text: /*
   * Virtio Network Device
   *
   * Copyright IBM, Corp. 2007
   *
   * Authors:
   *  Anthony Liguori   <aliguori@us.ibm.com>
   *
   * This work is licensed under the terms of the GNU GPL, version 2.  See
   * the COPYING file in the top-level directory.
   *
   */
  
  #include "qemu/osdep.h"
  #include "qemu/atomic.h"
  #include "qemu/iov.h"
  #include "qemu/main-loop.h"
  #include "qemu/module.h"
  #include "hw/virtio/virtio.h"
  #include "net/net.h"
  #include "net/checksum.h"
  #include "net/tap.h"
  #include "qemu/error-report.h"
  #include "qemu/timer.h"
  #include "qemu/option.h"
  #include "qemu/option_int.h"
  #include "qemu/config-file.h"
  #include "qapi/qmp/qdict.h"
  #include "hw/virtio/virtio-net.h"
  #include "net/vhost_net.h"
  #include "net/announce.h"
  #include "hw/virtio/virtio-bus.h"
  #include "qapi/error.h"
  #include "qapi/qapi-events-net.h"
  #include "hw/qdev-properties.h"
  #include "qapi/qapi-types-migration.h"
  #include "qapi/qapi-events-migration.h"
  #include "hw/virtio/virtio-access.h"
  #include "migration/misc.h"
  #include "standard-headers/linux/ethtool.h"
  #include "sysemu/sysemu.h"
  #include "trace.h"
  #include "monitor/qdev.h"
  #include "hw/pci/pci.h"
  #include "net_rx_pkt.h"
  #include "hw/virtio/vhost.h"
  
  #define VIRTIO_NET_VM_VERSION    11
  
  #define MAC_TABLE_ENTRIES    64
  #define MAX_VLAN    (1 << 12)   /* Per 802.1Q definition */
  
  /* previously fixed value */
  #define VIRTIO_NET_RX_QUEUE_DEFAULT_SIZE 256
  #define VIRTIO_NET_TX_QUEUE_DEFAULT_SIZE 256
  
  /* for now, only allow larger queues; with virtio-1, guest can downsize */
  #define VIRTIO_NET_RX_QUEUE_MIN_SIZE VIRTIO_NET_RX_QUEUE_DEFAULT_SIZE
  #define VIRTIO_NET_TX_QUEUE_MIN_SIZE VIRTIO_NET_TX_QUEUE_DEFAULT_SIZE
  
  #define VIRTIO_NET_IP4_ADDR_SIZE   8        /* ipv4 saddr + daddr */
  
  #define VIRTIO_NET_TCP_FLAG         0x3F
  #define VIRTIO_NET_TCP_HDR_LENGTH   0xF000
  
  /* IPv4 max payload, 16 bits in the header */
  #define VIRTIO_NET_MAX_IP4_PAYLOAD (65535 - sizeof(struct ip_header))
  #define VIRTIO_NET_MAX_TCP_PAYLOAD 65535
  
  /* header length value in ip header without option */
  #define VIRTIO_NET_IP4_HEADER_LENGTH 5
  
  #define VIRTIO_NET_IP6_ADDR_SIZE   32      /* ipv6 saddr + daddr */
  #define VIRTIO_NET_MAX_IP6_PAYLOAD VIRTIO_NET_MAX_TCP_PAYLOAD
  
  /* Purge coalesced packets timer interval, This value affects the performance
     a lot, and should be tuned carefully, '300000'(300us) is the recommended
     value to pass the WHQL test, '50000' can gain 2x netperf throughput with
     tso/gso/gro 'off'. */
  #define VIRTIO_NET_RSC_DEFAULT_INTERVAL 300000
  
  #define VIRTIO_NET_RSS_SUPPORTED_HASHES (VIRTIO_NET_RSS_HASH_TYPE_IPv4 | \
                                           VIRTIO_NET_RSS_HASH_TYPE_TCPv4 | \
                                           VIRTIO_NET_RSS_HASH_TYPE_UDPv4 | \
                                           VIRTIO_NET_RSS_HASH_TYPE_IPv6 | \
                                           VIRTIO_NET_RSS_HASH_TYPE_TCPv6 | \
                                           VIRTIO_NET_RSS_HASH_TYPE_UDPv6 | \
                                           VIRTIO_NET_RSS_HASH_TYPE_IP_EX | \
                                           VIRTIO_NET_RSS_HASH_TYPE_TCP_EX | \
                                           VIRTIO_NET_RSS_HASH_TYPE_UDP_EX)
  
  static VirtIOFeature feature_sizes[] = {
      {.flags = 1ULL << VIRTIO_NET_F_MAC,
       .end = endof(struct virtio_net_config, mac)},
      {.flags = 1ULL << VIRTIO_NET_F_STATUS,
       .end = endof(struct virtio_net_config, status)},
      {.flags = 1ULL << VIRTIO_NET_F_MQ,
       .end = endof(struct virtio_net_config, max_virtqueue_pairs)},
      {.flags = 1ULL << VIRTIO_NET_F_MTU,
       .end = endof(struct virtio_net_config, mtu)},
      {.flags = 1ULL << VIRTIO_NET_F_SPEED_DUPLEX,
       .end = endof(struct virtio_net_config, duplex)},
      {.flags = (1ULL << VIRTIO_NET_F_RSS) | (1ULL << VIRTIO_NET_F_HASH_REPORT),
       .end = endof(struct virtio_net_config, supported_hash_types)},
      {}
  };
  
  static VirtIONetQueue *virtio_net_get_subqueue(NetClientState *nc)
  {
      VirtIONet *n = qemu_get_nic_opaque(nc);
  
      return &n->vqs[nc->queue_index];
  }
  
  static int vq2q(int queue_index)
  {
      return queue_index / 2;
  }
  
  /* TODO
   * - we could suppress RX interrupt if we were so inclined.
   */
  
  static void virtio_net_get_config(VirtIODevice *vdev, uint8_t *config)
  {
      VirtIONet *n = VIRTIO_NET(vdev);
      struct virtio_net_config netcfg;
      NetClientState *nc = qemu_get_queue(n->nic);
      static const MACAddr zero = { .a = { 0, 0, 0, 0, 0, 0 } };
  
      int ret = 0;
      memset(&netcfg, 0 , sizeof(struct virtio_net_config));
      virtio_stw_p(vdev, &netcfg.status, n->status);
      virtio_stw_p(vdev, &netcfg.max_virtqueue_pairs, n->max_queues);
      virtio_stw_p(vdev, &netcfg.mtu, n->net_conf.mtu);
      memcpy(netcfg.mac, n->mac, ETH_ALEN);
      virtio_stl_p(vdev, &netcfg.speed, n->net_conf.speed);
      netcfg.duplex = n->net_conf.duplex;
      netcfg.rss_max_key_size = VIRTIO_NET_RSS_MAX_KEY_SIZE;
      virtio_stw_p(vdev, &netcfg.rss_max_indirection_table_length,
                   virtio_host_has_feature(vdev, VIRTIO_NET_F_RSS) ?
                   VIRTIO_NET_RSS_MAX_TABLE_LEN : 1);
      virtio_stl_p(vdev, &netcfg.supported_hash_types,
                   VIRTIO_NET_RSS_SUPPORTED_HASHES);
      memcpy(config, &netcfg, n->config_size);
  
      /*
       * Is this VDPA? No peer means not VDPA: there's no way to
       * disconnect/reconnect a VDPA peer.
       */
      if (nc->peer && nc->peer->info->type == NET_CLIENT_DRIVER_VHOST_VDPA) {
          ret = vhost_net_get_config(get_vhost_net(nc->peer), (uint8_t *)&netcfg,
                                     n->config_size);
          if (ret != -1) {
              /*
               * Some NIC/kernel combinations present 0 as the mac address.  As
               * that is not a legal address, try to proceed with the
               * address from the QEMU command line in the hope that the
               * address has been configured correctly elsewhere - just not
               * reported by the device.
               */
              if (memcmp(&netcfg.mac, &zero, sizeof(zero)) == 0) {
                  info_report("Zero hardware mac address detected. Ignoring.");
                  memcpy(netcfg.mac, n->mac, ETH_ALEN);
              }
              memcpy(config, &netcfg, n->config_size);
          }
      }
  }
  
  static void virtio_net_set_config(VirtIODevice *vdev, const uint8_t *config)
  {
      VirtIONet *n = VIRTIO_NET(vdev);
      struct virtio_net_config netcfg = {};
      NetClientState *nc = qemu_get_queue(n->nic);
  
      memcpy(&netcfg, config, n->config_size);
  
      if (!virtio_vdev_has_feature(vdev, VIRTIO_NET_F_CTRL_MAC_ADDR) &&
          !virtio_vdev_has_feature(vdev, VIRTIO_F_VERSION_1) &&
          memcmp(netcfg.mac, n->mac, ETH_ALEN)) {
          memcpy(n->mac, netcfg.mac, ETH_ALEN);
          qemu_format_nic_info_str(qemu_get_queue(n->nic), n->mac);
      }
  
      /*
       * Is this VDPA? No peer means not VDPA: there's no way to
       * disconnect/reconnect a VDPA peer.
       */
      if (nc->peer && nc->peer->info->type == NET_CLIENT_DRIVER_VHOST_VDPA) {
          vhost_net_set_config(get_vhost_net(nc->peer),
                               (uint8_t *)&netcfg, 0, n->config_size,
                               VHOST_SET_CONFIG_TYPE_MASTER);
        }
  }
  
  static bool virtio_net_started(VirtIONet *n, uint8_t status)
  {
      VirtIODevice *vdev = VIRTIO_DEVICE(n);
      return (status & VIRTIO_CONFIG_S_DRIVER_OK) &&
          (n->status & VIRTIO_NET_S_LINK_UP) && vdev->vm_running;
  }
  
  static void virtio_net_announce_notify(VirtIONet *net)
  {
      VirtIODevice *vdev = VIRTIO_DEVICE(net);
      trace_virtio_net_announce_notify();
  
      net->status |= VIRTIO_NET_S_ANNOUNCE;
      virtio_notify_config(vdev);
  }
  
  static void virtio_net_announce_timer(void *opaque)
  {
      VirtIONet *n = opaque;
      trace_virtio_net_announce_timer(n->announce_timer.round);
  
      n->announce_timer.round--;
      virtio_net_announce_notify(n);
  }
  
  static void virtio_net_announce(NetClientState *nc)
  {
      VirtIONet *n = qemu_get_nic_opaque(nc);
      VirtIODevice *vdev = VIRTIO_DEVICE(n);
  
      /*
       * Make sure the virtio migration announcement timer isn't running
       * If it is, let it trigger announcement so that we do not cause
       * confusion.
       */
      if (n->announce_timer.round) {
          return;
      }
  
      if (virtio_vdev_has_feature(vdev, VIRTIO_NET_F_GUEST_ANNOUNCE) &&
          virtio_vdev_has_feature(vdev, VIRTIO_NET_F_CTRL_VQ)) {
              virtio_net_announce_notify(n);
      }
  }
  
  static void virtio_net_vhost_status(VirtIONet *n, uint8_t status)
  {
      VirtIODevice *vdev = VIRTIO_DEVICE(n);
      NetClientState *nc = qemu_get_queue(n->nic);
      int queues = n->multiqueue ? n->max_queues : 1;
  
      if (!get_vhost_net(nc->peer)) {
          return;
      }
  
      if ((virtio_net_started(n, status) && !nc->peer->link_down) ==
          !!n->vhost_started) {
          return;
      }
      if (!n->vhost_started) {
          int r, i;
  
          if (n->needs_vnet_hdr_swap) {
              error_report("backend does not support %s vnet headers; "
                           "falling back on userspace virtio",
                           virtio_is_big_endian(vdev) ? "BE" : "LE");
              return;
          }
  
          /* Any packets outstanding? Purge them to avoid touching rings
           * when vhost is running.
           */
          for (i = 0;  i < queues; i++) {
              NetClientState *qnc = qemu_get_subqueue(n->nic, i);
  
              /* Purge both directions: TX and RX. */
              qemu_net_queue_purge(qnc->peer->incoming_queue, qnc);
              qemu_net_queue_purge(qnc->incoming_queue, qnc->peer);
          }
  
          if (virtio_has_feature(vdev->guest_features, VIRTIO_NET_F_MTU)) {
              r = vhost_net_set_mtu(get_vhost_net(nc->peer), n->net_conf.mtu);
              if (r < 0) {
                  error_report("%uBytes MTU not supported by the backend",
                               n->net_conf.mtu);
  
                  return;
              }
          }
  
          n->vhost_started = 1;
          r = vhost_net_start(vdev, n->nic->ncs, queues);
          if (r < 0) {
              error_report("unable to start vhost net: %d: "
                           "falling back on userspace virtio", -r);
              n->vhost_started = 0;
          }
      } else {
          vhost_net_stop(vdev, n->nic->ncs, queues);
          n->vhost_started = 0;
      }
  }
  
  static int virtio_net_set_vnet_endian_one(VirtIODevice *vdev,
                                            NetClientState *peer,
                                            bool enable)
  {
      if (virtio_is_big_endian(vdev)) {
          return qemu_set_vnet_be(peer, enable);
      } else {
          return qemu_set_vnet_le(peer, enable);
      }
  }
  
  static bool virtio_net_set_vnet_endian(VirtIODevice *vdev, NetClientState *ncs,
                                         int queues, bool enable)
  {
      int i;
  
      for (i = 0; i < queues; i++) {
          if (virtio_net_set_vnet_endian_one(vdev, ncs[i].peer, enable) < 0 &&
              enable) {
              while (--i >= 0) {
                  virtio_net_set_vnet_endian_one(vdev, ncs[i].peer, false);
              }
  
              return true;
          }
      }
  
      return false;
  }
  
  static void virtio_net_vnet_endian_status(VirtIONet *n, uint8_t status)
  {
      VirtIODevice *vdev = VIRTIO_DEVICE(n);
      int queues = n->multiqueue ? n->max_queues : 1;
  
      if (virtio_net_started(n, status)) {
          /* Before using the device, we tell the network backend about the
           * endianness to use when parsing vnet headers. If the backend
           * can't do it, we fallback onto fixing the headers in the core
           * virtio-net code.
           */
          n->needs_vnet_hdr_swap = virtio_net_set_vnet_endian(vdev, n->nic->ncs,
                                                              queues, true);
      } else if (virtio_net_started(n, vdev->status)) {
          /* After using the device, we need to reset the network backend to
           * the default (guest native endianness), otherwise the guest may
           * lose network connectivity if it is rebooted into a different
           * endianness.
           */
          virtio_net_set_vnet_endian(vdev, n->nic->ncs, queues, false);
      }
  }
  
  static void virtio_net_drop_tx_queue_data(VirtIODevice *vdev, VirtQueue *vq)
  {
      unsigned int dropped = virtqueue_drop_all(vq);
      if (dropped) {
          virtio_notify(vdev, vq);
      }
  }
  
  static void virtio_net_set_status(struct VirtIODevice *vdev, uint8_t status)
  {
      VirtIONet *n = VIRTIO_NET(vdev);
      VirtIONetQueue *q;
      int i;
      uint8_t queue_status;
  
      virtio_net_vnet_endian_status(n, status);
      virtio_net_vhost_status(n, status);
  
      for (i = 0; i < n->max_queues; i++) {
          NetClientState *ncs = qemu_get_subqueue(n->nic, i);
          bool queue_started;
          q = &n->vqs[i];
  
          if ((!n->multiqueue && i != 0) || i >= n->curr_queues) {
              queue_status = 0;
          } else {
              queue_status = status;
          }
          queue_started =
              virtio_net_started(n, queue_status) && !n->vhost_started;
  
          if (queue_started) {
              qemu_flush_queued_packets(ncs);
          }
  
          if (!q->tx_waiting) {
              continue;
          }
  
          if (queue_started) {
              if (q->tx_timer) {
                  timer_mod(q->tx_timer,
                                 qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) + n->tx_timeout);
              } else {
                  qemu_bh_schedule(q->tx_bh);
              }
          } else {
              if (q->tx_timer) {
                  timer_del(q->tx_timer);
              } else {
                  qemu_bh_cancel(q->tx_bh);
              }
              if ((n->status & VIRTIO_NET_S_LINK_UP) == 0 &&
                  (queue_status & VIRTIO_CONFIG_S_DRIVER_OK) &&
                  vdev->vm_running) {
                  /* if tx is waiting we are likely have some packets in tx queue
                   * and disabled notification */
                  q->tx_waiting = 0;
                  virtio_queue_set_notification(q->tx_vq, 1);
                  virtio_net_drop_tx_queue_data(vdev, q->tx_vq);
              }
          }
      }
  }
  
  static void virtio_net_set_link_status(NetClientState *nc)
  {
      VirtIONet *n = qemu_get_nic_opaque(nc);
      VirtIODevice *vdev = VIRTIO_DEVICE(n);
      uint16_t old_status = n->status;
  
      if (nc->link_down)
          n->status &= ~VIRTIO_NET_S_LINK_UP;
      else
          n->status |= VIRTIO_NET_S_LINK_UP;
  
      if (n->status != old_status)
          virtio_notify_config(vdev);
  
      virtio_net_set_status(vdev, vdev->status);
  }
  
  static void rxfilter_notify(NetClientState *nc)
  {
      VirtIONet *n = qemu_get_nic_opaque(nc);
  
      if (nc->rxfilter_notify_enabled) {
          char *path = object_get_canonical_path(OBJECT(n->qdev));
          qapi_event_send_nic_rx_filter_changed(!!n->netclient_name,
                                                n->netclient_name, path);
          g_free(path);
  
