Virtualbox enable nested vtx/amd-v greyed out - virtualbox

Question

On my Ubuntu 18.04, I've installed VirtualBox 6.0 in order to have nested virtualization. Virtualization is enabled in my bios.
However, when I open the settings of my (powered off) virtual machine and go to System -> Processor, the option "Enable Nested VT-x/AMD-V" is greyed out and I cannot enable it.

Answer 1

Execute this:
$ VBoxManage modifyvm <VirtualMachineName> --nested-hw-virt on

Answer 2

For Windows
In Windows, go to VirtualBox installation folders -> type cmd on the bar (it will pop up cmd in that folder) -> type VBoxManage modifyvm <YourVirtualMachineName> --nested-hw-virt on -> enter.
Now the option should be checked.

Answer 3

On VirtualBox 6.1.2 that worked (intel i7 2630QM)
(VBoxManage modifyvm lubuntu18 --nested-hw-virt on)

Answer 4

From what I understand, this option is only available with AMD CPUs, and cannot be enabled on Intel CPUs. This is a little misleading, since the option clearly states both Intel, and AMD virtualization technologies.
Here is an official confirmation in VirtualBox doc:
https://www.virtualbox.org/manual/ch03.html
Chapter 3.5.2. Processor Tab
Enable Nested VT-x/AMD-V: Enables nested virtualization, with passthrough of hardware virtualization functions to the guest VM.
This feature is available on host systems that use an AMD CPU. For Intel CPUs, the option is grayed out.

Answer 5

So far it only works with AMD CPUs (forget about the confusing option title).
Initially this is for AMD CPUs only.
All Intel CPU posts will be deleted/split.
https://forums.virtualbox.org/viewtopic.php?f=1&t=90831
https://forums.virtualbox.org/viewtopic.php?f=7&t=90874

Answer 6

In Windows 10 this problem is caused because you have Memory Integrity active.
Windows Security -> Device security -> Core isolation details
Disable Memory integrity and then restart Windows.
The VB option "Enable Nested VT-x/AMD-V" should be still greyed out.
Now, open a new PowerShell in your VB installation folder and type: ./VBoxManage modifyvm "Virtual Machine Name" --nested-hw-virt on
You'll find detailed information here (idk why Microsoft does not mention this issue anywere).

Answer 7

recently this popped up for me out of the blue on Windows 11. I already had hyper-v disabled from previous tweaks and everything had been working. in the end I had to use this command:
bcdedit /set hypervisorlaunchtype off
which fixed it, but it broke the Windows Subsystem for Android recently introduced in 11, so, there's that...

Answer 8

From the directory where VirtualBox is executed, I run a similar command that works (note the placement of the quotes!
VBoxManage modifyvm "path\to\ubuntu 18.04.3.vbox" --nested-hw-virt on
Hope this helps.
BD

Answer 9

It's alive on VirtualBox 6.1.2 r135662 (Qt5.6.2) and Intel Core i3-8100!
CMD's output from image as text:
C:\WINDOWS\system32>ssh myuser#192.168.56.111
myuser#192.168.56.111's password:
Last login: Mon Feb 17 10:11:06 2020 from 192.168.56.1
myuser#nestedvt ~ $ su
Пароль:
root#nestedvt /home/myuser # egrep "svm|vmx" /proc/cpuinfo
root#nestedvt /home/myuser #
root#nestedvt /home/myuser # poweroff
Connection to 192.168.56.111 closed by remote host.
Connection to 192.168.56.111 closed.
C:\WINDOWS\system32>cd "C:\Program Files\Oracle\VirtualBox"
C:\Program Files\Oracle\VirtualBox>VBoxManage modifyvm CentOS7_nestedVT --nested-hw-virt on
C:\Program Files\Oracle\VirtualBox>VBoxManage startvm CentOS7_nestedVT
Waiting for VM "CentOS7_nestedVT" to power on...
VM "CentOS7_nestedVT" has been successfully started.
C:\Program Files\Oracle\VirtualBox>ssh myuser#192.168.56.111
myuser#192.168.56.111's password:
Last login: Mon Feb 17 10:12:08 2020 from 192.168.56.1
myuser#nestedvt ~ $ su
Пароль:
root#nestedvt /home/myuser # egrep "svm|vmx" /proc/cpuinfo
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx rdtscp lm constant_tsc rep_good nopl xtopology nonstop_tsc eagerfpu pni pclmulqdq vmx ssse3 cx16 pcid sse4_1 sse4_2 x2apic movbe popcnt aes xsave avx rdrand hypervisor lahf_lm abm 3dnowprefetch invpcid_single tpr_shadow flexpriority fsgsbase avx2 invpcid rdseed clflushopt md_clear flush_l1d
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx rdtscp lm constant_tsc rep_good nopl xtopology nonstop_tsc eagerfpu pni pclmulqdq vmx ssse3 cx16 pcid sse4_1 sse4_2 x2apic movbe popcnt aes xsave avx rdrand hypervisor lahf_lm abm 3dnowprefetch invpcid_single tpr_shadow flexpriority fsgsbase avx2 invpcid rdseed clflushopt md_clear flush_l1d
root#nestedvt /home/myuser # exit
exit
myuser#nestedvt ~ $ exit
logout
Connection to 192.168.56.111 closed.
C:\Program Files\Oracle\VirtualBox>wmic cpu get name
Name
Intel(R) Core(TM) i3-8100 CPU # 3.60GHz
C:\Program Files\Oracle\VirtualBox>wmic os get caption
Caption
Microsoft Windows 10 Pro

Answer 10

It turned out it was greyed out for a reason! I have Windows 10 host and I used Docker for some time and uninstalled but it kept Hyper-V technology enabled (Which is incompatible with virtualization).
DO NOT DO ON A SERVER | THIS WILL DISABLE Hyper-V Technology - USE AT YOUR OWN RISK
Open command prompt as admin and run the following then restart your PC
DISM /Online /Disable-Feature:Microsoft-Hyper-V
PowerShell Disable-WindowsOptionalFeature -Online -FeatureName Microsoft-Hyper-V-Hypervisor -All
bcdedit /set hypervisorlaunchtype off

Answer 11

The cause of the problem is Hyper-V.
If you want to use nseted virtualization, you should turn off hypervisorlaunchtype.
It's worked for me: bcdedit /set hypervisorlaunchtype off

Answer 12

FYI,
Oracle VM VirtualBox supports nested virtualization on host systems that run AMD and Intel CPUs.
For more details, check:
https://docs.oracle.com/en/virtualization/virtualbox/6.0/admin/nested-virt.html

Answer 13

VBoxManage modifyvm --nested-hw-virt on
this works..

Answer 14

Enable VT-x/AMD-V in Virtualbox from Windows host pc.
Open oracle virtual box installed folder location from cmd with
administrator. cd C:\Program Files\Oracle\VirtualBox
then run the command.
VBoxManage modifyvm --nested-hw-virt on
is your vm name then enable nested VT-x/AMD-V in
your virtual box

Answer 15

The problem sometimes is your machine has saved its state, but the saved state is not the correct one, so you click on your machine and then on forget at the top to forget any saved state. In my case this solved the case