hw/virtio/virtio-bus.c - third_party/qemu - Git at Google

 /*
  * VirtioBus
  *
  *  Copyright (C) 2012 : GreenSocs Ltd
  *      http://www.greensocs.com/ , email: info@greensocs.com
  *
  *  Developed by :
  *  Frederic Konrad   <fred.konrad@greensocs.com>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  * the Free Software Foundation, either version 2 of the License, or
  * (at your option) any later version.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License along
  * with this program; if not, see <http://www.gnu.org/licenses/>.
  *
  */

 #include "qemu/osdep.h"
 #include "qemu/error-report.h"
 #include "qemu/module.h"
 #include "qapi/error.h"
 #include "hw/virtio/virtio-bus.h"
 #include "hw/virtio/virtio.h"
 #include "exec/address-spaces.h"

 /* #define DEBUG_VIRTIO_BUS */

 #ifdef DEBUG_VIRTIO_BUS
 #define DPRINTF(fmt, ...) \
 do { printf("virtio_bus: " fmt , ## __VA_ARGS__); } while (0)
 #else
 #define DPRINTF(fmt, ...) do { } while (0)
 #endif

 /* A VirtIODevice is being plugged */
 void virtio_bus_device_plugged(VirtIODevice *vdev, Error **errp)
 {
     DeviceState *qdev = DEVICE(vdev);
     BusState *qbus = BUS(qdev_get_parent_bus(qdev));
     VirtioBusState *bus = VIRTIO_BUS(qbus);
     VirtioBusClass *klass = VIRTIO_BUS_GET_CLASS(bus);
     VirtioDeviceClass *vdc = VIRTIO_DEVICE_GET_CLASS(vdev);
     bool has_iommu = virtio_host_has_feature(vdev, VIRTIO_F_IOMMU_PLATFORM);
     bool vdev_has_iommu;
     Error *local_err = NULL;

     DPRINTF("%s: plug device.\n", qbus->name);

     if (klass->pre_plugged != NULL) {
         klass->pre_plugged(qbus->parent, &local_err);
         if (local_err) {
             error_propagate(errp, local_err);
             return;
         }
     }

     /* Get the features of the plugged device. */
     assert(vdc->get_features != NULL);
     vdev->host_features = vdc->get_features(vdev, vdev->host_features,
                                             &local_err);
     if (local_err) {
         error_propagate(errp, local_err);
         return;
     }

     if (klass->device_plugged != NULL) {
         klass->device_plugged(qbus->parent, &local_err);
     }
     if (local_err) {
         error_propagate(errp, local_err);
         return;
     }

     vdev->dma_as = &address_space_memory;
     if (has_iommu) {
         vdev_has_iommu = virtio_host_has_feature(vdev, VIRTIO_F_IOMMU_PLATFORM);
         /*
          * Present IOMMU_PLATFORM to the driver iff iommu_plattform=on and
          * device operational. If the driver does not accept IOMMU_PLATFORM
          * we fail the device.
          */
         virtio_add_feature(&vdev->host_features, VIRTIO_F_IOMMU_PLATFORM);
         if (klass->get_dma_as) {
             vdev->dma_as = klass->get_dma_as(qbus->parent);
             if (!vdev_has_iommu && vdev->dma_as != &address_space_memory) {
                 error_setg(errp,
                        "iommu_platform=true is not supported by the device");
                 return;
             }
         }
     }
 }

 /* Reset the virtio_bus */
 void virtio_bus_reset(VirtioBusState *bus)
 {
     VirtIODevice *vdev = virtio_bus_get_device(bus);

     DPRINTF("%s: reset device.\n", BUS(bus)->name);
     virtio_bus_stop_ioeventfd(bus);
     if (vdev != NULL) {
         virtio_reset(vdev);
     }
 }

 /* A VirtIODevice is being unplugged */
 void virtio_bus_device_unplugged(VirtIODevice *vdev)
 {
     DeviceState *qdev = DEVICE(vdev);
     BusState *qbus = BUS(qdev_get_parent_bus(qdev));
     VirtioBusClass *klass = VIRTIO_BUS_GET_CLASS(qbus);

