hw/net/vhost_net.c - qemu - Git at Google

 /*
  * vhost-net support
  *
  * Copyright Red Hat, Inc. 2010
  *
  * Authors:
  *  Michael S. Tsirkin <mst@redhat.com>
  *
  * This work is licensed under the terms of the GNU GPL, version 2.  See
  * the COPYING file in the top-level directory.
  *
  * Contributions after 2012-01-13 are licensed under the terms of the
  * GNU GPL, version 2 or (at your option) any later version.
  */

 #include "net/net.h"
 #include "net/tap.h"
 #include "net/vhost-user.h"

 #include "hw/virtio/virtio-net.h"
 #include "net/vhost_net.h"
 #include "qemu/error-report.h"

 #include "config.h"

 #ifdef CONFIG_VHOST_NET
 #include <linux/vhost.h>
 #include <sys/socket.h>
 #include <linux/kvm.h>
 #include <fcntl.h>
 #include <netpacket/packet.h>
 #include <net/ethernet.h>
 #include <net/if.h>
 #include <netinet/in.h>

 #include <stdio.h>

 #include "standard-headers/linux/virtio_ring.h"
 #include "hw/virtio/vhost.h"
 #include "hw/virtio/virtio-bus.h"
 #include "hw/virtio/virtio-access.h"

 struct vhost_net {
     struct vhost_dev dev;
     struct vhost_virtqueue vqs[2];
     int backend;
     NetClientState *nc;
 };

 /* Features supported by host kernel. */
 static const int kernel_feature_bits[] = {
     VIRTIO_F_NOTIFY_ON_EMPTY,
     VIRTIO_RING_F_INDIRECT_DESC,
     VIRTIO_RING_F_EVENT_IDX,
     VIRTIO_NET_F_MRG_RXBUF,
     VIRTIO_F_VERSION_1,
     VHOST_INVALID_FEATURE_BIT
 };

 /* Features supported by others. */
 static const int user_feature_bits[] = {
     VIRTIO_F_NOTIFY_ON_EMPTY,
     VIRTIO_RING_F_INDIRECT_DESC,
     VIRTIO_RING_F_EVENT_IDX,

     VIRTIO_F_ANY_LAYOUT,
     VIRTIO_F_VERSION_1,
     VIRTIO_NET_F_CSUM,
     VIRTIO_NET_F_GUEST_CSUM,
     VIRTIO_NET_F_GSO,
     VIRTIO_NET_F_GUEST_TSO4,
     VIRTIO_NET_F_GUEST_TSO6,
     VIRTIO_NET_F_GUEST_ECN,
     VIRTIO_NET_F_GUEST_UFO,
     VIRTIO_NET_F_HOST_TSO4,
     VIRTIO_NET_F_HOST_TSO6,
     VIRTIO_NET_F_HOST_ECN,
     VIRTIO_NET_F_HOST_UFO,
     VIRTIO_NET_F_MRG_RXBUF,
     VIRTIO_NET_F_STATUS,
     VIRTIO_NET_F_CTRL_VQ,
     VIRTIO_NET_F_CTRL_RX,
     VIRTIO_NET_F_CTRL_VLAN,
     VIRTIO_NET_F_CTRL_RX_EXTRA,
     VIRTIO_NET_F_CTRL_MAC_ADDR,
     VIRTIO_NET_F_CTRL_GUEST_OFFLOADS,

     VIRTIO_NET_F_MQ,

     VHOST_INVALID_FEATURE_BIT
 };

 static const int *vhost_net_get_feature_bits(struct vhost_net *net)
 {
     const int *feature_bits = 0;

     switch (net->nc->info->type) {
     case NET_CLIENT_OPTIONS_KIND_TAP:
         feature_bits = kernel_feature_bits;
         break;
     case NET_CLIENT_OPTIONS_KIND_VHOST_USER:
         feature_bits = user_feature_bits;
         break;
     default:
         error_report("Feature bits not defined for this type: %d",
                 net->nc->info->type);
         break;
     }

