Description of problem:
after hotplugging 160 vcpus to guest,Opening Task Manager and going to the Tab 'Performance' will only show 8 vcpus. if rebooting guest, Performance will show 64 vcpus

Version-Release number of selected component (if applicable):
rpm -qa|grep qemu
qemu-kvm-0.12.1.2-2.267.el6.x86_64

uname -r
2.6.32-257.el6.x86_64

How reproducible:
100%

Steps to Reproduce:
1.Steps to Reproduce:
1./usr/libexec/qemu-kvm run -M rhel6.3.0 --enable-kvm -m 4G -smp 1,maxcpus=161
-name rhel6.3 -uuid ddcbfb49-3411-1701-3c36-6bdbc00bedbb -rtc
base=utc,clock=host,driftfix=slew -boot c -drive
file=/dev/vg-qzhang/lv-2k8r2,if=none,id=virtio,format=raw,cache=none,werror=stop,rerror=stop,boot=on
-device virtio-blk-pci,drive=virtio,id=drive-virtio0-0-0,bootindex=1 -netdev
tap,id=hostnet1 -device
virtio-net-pci,netdev=hostnet1,id=net1,mac=32:12:50:a4:32:74 -spice
port=5914,disable-ticketing -vga qxl -device sga -chardev
socket,id=serial0,path=/var/test3,server,nowait -device
isa-serial,chardev=serial0 -monitor unix:/tmp/monitor4,server,nowait -monitor
stdio -qmp tcp:0:6667,server,nowait

2.hotplug with script
i=1
while [ $i -lt 160 ]
do
sleep 2
echo "cpu_set $i online"|nc -U /tmp/monitor4
i=$(($i+1))
done

3.check online vcpus 
Opening Task Manager and going to the Tab 'Performance' 

Actual results:
show 8 vcpus

Expected results:
show 160 vcpus
  

Additional info: