Add qemu 2.4.0

Change-Id: Ic99cbad4b61f8b127b7dc74d04576c0bcbaaf4f5
Signed-off-by: Yang Zhang <yang.z.zhang@intel.com>

1 files changed, 1863 insertions, 0 deletions

diff --git a/qemu/hw/net/virtio-net.c b/qemu/hw/net/virtio-net.c
new file mode 100644
index 000000000..151083954
--- /dev/null
+++ b/qemu/hw/net/virtio-net.c
@@ -0,0 +1,1863 @@
+/*
+ * 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/iov.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 "hw/virtio/virtio-net.h"
+#include "net/vhost_net.h"
+#include "hw/virtio/virtio-bus.h"
+#include "qapi/qmp/qjson.h"
+#include "qapi-event.h"
+#include "hw/virtio/virtio-access.h"
+
+#define VIRTIO_NET_VM_VERSION    11
+
+#define MAC_TABLE_ENTRIES    64
+#define MAX_VLAN    (1 << 12)   /* Per 802.1Q definition */
+
+/*
+ * Calculate the number of bytes up to and including the given 'field' of
+ * 'container'.
+ */
+#define endof(container, field) \
+    (offsetof(container, field) + sizeof(((container *)0)->field))
+
+typedef struct VirtIOFeature {
+    uint32_t flags;
+    size_t end;
+} VirtIOFeature;
+
+static VirtIOFeature feature_sizes[] = {
+    {.flags = 1 << VIRTIO_NET_F_MAC,
+     .end = endof(struct virtio_net_config, mac)},
+    {.flags = 1 << VIRTIO_NET_F_STATUS,
+     .end = endof(struct virtio_net_config, status)},
+    {.flags = 1 << VIRTIO_NET_F_MQ,
+     .end = endof(struct virtio_net_config, max_virtqueue_pairs)},
+    {}
+};
+
+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;
+
+    virtio_stw_p(vdev, &netcfg.status, n->status);
+    virtio_stw_p(vdev, &netcfg.max_virtqueue_pairs, n->max_queues);
+    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 = {};
+
+    memcpy(&netcfg, config, n->config_size);
+
+    if (!virtio_has_feature(vdev, VIRTIO_NET_F_CTRL_MAC_ADDR) &&
+        !virtio_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);
+    }
+}
+
+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_timer(void *opaque)
+{
+    VirtIONet *n = opaque;
+    VirtIODevice *vdev = VIRTIO_DEVICE(n);
+
+    n->announce_counter--;
+    n->status |= VIRTIO_NET_S_ANNOUNCE;
+    virtio_notify_config(vdev);
+}
+
+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;
+
+        /* 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);
+        }
+
+        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 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_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);
+            }
+        }
+    }
+}
+
+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) {
+        gchar *path = object_get_canonical_path(OBJECT(n->qdev));
+        qapi_event_send_nic_rx_filter_changed(!!n->netclient_name,
+                                              n->netclient_name, path, &error_abort);
+        g_free(path);
+
+        /* disable event notification to avoid events flooding */
+        nc->rxfilter_notify_enabled = 0;
+    }
+}
+
+static intList *get_vlan_table(VirtIONet *n)
+{
+    intList *list, *entry;
+    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)) {
+                entry = g_malloc0(sizeof(*entry));
+                entry->value = (i << 5) + j;
+                entry->next = list;
+                list = entry;
+            }
+        }
+    }
+
+    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, *entry;
+    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++) {
+        entry = g_malloc0(sizeof(*entry));
+        entry->value = qemu_mac_strdup_printf(n->mac_table.macs + i * ETH_ALEN);
+        entry->next = str_list;
+        str_list = entry;
+    }
+    info->unicast_table = str_list;
+
+    str_list = NULL;