          /* disable event notification to avoid events flooding */
          nc->rxfilter_notify_enabled = 0;
      }
  }
  
  static intList *get_vlan_table(VirtIONet *n)
  {
      intList *list;
      int i, j;
  
      list = NULL;
      for (i = 0; i < MAX_VLAN >> 5; i++) {
          for (j = 0; n->vlans[i] && j <= 0x1f; j++) {
              if (n->vlans[i] & (1U << j)) {
                  QAPI_LIST_PREPEND(list, (i << 5) + j);
              }
          }
      }
  
      return list;
  }
  
  static RxFilterInfo *virtio_net_query_rxfilter(NetClientState *nc)
  {
      VirtIONet *n = qemu_get_nic_opaque(nc);
      VirtIODevice *vdev = VIRTIO_DEVICE(n);
      RxFilterInfo *info;
      strList *str_list;
      int i;
  
      info = g_malloc0(sizeof(*info));
      info->name = g_strdup(nc->name);
      info->promiscuous = n->promisc;
  
      if (n->nouni) {
          info->unicast = RX_STATE_NONE;
      } else if (n->alluni) {
          info->unicast = RX_STATE_ALL;
      } else {
          info->unicast = RX_STATE_NORMAL;
      }
  
      if (n->nomulti) {
          info->multicast = RX_STATE_NONE;
      } else if (n->allmulti) {
          info->multicast = RX_STATE_ALL;
      } else {
          info->multicast = RX_STATE_NORMAL;
      }
  
      info->broadcast_allowed = n->nobcast;
      info->multicast_overflow = n->mac_table.multi_overflow;
      info->unicast_overflow = n->mac_table.uni_overflow;
  
      info->main_mac = qemu_mac_strdup_printf(n->mac);
  
      str_list = NULL;
      for (i = 0; i < n->mac_table.first_multi; i++) {
          QAPI_LIST_PREPEND(str_list,
                        qemu_mac_strdup_printf(n->mac_table.macs + i * ETH_ALEN));
      }
      info->unicast_table = str_list;
  
      str_list = NULL;
      for (i = n->mac_table.first_multi; i < n->mac_table.in_use; i++) {
          QAPI_LIST_PREPEND(str_list,
                        qemu_mac_strdup_printf(n->mac_table.macs + i * ETH_ALEN));
      }
      info->multicast_table = str_list;
      info->vlan_table = get_vlan_table(n);
  
      if (!virtio_vdev_has_feature(vdev, VIRTIO_NET_F_CTRL_VLAN)) {
          info->vlan = RX_STATE_ALL;
      } else if (!info->vlan_table) {
          info->vlan = RX_STATE_NONE;
      } else {
          info->vlan = RX_STATE_NORMAL;
      }
  
      /* enable event notification after query */
      nc->rxfilter_notify_enabled = 1;
  
      return info;
  }
  
  static void virtio_net_reset(VirtIODevice *vdev)
  {
      VirtIONet *n = VIRTIO_NET(vdev);
      int i;
  
      /* Reset back to compatibility mode */
      n->promisc = 1;
      n->allmulti = 0;
      n->alluni = 0;
      n->nomulti = 0;
      n->nouni = 0;
      n->nobcast = 0;
      /* multiqueue is disabled by default */
      n->curr_queues = 1;
      timer_del(n->announce_timer.tm);
      n->announce_timer.round = 0;
      n->status &= ~VIRTIO_NET_S_ANNOUNCE;
  
      /* Flush any MAC and VLAN filter table state */
      n->mac_table.in_use = 0;
      n->mac_table.first_multi = 0;
      n->mac_table.multi_overflow = 0;
      n->mac_table.uni_overflow = 0;
      memset(n->mac_table.macs, 0, MAC_TABLE_ENTRIES * ETH_ALEN);
      memcpy(&n->mac[0], &n->nic->conf->macaddr, sizeof(n->mac));
      qemu_format_nic_info_str(qemu_get_queue(n->nic), n->mac);
      memset(n->vlans, 0, MAX_VLAN >> 3);
  
      /* Flush any async TX */
      for (i = 0;  i < n->max_queues; i++) {
          NetClientState *nc = qemu_get_subqueue(n->nic, i);
  
          if (nc->peer) {
              qemu_flush_or_purge_queued_packets(nc->peer, true);
              assert(!virtio_net_get_subqueue(nc)->async_tx.elem);
          }
      }
  }
  
  static void peer_test_vnet_hdr(VirtIONet *n)
  {
      NetClientState *nc = qemu_get_queue(n->nic);
      if (!nc->peer) {
          return;
      }
  
      n->has_vnet_hdr = qemu_has_vnet_hdr(nc->peer);
  }
  
  static int peer_has_vnet_hdr(VirtIONet *n)
  {
      return n->has_vnet_hdr;
  }
  
  static int peer_has_ufo(VirtIONet *n)
  {
      if (!peer_has_vnet_hdr(n))
          return 0;
  
      n->has_ufo = qemu_has_ufo(qemu_get_queue(n->nic)->peer);
  
      return n->has_ufo;
  }
  
  static void virtio_net_set_mrg_rx_bufs(VirtIONet *n, int mergeable_rx_bufs,
                                         int version_1, int hash_report)
  {
      int i;
      NetClientState *nc;
  
      n->mergeable_rx_bufs = mergeable_rx_bufs;
  
      if (version_1) {
          n->guest_hdr_len = hash_report ?
              sizeof(struct virtio_net_hdr_v1_hash) :
              sizeof(struct virtio_net_hdr_mrg_rxbuf);
          n->rss_data.populate_hash = !!hash_report;
      } else {
          n->guest_hdr_len = n->mergeable_rx_bufs ?
              sizeof(struct virtio_net_hdr_mrg_rxbuf) :
              sizeof(struct virtio_net_hdr);
      }
  
      for (i = 0; i < n->max_queues; i++) {
          nc = qemu_get_subqueue(n->nic, i);
  
          if (peer_has_vnet_hdr(n) &&
              qemu_has_vnet_hdr_len(nc->peer, n->guest_hdr_len)) {
              qemu_set_vnet_hdr_len(nc->peer, n->guest_hdr_len);
              n->host_hdr_len = n->guest_hdr_len;
          }
      }
  }
  
  static int virtio_net_max_tx_queue_size(VirtIONet *n)
  {
      NetClientState *peer = n->nic_conf.peers.ncs[0];
  
      /*
       * Backends other than vhost-user don't support max queue size.
       */
      if (!peer) {
          return VIRTIO_NET_TX_QUEUE_DEFAULT_SIZE;
      }
  
      if (peer->info->type != NET_CLIENT_DRIVER_VHOST_USER) {
          return VIRTIO_NET_TX_QUEUE_DEFAULT_SIZE;
      }
  
      return VIRTQUEUE_MAX_SIZE;
  }
  
  static int peer_attach(VirtIONet *n, int index)
  {
      NetClientState *nc = qemu_get_subqueue(n->nic, index);
  
      if (!nc->peer) {
          return 0;
      }
  
      if (nc->peer->info->type == NET_CLIENT_DRIVER_VHOST_USER) {
          vhost_set_vring_enable(nc->peer, 1);
      }
  
      if (nc->peer->info->type != NET_CLIENT_DRIVER_TAP) {
          return 0;
      }
  
      if (n->max_queues == 1) {
          return 0;
      }
  
      return tap_enable(nc->peer);
  }
  
  static int peer_detach(VirtIONet *n, int index)
  {
      NetClientState *nc = qemu_get_subqueue(n->nic, index);
  
      if (!nc->peer) {
          return 0;
      }
  
      if (nc->peer->info->type == NET_CLIENT_DRIVER_VHOST_USER) {
          vhost_set_vring_enable(nc->peer, 0);
      }
  
      if (nc->peer->info->type !=  NET_CLIENT_DRIVER_TAP) {
          return 0;
      }
  
      return tap_disable(nc->peer);
  }
  
  static void virtio_net_set_queues(VirtIONet *n)
  {
      int i;
      int r;
  
      if (n->nic->peer_deleted) {
          return;
      }
  
      for (i = 0; i < n->max_queues; i++) {
          if (i < n->curr_queues) {
              r = peer_attach(n, i);
              assert(!r);
          } else {
              r = peer_detach(n, i);
              assert(!r);
          }
      }
  }
  
  static void virtio_net_set_multiqueue(VirtIONet *n, int multiqueue);
  
  static uint64_t virtio_net_get_features(VirtIODevice *vdev, uint64_t features,
                                          Error **errp)
  {
      VirtIONet *n = VIRTIO_NET(vdev);
      NetClientState *nc = qemu_get_queue(n->nic);
  
      /* Firstly sync all virtio-net possible supported features */
      features |= n->host_features;
  
      virtio_add_feature(&features, VIRTIO_NET_F_MAC);
  
      if (!peer_has_vnet_hdr(n)) {
          virtio_clear_feature(&features, VIRTIO_NET_F_CSUM);
          virtio_clear_feature(&features, VIRTIO_NET_F_HOST_TSO4);
          virtio_clear_feature(&features, VIRTIO_NET_F_HOST_TSO6);
          virtio_clear_feature(&features, VIRTIO_NET_F_HOST_ECN);
  
          virtio_clear_feature(&features, VIRTIO_NET_F_GUEST_CSUM);
          virtio_clear_feature(&features, VIRTIO_NET_F_GUEST_TSO4);
          virtio_clear_feature(&features, VIRTIO_NET_F_GUEST_TSO6);
          virtio_clear_feature(&features, VIRTIO_NET_F_GUEST_ECN);
  
          virtio_clear_feature(&features, VIRTIO_NET_F_HASH_REPORT);
      }
  
      if (!peer_has_vnet_hdr(n) || !peer_has_ufo(n)) {
          virtio_clear_feature(&features, VIRTIO_NET_F_GUEST_UFO);
          virtio_clear_feature(&features, VIRTIO_NET_F_HOST_UFO);
      }
  
      if (!get_vhost_net(nc->peer)) {
          return features;
      }
  
      virtio_clear_feature(&features, VIRTIO_NET_F_RSS);
      virtio_clear_feature(&features, VIRTIO_NET_F_HASH_REPORT);
      features = vhost_net_get_features(get_vhost_net(nc->peer), features);
      vdev->backend_features = features;
  
      if (n->mtu_bypass_backend &&
              (n->host_features & 1ULL << VIRTIO_NET_F_MTU)) {
          features |= (1ULL << VIRTIO_NET_F_MTU);
      }
  
      return features;
  }
  
  static uint64_t virtio_net_bad_features(VirtIODevice *vdev)
  {
      uint64_t features = 0;
  
      /* Linux kernel 2.6.25.  It understood MAC (as everyone must),
       * but also these: */
      virtio_add_feature(&features, VIRTIO_NET_F_MAC);
      virtio_add_feature(&features, VIRTIO_NET_F_CSUM);
      virtio_add_feature(&features, VIRTIO_NET_F_HOST_TSO4);
      virtio_add_feature(&features, VIRTIO_NET_F_HOST_TSO6);
      virtio_add_feature(&features, VIRTIO_NET_F_HOST_ECN);
  
      return features;
  }
  
  static void virtio_net_apply_guest_offloads(VirtIONet *n)
  {
      qemu_set_offload(qemu_get_queue(n->nic)->peer,
              !!(n->curr_guest_offloads & (1ULL << VIRTIO_NET_F_GUEST_CSUM)),
              !!(n->curr_guest_offloads & (1ULL << VIRTIO_NET_F_GUEST_TSO4)),
              !!(n->curr_guest_offloads & (1ULL << VIRTIO_NET_F_GUEST_TSO6)),
              !!(n->curr_guest_offloads & (1ULL << VIRTIO_NET_F_GUEST_ECN)),
              !!(n->curr_guest_offloads & (1ULL << VIRTIO_NET_F_GUEST_UFO)));
  }
  
  static uint64_t virtio_net_guest_offloads_by_features(uint32_t features)
  {
      static const uint64_t guest_offloads_mask =
          (1ULL << VIRTIO_NET_F_GUEST_CSUM) |
          (1ULL << VIRTIO_NET_F_GUEST_TSO4) |
          (1ULL << VIRTIO_NET_F_GUEST_TSO6) |
          (1ULL << VIRTIO_NET_F_GUEST_ECN)  |
          (1ULL << VIRTIO_NET_F_GUEST_UFO);
  
      return guest_offloads_mask & features;
  }
  
  static inline uint64_t virtio_net_supported_guest_offloads(VirtIONet *n)
  {
      VirtIODevice *vdev = VIRTIO_DEVICE(n);
      return virtio_net_guest_offloads_by_features(vdev->guest_features);
  }
  
  typedef struct {
      VirtIONet *n;
      char *id;
  } FailoverId;
  
  /**
   * Set the id of the failover primary device
   *
   * @opaque: FailoverId to setup
   * @opts: opts for device we are handling
   * @errp: returns an error if this function fails
   */
  static int failover_set_primary(void *opaque, QemuOpts *opts, Error **errp)
  {
      FailoverId *fid = opaque;
      const char *standby_id = qemu_opt_get(opts, "failover_pair_id");
  
      if (g_strcmp0(standby_id, fid->n->netclient_name) == 0) {
          fid->id = g_strdup(opts->id);
          return 1;
      }
  
      return 0;
  }
  
  /**
   * Find the primary device id for this failover virtio-net
   *
   * @n: VirtIONet device
   * @errp: returns an error if this function fails
   */
  static char *failover_find_primary_device_id(VirtIONet *n)
  {
      Error *err = NULL;
      FailoverId fid;
  
      fid.n = n;
      if (!qemu_opts_foreach(qemu_find_opts("device"),
                             failover_set_primary, &fid, &err)) {
          return NULL;
      }
      return fid.id;
  }
  
  /**
   * Find the primary device for this failover virtio-net
   *
   * @n: VirtIONet device
   * @errp: returns an error if this function fails
   */
  static DeviceState *failover_find_primary_device(VirtIONet *n)
  {
      char *id = failover_find_primary_device_id(n);
  
      if (!id) {
          return NULL;
      }
  
      return qdev_find_recursive(sysbus_get_default(), id);
  }
  
  static void failover_add_primary(VirtIONet *n, Error **errp)
  {
      Error *err = NULL;
      QemuOpts *opts;
      char *id;
      DeviceState *dev = failover_find_primary_device(n);
  
      if (dev) {
          return;
      }
  
      id = failover_find_primary_device_id(n);
      if (!id) {
          error_setg(errp, "Primary device not found");
          error_append_hint(errp, "Virtio-net failover will not work. Make "
                            "sure primary device has parameter"
                            " failover_pair_id=%s\n", n->netclient_name);
          return;
      }
      opts = qemu_opts_find(qemu_find_opts("device"), id);
      g_assert(opts); /* cannot be NULL because id was found using opts list */
      dev = qdev_device_add(opts, &err);
      if (err) {
          qemu_opts_del(opts);
      } else {
          object_unref(OBJECT(dev));
      }
      error_propagate(errp, err);
  }
  
  static void virtio_net_set_features(VirtIODevice *vdev, uint64_t features)
  {
      VirtIONet *n = VIRTIO_NET(vdev);
      Error *err = NULL;
      int i;
  
      if (n->mtu_bypass_backend &&
              !virtio_has_feature(vdev->backend_features, VIRTIO_NET_F_MTU)) {
          features &= ~(1ULL << VIRTIO_NET_F_MTU);
      }
  
      virtio_net_set_multiqueue(n,
                                virtio_has_feature(features, VIRTIO_NET_F_RSS) ||
                                virtio_has_feature(features, VIRTIO_NET_F_MQ));
  
      virtio_net_set_mrg_rx_bufs(n,
                                 virtio_has_feature(features,
                                                    VIRTIO_NET_F_MRG_RXBUF),
                                 virtio_has_feature(features,
                                                    VIRTIO_F_VERSION_1),
                                 virtio_has_feature(features,
                                                    VIRTIO_NET_F_HASH_REPORT));
  
      n->rsc4_enabled = virtio_has_feature(features, VIRTIO_NET_F_RSC_EXT) &&
          virtio_has_feature(features, VIRTIO_NET_F_GUEST_TSO4);
      n->rsc6_enabled = virtio_has_feature(features, VIRTIO_NET_F_RSC_EXT) &&
          virtio_has_feature(features, VIRTIO_NET_F_GUEST_TSO6);
      n->rss_data.redirect = virtio_has_feature(features, VIRTIO_NET_F_RSS);
  
      if (n->has_vnet_hdr) {
          n->curr_guest_offloads =
              virtio_net_guest_offloads_by_features(features);
          virtio_net_apply_guest_offloads(n);
      }
  
      for (i = 0;  i < n->max_queues; i++) {
          NetClientState *nc = qemu_get_subqueue(n->nic, i);
  
          if (!get_vhost_net(nc->peer)) {
              continue;
          }
          vhost_net_ack_features(get_vhost_net(nc->peer), features);
      }
  
      if (virtio_has_feature(features, VIRTIO_NET_F_CTRL_VLAN)) {
          memset(n->vlans, 0, MAX_VLAN >> 3);
      } else {
          memset(n->vlans, 0xff, MAX_VLAN >> 3);
      }
  
