On aarch64 in EL2, there aren't any addresses after 2^48 and so the
any kernel device untypeds that have very large physical addresses could
potentially move into an invalid address range when translated to a
Kernel window PPTR address when being stored in a cap slot. The kernel
in EL2 doesn't need to share its address space with user level and so we
can make the kernel window start low enough that we can't get overflows.
We start from the second entry in the top level page table so that we
don't conflict with any setup code running in the lowest 512GiB of
virtual addresses.
Signed-off-by: Kent McLeod <kent@kry10.com>
a94d90598f