+    for (i = n->mac_table.first_multi; i < n->mac_table.in_use; i++) {
+        entry = g_malloc0(sizeof(*entry));
+        entry->value = qemu_mac_strdup_printf(n->mac_table.macs + i * ETH_ALEN);
+        entry->next = str_list;
+        str_list = entry;
+    }
+    info->multicast_table = str_list;
+    info->vlan_table = get_vlan_table(n);
+
+    if (!virtio_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);
+
+    /* 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);
+    n->announce_counter = 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);
+}
+
+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 i;
+    NetClientState *nc;
+
+    n->mergeable_rx_bufs = mergeable_rx_bufs;
+
+    if (version_1) {
+        n->guest_hdr_len = sizeof(struct virtio_net_hdr_mrg_rxbuf);
+    } 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 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_OPTIONS_KIND_TAP) {
+        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_OPTIONS_KIND_TAP) {
+        return 0;
+    }
+
+    return tap_disable(nc->peer);
+}
+
+static void virtio_net_set_queues(VirtIONet *n)
+{
+    int i;
+    int r;
+
+    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);
+    }
+
+    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;
+    }
+    return vhost_net_get_features(get_vhost_net(nc->peer), 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);
+}
+
+static void virtio_net_set_features(VirtIODevice *vdev, uint64_t features)
+{
+    VirtIONet *n = VIRTIO_NET(vdev);
+    int i;
+
+    virtio_net_set_multiqueue(n,
+                              __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));
+
+    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);
+    }
+}
+
+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_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;
+
+        if (!n->has_vnet_hdr) {
+            return VIRTIO_NET_ERR;
+        }
+
+        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)
+{
+    if (cmd == VIRTIO_NET_CTRL_ANNOUNCE_ACK &&
+        n->status & VIRTIO_NET_S_ANNOUNCE) {
+        n->status &= ~VIRTIO_NET_S_ANNOUNCE;
+        if (n->announce_counter) {
+            timer_mod(n->announce_timer,
+                      qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL) +
+                      self_announce_delay(n->announce_counter));
+        }
+        return VIRTIO_NET_OK;
+    } else {
+        return VIRTIO_NET_ERR;
+    }
+}
+
+static int virtio_net_handle_mq(VirtIONet *n, uint8_t cmd,
+                                struct iovec *iov, unsigned int iov_cnt)
+{
+    VirtIODevice *vdev = VIRTIO_DEVICE(n);
+    struct virtio_net_ctrl_mq mq;
+    size_t s;
+    uint16_t queues;
+
+    s = iov_to_buf(iov, iov_cnt, 0, &mq, sizeof(mq));
+    if (s != sizeof(mq)) {
+        return VIRTIO_NET_ERR;
+    }
+
+    if (cmd != VIRTIO_NET_CTRL_MQ_VQ_PAIRS_SET) {
+        return VIRTIO_NET_ERR;
+    }
+
+    queues = virtio_lduw_p(vdev, &mq.virtqueue_pairs);
+
+    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;
+
+    while (virtqueue_pop(vq, &elem)) {
+        if (iov_size(elem.in_sg, elem.in_num) < sizeof(status) ||
+            iov_size(elem.out_sg, elem.out_num) < sizeof(ctrl)) {
+            error_report("virtio-net ctrl missing headers");
+            exit(1);
+        }
+
+        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);
+    }
+}
+
+/* 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 int 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 0;
+    }
+
+    if (nc->queue_index >= n->curr_queues) {
+        return 0;
+    }
+