     DPRINTF("%s: remove device.\n", qbus->name);

     if (vdev != NULL) {
         if (klass->device_unplugged != NULL) {
             klass->device_unplugged(qbus->parent);
         }
     }
 }

 /* Get the device id of the plugged device. */
 uint16_t virtio_bus_get_vdev_id(VirtioBusState *bus)
 {
     VirtIODevice *vdev = virtio_bus_get_device(bus);
     assert(vdev != NULL);
     return vdev->device_id;
 }

 /* Get the config_len field of the plugged device. */
 size_t virtio_bus_get_vdev_config_len(VirtioBusState *bus)
 {
     VirtIODevice *vdev = virtio_bus_get_device(bus);
     assert(vdev != NULL);
     return vdev->config_len;
 }

 /* Get bad features of the plugged device. */
 uint32_t virtio_bus_get_vdev_bad_features(VirtioBusState *bus)
 {
     VirtIODevice *vdev = virtio_bus_get_device(bus);
     VirtioDeviceClass *k;

     assert(vdev != NULL);
     k = VIRTIO_DEVICE_GET_CLASS(vdev);
     if (k->bad_features != NULL) {
         return k->bad_features(vdev);
     } else {
         return 0;
     }
 }

 /* Get config of the plugged device. */
 void virtio_bus_get_vdev_config(VirtioBusState *bus, uint8_t *config)
 {
     VirtIODevice *vdev = virtio_bus_get_device(bus);
     VirtioDeviceClass *k;

     assert(vdev != NULL);
     k = VIRTIO_DEVICE_GET_CLASS(vdev);
     if (k->get_config != NULL) {
         k->get_config(vdev, config);
     }
 }

 /* Set config of the plugged device. */
 void virtio_bus_set_vdev_config(VirtioBusState *bus, uint8_t *config)
 {
     VirtIODevice *vdev = virtio_bus_get_device(bus);
     VirtioDeviceClass *k;

     assert(vdev != NULL);
     k = VIRTIO_DEVICE_GET_CLASS(vdev);
     if (k->set_config != NULL) {
         k->set_config(vdev, config);
     }
 }

 /* On success, ioeventfd ownership belongs to the caller.  */
 int virtio_bus_grab_ioeventfd(VirtioBusState *bus)
 {
     VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(bus);

     /* vhost can be used even if ioeventfd=off in the proxy device,
      * so do not check k->ioeventfd_enabled.
      */
     if (!k->ioeventfd_assign) {
         return -ENOSYS;
     }

     if (bus->ioeventfd_grabbed == 0 && bus->ioeventfd_started) {
         virtio_bus_stop_ioeventfd(bus);
         /* Remember that we need to restart ioeventfd
          * when ioeventfd_grabbed becomes zero.
          */
         bus->ioeventfd_started = true;
     }
     bus->ioeventfd_grabbed++;
     return 0;
 }

 void virtio_bus_release_ioeventfd(VirtioBusState *bus)
 {
     assert(bus->ioeventfd_grabbed != 0);
     if (--bus->ioeventfd_grabbed == 0 && bus->ioeventfd_started) {
         /* Force virtio_bus_start_ioeventfd to act.  */
         bus->ioeventfd_started = false;
         virtio_bus_start_ioeventfd(bus);
     }
 }

 int virtio_bus_start_ioeventfd(VirtioBusState *bus)
 {
     VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(bus);
     DeviceState *proxy = DEVICE(BUS(bus)->parent);
     VirtIODevice *vdev = virtio_bus_get_device(bus);
     VirtioDeviceClass *vdc = VIRTIO_DEVICE_GET_CLASS(vdev);
     int r;

     if (!k->ioeventfd_assign || !k->ioeventfd_enabled(proxy)) {
         return -ENOSYS;
     }
     if (bus->ioeventfd_started) {
         return 0;
     }

