How to detect if VT-X has been turned on in the BIOS?

I know I can check is VT-X is supported by a processor by egrep '(vmx|svm)' /proc/cpuinfo. But even if it's supported, it can be turned off in the BIOS. How can I detect if it's turned on or off?

3 Answers

VT-X information is stored in model-specific registers (MSR) 0x34 which can be accessed via msr-tools. Install it by running sudo apt-get install msr-tools then run the following commands

sudo modprobe msr
sudo rdmsr 0x3A

If the return value is 3, 5 or 7 then VT-X is enabled

See Reliably detecting if Intel VT is disabled in the BIOS

There are two ways to verify:

1. On Debian-based distros (such as Ubuntu), you can check support for VT-x by installing cpu-checker and run kvm-ok with sudo rights.

   If the CPU is enabled, you should see something like:

    INFO: /dev/kvm exists KVM acceleration can be used

   Otherwise, you'll get:

    INFO: /dev/kvm does not exist HINT: sudo modprobe kvm_intel INFO: Your CPU supports KVM extensions INFO: KVM (vmx) is disabled by your BIOS HINT: Enter your BIOS setup and enable Virtualization Technology (VT), and then hard poweroff/poweron your system KVM acceleration can NOT be used

2. On Debian-based and RHEL-based systems, you can use virt-host-validate which is provided by the libvirt-client package. Documentation on usage can be found here.

A very unenviable way to check (without going into the BIOS) would be to install/open Virtualbox hypervisor, and try installing a 64-bit Linux VM and see if the settings allow you to enable VT-X. Installation of VM in virtualbox is the only context where I've encountered the need to enable VT-X/AMD-V.