hmmm, the point is that we need to ensure that we have a properly
aligned allocated PGD, that's what this patch currently addresses, and as
you pointed out, the BUG_ON() just before trying to run a VM is not the
nicest solution - we should really be dealing with this properly at
allocation time.

But, if you don't have time to look at that, then ok, I'll have to pick
it up myself.

However, you are hinting that we do not support 4 levels of page tables,
yet you do allow the t0sz_to_vttbr_x funciton to pass even when using
t0sz values only supported under 4 levels of page tables....  What is
the rationale for that?

Minimizing merge conflicts. I figure both are going in within the next
month or two.