      if (virtio_has_feature(features, VIRTIO_NET_F_STANDBY)) {
          qapi_event_send_failover_negotiated(n->netclient_name);
          qatomic_set(&n->failover_primary_hidden, false);
          failover_add_primary(n, &err);
          if (err) {
              warn_report_err(err);
          }
      }
  }
  
  static int virtio_net_handle_rx_mode(VirtIONet *n, uint8_t cmd,
                                       struct iovec *iov, unsigned int iov_cnt)
  {
      uint8_t on;
      size_t s;
      NetClientState *nc = qemu_get_queue(n->nic);
  
      s = iov_to_buf(iov, iov_cnt, 0, &on, sizeof(on));
      if (s != sizeof(on)) {
          return VIRTIO_NET_ERR;
      }
  
      if (cmd == VIRTIO_NET_CTRL_RX_PROMISC) {
          n->promisc = on;
      } else if (cmd == VIRTIO_NET_CTRL_RX_ALLMULTI) {
          n->allmulti = on;
      } else if (cmd == VIRTIO_NET_CTRL_RX_ALLUNI) {
          n->alluni = on;
      } else if (cmd == VIRTIO_NET_CTRL_RX_NOMULTI) {
          n->nomulti = on;
      } else if (cmd == VIRTIO_NET_CTRL_RX_NOUNI) {
          n->nouni = on;
      } else if (cmd == VIRTIO_NET_CTRL_RX_NOBCAST) {
          n->nobcast = on;
      } else {
          return VIRTIO_NET_ERR;
      }
  
      rxfilter_notify(nc);
  
      return VIRTIO_NET_OK;
  }
  
  static int virtio_net_handle_offloads(VirtIONet *n, uint8_t cmd,
                                       struct iovec *iov, unsigned int iov_cnt)
  {
      VirtIODevice *vdev = VIRTIO_DEVICE(n);
      uint64_t offloads;
      size_t s;
  
      if (!virtio_vdev_has_feature(vdev, VIRTIO_NET_F_CTRL_GUEST_OFFLOADS)) {
          return VIRTIO_NET_ERR;
      }
  
      s = iov_to_buf(iov, iov_cnt, 0, &offloads, sizeof(offloads));
      if (s != sizeof(offloads)) {
          return VIRTIO_NET_ERR;
      }
  
      if (cmd == VIRTIO_NET_CTRL_GUEST_OFFLOADS_SET) {
          uint64_t supported_offloads;
  
          offloads = virtio_ldq_p(vdev, &offloads);
  
          if (!n->has_vnet_hdr) {
              return VIRTIO_NET_ERR;
          }
  
          n->rsc4_enabled = virtio_has_feature(offloads, VIRTIO_NET_F_RSC_EXT) &&
              virtio_has_feature(offloads, VIRTIO_NET_F_GUEST_TSO4);
          n->rsc6_enabled = virtio_has_feature(offloads, VIRTIO_NET_F_RSC_EXT) &&
              virtio_has_feature(offloads, VIRTIO_NET_F_GUEST_TSO6);
          virtio_clear_feature(&offloads, VIRTIO_NET_F_RSC_EXT);
  
          supported_offloads = virtio_net_supported_guest_offloads(n);
          if (offloads & ~supported_offloads) {
              return VIRTIO_NET_ERR;
          }
  
          n->curr_guest_offloads = offloads;
          virtio_net_apply_guest_offloads(n);
  
          return VIRTIO_NET_OK;
      } else {
          return VIRTIO_NET_ERR;
      }
  }
  
  static int virtio_net_handle_mac(VirtIONet *n, uint8_t cmd,
                                   struct iovec *iov, unsigned int iov_cnt)
  {
      VirtIODevice *vdev = VIRTIO_DEVICE(n);
      struct virtio_net_ctrl_mac mac_data;
      size_t s;
      NetClientState *nc = qemu_get_queue(n->nic);
  
      if (cmd == VIRTIO_NET_CTRL_MAC_ADDR_SET) {
          if (iov_size(iov, iov_cnt) != sizeof(n->mac)) {
              return VIRTIO_NET_ERR;
          }
          s = iov_to_buf(iov, iov_cnt, 0, &n->mac, sizeof(n->mac));
          assert(s == sizeof(n->mac));
          qemu_format_nic_info_str(qemu_get_queue(n->nic), n->mac);
          rxfilter_notify(nc);
  
          return VIRTIO_NET_OK;
      }
  
      if (cmd != VIRTIO_NET_CTRL_MAC_TABLE_SET) {
          return VIRTIO_NET_ERR;
      }
  
      int in_use = 0;
      int first_multi = 0;
      uint8_t uni_overflow = 0;
      uint8_t multi_overflow = 0;
      uint8_t *macs = g_malloc0(MAC_TABLE_ENTRIES * ETH_ALEN);
  
      s = iov_to_buf(iov, iov_cnt, 0, &mac_data.entries,
                     sizeof(mac_data.entries));
      mac_data.entries = virtio_ldl_p(vdev, &mac_data.entries);
      if (s != sizeof(mac_data.entries)) {
          goto error;
      }
      iov_discard_front(&iov, &iov_cnt, s);
  
      if (mac_data.entries * ETH_ALEN > iov_size(iov, iov_cnt)) {
          goto error;
      }
  
      if (mac_data.entries <= MAC_TABLE_ENTRIES) {
          s = iov_to_buf(iov, iov_cnt, 0, macs,
                         mac_data.entries * ETH_ALEN);
          if (s != mac_data.entries * ETH_ALEN) {
              goto error;
          }
          in_use += mac_data.entries;
      } else {
          uni_overflow = 1;
      }
  
      iov_discard_front(&iov, &iov_cnt, mac_data.entries * ETH_ALEN);
  
      first_multi = in_use;
  
      s = iov_to_buf(iov, iov_cnt, 0, &mac_data.entries,
                     sizeof(mac_data.entries));
      mac_data.entries = virtio_ldl_p(vdev, &mac_data.entries);
      if (s != sizeof(mac_data.entries)) {
          goto error;
      }
  
      iov_discard_front(&iov, &iov_cnt, s);
  
      if (mac_data.entries * ETH_ALEN != iov_size(iov, iov_cnt)) {
          goto error;
      }
  
      if (mac_data.entries <= MAC_TABLE_ENTRIES - in_use) {
          s = iov_to_buf(iov, iov_cnt, 0, &macs[in_use * ETH_ALEN],
                         mac_data.entries * ETH_ALEN);
          if (s != mac_data.entries * ETH_ALEN) {
              goto error;
          }
          in_use += mac_data.entries;
      } else {
          multi_overflow = 1;
      }
  
      n->mac_table.in_use = in_use;
      n->mac_table.first_multi = first_multi;
      n->mac_table.uni_overflow = uni_overflow;
      n->mac_table.multi_overflow = multi_overflow;
      memcpy(n->mac_table.macs, macs, MAC_TABLE_ENTRIES * ETH_ALEN);
      g_free(macs);
      rxfilter_notify(nc);
  
      return VIRTIO_NET_OK;
  
  error:
      g_free(macs);
      return VIRTIO_NET_ERR;
  }
  
  static int virtio_net_handle_vlan_table(VirtIONet *n, uint8_t cmd,
                                          struct iovec *iov, unsigned int iov_cnt)
  {
      VirtIODevice *vdev = VIRTIO_DEVICE(n);
      uint16_t vid;
      size_t s;
      NetClientState *nc = qemu_get_queue(n->nic);
  
      s = iov_to_buf(iov, iov_cnt, 0, &vid, sizeof(vid));
      vid = virtio_lduw_p(vdev, &vid);
      if (s != sizeof(vid)) {
          return VIRTIO_NET_ERR;
      }
  
      if (vid >= MAX_VLAN)
          return VIRTIO_NET_ERR;
  
      if (cmd == VIRTIO_NET_CTRL_VLAN_ADD)
          n->vlans[vid >> 5] |= (1U << (vid & 0x1f));
      else if (cmd == VIRTIO_NET_CTRL_VLAN_DEL)
          n->vlans[vid >> 5] &= ~(1U << (vid & 0x1f));
      else
          return VIRTIO_NET_ERR;
  
      rxfilter_notify(nc);
  
      return VIRTIO_NET_OK;
  }
  
  static int virtio_net_handle_announce(VirtIONet *n, uint8_t cmd,
                                        struct iovec *iov, unsigned int iov_cnt)
  {
      trace_virtio_net_handle_announce(n->announce_timer.round);
      if (cmd == VIRTIO_NET_CTRL_ANNOUNCE_ACK &&
          n->status & VIRTIO_NET_S_ANNOUNCE) {
          n->status &= ~VIRTIO_NET_S_ANNOUNCE;
          if (n->announce_timer.round) {
              qemu_announce_timer_step(&n->announce_timer);
          }
          return VIRTIO_NET_OK;
      } else {
          return VIRTIO_NET_ERR;
      }
  }
  
  static void virtio_net_disable_rss(VirtIONet *n)
  {
      if (n->rss_data.enabled) {
          trace_virtio_net_rss_disable();
      }
      n->rss_data.enabled = false;
  }
  
  static uint16_t virtio_net_handle_rss(VirtIONet *n,
                                        struct iovec *iov,
                                        unsigned int iov_cnt,
                                        bool do_rss)
  {
      VirtIODevice *vdev = VIRTIO_DEVICE(n);
      struct virtio_net_rss_config cfg;
      size_t s, offset = 0, size_get;
      uint16_t queues, i;
      struct {
          uint16_t us;
          uint8_t b;
      } QEMU_PACKED temp;
      const char *err_msg = "";
      uint32_t err_value = 0;
  
      if (do_rss && !virtio_vdev_has_feature(vdev, VIRTIO_NET_F_RSS)) {
          err_msg = "RSS is not negotiated";
          goto error;
      }
      if (!do_rss && !virtio_vdev_has_feature(vdev, VIRTIO_NET_F_HASH_REPORT)) {
          err_msg = "Hash report is not negotiated";
          goto error;
      }
      size_get = offsetof(struct virtio_net_rss_config, indirection_table);
      s = iov_to_buf(iov, iov_cnt, offset, &cfg, size_get);
      if (s != size_get) {
          err_msg = "Short command buffer";
          err_value = (uint32_t)s;
          goto error;
      }
      n->rss_data.hash_types = virtio_ldl_p(vdev, &cfg.hash_types);
      n->rss_data.indirections_len =
          virtio_lduw_p(vdev, &cfg.indirection_table_mask);
      n->rss_data.indirections_len++;
      if (!do_rss) {
          n->rss_data.indirections_len = 1;
      }
      if (!is_power_of_2(n->rss_data.indirections_len)) {
          err_msg = "Invalid size of indirection table";
          err_value = n->rss_data.indirections_len;
          goto error;
      }
      if (n->rss_data.indirections_len > VIRTIO_NET_RSS_MAX_TABLE_LEN) {
          err_msg = "Too large indirection table";
          err_value = n->rss_data.indirections_len;
          goto error;
      }
      n->rss_data.default_queue = do_rss ?
          virtio_lduw_p(vdev, &cfg.unclassified_queue) : 0;
      if (n->rss_data.default_queue >= n->max_queues) {
          err_msg = "Invalid default queue";
          err_value = n->rss_data.default_queue;
          goto error;
      }
      offset += size_get;
      size_get = sizeof(uint16_t) * n->rss_data.indirections_len;
      g_free(n->rss_data.indirections_table);
      n->rss_data.indirections_table = g_malloc(size_get);
      if (!n->rss_data.indirections_table) {
          err_msg = "Can't allocate indirections table";
          err_value = n->rss_data.indirections_len;
          goto error;
      }
      s = iov_to_buf(iov, iov_cnt, offset,
                     n->rss_data.indirections_table, size_get);
      if (s != size_get) {
          err_msg = "Short indirection table buffer";
          err_value = (uint32_t)s;
          goto error;
      }
      for (i = 0; i < n->rss_data.indirections_len; ++i) {
          uint16_t val = n->rss_data.indirections_table[i];
          n->rss_data.indirections_table[i] = virtio_lduw_p(vdev, &val);
      }
      offset += size_get;
      size_get = sizeof(temp);
      s = iov_to_buf(iov, iov_cnt, offset, &temp, size_get);
      if (s != size_get) {
          err_msg = "Can't get queues";
          err_value = (uint32_t)s;
          goto error;
      }
      queues = do_rss ? virtio_lduw_p(vdev, &temp.us) : n->curr_queues;
      if (queues == 0 || queues > n->max_queues) {
          err_msg = "Invalid number of queues";
          err_value = queues;
          goto error;
      }
      if (temp.b > VIRTIO_NET_RSS_MAX_KEY_SIZE) {
          err_msg = "Invalid key size";
          err_value = temp.b;
          goto error;
      }
      if (!temp.b && n->rss_data.hash_types) {
          err_msg = "No key provided";
          err_value = 0;
          goto error;
      }
      if (!temp.b && !n->rss_data.hash_types) {
          virtio_net_disable_rss(n);
          return queues;
      }
      offset += size_get;
      size_get = temp.b;
      s = iov_to_buf(iov, iov_cnt, offset, n->rss_data.key, size_get);
      if (s != size_get) {
          err_msg = "Can get key buffer";
          err_value = (uint32_t)s;
          goto error;
      }
      n->rss_data.enabled = true;
      trace_virtio_net_rss_enable(n->rss_data.hash_types,
                                  n->rss_data.indirections_len,
                                  temp.b);
      return queues;
  error:
      trace_virtio_net_rss_error(err_msg, err_value);
      virtio_net_disable_rss(n);
      return 0;
  }
  
  static int virtio_net_handle_mq(VirtIONet *n, uint8_t cmd,
                                  struct iovec *iov, unsigned int iov_cnt)
  {
      VirtIODevice *vdev = VIRTIO_DEVICE(n);
      uint16_t queues;
  
      virtio_net_disable_rss(n);
      if (cmd == VIRTIO_NET_CTRL_MQ_HASH_CONFIG) {
          queues = virtio_net_handle_rss(n, iov, iov_cnt, false);
          return queues ? VIRTIO_NET_OK : VIRTIO_NET_ERR;
      }
      if (cmd == VIRTIO_NET_CTRL_MQ_RSS_CONFIG) {
          queues = virtio_net_handle_rss(n, iov, iov_cnt, true);
      } else if (cmd == VIRTIO_NET_CTRL_MQ_VQ_PAIRS_SET) {
          struct virtio_net_ctrl_mq mq;
          size_t s;
          if (!virtio_vdev_has_feature(vdev, VIRTIO_NET_F_MQ)) {
              return VIRTIO_NET_ERR;
          }
          s = iov_to_buf(iov, iov_cnt, 0, &mq, sizeof(mq));
          if (s != sizeof(mq)) {
              return VIRTIO_NET_ERR;
          }
          queues = virtio_lduw_p(vdev, &mq.virtqueue_pairs);
  
      } else {
          return VIRTIO_NET_ERR;
      }
  
      if (queues < VIRTIO_NET_CTRL_MQ_VQ_PAIRS_MIN ||
          queues > VIRTIO_NET_CTRL_MQ_VQ_PAIRS_MAX ||
          queues > n->max_queues ||
          !n->multiqueue) {
          return VIRTIO_NET_ERR;
      }
  
      n->curr_queues = queues;
      /* stop the backend before changing the number of queues to avoid handling a
       * disabled queue */
      virtio_net_set_status(vdev, vdev->status);
      virtio_net_set_queues(n);
  
      return VIRTIO_NET_OK;
  }
  
  static void virtio_net_handle_ctrl(VirtIODevice *vdev, VirtQueue *vq)
  {
      VirtIONet *n = VIRTIO_NET(vdev);
      struct virtio_net_ctrl_hdr ctrl;
      virtio_net_ctrl_ack status = VIRTIO_NET_ERR;
      VirtQueueElement *elem;
      size_t s;
      struct iovec *iov, *iov2;
      unsigned int iov_cnt;
  
      for (;;) {
          elem = virtqueue_pop(vq, sizeof(VirtQueueElement));
          if (!elem) {
              break;
          }
          if (iov_size(elem->in_sg, elem->in_num) < sizeof(status) ||
              iov_size(elem->out_sg, elem->out_num) < sizeof(ctrl)) {
              virtio_error(vdev, "virtio-net ctrl missing headers");
              virtqueue_detach_element(vq, elem, 0);
              g_free(elem);
              break;
          }
  
          iov_cnt = elem->out_num;
          iov2 = iov = g_memdup(elem->out_sg, sizeof(struct iovec) * elem->out_num);
          s = iov_to_buf(iov, iov_cnt, 0, &ctrl, sizeof(ctrl));
          iov_discard_front(&iov, &iov_cnt, sizeof(ctrl));
          if (s != sizeof(ctrl)) {
              status = VIRTIO_NET_ERR;
          } else if (ctrl.class == VIRTIO_NET_CTRL_RX) {
              status = virtio_net_handle_rx_mode(n, ctrl.cmd, iov, iov_cnt);
          } else if (ctrl.class == VIRTIO_NET_CTRL_MAC) {
              status = virtio_net_handle_mac(n, ctrl.cmd, iov, iov_cnt);
          } else if (ctrl.class == VIRTIO_NET_CTRL_VLAN) {
              status = virtio_net_handle_vlan_table(n, ctrl.cmd, iov, iov_cnt);
          } else if (ctrl.class == VIRTIO_NET_CTRL_ANNOUNCE) {
              status = virtio_net_handle_announce(n, ctrl.cmd, iov, iov_cnt);
          } else if (ctrl.class == VIRTIO_NET_CTRL_MQ) {
              status = virtio_net_handle_mq(n, ctrl.cmd, iov, iov_cnt);
          } else if (ctrl.class == VIRTIO_NET_CTRL_GUEST_OFFLOADS) {
              status = virtio_net_handle_offloads(n, ctrl.cmd, iov, iov_cnt);
          }
  
          s = iov_from_buf(elem->in_sg, elem->in_num, 0, &status, sizeof(status));
          assert(s == sizeof(status));
  
          virtqueue_push(vq, elem, sizeof(status));
          virtio_notify(vdev, vq);
          g_free(iov2);
          g_free(elem);
      }
  }
  
  /* RX */
  
  static void virtio_net_handle_rx(VirtIODevice *vdev, VirtQueue *vq)
  {
      VirtIONet *n = VIRTIO_NET(vdev);
      int queue_index = vq2q(virtio_get_queue_index(vq));
  
      qemu_flush_queued_packets(qemu_get_subqueue(n->nic, queue_index));
  }
  
  static bool virtio_net_can_receive(NetClientState *nc)
  {
      VirtIONet *n = qemu_get_nic_opaque(nc);
      VirtIODevice *vdev = VIRTIO_DEVICE(n);
      VirtIONetQueue *q = virtio_net_get_subqueue(nc);
  
      if (!vdev->vm_running) {
          return false;
      }
  
      if (nc->queue_index >= n->curr_queues) {
          return false;
      }
  
      if (!virtio_queue_ready(q->rx_vq) ||
          !(vdev->status & VIRTIO_CONFIG_S_DRIVER_OK)) {
          return false;
      }
  
      return true;
  }
  
  static int virtio_net_has_buffers(VirtIONetQueue *q, int bufsize)
  {
      VirtIONet *n = q->n;
      if (virtio_queue_empty(q->rx_vq) ||
          (n->mergeable_rx_bufs &&
           !virtqueue_avail_bytes(q->rx_vq, bufsize, 0))) {
          virtio_queue_set_notification(q->rx_vq, 1);
  
          /* To avoid a race condition where the guest has made some buffers
           * available after the above check but before notification was
           * enabled, check for available buffers again.
           */
          if (virtio_queue_empty(q->rx_vq) ||
              (n->mergeable_rx_bufs &&
               !virtqueue_avail_bytes(q->rx_vq, bufsize, 0))) {
              return 0;
          }
      }
  
      virtio_queue_set_notification(q->rx_vq, 0);
      return 1;
  }
  
  static void virtio_net_hdr_swap(VirtIODevice *vdev, struct virtio_net_hdr *hdr)
  {
      virtio_tswap16s(vdev, &hdr->hdr_len);
      virtio_tswap16s(vdev, &hdr->gso_size);
      virtio_tswap16s(vdev, &hdr->csum_start);
      virtio_tswap16s(vdev, &hdr->csum_offset);
  }
  
  /* dhclient uses AF_PACKET but doesn't pass auxdata to the kernel so
   * it never finds out that the packets don't have valid checksums.  This
   * causes dhclient to get upset.  Fedora's carried a patch for ages to
   * fix this with Xen but it hasn't appeared in an upstream release of
   * dhclient yet.
   *
   * To avoid breaking existing guests, we catch udp packets and add
   * checksums.  This is terrible but it's better than hacking the guest
   * kernels.
   *
   * N.B. if we introduce a zero-copy API, this operation is no longer free so
   * we should provide a mechanism to disable it to avoid polluting the host
   * cache.
   */
  static void work_around_broken_dhclient(struct virtio_net_hdr *hdr,
                                          uint8_t *buf, size_t size)
  {
      if ((hdr->flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) && /* missing csum */
          (size > 27 && size < 1500) && /* normal sized MTU */
          (buf[12] == 0x08 && buf[13] == 0x00) && /* ethertype == IPv4 */
          (buf[23] == 17) && /* ip.protocol == UDP */
          (buf[34] == 0 && buf[35] == 67)) { /* udp.srcport == bootps */
          net_checksum_calculate(buf, size, CSUM_UDP);
          hdr->flags &= ~VIRTIO_NET_HDR_F_NEEDS_CSUM;
      }
  }
  
  static void receive_header(VirtIONet *n, const struct iovec *iov, int iov_cnt,
                             const void *buf, size_t size)
  {
      if (n->has_vnet_hdr) {
          /* FIXME this cast is evil */
          void *wbuf = (void *)buf;
          work_around_broken_dhclient(wbuf, wbuf + n->host_hdr_len,
                                      size - n->host_hdr_len);
  
          if (n->needs_vnet_hdr_swap) {
              virtio_net_hdr_swap(VIRTIO_DEVICE(n), wbuf);
          }
          iov_from_buf(iov, iov_cnt, 0, buf, sizeof(struct virtio_net_hdr));
      } else {
          struct virtio_net_hdr hdr = {
              .flags = 0,
              .gso_type = VIRTIO_NET_HDR_GSO_NONE
          };
          iov_from_buf(iov, iov_cnt, 0, &hdr, sizeof hdr);
      }
  }
  
  static int receive_filter(VirtIONet *n, const uint8_t *buf, int size)
  {
      static const uint8_t bcast[] = {0xff, 0xff, 0xff, 0xff, 0xff, 0xff};
      static const uint8_t vlan[] = {0x81, 0x00};
      uint8_t *ptr = (uint8_t *)buf;
      int i;
  
      if (n->promisc)
          return 1;
  
      ptr += n->host_hdr_len;
  
      if (!memcmp(&ptr[12], vlan, sizeof(vlan))) {
          int vid = lduw_be_p(ptr + 14) & 0xfff;
          if (!(n->vlans[vid >> 5] & (1U << (vid & 0x1f))))
              return 0;
      }
  
      if (ptr[0] & 1) { // multicast
          if (!memcmp(ptr, bcast, sizeof(bcast))) {
              return !n->nobcast;
          } else if (n->nomulti) {
              return 0;
          } else if (n->allmulti || n->mac_table.multi_overflow) {
              return 1;
          }
  
          for (i = n->mac_table.first_multi; i < n->mac_table.in_use; i++) {
              if (!memcmp(ptr, &n->mac_table.macs[i * ETH_ALEN], ETH_ALEN)) {
                  return 1;
              }
          }
      } else { // unicast
          if (n->nouni) {
              return 0;
          } else if (n->alluni || n->mac_table.uni_overflow) {
              return 1;
          } else if (!memcmp(ptr, n->mac, ETH_ALEN)) {
              return 1;
          }
  
          for (i = 0; i < n->mac_table.first_multi; i++) {
              if (!memcmp(ptr, &n->mac_table.macs[i * ETH_ALEN], ETH_ALEN)) {
                  return 1;
              }
          }
      }
  
      return 0;
  }
  
  static uint8_t virtio_net_get_hash_type(bool isip4,
                                          bool isip6,
                                          bool isudp,
                                          bool istcp,
                                          uint32_t types)
  {
      if (isip4) {
          if (istcp && (types & VIRTIO_NET_RSS_HASH_TYPE_TCPv4)) {
              return NetPktRssIpV4Tcp;
          }
          if (isudp && (types & VIRTIO_NET_RSS_HASH_TYPE_UDPv4)) {
              return NetPktRssIpV4Udp;
          }
          if (types & VIRTIO_NET_RSS_HASH_TYPE_IPv4) {
              return NetPktRssIpV4;
          }
      } else if (isip6) {
          uint32_t mask = VIRTIO_NET_RSS_HASH_TYPE_TCP_EX |
                          VIRTIO_NET_RSS_HASH_TYPE_TCPv6;
  
          if (istcp && (types & mask)) {
              return (types & VIRTIO_NET_RSS_HASH_TYPE_TCP_EX) ?
                  NetPktRssIpV6TcpEx : NetPktRssIpV6Tcp;
          }
          mask = VIRTIO_NET_RSS_HASH_TYPE_UDP_EX | VIRTIO_NET_RSS_HASH_TYPE_UDPv6;
          if (isudp && (types & mask)) {
              return (types & VIRTIO_NET_RSS_HASH_TYPE_UDP_EX) ?
                  NetPktRssIpV6UdpEx : NetPktRssIpV6Udp;
          }
          mask = VIRTIO_NET_RSS_HASH_TYPE_IP_EX | VIRTIO_NET_RSS_HASH_TYPE_IPv6;
          if (types & mask) {
              return (types & VIRTIO_NET_RSS_HASH_TYPE_IP_EX) ?
                  NetPktRssIpV6Ex : NetPktRssIpV6;
          }
      }
      return 0xff;
  }
  
  static void virtio_set_packet_hash(const uint8_t *buf, uint8_t report,
                                     uint32_t hash)
  {
      struct virtio_net_hdr_v1_hash *hdr = (void *)buf;
      hdr->hash_value = hash;
      hdr->hash_report = report;
  }
  
  static int virtio_net_process_rss(NetClientState *nc, const uint8_t *buf,
                                    size_t size)
  {
      VirtIONet *n = qemu_get_nic_opaque(nc);
      unsigned int index = nc->queue_index, new_index = index;
      struct NetRxPkt *pkt = n->rx_pkt;
      uint8_t net_hash_type;
      uint32_t hash;
      bool isip4, isip6, isudp, istcp;
      static const uint8_t reports[NetPktRssIpV6UdpEx + 1] = {
          VIRTIO_NET_HASH_REPORT_IPv4,
          VIRTIO_NET_HASH_REPORT_TCPv4,
          VIRTIO_NET_HASH_REPORT_TCPv6,
          VIRTIO_NET_HASH_REPORT_IPv6,
          VIRTIO_NET_HASH_REPORT_IPv6_EX,
          VIRTIO_NET_HASH_REPORT_TCPv6_EX,
          VIRTIO_NET_HASH_REPORT_UDPv4,
          VIRTIO_NET_HASH_REPORT_UDPv6,
          VIRTIO_NET_HASH_REPORT_UDPv6_EX
      };
  
      net_rx_pkt_set_protocols(pkt, buf + n->host_hdr_len,
                               size - n->host_hdr_len);
      net_rx_pkt_get_protocols(pkt, &isip4, &isip6, &isudp, &istcp);
      if (isip4 && (net_rx_pkt_get_ip4_info(pkt)->fragment)) {
          istcp = isudp = false;
      }
      if (isip6 && (net_rx_pkt_get_ip6_info(pkt)->fragment)) {
          istcp = isudp = false;
      }
      net_hash_type = virtio_net_get_hash_type(isip4, isip6, isudp, istcp,
                                               n->rss_data.hash_types);
      if (net_hash_type > NetPktRssIpV6UdpEx) {
          if (n->rss_data.populate_hash) {
              virtio_set_packet_hash(buf, VIRTIO_NET_HASH_REPORT_NONE, 0);
          }
          return n->rss_data.redirect ? n->rss_data.default_queue : -1;
      }
  
      hash = net_rx_pkt_calc_rss_hash(pkt, net_hash_type, n->rss_data.key);
  
      if (n->rss_data.populate_hash) {
          virtio_set_packet_hash(buf, reports[net_hash_type], hash);
      }
  
      if (n->rss_data.redirect) {
          new_index = hash & (n->rss_data.indirections_len - 1);
          new_index = n->rss_data.indirections_table[new_index];
      }
  
      return (index == new_index) ? -1 : new_index;
  }
  
  static ssize_t virtio_net_receive_rcu(NetClientState *nc, const uint8_t *buf,
                                        size_t size, bool no_rss)
  {
      VirtIONet *n = qemu_get_nic_opaque(nc);
      VirtIONetQueue *q = virtio_net_get_subqueue(nc);
      VirtIODevice *vdev = VIRTIO_DEVICE(n);
      struct iovec mhdr_sg[VIRTQUEUE_MAX_SIZE];
      struct virtio_net_hdr_mrg_rxbuf mhdr;
      unsigned mhdr_cnt = 0;
      size_t offset, i, guest_offset;
  
      if (!virtio_net_can_receive(nc)) {
          return -1;
      }
  
      if (!no_rss && n->rss_data.enabled) {
          int index = virtio_net_process_rss(nc, buf, size);
          if (index >= 0) {
              NetClientState *nc2 = qemu_get_subqueue(n->nic, index);
              return virtio_net_receive_rcu(nc2, buf, size, true);
          }
      }
  
      /* hdr_len refers to the header we supply to the guest */
      if (!virtio_net_has_buffers(q, size + n->guest_hdr_len - n->host_hdr_len)) {
          return 0;
      }
  
      if (!receive_filter(n, buf, size))
          return size;
  
      offset = i = 0;
  
      while (offset < size) {
          VirtQueueElement *elem;
          int len, total;
          const struct iovec *sg;
  
          total = 0;
  
          elem = virtqueue_pop(q->rx_vq, sizeof(VirtQueueElement));
          if (!elem) {
              if (i) {
                  virtio_error(vdev, "virtio-net unexpected empty queue: "
                               "i %zd mergeable %d offset %zd, size %zd, "
                               "guest hdr len %zd, host hdr len %zd "
                               "guest features 0x%" PRIx64,
                               i, n->mergeable_rx_bufs, offset, size,
                               n->guest_hdr_len, n->host_hdr_len,
                               vdev->guest_features);
              }
              return -1;
          }
  
          if (elem->in_num < 1) {
              virtio_error(vdev,
                           "virtio-net receive queue contains no in buffers");
              virtqueue_detach_element(q->rx_vq, elem, 0);
              g_free(elem);
              return -1;
          }
  
          sg = elem->in_sg;
          if (i == 0) {
              assert(offset == 0);
              if (n->mergeable_rx_bufs) {
                  mhdr_cnt = iov_copy(mhdr_sg, ARRAY_SIZE(mhdr_sg),
                                      sg, elem->in_num,
                                      offsetof(typeof(mhdr), num_buffers),
                                      sizeof(mhdr.num_buffers));
              }
  
              receive_header(n, sg, elem->in_num, buf, size);
              if (n->rss_data.populate_hash) {
                  offset = sizeof(mhdr);
                  iov_from_buf(sg, elem->in_num, offset,
                               buf + offset, n->host_hdr_len - sizeof(mhdr));
              }
              offset = n->host_hdr_len;
              total += n->guest_hdr_len;
              guest_offset = n->guest_hdr_len;
          } else {
              guest_offset = 0;
          }
  
          /* copy in packet.  ugh */
          len = iov_from_buf(sg, elem->in_num, guest_offset,
                             buf + offset, size - offset);
          total += len;
          offset += len;
          /* If buffers can't be merged, at this point we
           * must have consumed the complete packet.
           * Otherwise, drop it. */
          if (!n->mergeable_rx_bufs && offset < size) {
              virtqueue_unpop(q->rx_vq, elem, total);
              g_free(elem);
              return size;
          }
  
          /* signal other side */
          virtqueue_fill(q->rx_vq, elem, total, i++);
          g_free(elem);
      }
  
      if (mhdr_cnt) {
          virtio_stw_p(vdev, &mhdr.num_buffers, i);
          iov_from_buf(mhdr_sg, mhdr_cnt,
                       0,
                       &mhdr.num_buffers, sizeof mhdr.num_buffers);
      }
  
      virtqueue_flush(q->rx_vq, i);
      virtio_notify(vdev, q->rx_vq);
  
      return size;
  }
  
  static ssize_t virtio_net_do_receive(NetClientState *nc, const uint8_t *buf,
                                    size_t size)
  {
      RCU_READ_LOCK_GUARD();
  
      return virtio_net_receive_rcu(nc, buf, size, false);
  }
  
  static void virtio_net_rsc_extract_unit4(VirtioNetRscChain *chain,
                                           const uint8_t *buf,
                                           VirtioNetRscUnit *unit)
  {
      uint16_t ip_hdrlen;
      struct ip_header *ip;
  
      ip = (struct ip_header *)(buf + chain->n->guest_hdr_len
                                + sizeof(struct eth_header));
      unit->ip = (void *)ip;
      ip_hdrlen = (ip->ip_ver_len & 0xF) << 2;
      unit->ip_plen = &ip->ip_len;
      unit->tcp = (struct tcp_header *)(((uint8_t *)unit->ip) + ip_hdrlen);
      unit->tcp_hdrlen = (htons(unit->tcp->th_offset_flags) & 0xF000) >> 10;
      unit->payload = htons(*unit->ip_plen) - ip_hdrlen - unit->tcp_hdrlen;
  }
  
  static void virtio_net_rsc_extract_unit6(VirtioNetRscChain *chain,
                                           const uint8_t *buf,
                                           VirtioNetRscUnit *unit)
  {
      struct ip6_header *ip6;
  
      ip6 = (struct ip6_header *)(buf + chain->n->guest_hdr_len
                                   + sizeof(struct eth_header));
      unit->ip = ip6;
      unit->ip_plen = &(ip6->ip6_ctlun.ip6_un1.ip6_un1_plen);
      unit->tcp = (struct tcp_header *)(((uint8_t *)unit->ip)
                                          + sizeof(struct ip6_header));
      unit->tcp_hdrlen = (htons(unit->tcp->th_offset_flags) & 0xF000) >> 10;
  
