Android Studio: /dev/kvm device permission denied

/dev/kvm permission denied.

After updating Ubuntu to 18.04 version you should install qemu-kvm

sudo apt install qemu-kvm

Check the owner of /dev/kvm 

ls -al /dev/kvm

It should return User root, group kvm.
To check which users are in kvm group:

grep kvm /etc/group

It should return something like that:

kvm:x:some_number:

There was not a value after the last colon after I've updated my OS. This means that no users are present in kvm Group.

To add your user to kvm Group use the command:

sudo adduser $USER kvm

Check if the user was added:

grep kvm /etc/group.

If after those actions you still see an error message - try to re-login to make user permission refreshed.