hw: move virtio devices to hw/ subdirectories

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

3 files changed, 1701 insertions, 0 deletions

diff --git a/hw/net/Makefile.objs b/hw/net/Makefile.objs
index ad91293fe4..73217d80ae 100644
--- a/hw/net/Makefile.objs
+++ b/hw/net/Makefile.objs
@@ -20,3 +20,6 @@ common-obj-$(CONFIG_MIPSNET) += mipsnet.o
 common-obj-$(CONFIG_XILINX_AXI) += xilinx_axienet.o
 
 common-obj-$(CONFIG_CADENCE) += cadence_gem.o
+
+obj-$(CONFIG_VIRTIO) += virtio-net.o
+obj-y += vhost_net.o
diff --git a/hw/net/vhost_net.c b/hw/net/vhost_net.c
new file mode 100644
index 0000000000..8c5384cf76
--- /dev/null
+++ b/hw/net/vhost_net.c
@@ -0,0 +1,328 @@
+/*
+ * vhost-net support
+ *
+ * Copyright Red Hat, Inc. 2010
+ *
+ * Authors:
+ *  Michael S. Tsirkin <mst@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.  See
+ * the COPYING file in the top-level directory.
+ *
+ * Contributions after 2012-01-13 are licensed under the terms of the
+ * GNU GPL, version 2 or (at your option) any later version.
+ */
+
+#include "net/net.h"
+#include "net/tap.h"
+
+#include "hw/virtio/virtio-net.h"
+#include "net/vhost_net.h"
+#include "qemu/error-report.h"
+
+#include "config.h"
+
+#ifdef CONFIG_VHOST_NET
+#include <linux/vhost.h>
+#include <sys/socket.h>
+#include <linux/kvm.h>
+#include <fcntl.h>
+#include <sys/ioctl.h>
+#include <linux/virtio_ring.h>
+#include <netpacket/packet.h>
+#include <net/ethernet.h>
+#include <net/if.h>
+#include <netinet/in.h>
+
+#include <stdio.h>
+
+#include "hw/virtio/vhost.h"
+
+struct vhost_net {
+    struct vhost_dev dev;
+    struct vhost_virtqueue vqs[2];
+    int backend;
+    NetClientState *nc;
+};
+
+unsigned vhost_net_get_features(struct vhost_net *net, unsigned features)
+{
+    /* Clear features not supported by host kernel. */
+    if (!(net->dev.features & (1 << VIRTIO_F_NOTIFY_ON_EMPTY))) {
+        features &= ~(1 << VIRTIO_F_NOTIFY_ON_EMPTY);
+    }
+    if (!(net->dev.features & (1 << VIRTIO_RING_F_INDIRECT_DESC))) {
+        features &= ~(1 << VIRTIO_RING_F_INDIRECT_DESC);
+    }
+    if (!(net->dev.features & (1 << VIRTIO_RING_F_EVENT_IDX))) {
+        features &= ~(1 << VIRTIO_RING_F_EVENT_IDX);
+    }
+    if (!(net->dev.features & (1 << VIRTIO_NET_F_MRG_RXBUF))) {
+        features &= ~(1 << VIRTIO_NET_F_MRG_RXBUF);
+    }
+    return features;
+}
+
+void vhost_net_ack_features(struct vhost_net *net, unsigned features)
+{
+    net->dev.acked_features = net->dev.backend_features;
+    if (features & (1 << VIRTIO_F_NOTIFY_ON_EMPTY)) {
+        net->dev.acked_features |= (1 << VIRTIO_F_NOTIFY_ON_EMPTY);
+    }
+    if (features & (1 << VIRTIO_RING_F_INDIRECT_DESC)) {
+        net->dev.acked_features |= (1 << VIRTIO_RING_F_INDIRECT_DESC);
+    }
+    if (features & (1 << VIRTIO_RING_F_EVENT_IDX)) {
+        net->dev.acked_features |= (1 << VIRTIO_RING_F_EVENT_IDX);
+    }
+    if (features & (1 << VIRTIO_NET_F_MRG_RXBUF)) {
+        net->dev.acked_features |= (1 << VIRTIO_NET_F_MRG_RXBUF);
+    }
+}
+
+static int vhost_net_get_fd(NetClientState *backend)
+{
+    switch (backend->info->type) {
+    case NET_CLIENT_OPTIONS_KIND_TAP:
+        return tap_get_fd(backend);
+    default:
+        fprintf(stderr, "vhost-net requires tap backend\n");
+        return -EBADFD;
+    }
+}
+
+struct vhost_net *vhost_net_init(NetClientState *backend, int devfd,
+                                 bool force)
+{
+    int r;
+    struct vhost_net *net = g_malloc(sizeof *net);
+    if (!backend) {
+        fprintf(stderr, "vhost-net requires backend to be setup\n");
+        goto fail;
+    }
+    r = vhost_net_get_fd(backend);
+    if (r < 0) {
+        goto fail;
+    }
+    net->nc = backend;
+    net->dev.backend_features = tap_has_vnet_hdr(backend) ? 0 :