     return feature_bits;
 }

 uint64_t vhost_net_get_features(struct vhost_net *net, uint64_t features)
 {
     return vhost_get_features(&net->dev, vhost_net_get_feature_bits(net),
             features);
 }

 void vhost_net_ack_features(struct vhost_net *net, uint64_t features)
 {
     net->dev.acked_features = net->dev.backend_features;
     vhost_ack_features(&net->dev, vhost_net_get_feature_bits(net), features);
 }

 uint64_t vhost_net_get_max_queues(VHostNetState *net)
 {
     return net->dev.max_queues;
 }

 static int vhost_net_get_fd(NetClientState *backend)
 {
     switch (backend->info->type) {
     case NET_CLIENT_OPTIONS_KIND_TAP:
         return tap_get_fd(backend);
     default:
         fprintf(stderr, "vhost-net requires tap backend\n");
         return -EBADFD;
     }
 }

 struct vhost_net *vhost_net_init(VhostNetOptions *options)
 {
     int r;
     bool backend_kernel = options->backend_type == VHOST_BACKEND_TYPE_KERNEL;
     struct vhost_net *net = g_malloc(sizeof *net);

     if (!options->net_backend) {
         fprintf(stderr, "vhost-net requires net backend to be setup\n");
         goto fail;
     }
     net->nc = options->net_backend;

     net->dev.max_queues = 1;
     net->dev.nvqs = 2;
     net->dev.vqs = net->vqs;

     if (backend_kernel) {
         r = vhost_net_get_fd(options->net_backend);
         if (r < 0) {
             goto fail;
         }
         net->dev.backend_features = qemu_has_vnet_hdr(options->net_backend)
             ? 0 : (1ULL << VHOST_NET_F_VIRTIO_NET_HDR);
         net->backend = r;
         net->dev.protocol_features = 0;
     } else {
         net->dev.backend_features = 0;
         net->dev.protocol_features = 0;
         net->backend = -1;

         /* vhost-user needs vq_index to initiate a specific queue pair */
         net->dev.vq_index = net->nc->queue_index * net->dev.nvqs;
     }

     r = vhost_dev_init(&net->dev, options->opaque,
                        options->backend_type);
     if (r < 0) {
         goto fail;
     }
     if (backend_kernel) {
         if (!qemu_has_vnet_hdr_len(options->net_backend,
                                sizeof(struct virtio_net_hdr_mrg_rxbuf))) {
             net->dev.features &= ~(1ULL << VIRTIO_NET_F_MRG_RXBUF);
         }
         if (~net->dev.features & net->dev.backend_features) {
             fprintf(stderr, "vhost lacks feature mask %" PRIu64
                    " for backend\n",
                    (uint64_t)(~net->dev.features & net->dev.backend_features));
             vhost_dev_cleanup(&net->dev);
             goto fail;
         }
     }
     /* Set sane init value. Override when guest acks. */
     vhost_net_ack_features(net, 0);
     return net;
 fail:
     g_free(net);
     return NULL;
 }

 static void vhost_net_set_vq_index(struct vhost_net *net, int vq_index)
 {
     net->dev.vq_index = vq_index;
 }

 static int vhost_net_set_vnet_endian(VirtIODevice *dev, NetClientState *peer,
                                      bool set)
 {
     int r = 0;

     if (virtio_vdev_has_feature(dev, VIRTIO_F_VERSION_1) ||
         (virtio_legacy_is_cross_endian(dev) && !virtio_is_big_endian(dev))) {
         r = qemu_set_vnet_le(peer, set);
         if (r) {
             error_report("backend does not support LE vnet headers");
         }
     } else if (virtio_legacy_is_cross_endian(dev)) {
         r = qemu_set_vnet_be(peer, set);
         if (r) {
             error_report("backend does not support BE vnet headers");
         }
     }

     return r;
 }

 static int vhost_net_start_one(struct vhost_net *net,
                                VirtIODevice *dev)
 {
     struct vhost_vring_file file = { };
     int r;

