Windows 11 and Nested Virtualisation

[MikeBou]

Hi all,

I am trying to set up Virtualbox (latest version) to run a GNS3 VM for my CCNA studies.

When I start VB, it does boot the GNS3 VM, but never recognises that it has started. But I can web into the VM and start creating a lab. But if I try to start any device, I get this error.

""KVM acceleration cannot be used (/dev/kvm doesn't exist). It is possible to turn off KVM support in the gns3_server.conf by adding enable_kvm = false to the [Qemu] section."

Things I have done:
I checked the setting of the VM in Virtualbox. I went to System, Processor and made sure that the "Enable Nested VT-x/AMD-V" feature is ticked and it was.

I started my windows command prompt and ran this command to ensure that nested virtualisation is enabled on my laptop.
"C:\Program Files\Oracle\VirtualBox>VBoxManage.exe modifyvm "GNS3 VM" --nested-hw-virt on" This made no difference.

I then checked that Virtualisation was enabled in the BIOS and it is. I checked Task Manager and made sure that Windows was showing that Virtualisation was enabled in the CPU section, and it is.

I have also made sure that all the applications involved have their ports open in the firewall. At one stage, I disabled the firewall and still had no success.

Attempting to run a device without this KVM enabled does not solve the issue as the device cannot start. With both Workstation packages, it fails with a message. "VMWare Workstation does not support nested virtualisation on this host. Module 'HV' power on failed. Failed to start the virtual machine."

My laptop is an Acer Predator Helios 300, Model Number N20C3 running a fully updated Windows 11 Operating System (not Pro). The CPU is an 11th Gen Intel Core i7-11800H, with 8 cores @ 2.3GHz per core. I have 16 Gigabytes of RAM and over 350 Gigabytes of storage available on the main SSD.

I am having the same issue with Workstation Pro and Player and if I try to start a device in a project accessed via the webpage.

So, at this stage with no other info I suspect that the Intel chip in a Windows 11 OS is not playing nicely with nested virtualisation, or maybe it supports virtualisation but not nested.

Has anyone been able to get nested virtualisation working on a Windows 11 computer with an Intel CPU?

Thanks in advance.

[fth0]

In general, nested virtualization can only be expected to work when the hypervisors are from the same manufacturer. But there are a few exceptions: For example, VirtualBox is supposed to support KVM as a nested hypervisor, which is what you probably want.

Also in general, only one hypervisor can run on a host at the same time, because they compete for VT-x/AMD-V. Again, there are a few exceptions: For example, VirtualBox and Parallels can simultaneously run VMs on a macOS host (which is not of relevance here).

Reading you post, I thought to have a picture in mind, until you mentioned VMware Workstation. Please describe your setup regarding all hypervisors. If you're only trying to use KVM inside VirtualBox, provide a (zipped) VBox.log file from a complete VM run.

Additionally, if you have Hyper-V active on your host, it cannot work. Thinking about it, you should probably check that first.

[MikeBou]

Hi Fth0,

Thanks for the reply. I'll try to clear up some of my post.

First of all, I have windows 11, non-pro, and so I cant install Hyper-V on it. This laptop is only 2 months old. And so the first hypervisor I installed on it was Virtualbox. So, at the start there was no other hypervisor software competing with VirtualBox. I then imported the GNS3 VM into VirtualBox. It would not start and the message was to do with KVM that I quote in my post.

After going through all the things I listed that I'd done to try and resolve the issue, I then turned first to VMWare Workstation Player, then to a trial version of VMWare Workstation Pro with similar results.

Subsequent to my opening post, I then completely uninstalled everything to do with virtualisation and then re-installed Workstation Pro fresh and imported the GNS3 VM with no success trying to start it. The same type of message.

I have now grabbed an old server, installed ESXi 6.5 on it, imported the GNS3 VM and it started. I then started a project, placed a Cisco router on it, and that also started. I was confident that this would work as we are not dealing with nested virtualisation in the same way as trying to do it through software like VirtualBox or Workstation. I now just need to learn how to get GNS3 to connect to a remote machine.

I would still like to try and get either VirtualBox or Workstation working with the GNS3 VM successfully. But I think not all hardware is able to handle nested virtualisation. I thought my issue might be the operating system. Windows 11 is pretty new at the moment. So I pulled out an old laptop with Windows 10 on it. I ensured Hyper-V, VB or Workstation was not installed on it. I then installed Workstation Pro on it, imported the GNS3 VM. But still no success. The same/similar message regarding KVM. So it's not an operating system issue from what I can tell at this stage.

Thanks for your input so far Fth0.

[scottgus1]

I'll just stick in one thing, because you might be able to check on it before fth0 gets back.

I have windows 11, non-pro, and so I cant install Hyper-V on it.

You don't have to, because it's already there. Yes, that's right: Windows non-Pro (Home) has Hyper-V. There are many other services from Microsoft that can or do use Hyper-V, besides running Hyper-V VMs. You can't run Hyper-V VMs in Home. but most if not all of the other Hyper-V services are in Home.


Please right-click the guest in the main Virtualbox window's guest list, choose Show Log.

Search the far left tab's log for this text:

Attempting fall back to NEM

If you find it, Hyper-V is enabled, and this applies:

if you have Hyper-V active on your host, it cannot work.

See HMR3Init: Attempting fall back to NEM (Hyper-V is active).

If you don't find that text, save the far left tab's log, zip the log file, and post the zip file, using the forum's Upload Attachment tab.

[fth0]

Thanks MikeBou for the further details, and thanks scottgus1 for helping with the instructions. I'll make an educated guess that when following the instructions from scottgus1, you'll discover that Hyper-V is active.

If you read this before having tried all the potential countermeasures in the FAQ link, please try if only disabling Start > Settings > Update & Security > Windows Security > Device security > Core isolation > Memory integrity on your Windows host, followed by a reboot of the Windows host, is sufficient to prevent Hyper-V from being used in your setup. If it's not sufficient, the FAQ link and the link therein provide a lot of additional countermeasures. I'm curious about your feedback.

[MikeBou]

Hi guys,

Thank you so much for all the info and articles. The article on type 1 and 2 hypervisors and how current windows OSs are designed to run were fantastic. And then the various ways that hypervisor services need to be turned off in windows OSs really helped.

So, I have VB running the GNS3 VM successfully! And I can remote in on a web page to the VM and start a project and devices in that project now run successfully. All your info that you provided got me to this point.

I'm thinking of collating all the info into one article and email the guys at Dynamips who sell fully configured GNS3 VMs for both VB and EVE-NG. Would that be OK? If not, all good.

All I need to do now is get the GNS3 console to recognise that the GNS3 VM has successfully started and can work with it. But that's a topic for another post over at GNS3.

Again, thank you so much for all your input and support. I really appreciated it.