Can you let me know what I am doing wrong to install the KVM in Virtual Machine Ubuntu that I see the error of "CPU does not support KVM extensions"?

I am running a Linux (Ubuntu 22.04.3 LTS) OS as a VM machine in VirtualBox (version 7.0) and My host machine is Windows 11 pro OS. My Virtualization is Enabled in the BIOS/UEFI of the host machine. I have turned off Hyper-V, Windows HyperVisor Platform, Virtual Machine Platform, and Windows Hypervisor Platform in the Windows Features. Then I have added the VM machine that trying to install KVM to the nested Virtualization by "VBoxManage modifyvm "YourVMName" --nested-hw-virt on" in my host PC. I have installed VM_VirtualBox_Extension_Pack-7.0.14 in Virtual Box.

I am trying to install Docker in my VM linux, for which I need the KVM. But after "sudo apt install qemu-kvm ovmf" it shows installed. But then after "sudo kvm-ok" I see the following error as KVM not supported in my machine:

"INFO: Your CPU does not support KVM extensions

KVM acceleration can NOT be used"

The linux architecture is in the following where KVM is also showed:

""Architecture: x86_64

CPU op-mode(s): 32-bit, 64-bit

Address sizes: 39 bits physical, 48 bits virtual

Byte Order: Little Endian

CPU(s): 4

On-line CPU(s) list: 0-3

Vendor ID: GenuineIntel

Model name: 11th Gen Intel(R) Core(TM) i9-11900 @ 2.50GHz

CPU family:          6

Model:               167

Thread(s) per core:  1

Core(s) per socket:  4

Socket(s):           1

Stepping:            1

BogoMIPS:            4991.99

Flags:               fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mc

                     a cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall n

                     x rdtscp lm constant_tsc rep_good nopl xtopology nonsto

                     p_tsc cpuid tsc_known_freq pni pclmulqdq ssse3 cx16 pci

                     d sse4_1 sse4_2 movbe popcnt aes rdrand hypervisor lahf

                     _lm abm 3dnowprefetch invpcid_single ibrs_enhanced fsgs

                     base bmi1 bmi2 invpcid rdseed clflushopt arat md_clear 

                     flush_l1d arch_capabilities

Virtualization features:

Hypervisor vendor: KVM

Virtualization type: full

Caches (sum of all):

L1d: 192 KiB (4 instances)

L1i: 128 KiB (4 instances)

L2: 2 MiB (4 instances)

L3: 64 MiB (4 instances)


NUMA node(s): 1

NUMA node0 CPU(s): 0-3


Gather data sampling: Not affected

Itlb multihit: Not affected

L1tf: Not affected

Mds: Not affected

Meltdown: Not affected

Mmio stale data: Vulnerable: Clear CPU buffers attempted, no microcode;

                     SMT Host state unknown

Retbleed: Mitigation; Enhanced IBRS

Spec rstack overflow: Not affected

Spec store bypass: Vulnerable

Spectre v1: Mitigation; usercopy/swapgs barriers and __user pointer


Spectre v2: Mitigation; Enhanced / Automatic IBRS, RSB filling, PBR

                     SB-eIBRS SW sequence

Srbds: Not affected

Tsx async abort: Not affected


1 Answer 1


The KVM detection is correct. You're nesting Linux inside a VM on Windows. So it cannot find the KVM features because you're not running Linux on bare metal, and it's not enabled in VirtualBox.

To enable nested KVM, from the VirtualBox Manager, select the "Enable Nested VT-x/AMD-V" check box on the Processor tab.

  • Thank you @popey. I already did that. But still getting the same error.
    – jarvis
    Commented Feb 8 at 17:31
  • Did you restart the VM?
    – popey
    Commented Feb 8 at 17:41
  • @popey..yes I did. And also I found somewhere: "Intel VT-x or AMD-V is required for running "Nested Virtualization" which supports nested 32-bit VMs Intel EPT or AMD RVI is required for running nested 64-bit VMs." mine is x86_64, but as far as I know EPT or AMD RVI is already available when "Intel VT-x or AMD-V" is checked? or I don't know.
    – jarvis
    Commented Feb 8 at 17:47

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