+        (1 << VHOST_NET_F_VIRTIO_NET_HDR);
+    net->backend = r;
+
+    net->dev.nvqs = 2;
+    net->dev.vqs = net->vqs;
+
+    r = vhost_dev_init(&net->dev, devfd, "/dev/vhost-net", force);
+    if (r < 0) {
+        goto fail;
+    }
+    if (!tap_has_vnet_hdr_len(backend,
+                              sizeof(struct virtio_net_hdr_mrg_rxbuf))) {
+        net->dev.features &= ~(1 << VIRTIO_NET_F_MRG_RXBUF);
+    }
+    if (~net->dev.features & net->dev.backend_features) {
+        fprintf(stderr, "vhost lacks feature mask %" PRIu64 " for backend\n",
+                (uint64_t)(~net->dev.features & net->dev.backend_features));
+        vhost_dev_cleanup(&net->dev);
+        goto fail;
+    }
+
+    /* Set sane init value. Override when guest acks. */
+    vhost_net_ack_features(net, 0);
+    return net;
+fail:
+    g_free(net);
+    return NULL;
+}
+
+bool vhost_net_query(VHostNetState *net, VirtIODevice *dev)
+{
+    return vhost_dev_query(&net->dev, dev);
+}
+
+static int vhost_net_start_one(struct vhost_net *net,
+                               VirtIODevice *dev,
+                               int vq_index)
+{
+    struct vhost_vring_file file = { };
+    int r;
+
+    if (net->dev.started) {
+        return 0;
+    }
+
+    net->dev.nvqs = 2;
+    net->dev.vqs = net->vqs;
+    net->dev.vq_index = vq_index;
+
+    r = vhost_dev_enable_notifiers(&net->dev, dev);
+    if (r < 0) {
+        goto fail_notifiers;
+    }
+
+    r = vhost_dev_start(&net->dev, dev);
+    if (r < 0) {
+        goto fail_start;
+    }
+
+    net->nc->info->poll(net->nc, false);
+    qemu_set_fd_handler(net->backend, NULL, NULL, NULL);
+    file.fd = net->backend;
+    for (file.index = 0; file.index < net->dev.nvqs; ++file.index) {
+        r = ioctl(net->dev.control, VHOST_NET_SET_BACKEND, &file);
+        if (r < 0) {
+            r = -errno;
+            goto fail;
+        }
+    }
+    return 0;
+fail:
+    file.fd = -1;
+    while (file.index-- > 0) {
+        int r = ioctl(net->dev.control, VHOST_NET_SET_BACKEND, &file);
+        assert(r >= 0);
+    }
+    net->nc->info->poll(net->nc, true);
+    vhost_dev_stop(&net->dev, dev);
+fail_start:
+    vhost_dev_disable_notifiers(&net->dev, dev);
+fail_notifiers:
+    return r;
+}
+
+static void vhost_net_stop_one(struct vhost_net *net,
+                               VirtIODevice *dev)
+{
+    struct vhost_vring_file file = { .fd = -1 };
+
+    if (!net->dev.started) {
+        return;
+    }
+
+    for (file.index = 0; file.index < net->dev.nvqs; ++file.index) {
+        int r = ioctl(net->dev.control, VHOST_NET_SET_BACKEND, &file);
+        assert(r >= 0);
+    }
+    net->nc->info->poll(net->nc, true);
+    vhost_dev_stop(&net->dev, dev);
+    vhost_dev_disable_notifiers(&net->dev, dev);
+}
+
+int vhost_net_start(VirtIODevice *dev, NetClientState *ncs,
+                    int total_queues)
+{
+    int r, i = 0;
+
+    if (!dev->binding->set_guest_notifiers) {
+        error_report("binding does not support guest notifiers");
+        r = -ENOSYS;
+        goto err;
+    }
+
+    for (i = 0; i < total_queues; i++) {
+        r = vhost_net_start_one(tap_get_vhost_net(ncs[i].peer), dev, i * 2);
+
+        if (r < 0) {
+            goto err;
+        }
+    }
+
+    r = dev->binding->set_guest_notifiers(dev->binding_opaque,
+                                          total_queues * 2,
+                                          true);
+    if (r < 0) {
+        error_report("Error binding guest notifier: %d", -r);
+        goto err;
+    }
+
+    return 0;
+
+err:
+    while (--i >= 0) {
+        vhost_net_stop_one(tap_get_vhost_net(ncs[i].peer), dev);
+    }
+    return r;
+}
+
+void vhost_net_stop(VirtIODevice *dev, NetClientState *ncs,
+                    int total_queues)
+{
+    int i, r;
+
