev);

     qemu_del_timer(vrng->rate_limit_timer);
     qemu_free_timer(vrng->rate_limit_timer);
     unregister_savevm(vrng->qdev, "virtio-rng", vrng);
     virtio_cleanup(vdev);
 }

 static int virtio_rng_device_init(VirtIODevice *vdev)
 {
     DeviceState *qdev = DEVICE(vdev);
     VirtIORNG *vrng = VIRTIO_RNG(vdev);

     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);
     }

     if (virtio_rng_common_init(qdev, &(vrng->conf), &vrng) == NULL) {
         return -1;
     }
     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)
	/*
	* 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 VirtIODevice virtio_rng_common_init(DeviceState dev,
	VirtIORNGConf *conf,
	VirtIORNG **pvrng)
	{
	VirtIORNG vrng = pvrng;
	VirtIODevice *vdev;
	Error *local_err = NULL;

	/*
	* We have two cases here: the old virtio-rng-x device, and the
	* refactored virtio-rng.
	* This will disappear later in the serie.
	*/
	if (vrng == NULL) {
	vdev = virtio_common_init("virtio-rng", VIRTIO_ID_RNG, 0,
	sizeof(VirtIORNG));
	vrng = DO_UPCAST(VirtIORNG, vdev, vdev);
	} else {
	vdev = VIRTIO_DEVICE(vrng);
	virtio_init(vdev, "virtio-rng", VIRTIO_ID_RNG, 0);
	}

	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;
	memcpy(&(vrng->conf), conf, sizeof(struct VirtIORNGConf));

	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(dev, "virtio-rng", -1, 1, virtio_rng_save,
	virtio_rng_load, vrng);

	return vdev;
	}

	/*
	* This two functions will be removed later in the serie.
	*/
	VirtIODevice virtio_rng_init(DeviceState dev, VirtIORNGConf *conf)
	{
	VirtIORNG *vdev = NULL;
	return virtio_rng_common_init(dev, conf, &vdev);
	}

	void virtio_rng_exit(VirtIODevice *vdev)
	{
	VirtIORNG *vrng = DO_UPCAST(VirtIORNG, vdev, vdev);

	qemu_del_timer(vrng->rate_limit_timer);
	qemu_free_timer(vrng->rate_limit_timer);
	unregister_savevm(vrng->qdev, "virtio-rng", vrng);
	virtio_cleanup(vdev);
	}

	static int virtio_rng_device_init(VirtIODevice *vdev)
	{
	DeviceState *qdev = DEVICE(vdev);
	VirtIORNG *vrng = VIRTIO_RNG(vdev);

	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);
	}

	if (virtio_rng_common_init(qdev, &(vrng->conf), &vrng) == NULL) {
	return -1;
	}
	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)