VT-x is being used by another hypervisor .. Please disable the KVM

while starting my VM using vagrant, I have following error :

The guest machine entered an invalid state while waiting for it
to boot. Valid states are ‘starting, running’. The machine is in the
‘poweroff’ state. Please verify everything is configured
properly and try again.

If the provider you’re using has a GUI that comes with it,
it is often helpful to open that and watch the machine
, since the
GUI often has more helpful error messages than Vagrant can retrieve.
For example, if you’re using VirtualBox, run vagrant up while the
VirtualBox GUI is open.

So, I edit my Vagrantfile and uncomment gui

Then I start my vm using VirtualBox. I have the following error :
VT-x is being used by another hypervisor … Please disable the KVM

what to do ?
1. see if kvm is running and is used

witr@serv:~$ lsmod | grep kvm
kvm_intel 143592 3
kvm 459835 1 kvm_intel

here kvm is used by one consumer (kvm_intel) and kvm_intel is used by 3 consumers.

2. stop kvm consumers
In my case it’s the android emulator i have launched from AndroidStudio which causes problem. I stop emulator.

3. restart vm
that’s all