+    if (!virtio_queue_ready(q->rx_vq) ||
+        !(vdev->status & VIRTIO_CONFIG_S_DRIVER_OK)) {
+        return 0;
+    }
+
+    return 1;
+}
+
+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);
+        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);
+        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 = be16_to_cpup((uint16_t *)(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 ssize_t virtio_net_receive(NetClientState *nc, const uint8_t *buf, size_t size)
+{
+    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;
+    }
+
+    /* 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 = elem.in_sg;
+
+        total = 0;
+
+        if (virtqueue_pop(q->rx_vq, &elem) == 0) {
+            if (i == 0)
+                return -1;
+            error_report("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);
+            exit(1);
+        }
+
+        if (elem.in_num < 1) {
+            error_report("virtio-net receive queue contains no in buffers");
+            exit(1);
+        }
+
+        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);
+            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) {
+#if 0
+            error_report("virtio-net truncated non-mergeable packet: "
+                         "i %zd mergeable %d offset %zd, size %zd, "
+                         "guest hdr len %zd, host hdr len %zd",
+                         i, n->mergeable_rx_bufs,
+                         offset, size, n->guest_hdr_len, n->host_hdr_len);
+#endif
+            return size;
+        }
+
+        /* signal other side */
+        virtqueue_fill(q->rx_vq, &elem, total, i++);
+    }
+
+    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 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);
+
+    q->async_tx.elem.out_num = q->async_tx.len = 0;
+
+    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.out_num) {
+        virtio_queue_set_notification(q->tx_vq, 0);
+        return num_packets;
+    }
+
+    while (virtqueue_pop(q->tx_vq, &elem)) {
+        ssize_t ret, len;
+        unsigned int out_num = elem.out_num;
+        struct iovec *out_sg = &elem.out_sg[0];
+        struct iovec sg[VIRTQUEUE_MAX_SIZE], sg2[VIRTQUEUE_MAX_SIZE + 1];
+        struct virtio_net_hdr_mrg_rxbuf mhdr;
+
+        if (out_num < 1) {
+            error_report("virtio-net header not in first element");
+            exit(1);
+        }
+
+        if (n->has_vnet_hdr) {
+            if (iov_to_buf(out_sg, out_num, 0, &mhdr, n->guest_hdr_len) <
+                n->guest_hdr_len) {
+                error_report("virtio-net header incorrect");
+                exit(1);
+            }
+            if (virtio_needs_swap(vdev)) {
+                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;
+        }
+
+        len = n->guest_hdr_len;
+
+        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;
+            q->async_tx.len  = len;
+            return -EBUSY;
+        }
+
+        len += ret;
+drop:
+        virtqueue_push(q->tx_vq, &elem, 0);
+        virtio_notify(vdev, q->tx_vq);
+
+        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))];
+
+    /* 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;
+        virtio_net_flush_tx(q);
+    } 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(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) {
+        return; /* Notification re-enable handled by tx_complete */
+    }
+
+    /* 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);
+    if (virtio_net_flush_tx(q) > 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, 256, virtio_net_handle_rx);
+    if (n->net_conf.tx && !strcmp(n->net_conf.tx, "timer")) {
