Description of problem:
On ppc64 machine, vdsm is unable to get the list of online logical CPUs. This feature is introduced in version 4.16.7.Aadding a host(any OS) on ppc64 machine to engine doesn't succeed.

Here is the o/p of /var/log/vdsm/vdsm.log
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
JsonRpcServer::DEBUG::2015-03-17 11:41:20,103::init::506::jsonrpc.JsonRpcServer::(serve_requests) Waiting for request
JsonRpc (StompReactor)::DEBUG::2015-03-17 11:41:23,380::stompReactor::95::Broker.StompAdapter::(handle_frame) Handling message <StompFrame command='SEND'>
JsonRpcServer::DEBUG::2015-03-17 11:41:23,381::init::506::jsonrpc.JsonRpcServer::(serve_requests) Waiting for request
Thread-42::DEBUG::2015-03-17 11:41:23,381::init::469::jsonrpc.JsonRpcServer::(_serveRequest) Calling 'Host.getCapabilities' in bridge with {}
Thread-42::ERROR::2015-03-17 11:41:23,382::init::493::jsonrpc.JsonRpcServer::(_serveRequest) Internal server error
Traceback (most recent call last):
  File "/usr/lib/python2.7/site-packages/yajsonrpc/init.py", line 488, in _serveRequest
    res = method(**params)
  File "/usr/share/vdsm/rpc/Bridge.py", line 270, in _dynamicMethod
    result = fn(*methodArgs)
  File "/usr/share/vdsm/API.py", line 1286, in getCapabilities
    c = caps.get()
  File "/usr/share/vdsm/caps.py", line 624, in get
    caps['onlineCpus'] = ','.join(cpuTopology.onlineCpus())
  File "/usr/share/vdsm/caps.py", line 212, in onlineCpus
    return self._topology['onlineCpus']
KeyError: 'onlineCpus'
Thread-42::DEBUG::2015-03-17 11:41:23,382::stompReactor::160::yajsonrpc.StompServer::(send) Sending response
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Here is the o/p of /var/log/ovirt-engine/engine.log
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
2015-03-17 15:28:04,313 ERROR [org.ovirt.engine.core.vdsbroker.VdsUpdateRunTimeInfo] (DefaultQuartzScheduler_Worker-86) Failure to refresh Vds runtime info: org.ovirt.engine.core.vdsbroker.vdsbroker.VDSErrorException: VDSGenericException: VDSErrorException: Failed to GetCapabilitiesVDS, error = 'onlineCpus', code = -32603
2015-03-17 15:28:04,323 WARN  [org.ovirt.engine.core.vdsbroker.VdsManager] (DefaultQuartzScheduler_Worker-86) Failed to refresh VDS , vds = 58313424-98eb-45ac-9d90-ab616485b4eb : ovirt-host1, error = org.ovirt.engine.core.vdsbroker.vdsbroker.VDSErrorException: VDSGenericException: VDSErrorException: Failed to GetCapabilitiesVDS, error = 'onlineCpus', code = -32603, continuing.: org.ovirt.engine.core.vdsbroker.vdsbroker.VDSErrorException: VDSGenericException: VDSErrorException: Failed to GetCapabilitiesVDS, error = 'onlineCpus', code = -32603
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

How reproducible:
Always

Steps to Reproduce:
1.on ppc64 machine add a host with vdsm version >= 4.16.7

Actual results:
Host installation failed 


Expected results:
Host installation successfully completed