+    r = dev->binding->set_guest_notifiers(dev->binding_opaque,
+                                          total_queues * 2,
+                                          false);
+    if (r < 0) {
+        fprintf(stderr, "vhost guest notifier cleanup failed: %d\n", r);
+        fflush(stderr);
+    }
+    assert(r >= 0);
+
+    for (i = 0; i < total_queues; i++) {
+        vhost_net_stop_one(tap_get_vhost_net(ncs[i].peer), dev);
+    }
+}
+
+void vhost_net_cleanup(struct vhost_net *net)
+{
+    vhost_dev_cleanup(&net->dev);
+    g_free(net);
+}
+
+bool vhost_net_virtqueue_pending(VHostNetState *net, int idx)
+{
+    return vhost_virtqueue_pending(&net->dev, idx);
+}
+
+void vhost_net_virtqueue_mask(VHostNetState *net, VirtIODevice *dev,
+                              int idx, bool mask)
+{
+    vhost_virtqueue_mask(&net->dev, dev, idx, mask);
+}
+#else
+struct vhost_net *vhost_net_init(NetClientState *backend, int devfd,
+                                 bool force)
+{
+    error_report("vhost-net support is not compiled in");
+    return NULL;
+}
+
+bool vhost_net_query(VHostNetState *net, VirtIODevice *dev)
+{
+    return false;
+}
+
+int vhost_net_start(VirtIODevice *dev,
+                    NetClientState *ncs,
+                    int total_queues)
+{
+    return -ENOSYS;
+}
+void vhost_net_stop(VirtIODevice *dev,
+                    NetClientState *ncs,
+                    int total_queues)
+{
+}
+
+void vhost_net_cleanup(struct vhost_net *net)
+{
+}
+
+unsigned vhost_net_get_features(struct vhost_net *net, unsigned features)
+{
+    return features;
+}
+void vhost_net_ack_features(struct vhost_net *net, unsigned features)
+{
+}
+
+bool vhost_net_virtqueue_pending(VHostNetState *net, int idx)
+{
+    return -ENOSYS;
+}
+
+void vhost_net_virtqueue_mask(VHostNetState *net, VirtIODevice *dev,
+                              int idx, bool mask)
+{
+}
+#endif
diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
new file mode 100644
index 0000000000..bc8fd43b4b
--- /dev/null
+++ b/hw/net/virtio-net.c
@@ -0,0 +1,1370 @@
+/*
+ * 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"
+
+#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 VirtIONet *to_virtio_net(VirtIODevice *vdev)
+{
+    return (VirtIONet *)vdev;
+}
+
+static void virtio_net_get_config(VirtIODevice *vdev, uint8_t *config)
+{
+    VirtIONet *n = to_virtio_net(vdev);
+    struct virtio_net_config netcfg;
+
+    stw_p(&netcfg.status, n->status);
+    stw_p(&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 = to_virtio_net(vdev);
+    struct virtio_net_config netcfg = {};
+
+    memcpy(&netcfg, config, n->config_size);
+
+    if (!(n->vdev.guest_features >> VIRTIO_NET_F_CTRL_MAC_ADDR & 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)
+{
+    return (status & VIRTIO_CONFIG_S_DRIVER_OK) &&
+        (n->status & VIRTIO_NET_S_LINK_UP) && n->vdev.vm_running;
+}
+
+static void virtio_net_vhost_status(VirtIONet *n, uint8_t status)
+{
+    NetClientState *nc = qemu_get_queue(n->nic);
+    int queues = n->multiqueue ? n->max_queues : 1;
+
+    if (!nc->peer) {
+        return;
+    }
+    if (nc->peer->info->type != NET_CLIENT_OPTIONS_KIND_TAP) {
+        return;
+    }
+
+    if (!tap_get_vhost_net(nc->peer)) {
+        return;
+    }
+
+    if (!!n->vhost_started == virtio_net_started(n, status) &&
+                              !nc->peer->link_down) {
+        return;
+    }
+    if (!n->vhost_started) {
+        int r;
+        if (!vhost_net_query(tap_get_vhost_net(nc->peer), &n->vdev)) {
+            return;
+        }
+        n->vhost_started = 1;
+        r = vhost_net_start(&n->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(&n->vdev, n->nic->ncs, queues);
+        n->vhost_started = 0;
+    }
+}
+