     /* Only set our notifier if we have ownership.  */
     if (!bus->ioeventfd_grabbed) {
         r = vdc->start_ioeventfd(vdev);
         if (r < 0) {
             error_report("%s: failed. Fallback to userspace (slower).", __func__);
             return r;
         }
     }
     bus->ioeventfd_started = true;
     return 0;
 }

 void virtio_bus_stop_ioeventfd(VirtioBusState *bus)
 {
     VirtIODevice *vdev;
     VirtioDeviceClass *vdc;

     if (!bus->ioeventfd_started) {
         return;
     }

     /* Only remove our notifier if we have ownership.  */
     if (!bus->ioeventfd_grabbed) {
         vdev = virtio_bus_get_device(bus);
         vdc = VIRTIO_DEVICE_GET_CLASS(vdev);
         vdc->stop_ioeventfd(vdev);
     }
     bus->ioeventfd_started = false;
 }

 bool virtio_bus_ioeventfd_enabled(VirtioBusState *bus)
 {
     VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(bus);
     DeviceState *proxy = DEVICE(BUS(bus)->parent);

     return k->ioeventfd_assign && k->ioeventfd_enabled(proxy);
 }

 /*
  * This function switches ioeventfd on/off in the device.
  * The caller must set or clear the handlers for the EventNotifier.
  */
 int virtio_bus_set_host_notifier(VirtioBusState *bus, int n, bool assign)
 {
     VirtIODevice *vdev = virtio_bus_get_device(bus);
     VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(bus);
     DeviceState *proxy = DEVICE(BUS(bus)->parent);
     VirtQueue *vq = virtio_get_queue(vdev, n);
     EventNotifier *notifier = virtio_queue_get_host_notifier(vq);
     int r = 0;

     if (!k->ioeventfd_assign) {
         return -ENOSYS;
     }

     if (assign) {
         r = event_notifier_init(notifier, 1);
         if (r < 0) {
             error_report("%s: unable to init event notifier: %s (%d)",
                          __func__, strerror(-r), r);
             return r;
         }
         r = k->ioeventfd_assign(proxy, notifier, n, true);
         if (r < 0) {
             error_report("%s: unable to assign ioeventfd: %d", __func__, r);
             virtio_bus_cleanup_host_notifier(bus, n);
         }
     } else {
         k->ioeventfd_assign(proxy, notifier, n, false);
     }

     if (r == 0) {
         virtio_queue_set_host_notifier_enabled(vq, assign);
     }

     return r;
 }

 void virtio_bus_cleanup_host_notifier(VirtioBusState *bus, int n)
 {
     VirtIODevice *vdev = virtio_bus_get_device(bus);
     VirtQueue *vq = virtio_get_queue(vdev, n);
     EventNotifier *notifier = virtio_queue_get_host_notifier(vq);

     /* Test and clear notifier after disabling event,
      * in case poll callback didn't have time to run.
      */
     virtio_queue_host_notifier_read(notifier);
     event_notifier_cleanup(notifier);
 }

 static char *virtio_bus_get_dev_path(DeviceState *dev)
 {
     BusState *bus = qdev_get_parent_bus(dev);
     DeviceState *proxy = DEVICE(bus->parent);
     return qdev_get_dev_path(proxy);
 }

 static char *virtio_bus_get_fw_dev_path(DeviceState *dev)
 {
     return NULL;
 }

 bool virtio_bus_device_iommu_enabled(VirtIODevice *vdev)
 {
     DeviceState *qdev = DEVICE(vdev);
     BusState *qbus = BUS(qdev_get_parent_bus(qdev));
     VirtioBusState *bus = VIRTIO_BUS(qbus);
     VirtioBusClass *klass = VIRTIO_BUS_GET_CLASS(bus);

     if (!klass->iommu_enabled) {
         return false;
     }

     return klass->iommu_enabled(qbus->parent);
 }

 static void virtio_bus_class_init(ObjectClass *klass, void *data)
 {
     BusClass *bus_class = BUS_CLASS(klass);
     bus_class->get_dev_path = virtio_bus_get_dev_path;
     bus_class->get_fw_dev_path = virtio_bus_get_fw_dev_path;
 }

 static const TypeInfo virtio_bus_info = {
     .name = TYPE_VIRTIO_BUS,
     .parent = TYPE_BUS,
     .instance_size = sizeof(VirtioBusState),
     .abstract = true,
     .class_size = sizeof(VirtioBusClass),
     .class_init = virtio_bus_class_init
 };

 static void virtio_register_types(void)
 {
     type_register_static(&virtio_bus_info);
 }

 type_init(virtio_register_types)
	/*
	* VirtioBus
	*
	* Copyright (C) 2012 : GreenSocs Ltd
	* http://www.greensocs.com/ , email: info@greensocs.com
	*
	* Developed by :
	* Frederic Konrad <fred.konrad@greensocs.com>
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License as published by
	* the Free Software Foundation, either version 2 of the License, or
	* (at your option) any later version.
	*
	* This program is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	* GNU General Public License for more details.
	*
	* You should have received a copy of the GNU General Public License along
	* with this program; if not, see <http://www.gnu.org/licenses/>.
	*
	*/