      /* There is a difference between payload lenght in ipv4 and v6,
         ip header is excluded in ipv6 */
      unit->payload = htons(*unit->ip_plen) - unit->tcp_hdrlen;
  }
  
  static size_t virtio_net_rsc_drain_seg(VirtioNetRscChain *chain,
                                         VirtioNetRscSeg *seg)
  {
      int ret;
      struct virtio_net_hdr_v1 *h;
  
      h = (struct virtio_net_hdr_v1 *)seg->buf;
      h->flags = 0;
      h->gso_type = VIRTIO_NET_HDR_GSO_NONE;
  
      if (seg->is_coalesced) {
          h->rsc.segments = seg->packets;
          h->rsc.dup_acks = seg->dup_ack;
          h->flags = VIRTIO_NET_HDR_F_RSC_INFO;
          if (chain->proto == ETH_P_IP) {
              h->gso_type = VIRTIO_NET_HDR_GSO_TCPV4;
          } else {
              h->gso_type = VIRTIO_NET_HDR_GSO_TCPV6;
          }
      }
  
      ret = virtio_net_do_receive(seg->nc, seg->buf, seg->size);
      QTAILQ_REMOVE(&chain->buffers, seg, next);
      g_free(seg->buf);
      g_free(seg);
  
      return ret;
  }
  
  static void virtio_net_rsc_purge(void *opq)
  {
      VirtioNetRscSeg *seg, *rn;
      VirtioNetRscChain *chain = (VirtioNetRscChain *)opq;
  
      QTAILQ_FOREACH_SAFE(seg, &chain->buffers, next, rn) {
          if (virtio_net_rsc_drain_seg(chain, seg) == 0) {
              chain->stat.purge_failed++;
              continue;
          }
      }
  
      chain->stat.timer++;
      if (!QTAILQ_EMPTY(&chain->buffers)) {
          timer_mod(chain->drain_timer,
                qemu_clock_get_ns(QEMU_CLOCK_HOST) + chain->n->rsc_timeout);
      }
  }
  
  static void virtio_net_rsc_cleanup(VirtIONet *n)
  {
      VirtioNetRscChain *chain, *rn_chain;
      VirtioNetRscSeg *seg, *rn_seg;
  
      QTAILQ_FOREACH_SAFE(chain, &n->rsc_chains, next, rn_chain) {
          QTAILQ_FOREACH_SAFE(seg, &chain->buffers, next, rn_seg) {
              QTAILQ_REMOVE(&chain->buffers, seg, next);
              g_free(seg->buf);
              g_free(seg);
          }
  
          timer_free(chain->drain_timer);
          QTAILQ_REMOVE(&n->rsc_chains, chain, next);
          g_free(chain);
      }
  }
  
  static void virtio_net_rsc_cache_buf(VirtioNetRscChain *chain,
                                       NetClientState *nc,
                                       const uint8_t *buf, size_t size)
  {
      uint16_t hdr_len;
      VirtioNetRscSeg *seg;
  
      hdr_len = chain->n->guest_hdr_len;
      seg = g_malloc(sizeof(VirtioNetRscSeg));
      seg->buf = g_malloc(hdr_len + sizeof(struct eth_header)
          + sizeof(struct ip6_header) + VIRTIO_NET_MAX_TCP_PAYLOAD);
      memcpy(seg->buf, buf, size);
      seg->size = size;
      seg->packets = 1;
      seg->dup_ack = 0;
      seg->is_coalesced = 0;
      seg->nc = nc;
  
      QTAILQ_INSERT_TAIL(&chain->buffers, seg, next);
      chain->stat.cache++;
  
      switch (chain->proto) {
      case ETH_P_IP:
          virtio_net_rsc_extract_unit4(chain, seg->buf, &seg->unit);
          break;
      case ETH_P_IPV6:
          virtio_net_rsc_extract_unit6(chain, seg->buf, &seg->unit);
          break;
      default:
          g_assert_not_reached();
      }
  }
  
  static int32_t virtio_net_rsc_handle_ack(VirtioNetRscChain *chain,
                                           VirtioNetRscSeg *seg,
                                           const uint8_t *buf,
                                           struct tcp_header *n_tcp,
                                           struct tcp_header *o_tcp)
  {
      uint32_t nack, oack;
      uint16_t nwin, owin;
  
      nack = htonl(n_tcp->th_ack);
      nwin = htons(n_tcp->th_win);
      oack = htonl(o_tcp->th_ack);
      owin = htons(o_tcp->th_win);
  
      if ((nack - oack) >= VIRTIO_NET_MAX_TCP_PAYLOAD) {
          chain->stat.ack_out_of_win++;
          return RSC_FINAL;
      } else if (nack == oack) {
          /* duplicated ack or window probe */
          if (nwin == owin) {
              /* duplicated ack, add dup ack count due to whql test up to 1 */
              chain->stat.dup_ack++;
              return RSC_FINAL;
          } else {
              /* Coalesce window update */
              o_tcp->th_win = n_tcp->th_win;
              chain->stat.win_update++;
              return RSC_COALESCE;
          }
      } else {
          /* pure ack, go to 'C', finalize*/
          chain->stat.pure_ack++;
          return RSC_FINAL;
      }
  }
  
  static int32_t virtio_net_rsc_coalesce_data(VirtioNetRscChain *chain,
                                              VirtioNetRscSeg *seg,
                                              const uint8_t *buf,
                                              VirtioNetRscUnit *n_unit)
  {
      void *data;
      uint16_t o_ip_len;
      uint32_t nseq, oseq;
      VirtioNetRscUnit *o_unit;
  
      o_unit = &seg->unit;
      o_ip_len = htons(*o_unit->ip_plen);
      nseq = htonl(n_unit->tcp->th_seq);
      oseq = htonl(o_unit->tcp->th_seq);
  
      /* out of order or retransmitted. */
      if ((nseq - oseq) > VIRTIO_NET_MAX_TCP_PAYLOAD) {
          chain->stat.data_out_of_win++;
          return RSC_FINAL;
      }
  
      data = ((uint8_t *)n_unit->tcp) + n_unit->tcp_hdrlen;
      if (nseq == oseq) {
          if ((o_unit->payload == 0) && n_unit->payload) {
              /* From no payload to payload, normal case, not a dup ack or etc */
              chain->stat.data_after_pure_ack++;
              goto coalesce;
          } else {
              return virtio_net_rsc_handle_ack(chain, seg, buf,
                                               n_unit->tcp, o_unit->tcp);
          }
      } else if ((nseq - oseq) != o_unit->payload) {
          /* Not a consistent packet, out of order */
          chain->stat.data_out_of_order++;
          return RSC_FINAL;
      } else {
  coalesce:
          if ((o_ip_len + n_unit->payload) > chain->max_payload) {
              chain->stat.over_size++;
              return RSC_FINAL;
          }
  
          /* Here comes the right data, the payload length in v4/v6 is different,
             so use the field value to update and record the new data len */
          o_unit->payload += n_unit->payload; /* update new data len */
  
          /* update field in ip header */
          *o_unit->ip_plen = htons(o_ip_len + n_unit->payload);
  
          /* Bring 'PUSH' big, the whql test guide says 'PUSH' can be coalesced
             for windows guest, while this may change the behavior for linux
             guest (only if it uses RSC feature). */
          o_unit->tcp->th_offset_flags = n_unit->tcp->th_offset_flags;
  
          o_unit->tcp->th_ack = n_unit->tcp->th_ack;
          o_unit->tcp->th_win = n_unit->tcp->th_win;
  
          memmove(seg->buf + seg->size, data, n_unit->payload);
          seg->size += n_unit->payload;
          seg->packets++;
          chain->stat.coalesced++;
          return RSC_COALESCE;
      }
  }
  
  static int32_t virtio_net_rsc_coalesce4(VirtioNetRscChain *chain,
                                          VirtioNetRscSeg *seg,
                                          const uint8_t *buf, size_t size,
                                          VirtioNetRscUnit *unit)
  {
      struct ip_header *ip1, *ip2;
  
      ip1 = (struct ip_header *)(unit->ip);
      ip2 = (struct ip_header *)(seg->unit.ip);
      if ((ip1->ip_src ^ ip2->ip_src) || (ip1->ip_dst ^ ip2->ip_dst)
          || (unit->tcp->th_sport ^ seg->unit.tcp->th_sport)
          || (unit->tcp->th_dport ^ seg->unit.tcp->th_dport)) {
          chain->stat.no_match++;
          return RSC_NO_MATCH;
      }
  
      return virtio_net_rsc_coalesce_data(chain, seg, buf, unit);
  }
  
  static int32_t virtio_net_rsc_coalesce6(VirtioNetRscChain *chain,
                                          VirtioNetRscSeg *seg,
                                          const uint8_t *buf, size_t size,
                                          VirtioNetRscUnit *unit)
  {
      struct ip6_header *ip1, *ip2;
  
      ip1 = (struct ip6_header *)(unit->ip);
      ip2 = (struct ip6_header *)(seg->unit.ip);
      if (memcmp(&ip1->ip6_src, &ip2->ip6_src, sizeof(struct in6_address))
          || memcmp(&ip1->ip6_dst, &ip2->ip6_dst, sizeof(struct in6_address))
          || (unit->tcp->th_sport ^ seg->unit.tcp->th_sport)
          || (unit->tcp->th_dport ^ seg->unit.tcp->th_dport)) {
              chain->stat.no_match++;
              return RSC_NO_MATCH;
      }
  
      return virtio_net_rsc_coalesce_data(chain, seg, buf, unit);
  }
  
  /* Packets with 'SYN' should bypass, other flag should be sent after drain
   * to prevent out of order */
  static int virtio_net_rsc_tcp_ctrl_check(VirtioNetRscChain *chain,
                                           struct tcp_header *tcp)
  {
      uint16_t tcp_hdr;
      uint16_t tcp_flag;
  
      tcp_flag = htons(tcp->th_offset_flags);
      tcp_hdr = (tcp_flag & VIRTIO_NET_TCP_HDR_LENGTH) >> 10;
      tcp_flag &= VIRTIO_NET_TCP_FLAG;
      if (tcp_flag & TH_SYN) {
          chain->stat.tcp_syn++;
          return RSC_BYPASS;
      }
  
      if (tcp_flag & (TH_FIN | TH_URG | TH_RST | TH_ECE | TH_CWR)) {
          chain->stat.tcp_ctrl_drain++;
          return RSC_FINAL;
      }
  
      if (tcp_hdr > sizeof(struct tcp_header)) {
          chain->stat.tcp_all_opt++;
          return RSC_FINAL;
      }
  
      return RSC_CANDIDATE;
  }
  
  static size_t virtio_net_rsc_do_coalesce(VirtioNetRscChain *chain,
                                           NetClientState *nc,
                                           const uint8_t *buf, size_t size,
                                           VirtioNetRscUnit *unit)
  {
      int ret;
      VirtioNetRscSeg *seg, *nseg;
  
      if (QTAILQ_EMPTY(&chain->buffers)) {
          chain->stat.empty_cache++;
          virtio_net_rsc_cache_buf(chain, nc, buf, size);
          timer_mod(chain->drain_timer,
                qemu_clock_get_ns(QEMU_CLOCK_HOST) + chain->n->rsc_timeout);
          return size;
      }
  
      QTAILQ_FOREACH_SAFE(seg, &chain->buffers, next, nseg) {
          if (chain->proto == ETH_P_IP) {
              ret = virtio_net_rsc_coalesce4(chain, seg, buf, size, unit);
          } else {
              ret = virtio_net_rsc_coalesce6(chain, seg, buf, size, unit);
          }
  
          if (ret == RSC_FINAL) {
              if (virtio_net_rsc_drain_seg(chain, seg) == 0) {
                  /* Send failed */
                  chain->stat.final_failed++;
                  return 0;
              }
  
              /* Send current packet */
              return virtio_net_do_receive(nc, buf, size);
          } else if (ret == RSC_NO_MATCH) {
              continue;
          } else {
              /* Coalesced, mark coalesced flag to tell calc cksum for ipv4 */
              seg->is_coalesced = 1;
              return size;
          }
      }
  
      chain->stat.no_match_cache++;
      virtio_net_rsc_cache_buf(chain, nc, buf, size);
      return size;
  }
  
  /* Drain a connection data, this is to avoid out of order segments */
  static size_t virtio_net_rsc_drain_flow(VirtioNetRscChain *chain,
                                          NetClientState *nc,
                                          const uint8_t *buf, size_t size,
                                          uint16_t ip_start, uint16_t ip_size,
                                          uint16_t tcp_port)
  {
      VirtioNetRscSeg *seg, *nseg;
      uint32_t ppair1, ppair2;
  
      ppair1 = *(uint32_t *)(buf + tcp_port);
      QTAILQ_FOREACH_SAFE(seg, &chain->buffers, next, nseg) {
          ppair2 = *(uint32_t *)(seg->buf + tcp_port);
          if (memcmp(buf + ip_start, seg->buf + ip_start, ip_size)
              || (ppair1 != ppair2)) {
              continue;
          }
          if (virtio_net_rsc_drain_seg(chain, seg) == 0) {
              chain->stat.drain_failed++;
          }
  
          break;
      }
  
      return virtio_net_do_receive(nc, buf, size);
  }
  
  static int32_t virtio_net_rsc_sanity_check4(VirtioNetRscChain *chain,
                                              struct ip_header *ip,
                                              const uint8_t *buf, size_t size)
  {
      uint16_t ip_len;
  
      /* Not an ipv4 packet */
      if (((ip->ip_ver_len & 0xF0) >> 4) != IP_HEADER_VERSION_4) {
          chain->stat.ip_option++;
          return RSC_BYPASS;
      }
  
      /* Don't handle packets with ip option */
      if ((ip->ip_ver_len & 0xF) != VIRTIO_NET_IP4_HEADER_LENGTH) {
          chain->stat.ip_option++;
          return RSC_BYPASS;
      }
  
      if (ip->ip_p != IPPROTO_TCP) {
          chain->stat.bypass_not_tcp++;
          return RSC_BYPASS;
      }
  
      /* Don't handle packets with ip fragment */
      if (!(htons(ip->ip_off) & IP_DF)) {
          chain->stat.ip_frag++;
          return RSC_BYPASS;
      }
  
      /* Don't handle packets with ecn flag */
      if (IPTOS_ECN(ip->ip_tos)) {
          chain->stat.ip_ecn++;
          return RSC_BYPASS;
      }
  
      ip_len = htons(ip->ip_len);
      if (ip_len < (sizeof(struct ip_header) + sizeof(struct tcp_header))
          || ip_len > (size - chain->n->guest_hdr_len -
                       sizeof(struct eth_header))) {
          chain->stat.ip_hacked++;
          return RSC_BYPASS;
      }
  
      return RSC_CANDIDATE;
  }
  
  static size_t virtio_net_rsc_receive4(VirtioNetRscChain *chain,
                                        NetClientState *nc,
                                        const uint8_t *buf, size_t size)
  {
      int32_t ret;
      uint16_t hdr_len;
      VirtioNetRscUnit unit;
  
      hdr_len = ((VirtIONet *)(chain->n))->guest_hdr_len;
  
      if (size < (hdr_len + sizeof(struct eth_header) + sizeof(struct ip_header)
          + sizeof(struct tcp_header))) {
          chain->stat.bypass_not_tcp++;
          return virtio_net_do_receive(nc, buf, size);
      }
  
      virtio_net_rsc_extract_unit4(chain, buf, &unit);
      if (virtio_net_rsc_sanity_check4(chain, unit.ip, buf, size)
          != RSC_CANDIDATE) {
          return virtio_net_do_receive(nc, buf, size);
      }
  
      ret = virtio_net_rsc_tcp_ctrl_check(chain, unit.tcp);
      if (ret == RSC_BYPASS) {
          return virtio_net_do_receive(nc, buf, size);
      } else if (ret == RSC_FINAL) {
          return virtio_net_rsc_drain_flow(chain, nc, buf, size,
                  ((hdr_len + sizeof(struct eth_header)) + 12),
                  VIRTIO_NET_IP4_ADDR_SIZE,
                  hdr_len + sizeof(struct eth_header) + sizeof(struct ip_header));
      }
  
      return virtio_net_rsc_do_coalesce(chain, nc, buf, size, &unit);
  }
  
  static int32_t virtio_net_rsc_sanity_check6(VirtioNetRscChain *chain,
                                              struct ip6_header *ip6,
                                              const uint8_t *buf, size_t size)
  {
      uint16_t ip_len;
  
      if (((ip6->ip6_ctlun.ip6_un1.ip6_un1_flow & 0xF0) >> 4)
          != IP_HEADER_VERSION_6) {
          return RSC_BYPASS;
      }
  
      /* Both option and protocol is checked in this */
      if (ip6->ip6_ctlun.ip6_un1.ip6_un1_nxt != IPPROTO_TCP) {
          chain->stat.bypass_not_tcp++;
          return RSC_BYPASS;
      }
  
      ip_len = htons(ip6->ip6_ctlun.ip6_un1.ip6_un1_plen);
      if (ip_len < sizeof(struct tcp_header) ||
          ip_len > (size - chain->n->guest_hdr_len - sizeof(struct eth_header)
                    - sizeof(struct ip6_header))) {
          chain->stat.ip_hacked++;
          return RSC_BYPASS;
      }
  
