Description of problem:
after migrated successfully,dest host hot-plug any device via monitor guest can not get it. 

Version-Release number of selected component (if applicable):


How reproducible:
# rpm -qa|grep kvm
kvm-83-232.el5
# uname -r
2.6.18-260.el5



Steps to Reproduce:
1.
src host:
/usr/libexec/qemu-kvm -no-hpet -usbdevice tablet -rtc-td-hack -name 61 -smp 2 -m 2G -uuid `uuidgen` -boot c -drive file=/mnt/rhel61.qcow2,if=ide,cache=none,boot=on,format=qcow2,werror=stop -net none -notify all -balloon none  -monitor stdio -vnc :1
dest host:
/usr/libexec/qemu-kvm -no-hpet -usbdevice tablet -rtc-td-hack -name 61 -smp 2 -m 2G -uuid `uuidgen` -boot c -drive file=/mnt/rhel61.qcow2,if=ide,cache=none,boot=on,format=qcow2,werror=stop -net none -notify all -balloon none  -monitor stdio -vnc :2 -incoming tcp:0:9000

2.migrate -d tcp:0:9000
3. hot-plug a nic
(qemu)  host_net_add tap vlan=5,script=/etc/qemu-ifup
(qemu) pci_add pci_addr=auto nic vlan=5,macaddr=1C:C1:DE:14:13:1c,model=virtio
  
Actual results:
guest can not get it

Expected results:
guest get it


Additional info:
info network can find nic info, only guest can not find it. guest is rhel6.1.