	#include "qemu/osdep.h"
	#include "qemu/error-report.h"
	#include "qemu/module.h"
	#include "qapi/error.h"
	#include "hw/virtio/virtio-bus.h"
	#include "hw/virtio/virtio.h"
	#include "exec/address-spaces.h"

	/* #define DEBUG_VIRTIO_BUS */

	#ifdef DEBUG_VIRTIO_BUS
	#define DPRINTF(fmt, ...) \
	do { printf("virtio_bus: " fmt , ## __VA_ARGS__); } while (0)
	#else
	#define DPRINTF(fmt, ...) do { } while (0)
	#endif

	/* A VirtIODevice is being plugged */
	void virtio_bus_device_plugged(VirtIODevice vdev, Error *errp)
	{
	DeviceState *qdev = DEVICE(vdev);
	BusState *qbus = BUS(qdev_get_parent_bus(qdev));
	VirtioBusState *bus = VIRTIO_BUS(qbus);
	VirtioBusClass *klass = VIRTIO_BUS_GET_CLASS(bus);
	VirtioDeviceClass *vdc = VIRTIO_DEVICE_GET_CLASS(vdev);
	bool has_iommu = virtio_host_has_feature(vdev, VIRTIO_F_IOMMU_PLATFORM);
	bool vdev_has_iommu;
	Error *local_err = NULL;

	DPRINTF("%s: plug device.\n", qbus->name);

	if (klass->pre_plugged != NULL) {
	klass->pre_plugged(qbus->parent, &local_err);
	if (local_err) {
	error_propagate(errp, local_err);
	return;
	}
	}

	/* Get the features of the plugged device. */
	assert(vdc->get_features != NULL);
	vdev->host_features = vdc->get_features(vdev, vdev->host_features,
	&local_err);
	if (local_err) {
	error_propagate(errp, local_err);
	return;
	}

	if (klass->device_plugged != NULL) {
	klass->device_plugged(qbus->parent, &local_err);
	}
	if (local_err) {
	error_propagate(errp, local_err);
	return;
	}

	vdev->dma_as = &address_space_memory;
	if (has_iommu) {
	vdev_has_iommu = virtio_host_has_feature(vdev, VIRTIO_F_IOMMU_PLATFORM);
	/*
	* Present IOMMU_PLATFORM to the driver iff iommu_plattform=on and
	* device operational. If the driver does not accept IOMMU_PLATFORM
	* we fail the device.
	*/
	virtio_add_feature(&vdev->host_features, VIRTIO_F_IOMMU_PLATFORM);
	if (klass->get_dma_as) {
	vdev->dma_as = klass->get_dma_as(qbus->parent);
	if (!vdev_has_iommu && vdev->dma_as != &address_space_memory) {
	error_setg(errp,
	"iommu_platform=true is not supported by the device");
	return;
	}
	}
	}
	}

	/* Reset the virtio_bus */
	void virtio_bus_reset(VirtioBusState *bus)
	{
	VirtIODevice *vdev = virtio_bus_get_device(bus);

	DPRINTF("%s: reset device.\n", BUS(bus)->name);
	virtio_bus_stop_ioeventfd(bus);
	if (vdev != NULL) {
	virtio_reset(vdev);
	}
	}

	/* A VirtIODevice is being unplugged */
	void virtio_bus_device_unplugged(VirtIODevice *vdev)
	{
	DeviceState *qdev = DEVICE(vdev);
	BusState *qbus = BUS(qdev_get_parent_bus(qdev));
	VirtioBusClass *klass = VIRTIO_BUS_GET_CLASS(qbus);

	DPRINTF("%s: remove device.\n", qbus->name);

	if (vdev != NULL) {
	if (klass->device_unplugged != NULL) {
	klass->device_unplugged(qbus->parent);
	}
	}
	}

	/* Get the device id of the plugged device. */
	uint16_t virtio_bus_get_vdev_id(VirtioBusState *bus)
	{
	VirtIODevice *vdev = virtio_bus_get_device(bus);
	assert(vdev != NULL);
	return vdev->device_id;
	}

	/* Get the config_len field of the plugged device. */
	size_t virtio_bus_get_vdev_config_len(VirtioBusState *bus)
	{
	VirtIODevice *vdev = virtio_bus_get_device(bus);
	assert(vdev != NULL);
	return vdev->config_len;
	}

	/* Get bad features of the plugged device. */
	uint32_t virtio_bus_get_vdev_bad_features(VirtioBusState *bus)
	{
	VirtIODevice *vdev = virtio_bus_get_device(bus);
	VirtioDeviceClass *k;

	assert(vdev != NULL);
	k = VIRTIO_DEVICE_GET_CLASS(vdev);
	if (k->bad_features != NULL) {
	return k->bad_features(vdev);
	} else {
	return 0;
	}
	}

	/* Get config of the plugged device. */
	void virtio_bus_get_vdev_config(VirtioBusState bus, uint8_t config)
	{
	VirtIODevice *vdev = virtio_bus_get_device(bus);
	VirtioDeviceClass *k;

	assert(vdev != NULL);
	k = VIRTIO_DEVICE_GET_CLASS(vdev);
	if (k->get_config != NULL) {
	k->get_config(vdev, config);
	}
	}

	/* Set config of the plugged device. */
	void virtio_bus_set_vdev_config(VirtioBusState bus, uint8_t config)
	{
	VirtIODevice *vdev = virtio_bus_get_device(bus);
	VirtioDeviceClass *k;

	assert(vdev != NULL);
	k = VIRTIO_DEVICE_GET_CLASS(vdev);
	if (k->set_config != NULL) {
	k->set_config(vdev, config);
	}
	}

	/* On success, ioeventfd ownership belongs to the caller. */
	int virtio_bus_grab_ioeventfd(VirtioBusState *bus)
	{
	VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(bus);

	/* vhost can be used even if ioeventfd=off in the proxy device,
	* so do not check k->ioeventfd_enabled.
	*/
	if (!k->ioeventfd_assign) {
	return -ENOSYS;
	}

	if (bus->ioeventfd_grabbed == 0 && bus->ioeventfd_started) {
	virtio_bus_stop_ioeventfd(bus);
	/* Remember that we need to restart ioeventfd
	* when ioeventfd_grabbed becomes zero.
	*/
	bus->ioeventfd_started = true;
	}
	bus->ioeventfd_grabbed++;
	return 0;
	}

	void virtio_bus_release_ioeventfd(VirtioBusState *bus)
	{
	assert(bus->ioeventfd_grabbed != 0);
	if (--bus->ioeventfd_grabbed == 0 && bus->ioeventfd_started) {
	/* Force virtio_bus_start_ioeventfd to act. */
	bus->ioeventfd_started = false;
	virtio_bus_start_ioeventfd(bus);
	}
	}

	int virtio_bus_start_ioeventfd(VirtioBusState *bus)
	{
	VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(bus);
	DeviceState *proxy = DEVICE(BUS(bus)->parent);
	VirtIODevice *vdev = virtio_bus_get_device(bus);
	VirtioDeviceClass *vdc = VIRTIO_DEVICE_GET_CLASS(vdev);
	int r;

	if (!k->ioeventfd_assign \|\| !k->ioeventfd_enabled(proxy)) {
	return -ENOSYS;
	}
	if (bus->ioeventfd_started) {
	return 0;
	}

