​July 12, 2013​​​​james​​​​ KVM​​, ​​ Ubuntu Server​

It is very easy to convert a VirtualBox .vdi disk images to KVM qcow2 file. You have to use the RAW file format as an intermediate.

1 – Make sure the VirtualBox machine is shutdown.

2 – Convert the vdi to a raw disk images. Note: vdi are compressed and raw images are not and so you will need to leave enough disk space for entire uncompressed disk.

​VBoxManage clonehd --format RAW vm.vdi vm.img​

3 – Then on your KVM host:

​qemu-img convert -f raw vm.img -O qcow2 vm.qcow2​

Hope this is helpful.