     net->dev.nvqs = 2;
     net->dev.vqs = net->vqs;

     r = vhost_dev_enable_notifiers(&net->dev, dev);
     if (r < 0) {
         goto fail_notifiers;
     }

     r = vhost_dev_start(&net->dev, dev);
     if (r < 0) {
         goto fail_start;
     }

     if (net->nc->info->poll) {
         net->nc->info->poll(net->nc, false);
     }

     if (net->nc->info->type == NET_CLIENT_OPTIONS_KIND_TAP) {
         qemu_set_fd_handler(net->backend, NULL, NULL, NULL);
         file.fd = net->backend;
         for (file.index = 0; file.index < net->dev.nvqs; ++file.index) {
             const VhostOps *vhost_ops = net->dev.vhost_ops;
             r = vhost_ops->vhost_call(&net->dev, VHOST_NET_SET_BACKEND,
                                       &file);
             if (r < 0) {
                 r = -errno;
                 goto fail;
             }
         }
     }
     return 0;
 fail:
     file.fd = -1;
     if (net->nc->info->type == NET_CLIENT_OPTIONS_KIND_TAP) {
         while (file.index-- > 0) {
             const VhostOps *vhost_ops = net->dev.vhost_ops;
             int r = vhost_ops->vhost_call(&net->dev, VHOST_NET_SET_BACKEND,
                                           &file);
             assert(r >= 0);
         }
     }
     if (net->nc->info->poll) {
         net->nc->info->poll(net->nc, true);
     }
     vhost_dev_stop(&net->dev, dev);
 fail_start:
     vhost_dev_disable_notifiers(&net->dev, dev);
 fail_notifiers:
     return r;
 }

 static void vhost_net_stop_one(struct vhost_net *net,
                                VirtIODevice *dev)
 {
     struct vhost_vring_file file = { .fd = -1 };

     if (net->nc->info->type == NET_CLIENT_OPTIONS_KIND_TAP) {
         for (file.index = 0; file.index < net->dev.nvqs; ++file.index) {
             const VhostOps *vhost_ops = net->dev.vhost_ops;
             int r = vhost_ops->vhost_call(&net->dev, VHOST_NET_SET_BACKEND,
                                           &file);
             assert(r >= 0);
         }
     } else if (net->nc->info->type == NET_CLIENT_OPTIONS_KIND_VHOST_USER) {
         for (file.index = 0; file.index < net->dev.nvqs; ++file.index) {
             const VhostOps *vhost_ops = net->dev.vhost_ops;
             int r = vhost_ops->vhost_call(&net->dev, VHOST_RESET_DEVICE,
                                           NULL);
             assert(r >= 0);
         }
     }
     if (net->nc->info->poll) {
         net->nc->info->poll(net->nc, true);
     }
     vhost_dev_stop(&net->dev, dev);
     vhost_dev_disable_notifiers(&net->dev, dev);
 }

 int vhost_net_start(VirtIODevice *dev, NetClientState *ncs,
                     int total_queues)
 {
     BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(dev)));
     VirtioBusState *vbus = VIRTIO_BUS(qbus);
     VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(vbus);
     int r, e, i;

     if (!k->set_guest_notifiers) {
         error_report("binding does not support guest notifiers");
         r = -ENOSYS;
         goto err;
     }

     r = vhost_net_set_vnet_endian(dev, ncs[0].peer, true);
     if (r < 0) {
         goto err;
     }

     for (i = 0; i < total_queues; i++) {
         vhost_net_set_vq_index(get_vhost_net(ncs[i].peer), i * 2);
     }

     r = k->set_guest_notifiers(qbus->parent, total_queues * 2, true);
     if (r < 0) {
         error_report("Error binding guest notifier: %d", -r);
         goto err_endian;
     }

     for (i = 0; i < total_queues; i++) {
         r = vhost_net_start_one(get_vhost_net(ncs[i].peer), dev);

         if (r < 0) {
             goto err_start;
         }
     }

     return 0;

