[Xen-devel] [PATCH RFC 0/9] xen: arm: support for > 40-bit physical addressing

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

ARM64 systems can support up to 48-bits of physical address, but
currently we configure both Stage-1 and Stage-2 for only 40-bits.
However there are systems with peripherals mapped higher up, in order to
support those we need to support 48-bits as output for stage-1 as well
as input and output for stage-2. Stage-2 support is needed in order to
map them 1:1 to dom0.

Unfortunately as the last commit message explains in a bit more detail
supporting larger input sizes on the p2m is a pain because it means we
can no longer statically decide to use a 3-level p2m with 2 concatenated
pages at the root and need to be able to support either that *or* a
4-level p2m with no root concatenation. There is simply no static choice
which supports both 40- and 48-bits of IPA.

So this series goes through the various functions which manipulate or
walk page tables and makes them able to support a dynamic starting level
and concatenation before switching arm64 to make the choice dependent on
the h/w capabilities.

This is somewhat loosely based on Vijay's original "Add 4-level page
table for stage 2 translation" series but due to the need to switch to
dynamic p2m levels not much of that remains.

I haven't actually been able to track down a system with >42-bit PASize.
Vijay, I'm hoping you can test the series on such a system/model. This
is the main reason for RFC.

I don't intend for this to go in before Arianna's MMIO mapping series.
IOW I will take care of rebasing this onto that.

Ian.


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