      /* Don't handle packets with ecn flag */
      if (IP6_ECN(ip6->ip6_ctlun.ip6_un3.ip6_un3_ecn)) {
          chain->stat.ip_ecn++;
          return RSC_BYPASS;
      }
  
      return RSC_CANDIDATE;
  }
  
  static size_t virtio_net_rsc_receive6(void *opq, NetClientState *nc,
                                        const uint8_t *buf, size_t size)
  {
      int32_t ret;
      uint16_t hdr_len;
      VirtioNetRscChain *chain;
      VirtioNetRscUnit unit;
  
      chain = (VirtioNetRscChain *)opq;
      hdr_len = ((VirtIONet *)(chain->n))->guest_hdr_len;
  
      if (size < (hdr_len + sizeof(struct eth_header) + sizeof(struct ip6_header)
          + sizeof(tcp_header))) {
          return virtio_net_do_receive(nc, buf, size);
      }
  
      virtio_net_rsc_extract_unit6(chain, buf, &unit);
      if (RSC_CANDIDATE != virtio_net_rsc_sanity_check6(chain,
                                                   unit.ip, buf, size)) {
          return virtio_net_do_receive(nc, buf, size);
      }
  
      ret = virtio_net_rsc_tcp_ctrl_check(chain, unit.tcp);
      if (ret == RSC_BYPASS) {
          return virtio_net_do_receive(nc, buf, size);
      } else if (ret == RSC_FINAL) {
          return virtio_net_rsc_drain_flow(chain, nc, buf, size,
                  ((hdr_len + sizeof(struct eth_header)) + 8),
                  VIRTIO_NET_IP6_ADDR_SIZE,
                  hdr_len + sizeof(struct eth_header)
                  + sizeof(struct ip6_header));
      }
  
      return virtio_net_rsc_do_coalesce(chain, nc, buf, size, &unit);
  }
  
  static VirtioNetRscChain *virtio_net_rsc_lookup_chain(VirtIONet *n,
                                                        NetClientState *nc,
                                                        uint16_t proto)
  {
      VirtioNetRscChain *chain;
  
      if ((proto != (uint16_t)ETH_P_IP) && (proto != (uint16_t)ETH_P_IPV6)) {
          return NULL;
      }
  
      QTAILQ_FOREACH(chain, &n->rsc_chains, next) {
          if (chain->proto == proto) {
              return chain;
          }
      }
  
      chain = g_malloc(sizeof(*chain));
      chain->n = n;
      chain->proto = proto;
      if (proto == (uint16_t)ETH_P_IP) {
          chain->max_payload = VIRTIO_NET_MAX_IP4_PAYLOAD;
          chain->gso_type = VIRTIO_NET_HDR_GSO_TCPV4;
      } else {
          chain->max_payload = VIRTIO_NET_MAX_IP6_PAYLOAD;
          chain->gso_type = VIRTIO_NET_HDR_GSO_TCPV6;
      }
      chain->drain_timer = timer_new_ns(QEMU_CLOCK_HOST,
                                        virtio_net_rsc_purge, chain);
      memset(&chain->stat, 0, sizeof(chain->stat));
  
      QTAILQ_INIT(&chain->buffers);
      QTAILQ_INSERT_TAIL(&n->rsc_chains, chain, next);
  
      return chain;
  }
  
  static ssize_t virtio_net_rsc_receive(NetClientState *nc,
                                        const uint8_t *buf,
                                        size_t size)
  {
      uint16_t proto;
      VirtioNetRscChain *chain;
      struct eth_header *eth;
      VirtIONet *n;
  
      n = qemu_get_nic_opaque(nc);
      if (size < (n->host_hdr_len + sizeof(struct eth_header))) {
          return virtio_net_do_receive(nc, buf, size);
      }
  
      eth = (struct eth_header *)(buf + n->guest_hdr_len);
      proto = htons(eth->h_proto);
  
      chain = virtio_net_rsc_lookup_chain(n, nc, proto);
      if (chain) {
          chain->stat.received++;
          if (proto == (uint16_t)ETH_P_IP && n->rsc4_enabled) {
              return virtio_net_rsc_receive4(chain, nc, buf, size);
          } else if (proto == (uint16_t)ETH_P_IPV6 && n->rsc6_enabled) {
              return virtio_net_rsc_receive6(chain, nc, buf, size);
          }
      }
      return virtio_net_do_receive(nc, buf, size);
  }
  
  static ssize_t virtio_net_receive(NetClientState *nc, const uint8_t *buf,
                                    size_t size)
  {
      VirtIONet *n = qemu_get_nic_opaque(nc);
      if ((n->rsc4_enabled || n->rsc6_enabled)) {
          return virtio_net_rsc_receive(nc, buf, size);
      } else {
          return virtio_net_do_receive(nc, buf, size);
      }
  }
  
  static int32_t virtio_net_flush_tx(VirtIONetQueue *q);
  
  static void virtio_net_tx_complete(NetClientState *nc, ssize_t len)
  {
      VirtIONet *n = qemu_get_nic_opaque(nc);
      VirtIONetQueue *q = virtio_net_get_subqueue(nc);
      VirtIODevice *vdev = VIRTIO_DEVICE(n);
  
      virtqueue_push(q->tx_vq, q->async_tx.elem, 0);
      virtio_notify(vdev, q->tx_vq);
  
      g_free(q->async_tx.elem);
      q->async_tx.elem = NULL;
  
      virtio_queue_set_notification(q->tx_vq, 1);
      virtio_net_flush_tx(q);
  }
  
  /* TX */
  static int32_t virtio_net_flush_tx(VirtIONetQueue *q)
  {
      VirtIONet *n = q->n;
      VirtIODevice *vdev = VIRTIO_DEVICE(n);
      VirtQueueElement *elem;
      int32_t num_packets = 0;
      int queue_index = vq2q(virtio_get_queue_index(q->tx_vq));
      if (!(vdev->status & VIRTIO_CONFIG_S_DRIVER_OK)) {
          return num_packets;
      }
  
      if (q->async_tx.elem) {
          virtio_queue_set_notification(q->tx_vq, 0);
          return num_packets;
      }
  
      for (;;) {
          ssize_t ret;
          unsigned int out_num;
          struct iovec sg[VIRTQUEUE_MAX_SIZE], sg2[VIRTQUEUE_MAX_SIZE + 1], *out_sg;
          struct virtio_net_hdr_mrg_rxbuf mhdr;
  
          elem = virtqueue_pop(q->tx_vq, sizeof(VirtQueueElement));
          if (!elem) {
              break;
          }
  
          out_num = elem->out_num;
          out_sg = elem->out_sg;
          if (out_num < 1) {
              virtio_error(vdev, "virtio-net header not in first element");
              virtqueue_detach_element(q->tx_vq, elem, 0);
              g_free(elem);
              return -EINVAL;
          }
  
          if (n->has_vnet_hdr) {
              if (iov_to_buf(out_sg, out_num, 0, &mhdr, n->guest_hdr_len) <
                  n->guest_hdr_len) {
                  virtio_error(vdev, "virtio-net header incorrect");
                  virtqueue_detach_element(q->tx_vq, elem, 0);
                  g_free(elem);
                  return -EINVAL;
              }
              if (n->needs_vnet_hdr_swap) {
                  virtio_net_hdr_swap(vdev, (void *) &mhdr);
                  sg2[0].iov_base = &mhdr;
                  sg2[0].iov_len = n->guest_hdr_len;
                  out_num = iov_copy(&sg2[1], ARRAY_SIZE(sg2) - 1,
                                     out_sg, out_num,
                                     n->guest_hdr_len, -1);
                  if (out_num == VIRTQUEUE_MAX_SIZE) {
                      goto drop;
                  }
                  out_num += 1;
                  out_sg = sg2;
              }
          }
          /*
           * If host wants to see the guest header as is, we can
           * pass it on unchanged. Otherwise, copy just the parts
           * that host is interested in.
           */
          assert(n->host_hdr_len <= n->guest_hdr_len);
          if (n->host_hdr_len != n->guest_hdr_len) {
              unsigned sg_num = iov_copy(sg, ARRAY_SIZE(sg),
                                         out_sg, out_num,
                                         0, n->host_hdr_len);
              sg_num += iov_copy(sg + sg_num, ARRAY_SIZE(sg) - sg_num,
                               out_sg, out_num,
                               n->guest_hdr_len, -1);
              out_num = sg_num;
              out_sg = sg;
          }
  
          ret = qemu_sendv_packet_async(qemu_get_subqueue(n->nic, queue_index),
                                        out_sg, out_num, virtio_net_tx_complete);
          if (ret == 0) {
              virtio_queue_set_notification(q->tx_vq, 0);
              q->async_tx.elem = elem;
              return -EBUSY;
          }
  
  drop:
          virtqueue_push(q->tx_vq, elem, 0);
          virtio_notify(vdev, q->tx_vq);
          g_free(elem);
  
          if (++num_packets >= n->tx_burst) {
              break;
          }
      }
      return num_packets;
  }
  
  static void virtio_net_handle_tx_timer(VirtIODevice *vdev, VirtQueue *vq)
  {
      VirtIONet *n = VIRTIO_NET(vdev);
      VirtIONetQueue *q = &n->vqs[vq2q(virtio_get_queue_index(vq))];
  
      if (unlikely((n->status & VIRTIO_NET_S_LINK_UP) == 0)) {
          virtio_net_drop_tx_queue_data(vdev, vq);
          return;
      }
  
      /* This happens when device was stopped but VCPU wasn't. */
      if (!vdev->vm_running) {
          q->tx_waiting = 1;
          return;
      }
  
      if (q->tx_waiting) {
          virtio_queue_set_notification(vq, 1);
          timer_del(q->tx_timer);
          q->tx_waiting = 0;
          if (virtio_net_flush_tx(q) == -EINVAL) {
              return;
          }
      } else {
          timer_mod(q->tx_timer,
                         qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) + n->tx_timeout);
          q->tx_waiting = 1;
          virtio_queue_set_notification(vq, 0);
      }
  }
  
  static void virtio_net_handle_tx_bh(VirtIODevice *vdev, VirtQueue *vq)
  {
      VirtIONet *n = VIRTIO_NET(vdev);
      VirtIONetQueue *q = &n->vqs[vq2q(virtio_get_queue_index(vq))];
  
      if (unlikely((n->status & VIRTIO_NET_S_LINK_UP) == 0)) {
          virtio_net_drop_tx_queue_data(vdev, vq);
          return;
      }
  
      if (unlikely(q->tx_waiting)) {
          return;
      }
      q->tx_waiting = 1;
      /* This happens when device was stopped but VCPU wasn't. */
      if (!vdev->vm_running) {
          return;
      }
      virtio_queue_set_notification(vq, 0);
      qemu_bh_schedule(q->tx_bh);
  }
  
  static void virtio_net_tx_timer(void *opaque)
  {
      VirtIONetQueue *q = opaque;
      VirtIONet *n = q->n;
      VirtIODevice *vdev = VIRTIO_DEVICE(n);
      /* This happens when device was stopped but BH wasn't. */
      if (!vdev->vm_running) {
          /* Make sure tx waiting is set, so we'll run when restarted. */
          assert(q->tx_waiting);
          return;
      }
  
      q->tx_waiting = 0;
  
      /* Just in case the driver is not ready on more */
      if (!(vdev->status & VIRTIO_CONFIG_S_DRIVER_OK)) {
          return;
      }
  
      virtio_queue_set_notification(q->tx_vq, 1);
      virtio_net_flush_tx(q);
  }
  
  static void virtio_net_tx_bh(void *opaque)
  {
      VirtIONetQueue *q = opaque;
      VirtIONet *n = q->n;
      VirtIODevice *vdev = VIRTIO_DEVICE(n);
      int32_t ret;
  
      /* This happens when device was stopped but BH wasn't. */
      if (!vdev->vm_running) {
          /* Make sure tx waiting is set, so we'll run when restarted. */
          assert(q->tx_waiting);
          return;
      }
  
      q->tx_waiting = 0;
  
      /* Just in case the driver is not ready on more */
      if (unlikely(!(vdev->status & VIRTIO_CONFIG_S_DRIVER_OK))) {
          return;
      }
  
      ret = virtio_net_flush_tx(q);
      if (ret == -EBUSY || ret == -EINVAL) {
          return; /* Notification re-enable handled by tx_complete or device
                   * broken */
      }
  
      /* If we flush a full burst of packets, assume there are
       * more coming and immediately reschedule */
      if (ret >= n->tx_burst) {
          qemu_bh_schedule(q->tx_bh);
          q->tx_waiting = 1;
          return;
      }
  
      /* If less than a full burst, re-enable notification and flush
       * anything that may have come in while we weren't looking.  If
       * we find something, assume the guest is still active and reschedule */
      virtio_queue_set_notification(q->tx_vq, 1);
      ret = virtio_net_flush_tx(q);
      if (ret == -EINVAL) {
          return;
      } else if (ret > 0) {
          virtio_queue_set_notification(q->tx_vq, 0);
          qemu_bh_schedule(q->tx_bh);
          q->tx_waiting = 1;
      }
  }
  
  static void virtio_net_add_queue(VirtIONet *n, int index)
  {
      VirtIODevice *vdev = VIRTIO_DEVICE(n);
  
      n->vqs[index].rx_vq = virtio_add_queue(vdev, n->net_conf.rx_queue_size,
                                             virtio_net_handle_rx);
  
      if (n->net_conf.tx && !strcmp(n->net_conf.tx, "timer")) {
          n->vqs[index].tx_vq =
              virtio_add_queue(vdev, n->net_conf.tx_queue_size,
                               virtio_net_handle_tx_timer);
          n->vqs[index].tx_timer = timer_new_ns(QEMU_CLOCK_VIRTUAL,
                                                virtio_net_tx_timer,
                                                &n->vqs[index]);
      } else {
          n->vqs[index].tx_vq =
              virtio_add_queue(vdev, n->net_conf.tx_queue_size,
                               virtio_net_handle_tx_bh);
          n->vqs[index].tx_bh = qemu_bh_new(virtio_net_tx_bh, &n->vqs[index]);
      }
  
      n->vqs[index].tx_waiting = 0;
      n->vqs[index].n = n;
  }
  
  static void virtio_net_del_queue(VirtIONet *n, int index)
  {
      VirtIODevice *vdev = VIRTIO_DEVICE(n);
      VirtIONetQueue *q = &n->vqs[index];
      NetClientState *nc = qemu_get_subqueue(n->nic, index);
  
      qemu_purge_queued_packets(nc);
  
      virtio_del_queue(vdev, index * 2);
      if (q->tx_timer) {
          timer_free(q->tx_timer);
          q->tx_timer = NULL;
      } else {
          qemu_bh_delete(q->tx_bh);
          q->tx_bh = NULL;
      }
      q->tx_waiting = 0;
      virtio_del_queue(vdev, index * 2 + 1);
  }
  
  static void virtio_net_change_num_queues(VirtIONet *n, int new_max_queues)
  {
      VirtIODevice *vdev = VIRTIO_DEVICE(n);
      int old_num_queues = virtio_get_num_queues(vdev);
      int new_num_queues = new_max_queues * 2 + 1;
      int i;
  
      assert(old_num_queues >= 3);
      assert(old_num_queues % 2 == 1);
  
      if (old_num_queues == new_num_queues) {
          return;
      }
  
      /*
       * We always need to remove and add ctrl vq if
       * old_num_queues != new_num_queues. Remove ctrl_vq first,
       * and then we only enter one of the following two loops.
       */
      virtio_del_queue(vdev, old_num_queues - 1);
  
      for (i = new_num_queues - 1; i < old_num_queues - 1; i += 2) {
          /* new_num_queues < old_num_queues */
          virtio_net_del_queue(n, i / 2);
      }
  
      for (i = old_num_queues - 1; i < new_num_queues - 1; i += 2) {
          /* new_num_queues > old_num_queues */
          virtio_net_add_queue(n, i / 2);
      }
  
      /* add ctrl_vq last */
      n->ctrl_vq = virtio_add_queue(vdev, 64, virtio_net_handle_ctrl);
  }
  
  static void virtio_net_set_multiqueue(VirtIONet *n, int multiqueue)
  {
      int max = multiqueue ? n->max_queues : 1;
  
      n->multiqueue = multiqueue;
      virtio_net_change_num_queues(n, max);
  
      virtio_net_set_queues(n);
  }
  
  static int virtio_net_post_load_device(void *opaque, int version_id)
  {
      VirtIONet *n = opaque;
      VirtIODevice *vdev = VIRTIO_DEVICE(n);
      int i, link_down;
  
      trace_virtio_net_post_load_device();
      virtio_net_set_mrg_rx_bufs(n, n->mergeable_rx_bufs,
                                 virtio_vdev_has_feature(vdev,
                                                         VIRTIO_F_VERSION_1),
                                 virtio_vdev_has_feature(vdev,
                                                         VIRTIO_NET_F_HASH_REPORT));
  
      /* MAC_TABLE_ENTRIES may be different from the saved image */
      if (n->mac_table.in_use > MAC_TABLE_ENTRIES) {
          n->mac_table.in_use = 0;
      }
  
      if (!virtio_vdev_has_feature(vdev, VIRTIO_NET_F_CTRL_GUEST_OFFLOADS)) {
          n->curr_guest_offloads = virtio_net_supported_guest_offloads(n);
      }
  