 err_start:
     while (--i >= 0) {
         vhost_net_stop_one(get_vhost_net(ncs[i].peer), dev);
     }
     e = k->set_guest_notifiers(qbus->parent, total_queues * 2, false);
     if (e < 0) {
         fprintf(stderr, "vhost guest notifier cleanup failed: %d\n", e);
         fflush(stderr);
     }
 err_endian:
     vhost_net_set_vnet_endian(dev, ncs[0].peer, false);
 err:
     return r;
 }

 void vhost_net_stop(VirtIODevice *dev, NetClientState *ncs,
                     int total_queues)
 {
     BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(dev)));
     VirtioBusState *vbus = VIRTIO_BUS(qbus);
     VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(vbus);
     int i, r;

     for (i = 0; i < total_queues; i++) {
         vhost_net_stop_one(get_vhost_net(ncs[i].peer), dev);
     }

     r = k->set_guest_notifiers(qbus->parent, total_queues * 2, false);
     if (r < 0) {
         fprintf(stderr, "vhost guest notifier cleanup failed: %d\n", r);
         fflush(stderr);
     }
     assert(r >= 0);

     assert(vhost_net_set_vnet_endian(dev, ncs[0].peer, false) >= 0);
 }

 void vhost_net_cleanup(struct vhost_net *net)
 {
     vhost_dev_cleanup(&net->dev);
     g_free(net);
 }

 bool vhost_net_virtqueue_pending(VHostNetState *net, int idx)
 {
     return vhost_virtqueue_pending(&net->dev, idx);
 }

 void vhost_net_virtqueue_mask(VHostNetState *net, VirtIODevice *dev,
                               int idx, bool mask)
 {
     vhost_virtqueue_mask(&net->dev, dev, idx, mask);
 }

 VHostNetState *get_vhost_net(NetClientState *nc)
 {
     VHostNetState *vhost_net = 0;

     if (!nc) {
         return 0;
     }

     switch (nc->info->type) {
     case NET_CLIENT_OPTIONS_KIND_TAP:
         vhost_net = tap_get_vhost_net(nc);
         break;
     case NET_CLIENT_OPTIONS_KIND_VHOST_USER:
         vhost_net = vhost_user_get_vhost_net(nc);
         break;
     default:
         break;
     }

     return vhost_net;
 }

 int vhost_set_vring_enable(NetClientState *nc, int enable)
 {
     VHostNetState *net = get_vhost_net(nc);
     const VhostOps *vhost_ops = net->dev.vhost_ops;

     if (vhost_ops->vhost_backend_set_vring_enable) {
         return vhost_ops->vhost_backend_set_vring_enable(&net->dev, enable);
     }

     return 0;
 }

 #else
 uint64_t vhost_net_get_max_queues(VHostNetState *net)
 {
     return 1;
 }

 struct vhost_net *vhost_net_init(VhostNetOptions *options)
 {
     error_report("vhost-net support is not compiled in");
     return NULL;
 }

 int vhost_net_start(VirtIODevice *dev,
                     NetClientState *ncs,
                     int total_queues)
 {
     return -ENOSYS;
 }
 void vhost_net_stop(VirtIODevice *dev,
                     NetClientState *ncs,
                     int total_queues)
 {
 }

 void vhost_net_cleanup(struct vhost_net *net)
 {
 }

 uint64_t vhost_net_get_features(struct vhost_net *net, uint64_t features)
 {
     return features;
 }
 void vhost_net_ack_features(struct vhost_net *net, uint64_t features)
 {
 }

 bool vhost_net_virtqueue_pending(VHostNetState *net, int idx)
 {
     return false;
 }

 void vhost_net_virtqueue_mask(VHostNetState *net, VirtIODevice *dev,
                               int idx, bool mask)
 {
 }

