How to enable nested virtualization in order to use VirtualBox inside of a KVM virtual machine?
We have a KVM hypervisor (L0, AMD, Kernel: Linux level0kvmhypervisor 4.19.0-12-amd64 #1 SMP Debian 4.19.152-1 (2020-10-18) x86_64 GNU/Linux), which runs a virtual machine that I would like to use as a nested VirtualBox hypervisor (L1). So what I'm trying to do is running VirtualBox inside of KVM. Some details about the KVM hypervisor (L0):
# cat /proc/cpuinfo
processor : 0 ... 23
vendor_id : AuthenticAMD
cpu family : 23
model : 113
model name : AMD Ryzen 9 3900 12-Core Processor
stepping : 0
microcode : 0x8701021
cpu MHz : 2193.155
cache size : 512 KB
physical id : 0
siblings : 24
core id : 0
cpu cores : 12
apicid : 0
initial apicid : 0
fpu : yes
fpu_exception : yes
cpuid level : 16
wp : yes
flags : ... svm ...
bugs : sysret_ss_attrs spectre_v1 spectre_v2 spec_store_bypass
bogomips : 6188.58
TLB size : 3072 4K pages
clflush size : 64
cache_alignment : 64
address sizes : 43 bits physical, 48 bits virtual
power management: ts ttp tm hwpstate cpb eff_freq_ro [13] [14]
# dpkg --list | egrep -- "(kvm|libvirt)" | sed 's/amd64.*//g'
ii libsys-virt-perl 5.0.0-1
ii libvirt-clients 5.0.0-4+deb10u1
ii libvirt-daemon 5.0.0-4+deb10u1
ii libvirt-daemon-system 5.0.0-4+deb10u1
ii libvirt-glib-1.0-0:
ii libvirt0:
ii python3-libvirt 5.0.0-1
ii qemu-kvm 1:3.1+dfsg-8+deb10u8
The nested option is enabled as well:
# cat /sys/module/kvm_amd/parameters/nested
1
Inside the KVM virtual machine, where VirtualBox is installed (L1): I'm trying to launch a VM created by Vagrant and get the following error message:
...
==> default: Booting VM...
There was an error while executing `VBoxManage`, a CLI used by Vagrant
for controlling VirtualBox. The command and stderr is shown below.
Command: ["startvm", "357a07b4-7d81-4336-9ea6-0dbf0ab49d18", "--type", "headless"]
Stderr: VBoxManage: error: AMD-V is not available (VERR_SVM_NO_SVM)
VBoxManage: error: Details: code NS_ERROR_FAILURE (0x80004005), component ConsoleWrap, interface IConsole
These are the KVM XML CPU setting for the VirtualBox L1 hypervisor:
<vcpu placement='static'>1</vcpu>
<cpu mode='host-model' check='partial'>
<model fallback='allow'/>
</cpu>
I believe something must be changed here, but I'm not quite sure what. I can't find any resources on that topic, that's why I'm asking here. How can I get the VirtualBox hypervisor (L1) running inside a KVM virtual machine in order to start a VM?
Any help would be highly appreciated.
Solution 1:
<cpu mode='host-passthrough'>
<feature policy='require' name='svm'/>
</cpu>
Use these settings for an AMD cpu in the virtualmachine settings file.