arm64: Cope with CPUs stuck in VHE mode

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It seems that the CPUs part of the SoC known as Apple M1 have the
terrible habit of being stuck with HCR_EL2.E2H==1, in violation
of the architecture.

Try and work around this deplorable state of affairs by detecting
the stuck bit early and short-circuit the nVHE dance. Additional
filtering code ensures that attempts at switching to nVHE from
the command-line are also ignored.

It is still unknown whether there are many more such nuggets
to be found...

Reported-by: Hector Martin <marcan@marcan.st>
Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210408131010.1109027-3-maz@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

...

This commit is contained in:

Marc Zyngier 2021-04-08 14:10:09 +01:00 • committed by Catalin Marinas

parent cac642c12a

commit 31a32b49b8

3 changed files with 52 additions and 8 deletions

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39

arch/arm64/kernel/head.S

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8

arch/arm64/kernel/hyp-stub.S

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13

arch/arm64/kernel/idreg-override.c

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