I’m following the kvm instructions step by step with whonix 9.6.
I got this error at the first gateway import step.
user@host:~$ virsh -c qemu:///system define ~/Whonix-Gateway_kvm-9.6.xml
error: Failed to define domain from /home/user/Whonix-Gateway_kvm-9.6.xml
error: internal error: no supported architecture for os type 'hvm'
The error means the KVM kernel modules are not loaded on your system. This happens when Linux can’t use your hardware’s virtualization extensions because they are either unavailable or not enabled in the BIOS.
You will need to go into the BIOS and enable virtualization then KVM will work.
Not related to your problem, but I recommend using Whonix 10 with a Debian Jessie host when it comes out later this month because the configuration works best with it. Wheezy doesn’t support some features in the newer libvirt and it will give you a headache to get working.