 VHostNetState *get_vhost_net(NetClientState *nc)
 {
     return 0;
 }

 int vhost_set_vring_enable(NetClientState *nc, int enable)
 {
     return 0;
 }
 #endif
	/*
	* vhost-net support
	*
	* Copyright Red Hat, Inc. 2010
	*
	* Authors:
	* Michael S. Tsirkin <mst@redhat.com>
	*
	* This work is licensed under the terms of the GNU GPL, version 2. See
	* the COPYING file in the top-level directory.
	*
	* Contributions after 2012-01-13 are licensed under the terms of the
	* GNU GPL, version 2 or (at your option) any later version.
	*/

	#include "net/net.h"
	#include "net/tap.h"
	#include "net/vhost-user.h"

	#include "hw/virtio/virtio-net.h"
	#include "net/vhost_net.h"
	#include "qemu/error-report.h"

	#include "config.h"

	#ifdef CONFIG_VHOST_NET
	#include <linux/vhost.h>
	#include <sys/socket.h>
	#include <linux/kvm.h>
	#include <fcntl.h>
	#include <netpacket/packet.h>
	#include <net/ethernet.h>
	#include <net/if.h>
	#include <netinet/in.h>

	#include <stdio.h>

	#include "standard-headers/linux/virtio_ring.h"
	#include "hw/virtio/vhost.h"
	#include "hw/virtio/virtio-bus.h"
	#include "hw/virtio/virtio-access.h"

	struct vhost_net {
	struct vhost_dev dev;
	struct vhost_virtqueue vqs[2];
	int backend;
	NetClientState *nc;
	};

	/* Features supported by host kernel. */
	static const int kernel_feature_bits[] = {
	VIRTIO_F_NOTIFY_ON_EMPTY,
	VIRTIO_RING_F_INDIRECT_DESC,
	VIRTIO_RING_F_EVENT_IDX,
	VIRTIO_NET_F_MRG_RXBUF,
	VIRTIO_F_VERSION_1,
	VHOST_INVALID_FEATURE_BIT
	};

	/* Features supported by others. */
	static const int user_feature_bits[] = {
	VIRTIO_F_NOTIFY_ON_EMPTY,
	VIRTIO_RING_F_INDIRECT_DESC,
	VIRTIO_RING_F_EVENT_IDX,

	VIRTIO_F_ANY_LAYOUT,
	VIRTIO_F_VERSION_1,
	VIRTIO_NET_F_CSUM,
	VIRTIO_NET_F_GUEST_CSUM,
	VIRTIO_NET_F_GSO,
	VIRTIO_NET_F_GUEST_TSO4,
	VIRTIO_NET_F_GUEST_TSO6,
	VIRTIO_NET_F_GUEST_ECN,
	VIRTIO_NET_F_GUEST_UFO,
	VIRTIO_NET_F_HOST_TSO4,
	VIRTIO_NET_F_HOST_TSO6,
	VIRTIO_NET_F_HOST_ECN,
	VIRTIO_NET_F_HOST_UFO,
	VIRTIO_NET_F_MRG_RXBUF,
	VIRTIO_NET_F_STATUS,
	VIRTIO_NET_F_CTRL_VQ,
	VIRTIO_NET_F_CTRL_RX,
	VIRTIO_NET_F_CTRL_VLAN,
	VIRTIO_NET_F_CTRL_RX_EXTRA,
	VIRTIO_NET_F_CTRL_MAC_ADDR,
	VIRTIO_NET_F_CTRL_GUEST_OFFLOADS,

	VIRTIO_NET_F_MQ,

	VHOST_INVALID_FEATURE_BIT
	};

	static const int vhost_net_get_feature_bits(struct vhost_net net)
	{
	const int *feature_bits = 0;

	switch (net->nc->info->type) {
	case NET_CLIENT_OPTIONS_KIND_TAP:
	feature_bits = kernel_feature_bits;
	break;
	case NET_CLIENT_OPTIONS_KIND_VHOST_USER:
	feature_bits = user_feature_bits;
	break;
	default:
	error_report("Feature bits not defined for this type: %d",
	net->nc->info->type);
	break;
	}

