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Description of problem:
Perpare a rhel6.2 guest, then change the vcpu,sometimes the guest will become not to respond.

Version-Release number of selected component (if applicable):
qemu-kvm-0.12.1.2-2.234.el6.x86_64
libvirt-0.9.10-3.el6.x86_64
virt-manager-0.9.0-10.el6.x86_64

How reproducible:
90%

Steps to Reproduce:
1.Start a rhel6.2 guest.
#virsh dumpxml rhel6.2-new
...
<currentMemory>1048576</currentMemory>
<vcpu current='2'>4</vcpu>
...
2. Wait for the guest boot completely,then run
#virsh setvcpus rhel6.2-new 1 --live
#virsh setvcpus rhel6.2-new 3 --live
Or
You can use virt-manager to change the Current allocation of CPU,then apply.

3.Check the guest with virt-manager or virt-viewer.

Actual results:
The guest become no respond.

Expected results:
The guest works well and the vcpu will not update.
As we know,the qemu-kvm doesn't support vcpu hotplug now.The libvirt provide the API for it.
But I think the guest should not become not to respond at least.

Additional info:
1. I can reproduce this issue on rhel6 guest 100%,and can not reproduce on rhel5 guest.
2. You can change the vcpus several times if you can not reproduce this issue.

Based on the fact that the reproduction is completely dependent on the guest OS, I believe this BZ is not a libvirt problem, so I'm reassigning to kernel.  Please correct me if I'm wrong about that.

Closingas duplicate of bug 788562

Please re-test with RHEL6.3 kernel (kernel-2.6.32-235.el6 or later), where issue is fixed or disable kvm-clock in qemu to workaround issue on RHEL6.2.

Dor:
It might be good idea to clone bug 788562 for RHEL6.2 z stream.

*** This bug has been marked as a duplicate of bug 788562 ***