Re: [libvirt-users] Help With Nested Virtualization

On Wed, Aug 31, 2016 at 12:48:33PM +0200, Martin Kletzander wrote: > On Mon, Aug 29, 2016 at 09:42:17PM -0400, Brandon Golway wrote: > > (Copied from my post on the Arch Linux forums: [...] > > Can someone clue me in on what the issue is? > > > > Here's the entire XML config for the FreeNAS VM > > > > [code]<!-- > > WARNING: THIS IS AN AUTO-GENERATED FILE. CHANGES TO IT ARE LIKELY TO BE > > OVERWRITTEN AND LOST. Changes to this xml configuration should be made > > using: > > virsh edit FreeNAS_10 > > or other application using the libvirt API. > > --> > > > > Just as I see you grabbed it from the place where it is stored, you > should rather instead do 'virsh dumpxml FreeNAS_10', or remove the > comment above. Otherwise it steers other users to believing that > mangling with internal XML files is safe. Yeah, or use the `virt-xml` tool (comes as part of `virt-install` package). To pass-through host CPU to the level-1 guest: $ virt-xml FreeNAS_10 --edit --cpu host-passthrough,clearxml=yes If you issue this while the guest is running, it'll take affect on next reboot. > > <domain type='kvm'> > > <name>FreeNAS_10</name> > > <uuid>ea816b85-7685-495a-bc97-28a882f190d7</uuid> > > <title>FreeNAS v10</title> > > <description>Nightly Alpha Test Releases</description> > > <memory unit='KiB'>6340608</memory> > > <currentMemory unit='KiB'>6340608</currentMemory> > > <vcpu placement='static'>4</vcpu> > > <os> > > <type arch='x86_64' machine='pc-i440fx-2.6'>hvm</type> > > <bootmenu enable='no'/> > > </os> > > <features> > > <acpi/> > > <apic/> > > <vmport state='off'/> > > </features> > > <cpu mode='host-passthrough'/> > > Although what you did should be enough for the nested virt to work, I > have just an idea to try out. I can't try it because I don't have > nested virt turned on for the module and don't want to reboot now. Assuming you're talking about the physical host, you don't need a reboot of the host :-) You can simply: $ sudo rmmod kvm-intel $ echo "options kvm-intel nested=y" > /etc/modprobe.d/dist.conf $ sudo modprobe kvm-intel

> But > if you have new enough libvirt, you should be able to do: > > <cpu mode='host-passthrough'> > <feature policy='require' name='vmx'/> > </cpu> > > Also check that you are not missing the kvm_intel module in the L1 guest > kernel and other similar non-nested troubleshooting steps as well. Yeah. If the L1 guest has the /dev/kvm character device, then he's good: $ file /dev/kvm /dev/kvm: character special (10/232) -- /kashyap