arm64: cpufeatures: Restrict NV support to FEAT_NV2

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To anyone who has played with FEAT_NV, it is obvious that the level
of performance is rather low due to the trap amplification that it
imposes on the host hypervisor. FEAT_NV2 solves a number of the
problems that FEAT_NV had.

It also turns out that all the existing hardware that has FEAT_NV
also has FEAT_NV2. Finally, it is now allowed by the architecture
to build FEAT_NV2 *only* (as denoted by ID_AA64MMFR4_EL1.NV_frac),
which effectively seals the fate of FEAT_NV.

Restrict the NV support to NV2, and be done with it. Nobody will
cry over the old crap. NV_frac will eventually be supported once
the intrastructure is ready.

Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
Signed-off-by: Marc Zyngier <maz@kernel.org>

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This commit is contained in:

Marc Zyngier 2023-11-09 15:47:49 +00:00

parent 2cc14f52ae

commit 2bfc654b89

1 changed files with 1 additions and 1 deletions

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arch/arm64/kernel/cpufeature.c

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