+        n->vqs[index].tx_vq =
+            virtio_add_queue(vdev, 256, 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, 256, 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_del(q->tx_timer);
+        timer_free(q->tx_timer);
+    } else {
+        qemu_bh_delete(q->tx_bh);
+    }
+    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 too 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 void virtio_net_save(QEMUFile *f, void *opaque)
+{
+    VirtIONet *n = opaque;
+    VirtIODevice *vdev = VIRTIO_DEVICE(n);
+
+    /* At this point, backend must be stopped, otherwise
+     * it might keep writing to memory. */
+    assert(!n->vhost_started);
+    virtio_save(vdev, f);
+}
+
+static void virtio_net_save_device(VirtIODevice *vdev, QEMUFile *f)
+{
+    VirtIONet *n = VIRTIO_NET(vdev);
+    int i;
+
+    qemu_put_buffer(f, n->mac, ETH_ALEN);
+    qemu_put_be32(f, n->vqs[0].tx_waiting);
+    qemu_put_be32(f, n->mergeable_rx_bufs);
+    qemu_put_be16(f, n->status);
+    qemu_put_byte(f, n->promisc);
+    qemu_put_byte(f, n->allmulti);
+    qemu_put_be32(f, n->mac_table.in_use);
+    qemu_put_buffer(f, n->mac_table.macs, n->mac_table.in_use * ETH_ALEN);
+    qemu_put_buffer(f, (uint8_t *)n->vlans, MAX_VLAN >> 3);
+    qemu_put_be32(f, n->has_vnet_hdr);
+    qemu_put_byte(f, n->mac_table.multi_overflow);
+    qemu_put_byte(f, n->mac_table.uni_overflow);
+    qemu_put_byte(f, n->alluni);
+    qemu_put_byte(f, n->nomulti);
+    qemu_put_byte(f, n->nouni);
+    qemu_put_byte(f, n->nobcast);
+    qemu_put_byte(f, n->has_ufo);
+    if (n->max_queues > 1) {
+        qemu_put_be16(f, n->max_queues);
+        qemu_put_be16(f, n->curr_queues);
+        for (i = 1; i < n->curr_queues; i++) {
+            qemu_put_be32(f, n->vqs[i].tx_waiting);
+        }
+    }
+
+    if (virtio_has_feature(vdev, VIRTIO_NET_F_CTRL_GUEST_OFFLOADS)) {
+        qemu_put_be64(f, n->curr_guest_offloads);
+    }
+}
+
+static int virtio_net_load(QEMUFile *f, void *opaque, int version_id)
+{
+    VirtIONet *n = opaque;
+    VirtIODevice *vdev = VIRTIO_DEVICE(n);
+
+    if (version_id < 2 || version_id > VIRTIO_NET_VM_VERSION)
+        return -EINVAL;
+
+    return virtio_load(vdev, f, version_id);
+}
+
+static int virtio_net_load_device(VirtIODevice *vdev, QEMUFile *f,
+                                  int version_id)
+{
+    VirtIONet *n = VIRTIO_NET(vdev);
+    int i, link_down;
+
+    qemu_get_buffer(f, n->mac, ETH_ALEN);
+    n->vqs[0].tx_waiting = qemu_get_be32(f);
+
+    virtio_net_set_mrg_rx_bufs(n, qemu_get_be32(f),
+                               virtio_has_feature(vdev, VIRTIO_F_VERSION_1));
+
+    if (version_id >= 3)
+        n->status = qemu_get_be16(f);
+
+    if (version_id >= 4) {
+        if (version_id < 8) {
+            n->promisc = qemu_get_be32(f);
+            n->allmulti = qemu_get_be32(f);
+        } else {
+            n->promisc = qemu_get_byte(f);
+            n->allmulti = qemu_get_byte(f);
+        }
+    }
+
+    if (version_id >= 5) {
+        n->mac_table.in_use = qemu_get_be32(f);
+        /* MAC_TABLE_ENTRIES may be different from the saved image */
+        if (n->mac_table.in_use <= MAC_TABLE_ENTRIES) {
+            qemu_get_buffer(f, n->mac_table.macs,
+                            n->mac_table.in_use * ETH_ALEN);
+        } else {
+            int64_t i;
+
+            /* Overflow detected - can happen if source has a larger MAC table.
+             * We simply set overflow flag so there's no need to maintain the
+             * table of addresses, discard them all.
+             * Note: 64 bit math to avoid integer overflow.