	return feature_bits;
	}

	uint64_t vhost_net_get_features(struct vhost_net *net, uint64_t features)
	{
	return vhost_get_features(&net->dev, vhost_net_get_feature_bits(net),
	features);
	}

	void vhost_net_ack_features(struct vhost_net *net, uint64_t features)
	{
	net->dev.acked_features = net->dev.backend_features;
	vhost_ack_features(&net->dev, vhost_net_get_feature_bits(net), features);
	}

	uint64_t vhost_net_get_max_queues(VHostNetState *net)
	{
	return net->dev.max_queues;
	}

	static int vhost_net_get_fd(NetClientState *backend)
	{
	switch (backend->info->type) {
	case NET_CLIENT_OPTIONS_KIND_TAP:
	return tap_get_fd(backend);
	default:
	fprintf(stderr, "vhost-net requires tap backend\n");
	return -EBADFD;
	}
	}

	struct vhost_net vhost_net_init(VhostNetOptions options)
	{
	int r;
	bool backend_kernel = options->backend_type == VHOST_BACKEND_TYPE_KERNEL;
	struct vhost_net net = g_malloc(sizeof net);

	if (!options->net_backend) {
	fprintf(stderr, "vhost-net requires net backend to be setup\n");
	goto fail;
	}
	net->nc = options->net_backend;

	net->dev.max_queues = 1;
	net->dev.nvqs = 2;
	net->dev.vqs = net->vqs;

	if (backend_kernel) {
	r = vhost_net_get_fd(options->net_backend);
	if (r < 0) {
	goto fail;
	}
	net->dev.backend_features = qemu_has_vnet_hdr(options->net_backend)
	? 0 : (1ULL << VHOST_NET_F_VIRTIO_NET_HDR);
	net->backend = r;
	net->dev.protocol_features = 0;
	} else {
	net->dev.backend_features = 0;
	net->dev.protocol_features = 0;
	net->backend = -1;

	/* vhost-user needs vq_index to initiate a specific queue pair */
	net->dev.vq_index = net->nc->queue_index * net->dev.nvqs;
	}

	r = vhost_dev_init(&net->dev, options->opaque,
	options->backend_type);
	if (r < 0) {
	goto fail;
	}
	if (backend_kernel) {
	if (!qemu_has_vnet_hdr_len(options->net_backend,
	sizeof(struct virtio_net_hdr_mrg_rxbuf))) {
	net->dev.features &= ~(1ULL << VIRTIO_NET_F_MRG_RXBUF);
	}
	if (~net->dev.features & net->dev.backend_features) {
	fprintf(stderr, "vhost lacks feature mask %" PRIu64
	" for backend\n",
	(uint64_t)(~net->dev.features & net->dev.backend_features));
	vhost_dev_cleanup(&net->dev);
	goto fail;
	}
	}
	/* Set sane init value. Override when guest acks. */
	vhost_net_ack_features(net, 0);
	return net;
	fail:
	g_free(net);
	return NULL;
	}

	static void vhost_net_set_vq_index(struct vhost_net *net, int vq_index)
	{
	net->dev.vq_index = vq_index;
	}

	static int vhost_net_set_vnet_endian(VirtIODevice dev, NetClientState peer,
	bool set)
	{
	int r = 0;

	if (virtio_vdev_has_feature(dev, VIRTIO_F_VERSION_1) \|\|
	(virtio_legacy_is_cross_endian(dev) && !virtio_is_big_endian(dev))) {
	r = qemu_set_vnet_le(peer, set);
	if (r) {
	error_report("backend does not support LE vnet headers");
	}
	} else if (virtio_legacy_is_cross_endian(dev)) {
	r = qemu_set_vnet_be(peer, set);
	if (r) {
	error_report("backend does not support BE vnet headers");
	}
	}

	return r;
	}

	static int vhost_net_start_one(struct vhost_net *net,
	VirtIODevice *dev)
	{
	struct vhost_vring_file file = { };
	int r;

	net->dev.nvqs = 2;
	net->dev.vqs = net->vqs;

