openstack nova : No valid host was found OR Build of instance ID was re-scheduled internal error no supported architecture for os type 'hvm'

openstack error

Environment:
Openstack Juno installed on 3 nodes of virtualbox ( compute , network and controller )
CentOS7

Just after fresh installation i received below error while launching instnace



2015-06-15 19:27:25.498 10480 ERROR nova.scheduler.utils [req-2237e384-b3a9-4aa1-ac96-898f5c5d72db None] [instance: 3def536d-858d-4631-954a-ca09e56bd71b] Error from last host: compute (node compute): [u'Traceback (most recent call last):\n', u'  File "/usr/lib/python2.7/site-packages/nova/compute/manager.py", line 2033, in _do_build_and_run_instance\n    filter_properties)\n', u'  File "/usr/lib/python2.7/site-packages/nova/compute/manager.py", line 2164, in _build_and_run_instance\n    instance_uuid=instance.uuid, reason=six.text_type(e))\n', u"RescheduledException: Build of instance 3def536d-858d-4631-954a-ca09e56bd71b was re-scheduled: internal error: no supported architecture for os type 'hvm'\n"]
2015-06-15 19:27:25.568 10480 WARNING nova.scheduler.driver [req-2237e384-b3a9-4aa1-ac96-898f5c5d72db None] [instance: 3def536d-858d-4631-954a-ca09e56bd71b] NoValidHost exception with message: 'No valid host was found.'
2015-06-15 19:27:25.569 10480 WARNING nova.scheduler.driver [req-2237e384-b3a9-4aa1-ac96-898f5c5d72db None] [instance: 3def536d-858d-4631-954a-ca09e56bd71b] Setting instance to ERROR state.

Solution : Since we are deploying openstack inside virtualbox , set virt_type to qemu under /etc/nova/nova.conf
virt_type=qemu
Restart compute services. This should fix this problem