      /*
       * curr_guest_offloads will be later overwritten by the
       * virtio_set_features_nocheck call done from the virtio_load.
       * Here we make sure it is preserved and restored accordingly
       * in the virtio_net_post_load_virtio callback.
       */
      n->saved_guest_offloads = n->curr_guest_offloads;
  
      virtio_net_set_queues(n);
  
      /* Find the first multicast entry in the saved MAC filter */
      for (i = 0; i < n->mac_table.in_use; i++) {
          if (n->mac_table.macs[i * ETH_ALEN] & 1) {
              break;
          }
      }
      n->mac_table.first_multi = i;
  
      /* nc.link_down can't be migrated, so infer link_down according
       * to link status bit in n->status */
      link_down = (n->status & VIRTIO_NET_S_LINK_UP) == 0;
      for (i = 0; i < n->max_queues; i++) {
          qemu_get_subqueue(n->nic, i)->link_down = link_down;
      }
  
      if (virtio_vdev_has_feature(vdev, VIRTIO_NET_F_GUEST_ANNOUNCE) &&
          virtio_vdev_has_feature(vdev, VIRTIO_NET_F_CTRL_VQ)) {
          qemu_announce_timer_reset(&n->announce_timer, migrate_announce_params(),
                                    QEMU_CLOCK_VIRTUAL,
                                    virtio_net_announce_timer, n);
          if (n->announce_timer.round) {
              timer_mod(n->announce_timer.tm,
                        qemu_clock_get_ms(n->announce_timer.type));
          } else {
              qemu_announce_timer_del(&n->announce_timer, false);
          }
      }
  
      if (n->rss_data.enabled) {
          trace_virtio_net_rss_enable(n->rss_data.hash_types,
                                      n->rss_data.indirections_len,
                                      sizeof(n->rss_data.key));
      } else {
          trace_virtio_net_rss_disable();
      }
      return 0;
  }
  
  static int virtio_net_post_load_virtio(VirtIODevice *vdev)
  {
      VirtIONet *n = VIRTIO_NET(vdev);
      /*
       * The actual needed state is now in saved_guest_offloads,
       * see virtio_net_post_load_device for detail.
       * Restore it back and apply the desired offloads.
       */
      n->curr_guest_offloads = n->saved_guest_offloads;
      if (peer_has_vnet_hdr(n)) {
          virtio_net_apply_guest_offloads(n);
      }
  
      return 0;
  }
  
  /* tx_waiting field of a VirtIONetQueue */
  static const VMStateDescription vmstate_virtio_net_queue_tx_waiting = {
      .name = "virtio-net-queue-tx_waiting",
      .fields = (VMStateField[]) {
          VMSTATE_UINT32(tx_waiting, VirtIONetQueue),
          VMSTATE_END_OF_LIST()
     },
  };
  
  static bool max_queues_gt_1(void *opaque, int version_id)
  {
      return VIRTIO_NET(opaque)->max_queues > 1;
  }
  
  static bool has_ctrl_guest_offloads(void *opaque, int version_id)
  {
      return virtio_vdev_has_feature(VIRTIO_DEVICE(opaque),
                                     VIRTIO_NET_F_CTRL_GUEST_OFFLOADS);
  }
  
  static bool mac_table_fits(void *opaque, int version_id)
  {
      return VIRTIO_NET(opaque)->mac_table.in_use <= MAC_TABLE_ENTRIES;
  }
  
  static bool mac_table_doesnt_fit(void *opaque, int version_id)
  {
      return !mac_table_fits(opaque, version_id);
  }
  
  /* This temporary type is shared by all the WITH_TMP methods
   * although only some fields are used by each.
   */
  struct VirtIONetMigTmp {
      VirtIONet      *parent;
      VirtIONetQueue *vqs_1;
      uint16_t        curr_queues_1;
      uint8_t         has_ufo;
      uint32_t        has_vnet_hdr;
  };
  
  /* The 2nd and subsequent tx_waiting flags are loaded later than
   * the 1st entry in the queues and only if there's more than one
   * entry.  We use the tmp mechanism to calculate a temporary
   * pointer and count and also validate the count.
   */
  
  static int virtio_net_tx_waiting_pre_save(void *opaque)
  {
      struct VirtIONetMigTmp *tmp = opaque;
  
      tmp->vqs_1 = tmp->parent->vqs + 1;
      tmp->curr_queues_1 = tmp->parent->curr_queues - 1;
      if (tmp->parent->curr_queues == 0) {
          tmp->curr_queues_1 = 0;
      }
  
      return 0;
  }
  
  static int virtio_net_tx_waiting_pre_load(void *opaque)
  {
      struct VirtIONetMigTmp *tmp = opaque;
  
      /* Reuse the pointer setup from save */
      virtio_net_tx_waiting_pre_save(opaque);
  
      if (tmp->parent->curr_queues > tmp->parent->max_queues) {
          error_report("virtio-net: curr_queues %x > max_queues %x",
              tmp->parent->curr_queues, tmp->parent->max_queues);
  
          return -EINVAL;
      }
  
      return 0; /* all good */
  }
  
  static const VMStateDescription vmstate_virtio_net_tx_waiting = {
      .name      = "virtio-net-tx_waiting",
      .pre_load  = virtio_net_tx_waiting_pre_load,
      .pre_save  = virtio_net_tx_waiting_pre_save,
      .fields    = (VMStateField[]) {
          VMSTATE_STRUCT_VARRAY_POINTER_UINT16(vqs_1, struct VirtIONetMigTmp,
                                       curr_queues_1,
                                       vmstate_virtio_net_queue_tx_waiting,
                                       struct VirtIONetQueue),
          VMSTATE_END_OF_LIST()
      },
  };
  
  /* the 'has_ufo' flag is just tested; if the incoming stream has the
   * flag set we need to check that we have it
   */
  static int virtio_net_ufo_post_load(void *opaque, int version_id)
  {
      struct VirtIONetMigTmp *tmp = opaque;
  
      if (tmp->has_ufo && !peer_has_ufo(tmp->parent)) {
          error_report("virtio-net: saved image requires TUN_F_UFO support");
          return -EINVAL;
      }
  
      return 0;
  }
  
  static int virtio_net_ufo_pre_save(void *opaque)
  {
      struct VirtIONetMigTmp *tmp = opaque;
  
      tmp->has_ufo = tmp->parent->has_ufo;
  
      return 0;
  }
  
  static const VMStateDescription vmstate_virtio_net_has_ufo = {
      .name      = "virtio-net-ufo",
      .post_load = virtio_net_ufo_post_load,
      .pre_save  = virtio_net_ufo_pre_save,
      .fields    = (VMStateField[]) {
          VMSTATE_UINT8(has_ufo, struct VirtIONetMigTmp),
          VMSTATE_END_OF_LIST()
      },
  };
  
  /* the 'has_vnet_hdr' flag is just tested; if the incoming stream has the
   * flag set we need to check that we have it
   */
  static int virtio_net_vnet_post_load(void *opaque, int version_id)
  {
      struct VirtIONetMigTmp *tmp = opaque;
  
      if (tmp->has_vnet_hdr && !peer_has_vnet_hdr(tmp->parent)) {
          error_report("virtio-net: saved image requires vnet_hdr=on");
          return -EINVAL;
      }
  
      return 0;
  }
  
  static int virtio_net_vnet_pre_save(void *opaque)
  {
      struct VirtIONetMigTmp *tmp = opaque;
  
      tmp->has_vnet_hdr = tmp->parent->has_vnet_hdr;
  
      return 0;
  }
  
  static const VMStateDescription vmstate_virtio_net_has_vnet = {
      .name      = "virtio-net-vnet",
      .post_load = virtio_net_vnet_post_load,
      .pre_save  = virtio_net_vnet_pre_save,
      .fields    = (VMStateField[]) {
          VMSTATE_UINT32(has_vnet_hdr, struct VirtIONetMigTmp),
          VMSTATE_END_OF_LIST()
      },
  };
  
  static bool virtio_net_rss_needed(void *opaque)
  {
      return VIRTIO_NET(opaque)->rss_data.enabled;
  }
  
  static const VMStateDescription vmstate_virtio_net_rss = {
      .name      = "virtio-net-device/rss",
      .version_id = 1,
      .minimum_version_id = 1,
      .needed = virtio_net_rss_needed,
      .fields = (VMStateField[]) {
          VMSTATE_BOOL(rss_data.enabled, VirtIONet),
          VMSTATE_BOOL(rss_data.redirect, VirtIONet),
          VMSTATE_BOOL(rss_data.populate_hash, VirtIONet),
          VMSTATE_UINT32(rss_data.hash_types, VirtIONet),
          VMSTATE_UINT16(rss_data.indirections_len, VirtIONet),
          VMSTATE_UINT16(rss_data.default_queue, VirtIONet),
          VMSTATE_UINT8_ARRAY(rss_data.key, VirtIONet,
                              VIRTIO_NET_RSS_MAX_KEY_SIZE),
          VMSTATE_VARRAY_UINT16_ALLOC(rss_data.indirections_table, VirtIONet,
                                      rss_data.indirections_len, 0,
                                      vmstate_info_uint16, uint16_t),
          VMSTATE_END_OF_LIST()
      },
  };
  
  static const VMStateDescription vmstate_virtio_net_device = {
      .name = "virtio-net-device",
      .version_id = VIRTIO_NET_VM_VERSION,
      .minimum_version_id = VIRTIO_NET_VM_VERSION,
      .post_load = virtio_net_post_load_device,
      .fields = (VMStateField[]) {
          VMSTATE_UINT8_ARRAY(mac, VirtIONet, ETH_ALEN),
          VMSTATE_STRUCT_POINTER(vqs, VirtIONet,
                                 vmstate_virtio_net_queue_tx_waiting,
                                 VirtIONetQueue),
          VMSTATE_UINT32(mergeable_rx_bufs, VirtIONet),
          VMSTATE_UINT16(status, VirtIONet),
          VMSTATE_UINT8(promisc, VirtIONet),
          VMSTATE_UINT8(allmulti, VirtIONet),
          VMSTATE_UINT32(mac_table.in_use, VirtIONet),
  
          /* Guarded pair: If it fits we load it, else we throw it away
           * - can happen if source has a larger MAC table.; post-load
           *  sets flags in this case.
           */
          VMSTATE_VBUFFER_MULTIPLY(mac_table.macs, VirtIONet,
                                  0, mac_table_fits, mac_table.in_use,
                                   ETH_ALEN),
          VMSTATE_UNUSED_VARRAY_UINT32(VirtIONet, mac_table_doesnt_fit, 0,
                                       mac_table.in_use, ETH_ALEN),
  
          /* Note: This is an array of uint32's that's always been saved as a
           * buffer; hold onto your endiannesses; it's actually used as a bitmap
           * but based on the uint.
           */
          VMSTATE_BUFFER_POINTER_UNSAFE(vlans, VirtIONet, 0, MAX_VLAN >> 3),
          VMSTATE_WITH_TMP(VirtIONet, struct VirtIONetMigTmp,
                           vmstate_virtio_net_has_vnet),
          VMSTATE_UINT8(mac_table.multi_overflow, VirtIONet),
          VMSTATE_UINT8(mac_table.uni_overflow, VirtIONet),
          VMSTATE_UINT8(alluni, VirtIONet),
          VMSTATE_UINT8(nomulti, VirtIONet),
          VMSTATE_UINT8(nouni, VirtIONet),
          VMSTATE_UINT8(nobcast, VirtIONet),
          VMSTATE_WITH_TMP(VirtIONet, struct VirtIONetMigTmp,
                           vmstate_virtio_net_has_ufo),
          VMSTATE_SINGLE_TEST(max_queues, VirtIONet, max_queues_gt_1, 0,
                              vmstate_info_uint16_equal, uint16_t),
          VMSTATE_UINT16_TEST(curr_queues, VirtIONet, max_queues_gt_1),
          VMSTATE_WITH_TMP(VirtIONet, struct VirtIONetMigTmp,
                           vmstate_virtio_net_tx_waiting),
          VMSTATE_UINT64_TEST(curr_guest_offloads, VirtIONet,
                              has_ctrl_guest_offloads),
          VMSTATE_END_OF_LIST()
     },
      .subsections = (const VMStateDescription * []) {
          &vmstate_virtio_net_rss,
          NULL
      }
  };
  
  static NetClientInfo net_virtio_info = {
      .type = NET_CLIENT_DRIVER_NIC,
      .size = sizeof(NICState),
      .can_receive = virtio_net_can_receive,
      .receive = virtio_net_receive,
      .link_status_changed = virtio_net_set_link_status,
      .query_rx_filter = virtio_net_query_rxfilter,
      .announce = virtio_net_announce,
  };
  
  static bool virtio_net_guest_notifier_pending(VirtIODevice *vdev, int idx)
  {
      VirtIONet *n = VIRTIO_NET(vdev);
      NetClientState *nc = qemu_get_subqueue(n->nic, vq2q(idx));
      assert(n->vhost_started);
      return vhost_net_virtqueue_pending(get_vhost_net(nc->peer), idx);
  }
  
  static void virtio_net_guest_notifier_mask(VirtIODevice *vdev, int idx,
                                             bool mask)
  {
      VirtIONet *n = VIRTIO_NET(vdev);
      NetClientState *nc = qemu_get_subqueue(n->nic, vq2q(idx));
      assert(n->vhost_started);
      vhost_net_virtqueue_mask(get_vhost_net(nc->peer),
                               vdev, idx, mask);
  }
  
  static void virtio_net_set_config_size(VirtIONet *n, uint64_t host_features)
  {
      virtio_add_feature(&host_features, VIRTIO_NET_F_MAC);
  
      n->config_size = virtio_feature_get_config_size(feature_sizes,
                                                      host_features);
  }
  
  void virtio_net_set_netclient_name(VirtIONet *n, const char *name,
                                     const char *type)
  {
      /*
       * The name can be NULL, the netclient name will be type.x.
       */
      assert(type != NULL);
  
      g_free(n->netclient_name);
      g_free(n->netclient_type);
      n->netclient_name = g_strdup(name);
      n->netclient_type = g_strdup(type);
  }
  
  static bool failover_unplug_primary(VirtIONet *n, DeviceState *dev)
  {
      HotplugHandler *hotplug_ctrl;
      PCIDevice *pci_dev;
      Error *err = NULL;
  
      hotplug_ctrl = qdev_get_hotplug_handler(dev);
      if (hotplug_ctrl) {
          pci_dev = PCI_DEVICE(dev);
          pci_dev->partially_hotplugged = true;
          hotplug_handler_unplug_request(hotplug_ctrl, dev, &err);
          if (err) {
              error_report_err(err);
              return false;
          }
      } else {
          return false;
      }
      return true;
  }
  
  static bool failover_replug_primary(VirtIONet *n, DeviceState *dev,
                                      Error **errp)
  {
      Error *err = NULL;
      HotplugHandler *hotplug_ctrl;
      PCIDevice *pdev = PCI_DEVICE(dev);
      BusState *primary_bus;
  
      if (!pdev->partially_hotplugged) {
          return true;
      }
      primary_bus = dev->parent_bus;
      if (!primary_bus) {
          error_setg(errp, "virtio_net: couldn't find primary bus");
          return false;
      }
      qdev_set_parent_bus(dev, primary_bus, &error_abort);
      qatomic_set(&n->failover_primary_hidden, false);
      hotplug_ctrl = qdev_get_hotplug_handler(dev);
      if (hotplug_ctrl) {
          hotplug_handler_pre_plug(hotplug_ctrl, dev, &err);
          if (err) {
              goto out;
          }
          hotplug_handler_plug(hotplug_ctrl, dev, &err);
      }
  
  out:
      error_propagate(errp, err);
      return !err;
  }
  
  static void virtio_net_handle_migration_primary(VirtIONet *n, MigrationState *s)
  {
      bool should_be_hidden;
      Error *err = NULL;
      DeviceState *dev = failover_find_primary_device(n);
  
      if (!dev) {
          return;
      }
  
      should_be_hidden = qatomic_read(&n->failover_primary_hidden);
  
      if (migration_in_setup(s) && !should_be_hidden) {
          if (failover_unplug_primary(n, dev)) {
              vmstate_unregister(VMSTATE_IF(dev), qdev_get_vmsd(dev), dev);
              qapi_event_send_unplug_primary(dev->id);
              qatomic_set(&n->failover_primary_hidden, true);
          } else {
              warn_report("couldn't unplug primary device");
          }
      } else if (migration_has_failed(s)) {
          /* We already unplugged the device let's plug it back */
          if (!failover_replug_primary(n, dev, &err)) {
              if (err) {
                  error_report_err(err);
              }
          }
      }
  }
  
  static void virtio_net_migration_state_notifier(Notifier *notifier, void *data)
  {
      MigrationState *s = data;
      VirtIONet *n = container_of(notifier, VirtIONet, migration_state);
      virtio_net_handle_migration_primary(n, s);
  }
  
  static bool failover_hide_primary_device(DeviceListener *listener,
                                           QemuOpts *device_opts)
  {
      VirtIONet *n = container_of(listener, VirtIONet, primary_listener);
      const char *standby_id;
  
      if (!device_opts) {
          return false;
      }
      standby_id = qemu_opt_get(device_opts, "failover_pair_id");
      if (g_strcmp0(standby_id, n->netclient_name) != 0) {
          return false;
      }
  