	r = vhost_dev_enable_notifiers(&net->dev, dev);
	if (r < 0) {
	goto fail_notifiers;
	}

	r = vhost_dev_start(&net->dev, dev);
	if (r < 0) {
	goto fail_start;
	}

	if (net->nc->info->poll) {
	net->nc->info->poll(net->nc, false);
	}

	if (net->nc->info->type == NET_CLIENT_OPTIONS_KIND_TAP) {
	qemu_set_fd_handler(net->backend, NULL, NULL, NULL);
	file.fd = net->backend;
	for (file.index = 0; file.index < net->dev.nvqs; ++file.index) {
	const VhostOps *vhost_ops = net->dev.vhost_ops;
	r = vhost_ops->vhost_call(&net->dev, VHOST_NET_SET_BACKEND,
	&file);
	if (r < 0) {
	r = -errno;
	goto fail;
	}
	}
	}
	return 0;
	fail:
	file.fd = -1;
	if (net->nc->info->type == NET_CLIENT_OPTIONS_KIND_TAP) {
	while (file.index-- > 0) {
	const VhostOps *vhost_ops = net->dev.vhost_ops;
	int r = vhost_ops->vhost_call(&net->dev, VHOST_NET_SET_BACKEND,
	&file);
	assert(r >= 0);
	}
	}
	if (net->nc->info->poll) {
	net->nc->info->poll(net->nc, true);
	}
	vhost_dev_stop(&net->dev, dev);
	fail_start:
	vhost_dev_disable_notifiers(&net->dev, dev);
	fail_notifiers:
	return r;
	}

	static void vhost_net_stop_one(struct vhost_net *net,
	VirtIODevice *dev)
	{
	struct vhost_vring_file file = { .fd = -1 };

	if (net->nc->info->type == NET_CLIENT_OPTIONS_KIND_TAP) {
	for (file.index = 0; file.index < net->dev.nvqs; ++file.index) {
	const VhostOps *vhost_ops = net->dev.vhost_ops;
	int r = vhost_ops->vhost_call(&net->dev, VHOST_NET_SET_BACKEND,
	&file);
	assert(r >= 0);
	}
	} else if (net->nc->info->type == NET_CLIENT_OPTIONS_KIND_VHOST_USER) {
	for (file.index = 0; file.index < net->dev.nvqs; ++file.index) {
	const VhostOps *vhost_ops = net->dev.vhost_ops;
	int r = vhost_ops->vhost_call(&net->dev, VHOST_RESET_DEVICE,
	NULL);
	assert(r >= 0);
	}
	}
	if (net->nc->info->poll) {
	net->nc->info->poll(net->nc, true);
	}
	vhost_dev_stop(&net->dev, dev);
	vhost_dev_disable_notifiers(&net->dev, dev);
	}

	int vhost_net_start(VirtIODevice dev, NetClientState ncs,
	int total_queues)
	{
	BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(dev)));
	VirtioBusState *vbus = VIRTIO_BUS(qbus);
	VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(vbus);
	int r, e, i;

	if (!k->set_guest_notifiers) {
	error_report("binding does not support guest notifiers");
	r = -ENOSYS;
	goto err;
	}

	r = vhost_net_set_vnet_endian(dev, ncs[0].peer, true);
	if (r < 0) {
	goto err;
	}

	for (i = 0; i < total_queues; i++) {
	vhost_net_set_vq_index(get_vhost_net(ncs[i].peer), i * 2);
	}

	r = k->set_guest_notifiers(qbus->parent, total_queues * 2, true);
	if (r < 0) {
	error_report("Error binding guest notifier: %d", -r);
	goto err_endian;
	}

	for (i = 0; i < total_queues; i++) {
	r = vhost_net_start_one(get_vhost_net(ncs[i].peer), dev);

	if (r < 0) {
	goto err_start;
	}
	}

	return 0;

