arm64: spectre-v2: Favour CPU-specific mitigation at EL2

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Spectre-v2 can be mitigated on Falkor CPUs either by calling into
firmware or by issuing a magic, CPU-specific sequence of branches.
Although the latter is faster, the size of the code sequence means that
it cannot be used in the EL2 vectors, and so there is a need for both
mitigations to co-exist in order to achieve optimal performance.

Change the mitigation selection logic for Spectre-v2 so that the
CPU-specific mitigation is used only when the firmware mitigation is
also available, rather than when a firmware mitigation is unavailable.

Cc: Marc Zyngier <maz@kernel.org>
Signed-off-by: Will Deacon <will@kernel.org>

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Will Deacon 2020-10-20 16:01:57 +01:00

parent 3b92fa7485

commit ea8f8c99a2

1 changed files with 17 additions and 19 deletions

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arch/arm64/kernel/proton-pack.c

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