+             */
+            for (i = 0; i < (int64_t)n->mac_table.in_use * ETH_ALEN; ++i) {
+                qemu_get_byte(f);
+            }
+            n->mac_table.multi_overflow = n->mac_table.uni_overflow = 1;
+            n->mac_table.in_use = 0;
+        }
+    }
+ 
+    if (version_id >= 6)
+        qemu_get_buffer(f, (uint8_t *)n->vlans, MAX_VLAN >> 3);
+
+    if (version_id >= 7) {
+        if (qemu_get_be32(f) && !peer_has_vnet_hdr(n)) {
+            error_report("virtio-net: saved image requires vnet_hdr=on");
+            return -1;
+        }
+    }
+
+    if (version_id >= 9) {
+        n->mac_table.multi_overflow = qemu_get_byte(f);
+        n->mac_table.uni_overflow = qemu_get_byte(f);
+    }
+
+    if (version_id >= 10) {
+        n->alluni = qemu_get_byte(f);
+        n->nomulti = qemu_get_byte(f);
+        n->nouni = qemu_get_byte(f);
+        n->nobcast = qemu_get_byte(f);
+    }
+
+    if (version_id >= 11) {
+        if (qemu_get_byte(f) && !peer_has_ufo(n)) {
+            error_report("virtio-net: saved image requires TUN_F_UFO support");
+            return -1;
+        }
+    }
+
+    if (n->max_queues > 1) {
+        if (n->max_queues != qemu_get_be16(f)) {
+            error_report("virtio-net: different max_queues ");
+            return -1;
+        }
+
+        n->curr_queues = qemu_get_be16(f);
+        if (n->curr_queues > n->max_queues) {
+            error_report("virtio-net: curr_queues %x > max_queues %x",
+                         n->curr_queues, n->max_queues);
+            return -1;
+        }
+        for (i = 1; i < n->curr_queues; i++) {
+            n->vqs[i].tx_waiting = qemu_get_be32(f);
+        }
+    }
+
+    if (virtio_has_feature(vdev, VIRTIO_NET_F_CTRL_GUEST_OFFLOADS)) {
+        n->curr_guest_offloads = qemu_get_be64(f);
+    } else {
+        n->curr_guest_offloads = virtio_net_supported_guest_offloads(n);
+    }
+
+    if (peer_has_vnet_hdr(n)) {
+        virtio_net_apply_guest_offloads(n);
+    }
+
+    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_has_feature(vdev, VIRTIO_NET_F_GUEST_ANNOUNCE) &&
+        virtio_has_feature(vdev, VIRTIO_NET_F_CTRL_VQ)) {
+        n->announce_counter = SELF_ANNOUNCE_ROUNDS;
+        timer_mod(n->announce_timer, qemu_clock_get_ms(QEMU_CLOCK_VIRTUAL));
+    }
+
+    return 0;
+}
+
+static NetClientInfo net_virtio_info = {
+    .type = NET_CLIENT_OPTIONS_KIND_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,
+};
+
+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)
+{
+    int i, config_size = 0;
+    virtio_add_feature(&host_features, VIRTIO_NET_F_MAC);
+    for (i = 0; feature_sizes[i].flags != 0; i++) {
+        if (host_features & feature_sizes[i].flags) {
+            config_size = MAX(feature_sizes[i].end, config_size);
+        }
+    }
+    n->config_size = config_size;
+}
+
+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 void virtio_net_device_realize(DeviceState *dev, Error **errp)
+{
+    VirtIODevice *vdev = VIRTIO_DEVICE(dev);
+    VirtIONet *n = VIRTIO_NET(dev);
+    NetClientState *nc;
+    int i;
+
+    virtio_net_set_config_size(n, n->host_features);
+    virtio_init(vdev, "virtio-net", VIRTIO_ID_NET, n->config_size);
+
+    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")) {
+        error_report("virtio-net: "
+                     "Unknown option tx=%s, valid options: \"timer\" \"bh\"",
+                     n->net_conf.tx);
+        error_report("Defaulting to \"bh\"");
+    }
+
+    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;
+    n->announce_timer = timer_new_ms(QEMU_CLOCK_VIRTUAL,
+                                     virtio_net_announce_timer, n);
+
+    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);