+static void virtio_net_set_status(struct VirtIODevice *vdev, uint8_t status)
+{
+    VirtIONet *n = to_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++) {
+        q = &n->vqs[i];
+
+        if ((!n->multiqueue && i != 0) || i >= n->curr_queues) {
+            queue_status = 0;
+        } else {
+            queue_status = status;
+        }
+
+        if (!q->tx_waiting) {
+            continue;
+        }
+
+        if (virtio_net_started(n, queue_status) && !n->vhost_started) {
+            if (q->tx_timer) {
+                qemu_mod_timer(q->tx_timer,
+                               qemu_get_clock_ns(vm_clock) + n->tx_timeout);
+            } else {
+                qemu_bh_schedule(q->tx_bh);
+            }
+        } else {
+            if (q->tx_timer) {
+                qemu_del_timer(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);
+    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(&n->vdev);
+
+    virtio_net_set_status(&n->vdev, n->vdev.status);
+}
+
+static void virtio_net_reset(VirtIODevice *vdev)
+{
+    VirtIONet *n = to_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;
+
+    /* 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));
+    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;
+    }
+
+    if (nc->peer->info->type != NET_CLIENT_OPTIONS_KIND_TAP) {
+        return;
+    }
+
+    n->has_vnet_hdr = tap_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 = tap_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 i;
+    NetClientState *nc;
+
+    n->mergeable_rx_bufs = mergeable_rx_bufs;
+
+    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) &&
+            tap_has_vnet_hdr_len(nc->peer, n->guest_hdr_len)) {
+            tap_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;
+
+    for (i = 0; i < n->max_queues; i++) {
+        if (i < n->curr_queues) {
+            assert(!peer_attach(n, i));
+        } else {
+            assert(!peer_detach(n, i));
+        }
+    }
+}
+
+static void virtio_net_set_multiqueue(VirtIONet *n, int multiqueue, int ctrl);
+
+static uint32_t virtio_net_get_features(VirtIODevice *vdev, uint32_t features)
+{
+    VirtIONet *n = to_virtio_net(vdev);
+    NetClientState *nc = qemu_get_queue(n->nic);
+
+    features |= (1 << VIRTIO_NET_F_MAC);
+
+    if (!peer_has_vnet_hdr(n)) {
+        features &= ~(0x1 << VIRTIO_NET_F_CSUM);
+        features &= ~(0x1 << VIRTIO_NET_F_HOST_TSO4);
+        features &= ~(0x1 << VIRTIO_NET_F_HOST_TSO6);
+        features &= ~(0x1 << VIRTIO_NET_F_HOST_ECN);
+
+        features &= ~(0x1 << VIRTIO_NET_F_GUEST_CSUM);
+        features &= ~(0x1 << VIRTIO_NET_F_GUEST_TSO4);
+        features &= ~(0x1 << VIRTIO_NET_F_GUEST_TSO6);
+        features &= ~(0x1 << VIRTIO_NET_F_GUEST_ECN);
+    }
+
+    if (!peer_has_vnet_hdr(n) || !peer_has_ufo(n)) {
+        features &= ~(0x1 << VIRTIO_NET_F_GUEST_UFO);
+        features &= ~(0x1 << VIRTIO_NET_F_HOST_UFO);
+    }
+
+    if (!nc->peer || nc->peer->info->type != NET_CLIENT_OPTIONS_KIND_TAP) {
+        return features;
+    }
+    if (!tap_get_vhost_net(nc->peer)) {
+        return features;
+    }
+    return vhost_net_get_features(tap_get_vhost_net(nc->peer), features);
+}
+
+static uint32_t virtio_net_bad_features(VirtIODevice *vdev)
+{
+    uint32_t features = 0;
+
+    /* Linux kernel 2.6.25.  It understood MAC (as everyone must),
+     * but also these: */
+    features |= (1 << VIRTIO_NET_F_MAC);
+    features |= (1 << VIRTIO_NET_F_CSUM);
+    features |= (1 << VIRTIO_NET_F_HOST_TSO4);
+    features |= (1 << VIRTIO_NET_F_HOST_TSO6);
+    features |= (1 << VIRTIO_NET_F_HOST_ECN);
+
+    return features;
+}
+
+static void virtio_net_set_features(VirtIODevice *vdev, uint32_t features)
+{
+    VirtIONet *n = to_virtio_net(vdev);
+    int i;
+
+    virtio_net_set_multiqueue(n, !!(features & (1 << VIRTIO_NET_F_MQ)),
