L1 had grown large enough? What do you mean? L1 was 32KB in the Pentium II days, and for the last ten years of Intel chips it's been an unchanging 64KB. Why would it have to fit into L1 specifically, rather than L2/L3? (If you do use L2/L3, that's also been big enough to spare the space for a hypervisor since the Pentium II, which had 512KB.)