One of the sticker things in the x86 attempt to do the same thing was
context switching, both between normal tasks and in/out of exceptions
and interrupts.
The easiest place this manifested for us was code chunk like this:
kpkeys_set_level(KPKEYS_LVL_PGTABLES);
// modify page tables here
kpkeys_restore_pkey_reg();
We had to make sure that we didn't get preempted and context switch over
to some other task that _wasn't_ doing page table manipulation while
page table writes were allowed.
On x86, we had to basically start context-switching the kernel pkey
register the same way we do GPRs.
How is SYS_POR_EL0 being context switched?
