Com base na resposta de Jo-Erlend Schinstad :
Instalar o cpu-checker
$ sudo apt-get update
$ sudo apt-get install cpu-checker
Em seguida, verifique:
$ kvm-ok
Se a CPU estiver ativada, você verá algo como:
INFO: /dev/kvm exists
KVM acceleration can be used
Caso contrário, você poderá ver algo como:
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