Commit f6f56291 authored by Thibaut Collet's avatar Thibaut Collet Committed by Michael S. Tsirkin
Browse files

vhost user: add support of live migration 



Some vhost user backends are able to support live migration.
To provide this service the following features must be added:
1. Add the VIRTIO_NET_F_GUEST_ANNOUNCE capability to vhost-net when netdev
   backend is vhost-user.
2. Provide a nop receive callback to vhost-user.
   This callback is called by:
    *  qemu_announce_self after a migration to send fake RARP to avoid network
       outage for peers talking to the migrated guest.
         - For guest with GUEST_ANNOUNCE capabilities, guest already sends GARP
           when the bit VIRTIO_NET_S_ANNOUNCE is set.
           => These packets must be discarded.
         - For guest without GUEST_ANNOUNCE capabilities, migration termination
           is notified when the guest sends packets.
           => These packets can be discarded.
    * virtio_net_tx_bh with a dummy boot to send fake bootp/dhcp request.
      BIOS guest manages virtio driver to send 4 bootp/dhcp request in case of
      dummy boot.
      => These packets must be discarded.

Signed-off-by: default avatarThibaut Collet <thibaut.collet@6wind.com>
Reviewed-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Tested-by: default avatarThibaut Collet <thibaut.collet@6wind.com>
parent 69b32a6c

hw/net/vhost_net.c

+2 −0
Original line number Diff line number Diff line
@@ -85,6 +85,8 @@ static const int user_feature_bits[] = { 
    VIRTIO_NET_F_CTRL_MAC_ADDR,

    VIRTIO_NET_F_CTRL_GUEST_OFFLOADS,



    VIRTIO_NET_F_GUEST_ANNOUNCE,



    VIRTIO_NET_F_MQ,



    VHOST_INVALID_FEATURE_BIT

net/vhost-user.c

+10 −2
Original line number Diff line number Diff line
@@ -103,6 +103,15 @@ err: 
    return -1;

}



static ssize_t vhost_user_receive(NetClientState *nc, const uint8_t *buf,

                                  size_t size)

{

    /* Discard the request that is received and managed by backend

     * by an other way.

     */

    return size;

}



static void vhost_user_cleanup(NetClientState *nc)

{

    VhostUserState *s = DO_UPCAST(VhostUserState, nc, nc);
@@ -132,6 +141,7 @@ static bool vhost_user_has_ufo(NetClientState *nc) 
static NetClientInfo net_vhost_user_info = {

        .type = NET_CLIENT_OPTIONS_KIND_VHOST_USER,

        .size = sizeof(VhostUserState),

        .receive = vhost_user_receive,

        .cleanup = vhost_user_cleanup,

        .has_vnet_hdr = vhost_user_has_vnet_hdr,

        .has_ufo = vhost_user_has_ufo,
@@ -182,8 +192,6 @@ static int net_vhost_user_init(NetClientState *peer, const char *device, 
        snprintf(nc->info_str, sizeof(nc->info_str), "vhost-user%d to %s",

                 i, chr->label);



        /* We don't provide a receive callback */

        nc->receive_disabled = 1;

        nc->queue_index = i;



        s = DO_UPCAST(VhostUserState, nc, nc);