This is effectively v2 of a previous series[*] that was intended to be x86-only, but accidentally disabled CPU mitigations by default for every other architectures. Unfortunately, the buggy code has already made it's way to Linus' tree. Patch 1 fixes that goof by adding a generic Kconfig to control the default behavior. Patch 2 disallows retroactively enabling mitigations via command line if the kernel was built with CPU_MITIGATIONS=n, i.e. with SPECULATION_MITIGATIONS=n on x86, as it's infeasible for the kernel to provide sane, predictable behavior for this scenario. [*] https://lore.kernel.org/all/20240409175108.1512861-1-seanjc@xxxxxxxxxx Sean Christopherson (2): cpu: Re-enable CPU mitigations by default for !X86 architectures cpu: Ignore "mitigations" kernel parameter if CPU_MITIGATIONS=n Documentation/admin-guide/kernel-parameters.txt | 3 +++ arch/x86/Kconfig | 11 ++++++++--- drivers/base/Kconfig | 3 +++ kernel/cpu.c | 6 ++++-- 4 files changed, 18 insertions(+), 5 deletions(-) base-commit: 96fca68c4fbf77a8185eb10f7557e23352732ea2 -- 2.44.0.683.g7961c838ac-goog
