Nested Virtulization CPU options not available


It types you need to install linux-image-amd64, but Whonix 14 use amd64 by default so I installed VirtualBox in my KVM.
When I go to Settings of VirtualBox VM System > Processor - the slider is grayed and I can’t use more than 1 processor and Acceleration tab is grayed I can’t access it.

That’s because the current config file masks out the virtualizaztion instruction. However you can change it to the config below to have all cpu features passed through.

Use on the host:

# EDITOR=kate virsh edit Whonix-Workstation

and replace all with the text linked here:

Your welcome.


I changed config but still the slider is grayed and Acceleration is grayed

Can you post the output of:

$ cat /proc/cpuinfo

Host or Workstation ?

click both there

Well vmx is there… so the only thing that explains it is VBox is buggy and/or you are assigning more resources to the VM than what is available so it refuses to even run.

I’m not interested in VBox so please any further questions about that platform are better discussed upstream. Nested KVM is mature enough by now.

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vmx is there only for Host $ cat /proc/cpuinfo
for Workstation $ cat /proc/cpuinfo vmx is missing
maybe I need to install some drivers or virtualbox modules ?

Or sudo apt install -t stretch-backports virtualbox
is enough ?

Try to reproduce it first on a debian VM. Also you might need to load some modules: Nested Guests - KVM
and afaik some (older) processors only support one virtualization layer.


# If you have an Intel CPU, use this:
$ cat /etc/modprobe.d/kvm_intel.conf
options kvm-intel nested=Y

# If you have an AMD CPU, then this:
$ cat /etc/modprobe.d/kvm_amd.conf
options kvm-amd nested=1

fixed it

New section on the wiki:


It’s very laggy. Can you give a link to KVM forum ? I can’t find any, I found only the IRC channel

There is only an IRC channel and maybe a mailing list. It is laggy because you are using an additional virtualization layer and nested virtualization is not really a priority for most vendors. I don’t think you will get acceptable performance any time soon. Though this might also depend on your workload, hardware and hypervisor. iirc from the benchmarks I saw a while back the the second layer was CPU wise mostly on a pentium level. Use your favorite search engine for more information, this is also not really a Whonix specific issue.