+                              !!(features & (1 << VIRTIO_NET_F_CTRL_VQ)));
+
+    virtio_net_set_mrg_rx_bufs(n, !!(features & (1 << VIRTIO_NET_F_MRG_RXBUF)));
+
+    if (n->has_vnet_hdr) {
+        tap_set_offload(qemu_get_subqueue(n->nic, 0)->peer,
+                        (features >> VIRTIO_NET_F_GUEST_CSUM) & 1,
+                        (features >> VIRTIO_NET_F_GUEST_TSO4) & 1,
+                        (features >> VIRTIO_NET_F_GUEST_TSO6) & 1,
+                        (features >> VIRTIO_NET_F_GUEST_ECN)  & 1,
+                        (features >> VIRTIO_NET_F_GUEST_UFO)  & 1);
+    }
+
+    for (i = 0;  i < n->max_queues; i++) {
+        NetClientState *nc = qemu_get_subqueue(n->nic, i);
+
+        if (!nc->peer || nc->peer->info->type != NET_CLIENT_OPTIONS_KIND_TAP) {
+            continue;
+        }
+        if (!tap_get_vhost_net(nc->peer)) {
+            continue;
+        }
+        vhost_net_ack_features(tap_get_vhost_net(nc->peer), features);
+    }
+}
+
+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;
+
+    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;
+    }
+
+    return VIRTIO_NET_OK;
+}
+
+static int virtio_net_handle_mac(VirtIONet *n, uint8_t cmd,
+                                 struct iovec *iov, unsigned int iov_cnt)
+{
+    struct virtio_net_ctrl_mac mac_data;
+    size_t s;
+
+    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);
+        return VIRTIO_NET_OK;
+    }
+
+    if (cmd != VIRTIO_NET_CTRL_MAC_TABLE_SET) {
+        return VIRTIO_NET_ERR;
+    }
+
+    n->mac_table.in_use = 0;
+    n->mac_table.first_multi = 0;
+    n->mac_table.uni_overflow = 0;
+    n->mac_table.multi_overflow = 0;
+    memset(n->mac_table.macs, 0, MAC_TABLE_ENTRIES * ETH_ALEN);
+
+    s = iov_to_buf(iov, iov_cnt, 0, &mac_data.entries,
+                   sizeof(mac_data.entries));
+    mac_data.entries = ldl_p(&mac_data.entries);
+    if (s != sizeof(mac_data.entries)) {
+        return VIRTIO_NET_ERR;
+    }
+    iov_discard_front(&iov, &iov_cnt, s);
+
+    if (mac_data.entries * ETH_ALEN > iov_size(iov, iov_cnt)) {
+        return VIRTIO_NET_ERR;
+    }
+
+    if (mac_data.entries <= MAC_TABLE_ENTRIES) {
+        s = iov_to_buf(iov, iov_cnt, 0, n->mac_table.macs,
+                       mac_data.entries * ETH_ALEN);
+        if (s != mac_data.entries * ETH_ALEN) {
+            return VIRTIO_NET_ERR;
+        }
+        n->mac_table.in_use += mac_data.entries;
+    } else {
+        n->mac_table.uni_overflow = 1;
+    }
+
+    iov_discard_front(&iov, &iov_cnt, mac_data.entries * ETH_ALEN);
+
+    n->mac_table.first_multi = n->mac_table.in_use;
+
+    s = iov_to_buf(iov, iov_cnt, 0, &mac_data.entries,
+                   sizeof(mac_data.entries));
+    mac_data.entries = ldl_p(&mac_data.entries);
+    if (s != sizeof(mac_data.entries)) {
+        return VIRTIO_NET_ERR;
+    }
+
+    iov_discard_front(&iov, &iov_cnt, s);
+
+    if (mac_data.entries * ETH_ALEN != iov_size(iov, iov_cnt)) {
+        return VIRTIO_NET_ERR;
+    }
+
+    if (n->mac_table.in_use + mac_data.entries <= MAC_TABLE_ENTRIES) {
+        s = iov_to_buf(iov, iov_cnt, 0, n->mac_table.macs,
+                       mac_data.entries * ETH_ALEN);
+        if (s != mac_data.entries * ETH_ALEN) {
+            return VIRTIO_NET_ERR;
+        }
+        n->mac_table.in_use += mac_data.entries;
+    } else {
+        n->mac_table.multi_overflow = 1;
+    }
+
+    return VIRTIO_NET_OK;
+}
+
+static int virtio_net_handle_vlan_table(VirtIONet *n, uint8_t cmd,
+                                        struct iovec *iov, unsigned int iov_cnt)
+{
+    uint16_t vid;
+    size_t s;
+
+    s = iov_to_buf(iov, iov_cnt, 0, &vid, sizeof(vid));
+    vid = lduw_p(&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;
