On Tue, Jul 06, 2021 at 03:01:04PM +0100, Robin Murphy wrote:

FWIW I was pondering the question of whether to do something along those 
lines or just scrap the default assignment entirely, so since I hadn't got 
round to saying that I've gone ahead and hacked up the alternative 
(similarly untested) for comparison :)

TBH I'm still not sure which one I prefer...

Claire did implement something like your suggestion originally, but
I don't really like it as it doesn't scale for adding multiple global
pools, e.g. for the 64-bit addressable one for the various encrypted
secure guest schemes.