      /* failover_primary_hidden is set during feature negotiation */
      return qatomic_read(&n->failover_primary_hidden);
  }
  
  static void virtio_net_device_realize(DeviceState *dev, Error **errp)
  {
      VirtIODevice *vdev = VIRTIO_DEVICE(dev);
      VirtIONet *n = VIRTIO_NET(dev);
      NetClientState *nc;
      int i;
  
      if (n->net_conf.mtu) {
          n->host_features |= (1ULL << VIRTIO_NET_F_MTU);
      }
  
      if (n->net_conf.duplex_str) {
          if (strncmp(n->net_conf.duplex_str, "half", 5) == 0) {
              n->net_conf.duplex = DUPLEX_HALF;
          } else if (strncmp(n->net_conf.duplex_str, "full", 5) == 0) {
              n->net_conf.duplex = DUPLEX_FULL;
          } else {
              error_setg(errp, "'duplex' must be 'half' or 'full'");
              return;
          }
          n->host_features |= (1ULL << VIRTIO_NET_F_SPEED_DUPLEX);
      } else {
          n->net_conf.duplex = DUPLEX_UNKNOWN;
      }
  
      if (n->net_conf.speed < SPEED_UNKNOWN) {
          error_setg(errp, "'speed' must be between 0 and INT_MAX");
          return;
      }
      if (n->net_conf.speed >= 0) {
          n->host_features |= (1ULL << VIRTIO_NET_F_SPEED_DUPLEX);
      }
  
      if (n->failover) {
          n->primary_listener.hide_device = failover_hide_primary_device;
          qatomic_set(&n->failover_primary_hidden, true);
          device_listener_register(&n->primary_listener);
          n->migration_state.notify = virtio_net_migration_state_notifier;
          add_migration_state_change_notifier(&n->migration_state);
          n->host_features |= (1ULL << VIRTIO_NET_F_STANDBY);
      }
  
      virtio_net_set_config_size(n, n->host_features);
      virtio_init(vdev, "virtio-net", VIRTIO_ID_NET, n->config_size);
  
      /*
       * We set a lower limit on RX queue size to what it always was.
       * Guests that want a smaller ring can always resize it without
       * help from us (using virtio 1 and up).
       */
      if (n->net_conf.rx_queue_size < VIRTIO_NET_RX_QUEUE_MIN_SIZE ||
          n->net_conf.rx_queue_size > VIRTQUEUE_MAX_SIZE ||
          !is_power_of_2(n->net_conf.rx_queue_size)) {
          error_setg(errp, "Invalid rx_queue_size (= %" PRIu16 "), "
                     "must be a power of 2 between %d and %d.",
                     n->net_conf.rx_queue_size, VIRTIO_NET_RX_QUEUE_MIN_SIZE,
                     VIRTQUEUE_MAX_SIZE);
          virtio_cleanup(vdev);
          return;
      }
  
      if (n->net_conf.tx_queue_size < VIRTIO_NET_TX_QUEUE_MIN_SIZE ||
          n->net_conf.tx_queue_size > VIRTQUEUE_MAX_SIZE ||
          !is_power_of_2(n->net_conf.tx_queue_size)) {
          error_setg(errp, "Invalid tx_queue_size (= %" PRIu16 "), "
                     "must be a power of 2 between %d and %d",
                     n->net_conf.tx_queue_size, VIRTIO_NET_TX_QUEUE_MIN_SIZE,
                     VIRTQUEUE_MAX_SIZE);
          virtio_cleanup(vdev);
          return;
      }
  
      n->max_queues = MAX(n->nic_conf.peers.queues, 1);
      if (n->max_queues * 2 + 1 > VIRTIO_QUEUE_MAX) {
          error_setg(errp, "Invalid number of queues (= %" PRIu32 "), "
                     "must be a positive integer less than %d.",
                     n->max_queues, (VIRTIO_QUEUE_MAX - 1) / 2);
          virtio_cleanup(vdev);
          return;
      }
      n->vqs = g_malloc0(sizeof(VirtIONetQueue) * n->max_queues);
      n->curr_queues = 1;
      n->tx_timeout = n->net_conf.txtimer;
  
      if (n->net_conf.tx && strcmp(n->net_conf.tx, "timer")
                         && strcmp(n->net_conf.tx, "bh")) {
          warn_report("virtio-net: "
                      "Unknown option tx=%s, valid options: \"timer\" \"bh\"",
                      n->net_conf.tx);
          error_printf("Defaulting to \"bh\"");
      }
  
      n->net_conf.tx_queue_size = MIN(virtio_net_max_tx_queue_size(n),
                                      n->net_conf.tx_queue_size);
  
      for (i = 0; i < n->max_queues; i++) {
          virtio_net_add_queue(n, i);
      }
  
      n->ctrl_vq = virtio_add_queue(vdev, 64, virtio_net_handle_ctrl);
      qemu_macaddr_default_if_unset(&n->nic_conf.macaddr);
      memcpy(&n->mac[0], &n->nic_conf.macaddr, sizeof(n->mac));
      n->status = VIRTIO_NET_S_LINK_UP;
      qemu_announce_timer_reset(&n->announce_timer, migrate_announce_params(),
                                QEMU_CLOCK_VIRTUAL,
                                virtio_net_announce_timer, n);
      n->announce_timer.round = 0;
  
      if (n->netclient_type) {
          /*
           * Happen when virtio_net_set_netclient_name has been called.
           */
          n->nic = qemu_new_nic(&net_virtio_info, &n->nic_conf,
                                n->netclient_type, n->netclient_name, n);
      } else {
          n->nic = qemu_new_nic(&net_virtio_info, &n->nic_conf,
                                object_get_typename(OBJECT(dev)), dev->id, n);
      }
  
      for (i = 0; i < n->max_queues; i++) {
          n->nic->ncs[i].do_not_pad = true;
      }
  
      peer_test_vnet_hdr(n);
      if (peer_has_vnet_hdr(n)) {
          for (i = 0; i < n->max_queues; i++) {
              qemu_using_vnet_hdr(qemu_get_subqueue(n->nic, i)->peer, true);
          }
          n->host_hdr_len = sizeof(struct virtio_net_hdr);
      } else {
          n->host_hdr_len = 0;
      }
  
      qemu_format_nic_info_str(qemu_get_queue(n->nic), n->nic_conf.macaddr.a);
  
      n->vqs[0].tx_waiting = 0;
      n->tx_burst = n->net_conf.txburst;
      virtio_net_set_mrg_rx_bufs(n, 0, 0, 0);
      n->promisc = 1; /* for compatibility */
  
      n->mac_table.macs = g_malloc0(MAC_TABLE_ENTRIES * ETH_ALEN);
  
      n->vlans = g_malloc0(MAX_VLAN >> 3);
  
      nc = qemu_get_queue(n->nic);
      nc->rxfilter_notify_enabled = 1;
  
     if (nc->peer && nc->peer->info->type == NET_CLIENT_DRIVER_VHOST_VDPA) {
          struct virtio_net_config netcfg = {};
          memcpy(&netcfg.mac, &n->nic_conf.macaddr, ETH_ALEN);
          vhost_net_set_config(get_vhost_net(nc->peer),
              (uint8_t *)&netcfg, 0, ETH_ALEN, VHOST_SET_CONFIG_TYPE_MASTER);
      }
      QTAILQ_INIT(&n->rsc_chains);
      n->qdev = dev;
  
      net_rx_pkt_init(&n->rx_pkt, false);
  }
  
  static void virtio_net_device_unrealize(DeviceState *dev)
  {
      VirtIODevice *vdev = VIRTIO_DEVICE(dev);
      VirtIONet *n = VIRTIO_NET(dev);
      int i, max_queues;
  
      /* This will stop vhost backend if appropriate. */
      virtio_net_set_status(vdev, 0);
  
      g_free(n->netclient_name);
      n->netclient_name = NULL;
      g_free(n->netclient_type);
      n->netclient_type = NULL;
  
      g_free(n->mac_table.macs);
      g_free(n->vlans);
  
      if (n->failover) {
          device_listener_unregister(&n->primary_listener);
      }
  
      max_queues = n->multiqueue ? n->max_queues : 1;
      for (i = 0; i < max_queues; i++) {
          virtio_net_del_queue(n, i);
      }
      /* delete also control vq */
      virtio_del_queue(vdev, max_queues * 2);
      qemu_announce_timer_del(&n->announce_timer, false);
      g_free(n->vqs);
      qemu_del_nic(n->nic);
      virtio_net_rsc_cleanup(n);
      g_free(n->rss_data.indirections_table);
      net_rx_pkt_uninit(n->rx_pkt);
      virtio_cleanup(vdev);
  }
  
  static void virtio_net_instance_init(Object *obj)
  {
      VirtIONet *n = VIRTIO_NET(obj);
  
      /*
       * The default config_size is sizeof(struct virtio_net_config).
       * Can be overriden with virtio_net_set_config_size.
       */
      n->config_size = sizeof(struct virtio_net_config);
      device_add_bootindex_property(obj, &n->nic_conf.bootindex,
                                    "bootindex", "/ethernet-phy@0",
                                    DEVICE(n));
  }
  
  static int virtio_net_pre_save(void *opaque)
  {
      VirtIONet *n = opaque;
  
      /* At this point, backend must be stopped, otherwise
       * it might keep writing to memory. */
      assert(!n->vhost_started);
  
      return 0;
  }
  
  static bool primary_unplug_pending(void *opaque)
  {
      DeviceState *dev = opaque;
      DeviceState *primary;
      VirtIODevice *vdev = VIRTIO_DEVICE(dev);
      VirtIONet *n = VIRTIO_NET(vdev);
  
      if (!virtio_vdev_has_feature(vdev, VIRTIO_NET_F_STANDBY)) {
          return false;
      }
      primary = failover_find_primary_device(n);
      return primary ? primary->pending_deleted_event : false;
  }
  
  static bool dev_unplug_pending(void *opaque)
  {
      DeviceState *dev = opaque;
      VirtioDeviceClass *vdc = VIRTIO_DEVICE_GET_CLASS(dev);
  
      return vdc->primary_unplug_pending(dev);
  }
  
  static const VMStateDescription vmstate_virtio_net = {
      .name = "virtio-net",
      .minimum_version_id = VIRTIO_NET_VM_VERSION,
      .version_id = VIRTIO_NET_VM_VERSION,
      .fields = (VMStateField[]) {
          VMSTATE_VIRTIO_DEVICE,
          VMSTATE_END_OF_LIST()
      },
      .pre_save = virtio_net_pre_save,
      .dev_unplug_pending = dev_unplug_pending,
  };
  
  static Property virtio_net_properties[] = {
      DEFINE_PROP_BIT64("csum", VirtIONet, host_features,
                      VIRTIO_NET_F_CSUM, true),
      DEFINE_PROP_BIT64("guest_csum", VirtIONet, host_features,
                      VIRTIO_NET_F_GUEST_CSUM, true),
      DEFINE_PROP_BIT64("gso", VirtIONet, host_features, VIRTIO_NET_F_GSO, true),
      DEFINE_PROP_BIT64("guest_tso4", VirtIONet, host_features,
                      VIRTIO_NET_F_GUEST_TSO4, true),
      DEFINE_PROP_BIT64("guest_tso6", VirtIONet, host_features,
                      VIRTIO_NET_F_GUEST_TSO6, true),
      DEFINE_PROP_BIT64("guest_ecn", VirtIONet, host_features,
                      VIRTIO_NET_F_GUEST_ECN, true),
      DEFINE_PROP_BIT64("guest_ufo", VirtIONet, host_features,
                      VIRTIO_NET_F_GUEST_UFO, true),
      DEFINE_PROP_BIT64("guest_announce", VirtIONet, host_features,
                      VIRTIO_NET_F_GUEST_ANNOUNCE, true),
      DEFINE_PROP_BIT64("host_tso4", VirtIONet, host_features,
                      VIRTIO_NET_F_HOST_TSO4, true),
      DEFINE_PROP_BIT64("host_tso6", VirtIONet, host_features,
                      VIRTIO_NET_F_HOST_TSO6, true),
      DEFINE_PROP_BIT64("host_ecn", VirtIONet, host_features,
                      VIRTIO_NET_F_HOST_ECN, true),
      DEFINE_PROP_BIT64("host_ufo", VirtIONet, host_features,
                      VIRTIO_NET_F_HOST_UFO, true),
      DEFINE_PROP_BIT64("mrg_rxbuf", VirtIONet, host_features,
                      VIRTIO_NET_F_MRG_RXBUF, true),
      DEFINE_PROP_BIT64("status", VirtIONet, host_features,
                      VIRTIO_NET_F_STATUS, true),
      DEFINE_PROP_BIT64("ctrl_vq", VirtIONet, host_features,
                      VIRTIO_NET_F_CTRL_VQ, true),
      DEFINE_PROP_BIT64("ctrl_rx", VirtIONet, host_features,
                      VIRTIO_NET_F_CTRL_RX, true),
      DEFINE_PROP_BIT64("ctrl_vlan", VirtIONet, host_features,
                      VIRTIO_NET_F_CTRL_VLAN, true),
      DEFINE_PROP_BIT64("ctrl_rx_extra", VirtIONet, host_features,
                      VIRTIO_NET_F_CTRL_RX_EXTRA, true),
      DEFINE_PROP_BIT64("ctrl_mac_addr", VirtIONet, host_features,
                      VIRTIO_NET_F_CTRL_MAC_ADDR, true),
      DEFINE_PROP_BIT64("ctrl_guest_offloads", VirtIONet, host_features,
                      VIRTIO_NET_F_CTRL_GUEST_OFFLOADS, true),
      DEFINE_PROP_BIT64("mq", VirtIONet, host_features, VIRTIO_NET_F_MQ, false),
      DEFINE_PROP_BIT64("rss", VirtIONet, host_features,
                      VIRTIO_NET_F_RSS, false),
      DEFINE_PROP_BIT64("hash", VirtIONet, host_features,
                      VIRTIO_NET_F_HASH_REPORT, false),
      DEFINE_PROP_BIT64("guest_rsc_ext", VirtIONet, host_features,
                      VIRTIO_NET_F_RSC_EXT, false),
      DEFINE_PROP_UINT32("rsc_interval", VirtIONet, rsc_timeout,
                         VIRTIO_NET_RSC_DEFAULT_INTERVAL),
      DEFINE_NIC_PROPERTIES(VirtIONet, nic_conf),
      DEFINE_PROP_UINT32("x-txtimer", VirtIONet, net_conf.txtimer,
                         TX_TIMER_INTERVAL),
      DEFINE_PROP_INT32("x-txburst", VirtIONet, net_conf.txburst, TX_BURST),
      DEFINE_PROP_STRING("tx", VirtIONet, net_conf.tx),
      DEFINE_PROP_UINT16("rx_queue_size", VirtIONet, net_conf.rx_queue_size,
                         VIRTIO_NET_RX_QUEUE_DEFAULT_SIZE),
      DEFINE_PROP_UINT16("tx_queue_size", VirtIONet, net_conf.tx_queue_size,
                         VIRTIO_NET_TX_QUEUE_DEFAULT_SIZE),
      DEFINE_PROP_UINT16("host_mtu", VirtIONet, net_conf.mtu, 0),
      DEFINE_PROP_BOOL("x-mtu-bypass-backend", VirtIONet, mtu_bypass_backend,
                       true),
      DEFINE_PROP_INT32("speed", VirtIONet, net_conf.speed, SPEED_UNKNOWN),
      DEFINE_PROP_STRING("duplex", VirtIONet, net_conf.duplex_str),
      DEFINE_PROP_BOOL("failover", VirtIONet, failover, false),
      DEFINE_PROP_END_OF_LIST(),
  };
  
  static void virtio_net_class_init(ObjectClass *klass, void *data)
  {
      DeviceClass *dc = DEVICE_CLASS(klass);
      VirtioDeviceClass *vdc = VIRTIO_DEVICE_CLASS(klass);
  
      device_class_set_props(dc, virtio_net_properties);
      dc->vmsd = &vmstate_virtio_net;
      set_bit(DEVICE_CATEGORY_NETWORK, dc->categories);
      vdc->realize = virtio_net_device_realize;
      vdc->unrealize = virtio_net_device_unrealize;
      vdc->get_config = virtio_net_get_config;
      vdc->set_config = virtio_net_set_config;
      vdc->get_features = virtio_net_get_features;
      vdc->set_features = virtio_net_set_features;
      vdc->bad_features = virtio_net_bad_features;
      vdc->reset = virtio_net_reset;
      vdc->set_status = virtio_net_set_status;
      vdc->guest_notifier_mask = virtio_net_guest_notifier_mask;
      vdc->guest_notifier_pending = virtio_net_guest_notifier_pending;
      vdc->legacy_features |= (0x1 << VIRTIO_NET_F_GSO);
      vdc->post_load = virtio_net_post_load_virtio;
      vdc->vmsd = &vmstate_virtio_net_device;
      vdc->primary_unplug_pending = primary_unplug_pending;
  }
  
  static const TypeInfo virtio_net_info = {
      .name = TYPE_VIRTIO_NET,
      .parent = TYPE_VIRTIO_DEVICE,
      .instance_size = sizeof(VirtIONet),
      .instance_init = virtio_net_instance_init,
      .class_init = virtio_net_class_init,
  };
  
  static void virtio_register_types(void)
  {
      type_register_static(&virtio_net_info);
  }
  
  type_init(virtio_register_types)
  