+
+    return VIRTIO_NET_OK;
+}
+
+static int virtio_net_handle_mq(VirtIONet *n, uint8_t cmd,
+                                struct iovec *iov, unsigned int iov_cnt)
+{
+    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 = lduw_p(&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(&n->vdev, n->vdev.status);
+    virtio_net_set_queues(n);
+
+    return VIRTIO_NET_OK;
+}
+static void virtio_net_handle_ctrl(VirtIODevice *vdev, VirtQueue *vq)
+{
+    VirtIONet *n = to_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;
+    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 = elem.out_sg;
+        iov_cnt = 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_MQ) {
+            status = virtio_net_handle_mq(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);
+    }
+}
+
+/* RX */
+
+static void virtio_net_handle_rx(VirtIODevice *vdev, VirtQueue *vq)
+{
+    VirtIONet *n = to_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);
+    VirtIONetQueue *q = virtio_net_get_subqueue(nc);
+
+    if (!n->vdev.vm_running) {
+        return 0;
+    }
+
+    if (nc->queue_index >= n->curr_queues) {
+        return 0;
+    }
+
+    if (!virtio_queue_ready(q->rx_vq) ||
+        !(n->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;
+}
+
+/* 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);
+        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);
+    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%x",
+                    i, n->mergeable_rx_bufs, offset, size,
+                    n->guest_hdr_len, n->host_hdr_len, n->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) {
+        stw_p(&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(&n->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);
+
+    virtqueue_push(q->tx_vq, &q->async_tx.elem, 0);
+    virtio_notify(&n->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;
+    VirtQueueElement elem;
+    int32_t num_packets = 0;
+    int queue_index = vq2q(virtio_get_queue_index(q->tx_vq));
+    if (!(n->vdev.status & VIRTIO_CONFIG_S_DRIVER_OK)) {
+        return num_packets;
+    }
+
+    assert(n->vdev.vm_running);
+
+    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];
+
+        if (out_num < 1) {
+            error_report("virtio-net header not in first element");
+            exit(1);
+        }
+
+        /*
+         * 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;
+
+        virtqueue_push(q->tx_vq, &elem, 0);
+        virtio_notify(&n->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 = to_virtio_net(vdev);
+    VirtIONetQueue *q = &n->vqs[vq2q(virtio_get_queue_index(vq))];
+
+    /* This happens when device was stopped but VCPU wasn't. */
+    if (!n->vdev.vm_running) {
+        q->tx_waiting = 1;
+        return;
+    }
+
+    if (q->tx_waiting) {
+        virtio_queue_set_notification(vq, 1);
+        qemu_del_timer(q->tx_timer);
+        q->tx_waiting = 0;
+        virtio_net_flush_tx(q);
+    } else {
+        qemu_mod_timer(q->tx_timer,
+                       qemu_get_clock_ns(vm_clock) + 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 = to_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 (!n->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;
+    assert(n->vdev.vm_running);
+
+    q->tx_waiting = 0;
+
+    /* Just in case the driver is not ready on more */
+    if (!(n->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;
+    int32_t ret;
+
+    assert(n->vdev.vm_running);
+
+    q->tx_waiting = 0;
+
+    /* Just in case the driver is not ready on more */
+    if (unlikely(!(n->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_set_multiqueue(VirtIONet *n, int multiqueue, int ctrl)
+{
+    VirtIODevice *vdev = &n->vdev;
+    int i, max = multiqueue ? n->max_queues : 1;
