Just a heads up, there's been a regression with libvirtd, and it's now once again hard coding /usr/bin/kvm-spice instead of using /usr/bin/qemu-system-x86_64.
This will cause libvirtd to fail when starting, and your VMs won't work.
However this fix is quite simple. Simply execute the following command:
ln -s /usr/bin/qemu-system-x86_64 /usr/bin/kvm-spice
And I apologize if this is the wrong place to report this, but it seems Manjaro no longer has an official bug tracking system.