[ovirt-users] oVirt Nested Virtualization

Barak Korren bkorren at redhat.com
Sun Mar 5 13:43:46 UTC 2017

oVirt system tests are indeed using nested virtualization, but it is
done to run oVirt nested on top of a stand-alone KVM host, and not to
run nested stuff on top of oVirt.

The steps Fred specified can be done manually on all hosts, but oVirt
offers a slightly more automated alternative. Simply install the
following vdsm hooks (available as packages) on all hosts:


And then reboot the hosts (You will need to put hosts into maintenance
mode to do that).

Adding Sandro and Fabian to comment about how to persist this
configuration across node-ng updates.

On 5 March 2017 at 14:20, Fred Rolland <frolland at redhat.com> wrote:
> Our system tests are using nested virtualization. [1]
> Here the relevant part :
> Make sure that virtualization extension is enabled on the CPU, otherwise,
> you might need to enable it in the BIOS. Generally, if virtualization
> extension is disabled, dmesg log would contain a line similar to:
>     kvm: disabled by BIOS
> Verify nested virtualization is enabled
>     $ cat /sys/module/kvm_intel/parameters/nested
>  This command should print `Y` if nested virtualization is enabled,
> otherwise,
>  enable it the following way:
>  Edit `/etc/modprobe.d/kvm-intel.conf` and add the following line:
>     options kvm-intel nested=y
> [1]
> http://ovirt-system-tests.readthedocs.io/en/latest/docs/general/installation.html
> On Sat, Mar 4, 2017 at 3:46 PM, Luca 'remix_tj' Lorenzetto
> <lorenzetto.luca at gmail.com> wrote:
>> Hello,
>> we're installing a small ovirt cluster for hosting some test
>> environments at work. We're interested in testing VM running
>> hypervisors (i.e ovirt itself or a small openstack deployment).
>> Is there any documentation showing how to enable nested virtualization in
>> ovirt?
>>  I've seen that while adding an host to the cluster there is the
>> opportunity to flag "Nested Virtualization" option, but i didn't
>> understand if other packages and configs are required.
>> Our environment is running latest ovirt 4.1 installed with ovirt-node-ng.
>> Luca
>> --
>> "E' assurdo impiegare gli uomini di intelligenza eccellente per fare
>> calcoli che potrebbero essere affidati a chiunque se si usassero delle
>> macchine"
>> Gottfried Wilhelm von Leibnitz, Filosofo e Matematico (1646-1716)
>> "Internet è la più grande biblioteca del mondo.
>> Ma il problema è che i libri sono tutti sparsi sul pavimento"
>> John Allen Paulos, Matematico (1945-vivente)
>> Luca 'remix_tj' Lorenzetto, http://www.remixtj.net ,
>> <lorenzetto.luca at gmail.com>
>> _______________________________________________
>> Users mailing list
>> Users at ovirt.org
>> http://lists.ovirt.org/mailman/listinfo/users
> _______________________________________________
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Barak Korren
bkorren at redhat.com
RHCE, RHCi, RHV-DevOps Team

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