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

Solution 1:

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

Solution 2:

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.