oVirt 3.4 adds a preview of a Hot-plug CPU feature that enables administrators to ensure customer's service-level agreements are being met, the full utilization of spare hardware, and the capability to dynamically to scale vertically, down or up, a system's hardware according to application needs without restarting the virtual machine. -- http://www.ovirt.org/OVirt_3.4_Release_Notes This feature is a tech preview.
See also: https://bugzilla.redhat.com/show_bug.cgi?id=833102
*** Bug 1092904 has been marked as a duplicate of this bug. ***
Any update on this BZ ? Can we expect some quick update in the admin guide about the hot plug CPU along with the proper supported guest os matrix as mentioned in: http://www.ovirt.org/Hot_plug_cpu