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>
Some CPUs are broken enough that some overrides need to be rejected
at the earliest opportunity. In some cases, that's right at cpu
feature override time.
Provide the necessary infrastructure to filter out overrides,
and to report such filtered out overrides to the core cpufeature code.
Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210408131010.1109027-2-maz@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
The built-in kernel commandline (CONFIG_CMDLINE) can be configured in
three different ways:
1. CMDLINE_FORCE: Use CONFIG_CMDLINE instead of any bootloader args
2. CMDLINE_EXTEND: Append the bootloader args to CONFIG_CMDLINE
3. CMDLINE_FROM_BOOTLOADER: Only use CONFIG_CMDLINE if there aren't
any bootloader args.
The early cmdline parsing to detect idreg overrides gets (2) and (3)
slightly wrong: in the case of (2) the bootloader args are parsed first
and in the case of (3) the CMDLINE is always parsed.
Fix these issues by moving the bootargs parsing out into a helper
function and following the same logic as that used by the EFI stub.
Reviewed-by: Marc Zyngier <maz@kernel.org>
Fixes: 3320030355 ("arm64: cpufeature: Add an early command-line cpufeature override facility")
Link: https://lore.kernel.org/r/20210303134927.18975-2-will@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
Admitedly, passing id_aa64mmfr1.vh=0 on the command-line isn't
that easy to understand, and it is likely that users would much
prefer write "kvm-arm.mode=nvhe", or "...=protected".
So here you go. This has the added advantage that we can now
always honor the "kvm-arm.mode=protected" option, even when
booting on a VHE system.
Signed-off-by: Marc Zyngier <maz@kernel.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: David Brazdil <dbrazdil@google.com>
Link: https://lore.kernel.org/r/20210208095732.3267263-18-maz@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
In order to be able to override CPU features at boot time,
let's add a command line parser that matches options of the
form "cpureg.feature=value", and store the corresponding
value into the override val/mask pair.
No features are currently defined, so no expected change in
functionality.
Signed-off-by: Marc Zyngier <maz@kernel.org>
Acked-by: David Brazdil <dbrazdil@google.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20210208095732.3267263-14-maz@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