	err_start:
	while (--i >= 0) {
	vhost_net_stop_one(get_vhost_net(ncs[i].peer), dev);
	}
	e = k->set_guest_notifiers(qbus->parent, total_queues * 2, false);
	if (e < 0) {
	fprintf(stderr, "vhost guest notifier cleanup failed: %d\n", e);
	fflush(stderr);
	}
	err_endian:
	vhost_net_set_vnet_endian(dev, ncs[0].peer, false);
	err:
	return r;
	}

	void vhost_net_stop(VirtIODevice dev, NetClientState ncs,
	int total_queues)
	{
	BusState *qbus = BUS(qdev_get_parent_bus(DEVICE(dev)));
	VirtioBusState *vbus = VIRTIO_BUS(qbus);
	VirtioBusClass *k = VIRTIO_BUS_GET_CLASS(vbus);
	int i, r;

	for (i = 0; i < total_queues; i++) {
	vhost_net_stop_one(get_vhost_net(ncs[i].peer), dev);
	}

	r = k->set_guest_notifiers(qbus->parent, total_queues * 2, false);
	if (r < 0) {
	fprintf(stderr, "vhost guest notifier cleanup failed: %d\n", r);
	fflush(stderr);
	}
	assert(r >= 0);

	assert(vhost_net_set_vnet_endian(dev, ncs[0].peer, false) >= 0);
	}

	void vhost_net_cleanup(struct vhost_net *net)
	{
	vhost_dev_cleanup(&net->dev);
	g_free(net);
	}

	bool vhost_net_virtqueue_pending(VHostNetState *net, int idx)
	{
	return vhost_virtqueue_pending(&net->dev, idx);
	}

	void vhost_net_virtqueue_mask(VHostNetState net, VirtIODevice dev,
	int idx, bool mask)
	{
	vhost_virtqueue_mask(&net->dev, dev, idx, mask);
	}

	VHostNetState get_vhost_net(NetClientState nc)
	{
	VHostNetState *vhost_net = 0;

	if (!nc) {
	return 0;
	}

	switch (nc->info->type) {
	case NET_CLIENT_OPTIONS_KIND_TAP:
	vhost_net = tap_get_vhost_net(nc);
	break;
	case NET_CLIENT_OPTIONS_KIND_VHOST_USER:
	vhost_net = vhost_user_get_vhost_net(nc);
	break;
	default:
	break;
	}

	return vhost_net;
	}

	int vhost_set_vring_enable(NetClientState *nc, int enable)
	{
	VHostNetState *net = get_vhost_net(nc);
	const VhostOps *vhost_ops = net->dev.vhost_ops;

	if (vhost_ops->vhost_backend_set_vring_enable) {
	return vhost_ops->vhost_backend_set_vring_enable(&net->dev, enable);
	}

	return 0;
	}

	#else
	uint64_t vhost_net_get_max_queues(VHostNetState *net)
	{
	return 1;
	}

	struct vhost_net vhost_net_init(VhostNetOptions options)
	{
	error_report("vhost-net support is not compiled in");
	return NULL;
	}

	int vhost_net_start(VirtIODevice *dev,
	NetClientState *ncs,
	int total_queues)
	{
	return -ENOSYS;
	}
	void vhost_net_stop(VirtIODevice *dev,
	NetClientState *ncs,
	int total_queues)
	{
	}

	void vhost_net_cleanup(struct vhost_net *net)
	{
	}

	uint64_t vhost_net_get_features(struct vhost_net *net, uint64_t features)
	{
	return features;
	}
	void vhost_net_ack_features(struct vhost_net *net, uint64_t features)
	{
	}

	bool vhost_net_virtqueue_pending(VHostNetState *net, int idx)
	{
	return false;
	}

	void vhost_net_virtqueue_mask(VHostNetState net, VirtIODevice dev,
	int idx, bool mask)
	{
	}

	VHostNetState get_vhost_net(NetClientState nc)
	{
	return 0;
	}

	int vhost_set_vring_enable(NetClientState *nc, int enable)
	{
	return 0;
	}
	#endif