[PATCH] arm64: mm: Align PGDs to at least 64 bytes

[Catalin Marinas]

On Tue, Nov 22, 2022 at 05:56:18PM +0100, Ard Biesheuvel wrote:
> My copy of the ARM ARM (DDI 0487G.a) no longer describes the 64 byte

G.a is nearly two years old. You may want to upgrade to H.a ;).

> minimum alignment of root page tables as being conditional on whether
> 52-bit physical addressing is supported and enabled, even though I seem
> to remember that this was the case formerly (and our code suggests the
> same).

The wording in the ARM ARM implies that it's only needed if we go beyond
48 bits for the base address:

  A translation table must be aligned to the size of the table, except
  that when using a translation table base address larger than 48 bits
  the minimum alignment of a table containing fewer than eight entries
  is 64 bytes.

But I'm fine with the patch, always forcing the 64 byte alignment. With
the 'max_t' instead of 'max' (or whatever solves Anshuman's error):

Acked-by: Catalin Marinas <catalin.marinas at arm.com>