xpti=0 hangs hypervisor on boot

For a reason (routing platform requiring high I/O performance, with no untrusted code) I tried to disable all Intel bug mitigations on hypervisor using option set of spec-ctrl=no-xen l1tf=no xpti=no

Alas, xpti=no hangs the server (even being the only option) on hypervisor boot, it does not even start to display any logging after grub finishes. Other options work as desired.