VirtualBox Can’t Operate In VMX Root Mode. Please Disable The KVM Kernel Extension 1
If you are using Linux Distro (Ubuntu in my case) and when you try to run VirtualBox, you might get the following error : VirtualBox can’t operate in VMX root mode. Please disable the KVM kernel extension, recompile your kernel and reboot (VERR_VMX_IN_VMX_ROOT_MODE). or something like VT-x is being used by another hypervisor (VERR_VMX_IN_VMX_ROOT_MODE).