+    }
+
+    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);
+    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;
+
+    n->qdev = dev;
+    register_savevm(dev, "virtio-net", -1, VIRTIO_NET_VM_VERSION,
+                    virtio_net_save, virtio_net_load, n);
+}
+
+static void virtio_net_device_unrealize(DeviceState *dev, Error **errp)
+{
+    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);
+
+    unregister_savevm(dev, "virtio-net", n);
+
+    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);
+
+    max_queues = n->multiqueue ? n->max_queues : 1;
+    for (i = 0; i < max_queues; i++) {
+        virtio_net_del_queue(n, i);
+    }
+
+    timer_del(n->announce_timer);
+    timer_free(n->announce_timer);
+    g_free(n->vqs);
+    qemu_del_nic(n->nic);
+    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), NULL);
+}
+
+static Property virtio_net_properties[] = {
+    DEFINE_PROP_BIT("csum", VirtIONet, host_features, VIRTIO_NET_F_CSUM, true),
+    DEFINE_PROP_BIT("guest_csum", VirtIONet, host_features,
+                    VIRTIO_NET_F_GUEST_CSUM, true),
+    DEFINE_PROP_BIT("gso", VirtIONet, host_features, VIRTIO_NET_F_GSO, true),
+    DEFINE_PROP_BIT("guest_tso4", VirtIONet, host_features,
+                    VIRTIO_NET_F_GUEST_TSO4, true),
+    DEFINE_PROP_BIT("guest_tso6", VirtIONet, host_features,
+                    VIRTIO_NET_F_GUEST_TSO6, true),
+    DEFINE_PROP_BIT("guest_ecn", VirtIONet, host_features,
+                    VIRTIO_NET_F_GUEST_ECN, true),
+    DEFINE_PROP_BIT("guest_ufo", VirtIONet, host_features,
+                    VIRTIO_NET_F_GUEST_UFO, true),
+    DEFINE_PROP_BIT("guest_announce", VirtIONet, host_features,
+                    VIRTIO_NET_F_GUEST_ANNOUNCE, true),
+    DEFINE_PROP_BIT("host_tso4", VirtIONet, host_features,
+                    VIRTIO_NET_F_HOST_TSO4, true),
+    DEFINE_PROP_BIT("host_tso6", VirtIONet, host_features,
+                    VIRTIO_NET_F_HOST_TSO6, true),
+    DEFINE_PROP_BIT("host_ecn", VirtIONet, host_features,
+                    VIRTIO_NET_F_HOST_ECN, true),
+    DEFINE_PROP_BIT("host_ufo", VirtIONet, host_features,
+                    VIRTIO_NET_F_HOST_UFO, true),
+    DEFINE_PROP_BIT("mrg_rxbuf", VirtIONet, host_features,
+                    VIRTIO_NET_F_MRG_RXBUF, true),
+    DEFINE_PROP_BIT("status", VirtIONet, host_features,
+                    VIRTIO_NET_F_STATUS, true),
+    DEFINE_PROP_BIT("ctrl_vq", VirtIONet, host_features,
+                    VIRTIO_NET_F_CTRL_VQ, true),
+    DEFINE_PROP_BIT("ctrl_rx", VirtIONet, host_features,
+                    VIRTIO_NET_F_CTRL_RX, true),
+    DEFINE_PROP_BIT("ctrl_vlan", VirtIONet, host_features,
+                    VIRTIO_NET_F_CTRL_VLAN, true),
+    DEFINE_PROP_BIT("ctrl_rx_extra", VirtIONet, host_features,
+                    VIRTIO_NET_F_CTRL_RX_EXTRA, true),
+    DEFINE_PROP_BIT("ctrl_mac_addr", VirtIONet, host_features,
+                    VIRTIO_NET_F_CTRL_MAC_ADDR, true),
+    DEFINE_PROP_BIT("ctrl_guest_offloads", VirtIONet, host_features,
+                    VIRTIO_NET_F_CTRL_GUEST_OFFLOADS, true),
+    DEFINE_PROP_BIT("mq", VirtIONet, host_features, VIRTIO_NET_F_MQ, false),
+    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_END_OF_LIST(),
+};
+
+static void virtio_net_class_init(ObjectClass *klass, void *data)
+{
+    DeviceClass *dc = DEVICE_CLASS(klass);
+    VirtioDeviceClass *vdc = VIRTIO_DEVICE_CLASS(klass);
+
+    dc->props = virtio_net_properties;
+    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->load = virtio_net_load_device;
+    vdc->save = virtio_net_save_device;
+}
+
+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)