Comment by mappu

VMs also don't always require hardware virtualization - Alibaba's PVM https://lkml.org/lkml/2024/2/26/1263 didn't get upstreamed, but, theoretically the MMU is all you need for complete isolation. This kind of idea is also how VM software worked before VT-x was introduced. And of course QEMU has the TCG which works with no kernel support at all.