arch-vega: Improve non-native page size support

Vega allows for any integer multiple of 4kB pages. However, the current
implementation is designed for 4kB page primarily. In order to support
variable page sizes, the physical address calculation needs to be
updated to add the virtual page offset to the base physical address
rather than bitwise-OR. Bitwise-OR assumes physical pages are at
aligned to the page size which is generally not the case for very
large pages (1GB+).

This changeset changes all of the physical address computations to add
the virtual offset to the physical page address. This fixes many GPUFS
applications which use larger pages. The support was tested by
hipMalloc'ing ~5GB to induce a large page being created. The test
application now passes verification with this change.

Change-Id: Ic8d1475e001def443f3e4ab609449bca0c40b638
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/64751
Reviewed-by: Matt Sinclair <mattdsinclair@gmail.com>
Maintainer: Matt Sinclair <mattdsinclair@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
2 files changed