On Tue, Mar 30, 2021 at 06:39:46PM +0100, Marc Zyngier wrote:

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 <redacted>
Signed-off-by: Marc Zyngier <maz@kernel.org>
---
 arch/arm64/kernel/head.S           | 39 +++++++++++++++++++++++++++---
 arch/arm64/kernel/hyp-stub.S       |  8 +++---
 arch/arm64/kernel/idreg-override.c | 13 +++++++++-
 3 files changed, 52 insertions(+), 8 deletions(-)

Acked-by: Will Deacon <will@kernel.org>

Will

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