arm64: Add override for MMFR1.HAFDBS

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In general it might be nice to have the ability to disable hardware
access/dirty bit management for debugging or performance comparison
purposes without having to rebuild the kernel. However once FEAT_HAFT
comes into the picture we also start to have a real functional concern
where the decision to use HAFT based on the boot CPUs can prevent SVA
or late-onlining if SMMUs/CPUs are later found to lack HAFT support.

To that end, add the appropriate MMFR1 override, with an easy "nohaft"
alias for the significant case, partly since the feature/field naming
isn't the most obvious, but also so it could potentially be redirected
in future if someone wanted to attempt a higher-level means of turning
off just HAFT usage independently from FEAT_HDBSS.

Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>

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Robin Murphy 2026-07-27 13:03:28 +01:00 • committed by Will Deacon

parent a86c36163c

commit 91038c83a2

2 changed files with 5 additions and 0 deletions

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3

Documentation/admin-guide/kernel-parameters.txt

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2

arch/arm64/kernel/pi/idreg-override.c

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