reproduce with 2.6.32-131.18.1.el6.x86_64 

steps to reproduce:

1.1. boot guest
/usr/libexec/qemu-kvm -M rhel6.1.0 -enable-kvm -name rhel6 -smp 4 -m 2G -uuid 9e6f04cf-2ad7-45aa-9333-2d2ee26570c8 -boot menu=on -rtc base=localtime,clock=host,driftfix=slew -no-kvm-pit-reinjection -drive file=/home/rhel64.qcow2,if=none,id=drive-virtio-disk0,format=qcow2,serial=fuxc,cache=none,werror=ignore,rerror=ignore,aio=native -device virtio-blk-pci,bus=pci.0,addr=0x5,drive=drive-virtio-disk0,id=virtio-disk0,bootindex=1 -netdev tap,id=hostnet0,vhost=on -device virtio-net-pci,netdev=hostnet0,id=net0,mac=00:1a:4a:42:0b:01 -balloon none -spice disable-ticketing,port=5912 -balloon none -vga qxl -monitor stdio -serial unix:/tmp/test0,server,nowait

1.2. in guest 
  #halt

testing result:
guest pause about 5 seconds after printing "Disabling non-boot
CPUs"

2.verify with 2.6.32-131.20.1.el6.x86_64

2.1 use the same steps 
testing result:

No pause after printing "Disabling non-boot
CPUs"


base on above testing result, this bug is fixed.

According to comment10,set this issue as verified.

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

http://rhn.redhat.com/errata/RHSA-2011-1465.html