+
+    n->multiqueue = multiqueue;
+
+    for (i = 2; i <= n->max_queues * 2 + 1; i++) {
+        virtio_del_queue(vdev, i);
+    }
+
+    for (i = 1; i < max; i++) {
+        n->vqs[i].rx_vq = virtio_add_queue(vdev, 256, virtio_net_handle_rx);
+        if (n->vqs[i].tx_timer) {
+            n->vqs[i].tx_vq =
+                virtio_add_queue(vdev, 256, virtio_net_handle_tx_timer);
+            n->vqs[i].tx_timer = qemu_new_timer_ns(vm_clock,
+                                                   virtio_net_tx_timer,
+                                                   &n->vqs[i]);
+        } else {
+            n->vqs[i].tx_vq =
+                virtio_add_queue(vdev, 256, virtio_net_handle_tx_bh);
+            n->vqs[i].tx_bh = qemu_bh_new(virtio_net_tx_bh, &n->vqs[i]);
+        }
+
+        n->vqs[i].tx_waiting = 0;
+        n->vqs[i].n = n;
+    }
+
+    if (ctrl) {
+        n->ctrl_vq = virtio_add_queue(vdev, 64, virtio_net_handle_ctrl);
+    }
+
+    virtio_net_set_queues(n);
+}
+
+static void virtio_net_save(QEMUFile *f, void *opaque)
+{
+    int i;
+    VirtIONet *n = opaque;
+
+    /* At this point, backend must be stopped, otherwise
+     * it might keep writing to memory. */
+    assert(!n->vhost_started);
+    virtio_save(&n->vdev, f);
+
+    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);
+        }
+    }
+}
+
+static int virtio_net_load(QEMUFile *f, void *opaque, int version_id)
+{
+    VirtIONet *n = opaque;
+    int ret, i, link_down;
+
+    if (version_id < 2 || version_id > VIRTIO_NET_VM_VERSION)
+        return -EINVAL;
+
+    ret = virtio_load(&n->vdev, f);
+    if (ret) {
+        return ret;
+    }
+
+    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));
+
+    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 if (n->mac_table.in_use) {
+            uint8_t *buf = g_malloc0(n->mac_table.in_use);
+            qemu_get_buffer(f, buf, n->mac_table.in_use * ETH_ALEN);
+            g_free(buf);
+            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 (n->has_vnet_hdr) {
+            tap_set_offload(qemu_get_queue(n->nic)->peer,
+                    (n->vdev.guest_features >> VIRTIO_NET_F_GUEST_CSUM) & 1,
+                    (n->vdev.guest_features >> VIRTIO_NET_F_GUEST_TSO4) & 1,
+                    (n->vdev.guest_features >> VIRTIO_NET_F_GUEST_TSO6) & 1,
+                    (n->vdev.guest_features >> VIRTIO_NET_F_GUEST_ECN)  & 1,
+                    (n->vdev.guest_features >> VIRTIO_NET_F_GUEST_UFO)  & 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);
+        for (i = 1; i < n->curr_queues; i++) {
+            n->vqs[i].tx_waiting = qemu_get_be32(f);
+        }
+    }
+
+    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;
+    }
+
+    return 0;
+}
+
+static void virtio_net_cleanup(NetClientState *nc)
+{
+    VirtIONet *n = qemu_get_nic_opaque(nc);
+
+    n->nic = NULL;
+}
+
+static NetClientInfo net_virtio_info = {
+    .type = NET_CLIENT_OPTIONS_KIND_NIC,
+    .size = sizeof(NICState),
+    .can_receive = virtio_net_can_receive,
+    .receive = virtio_net_receive,
+        .cleanup = virtio_net_cleanup,
+    .link_status_changed = virtio_net_set_link_status,
+};
+
+static bool virtio_net_guest_notifier_pending(VirtIODevice *vdev, int idx)
+{
+    VirtIONet *n = to_virtio_net(vdev);
+    NetClientState *nc = qemu_get_subqueue(n->nic, vq2q(idx));
+    assert(n->vhost_started);
+    return vhost_net_virtqueue_pending(tap_get_vhost_net(nc->peer), idx);
+}
+
+static void virtio_net_guest_notifier_mask(VirtIODevice *vdev, int idx,
+                                           bool mask)
+{
+    VirtIONet *n = to_virtio_net(vdev);
+    NetClientState *nc = qemu_get_subqueue(n->nic, vq2q(idx));
+    assert(n->vhost_started);
+    vhost_net_virtqueue_mask(tap_get_vhost_net(nc->peer),
+                             vdev, idx, mask);
+}
+
+VirtIODevice *virtio_net_init(DeviceState *dev, NICConf *conf,
+                              virtio_net_conf *net, uint32_t host_features)
+{
+    VirtIONet *n;
+    int i, config_size = 0;
+
+    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 = (VirtIONet *)virtio_common_init("virtio-net", VIRTIO_ID_NET,
+                                        config_size, sizeof(VirtIONet));
+
+    n->config_size = config_size;
+    n->vdev.get_config = virtio_net_get_config;
+    n->vdev.set_config = virtio_net_set_config;
+    n->vdev.get_features = virtio_net_get_features;
+    n->vdev.set_features = virtio_net_set_features;
+    n->vdev.bad_features = virtio_net_bad_features;
+    n->vdev.reset = virtio_net_reset;
+    n->vdev.set_status = virtio_net_set_status;
+    n->vdev.guest_notifier_mask = virtio_net_guest_notifier_mask;
+    n->vdev.guest_notifier_pending = virtio_net_guest_notifier_pending;
+    n->max_queues = MAX(conf->queues, 1);
+    n->vqs = g_malloc0(sizeof(VirtIONetQueue) * n->max_queues);
+    n->vqs[0].rx_vq = virtio_add_queue(&n->vdev, 256, virtio_net_handle_rx);
+    n->curr_queues = 1;
+    n->vqs[0].n = n;
+    n->tx_timeout = net->txtimer;
+
+    if (net->tx && strcmp(net->tx, "timer") && strcmp(net->tx, "bh")) {
+        error_report("virtio-net: "
+                     "Unknown option tx=%s, valid options: \"timer\" \"bh\"",
+                     net->tx);
+        error_report("Defaulting to \"bh\"");
+    }
+
+    if (net->tx && !strcmp(net->tx, "timer")) {
+        n->vqs[0].tx_vq = virtio_add_queue(&n->vdev, 256,
+                                           virtio_net_handle_tx_timer);
+        n->vqs[0].tx_timer = qemu_new_timer_ns(vm_clock, virtio_net_tx_timer,
+                                               &n->vqs[0]);
+    } else {
+        n->vqs[0].tx_vq = virtio_add_queue(&n->vdev, 256,
+                                           virtio_net_handle_tx_bh);
+        n->vqs[0].tx_bh = qemu_bh_new(virtio_net_tx_bh, &n->vqs[0]);
+    }
+    n->ctrl_vq = virtio_add_queue(&n->vdev, 64, virtio_net_handle_ctrl);
+    qemu_macaddr_default_if_unset(&conf->macaddr);
+    memcpy(&n->mac[0], &conf->macaddr, sizeof(n->mac));
+    n->status = VIRTIO_NET_S_LINK_UP;
+
+    n->nic = qemu_new_nic(&net_virtio_info, 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++) {
+            tap_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), conf->macaddr.a);
+
+    n->vqs[0].tx_waiting = 0;
+    n->tx_burst = net->txburst;
+    virtio_net_set_mrg_rx_bufs(n, 0);
+    n->promisc = 1; /* for compatibility */
+
+    n->mac_table.macs = g_malloc0(MAC_TABLE_ENTRIES * ETH_ALEN);
+
+    n->vlans = g_malloc0(MAX_VLAN >> 3);
+
+    n->qdev = dev;
+    register_savevm(dev, "virtio-net", -1, VIRTIO_NET_VM_VERSION,
+                    virtio_net_save, virtio_net_load, n);
+
+    add_boot_device_path(conf->bootindex, dev, "/ethernet-phy@0");
+
+    return &n->vdev;
+}
+
+void virtio_net_exit(VirtIODevice *vdev)
+{
+    VirtIONet *n = DO_UPCAST(VirtIONet, vdev, vdev);
+    int i;
+
+    /* This will stop vhost backend if appropriate. */
+    virtio_net_set_status(vdev, 0);
+
+    unregister_savevm(n->qdev, "virtio-net", n);
+
+    g_free(n->mac_table.macs);
+    g_free(n->vlans);
+
+    for (i = 0; i < n->max_queues; i++) {
+        VirtIONetQueue *q = &n->vqs[i];
+        NetClientState *nc = qemu_get_subqueue(n->nic, i);
+
+        qemu_purge_queued_packets(nc);
+
+        if (q->tx_timer) {
+            qemu_del_timer(q->tx_timer);
+            qemu_free_timer(q->tx_timer);
+        } else {
+            qemu_bh_delete(q->tx_bh);
+        }
+    }
+
+    g_free(n->vqs);
+    qemu_del_nic(n->nic);
+    virtio_cleanup(&n->vdev);
+}