	/* Only set our notifier if we have ownership. */
	if (!bus->ioeventfd_grabbed) {
	r = vdc->start_ioeventfd(vdev);
	if (r < 0) {
	error_report("%s: failed. Fallback to userspace (slower).", __func__);
	return r;
	}
	}
	bus->ioeventfd_started = true;
	return 0;
	}

	void virtio_bus_stop_ioeventfd(VirtioBusState *bus)
	{
	VirtIODevice *vdev;
	VirtioDeviceClass *vdc;

	if (!bus->ioeventfd_started) {
	return;
	}

	/* Only remove our notifier if we have ownership. */
	if (!bus->ioeventfd_grabbed) {
	vdev = virtio_bus_get_device(bus);
	vdc = VIRTIO_DEVICE_GET_CLASS(vdev);
	vdc->stop_ioeventfd(vdev);
	}
	bus->ioeventfd_started = false;
	}

	bool virtio_bus_ioeventfd_enabled(VirtioBusState *bus)
	{
	VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(bus);
	DeviceState *proxy = DEVICE(BUS(bus)->parent);

	return k->ioeventfd_assign && k->ioeventfd_enabled(proxy);
	}

	/*
	* This function switches ioeventfd on/off in the device.
	* The caller must set or clear the handlers for the EventNotifier.
	*/
	int virtio_bus_set_host_notifier(VirtioBusState *bus, int n, bool assign)
	{
	VirtIODevice *vdev = virtio_bus_get_device(bus);
	VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(bus);
	DeviceState *proxy = DEVICE(BUS(bus)->parent);
	VirtQueue *vq = virtio_get_queue(vdev, n);
	EventNotifier *notifier = virtio_queue_get_host_notifier(vq);
	int r = 0;

	if (!k->ioeventfd_assign) {
	return -ENOSYS;
	}

	if (assign) {
	r = event_notifier_init(notifier, 1);
	if (r < 0) {
	error_report("%s: unable to init event notifier: %s (%d)",
	__func__, strerror(-r), r);
	return r;
	}
	r = k->ioeventfd_assign(proxy, notifier, n, true);
	if (r < 0) {
	error_report("%s: unable to assign ioeventfd: %d", __func__, r);
	virtio_bus_cleanup_host_notifier(bus, n);
	}
	} else {
	k->ioeventfd_assign(proxy, notifier, n, false);
	}

	if (r == 0) {
	virtio_queue_set_host_notifier_enabled(vq, assign);
	}

	return r;
	}

	void virtio_bus_cleanup_host_notifier(VirtioBusState *bus, int n)
	{
	VirtIODevice *vdev = virtio_bus_get_device(bus);
	VirtQueue *vq = virtio_get_queue(vdev, n);
	EventNotifier *notifier = virtio_queue_get_host_notifier(vq);

	/* Test and clear notifier after disabling event,
	* in case poll callback didn't have time to run.
	*/
	virtio_queue_host_notifier_read(notifier);
	event_notifier_cleanup(notifier);
	}

	static char virtio_bus_get_dev_path(DeviceState dev)
	{
	BusState *bus = qdev_get_parent_bus(dev);
	DeviceState *proxy = DEVICE(bus->parent);
	return qdev_get_dev_path(proxy);
	}

	static char virtio_bus_get_fw_dev_path(DeviceState dev)
	{
	return NULL;
	}

	bool virtio_bus_device_iommu_enabled(VirtIODevice *vdev)
	{
	DeviceState *qdev = DEVICE(vdev);
	BusState *qbus = BUS(qdev_get_parent_bus(qdev));
	VirtioBusState *bus = VIRTIO_BUS(qbus);
	VirtioBusClass *klass = VIRTIO_BUS_GET_CLASS(bus);

	if (!klass->iommu_enabled) {
	return false;
	}

	return klass->iommu_enabled(qbus->parent);
	}

	static void virtio_bus_class_init(ObjectClass klass, void data)
	{
	BusClass *bus_class = BUS_CLASS(klass);
	bus_class->get_dev_path = virtio_bus_get_dev_path;
	bus_class->get_fw_dev_path = virtio_bus_get_fw_dev_path;
	}

	static const TypeInfo virtio_bus_info = {
	.name = TYPE_VIRTIO_BUS,
	.parent = TYPE_BUS,
	.instance_size = sizeof(VirtioBusState),
	.abstract = true,
	.class_size = sizeof(VirtioBusClass),
	.class_init = virtio_bus_class_init
	};

	static void virtio_register_types(void)
	{
	type_register_static(&virtio_bus_info);
	}

	type_init(virtio_register_types)