Re: [PATCH v2 1/2] cpu: Re-enable CPU mitigations by default for !X86 architectures

[Josh Poimboeuf]

On Fri, Apr 19, 2024 at 05:05:54PM -0700, Sean Christopherson wrote:
> Rename x86's to CPU_MITIGATIONS, define it in generic code, and force it
> on for all architectures exception x86.  A recent commit to turn
> mitigations off by default if SPECULATION_MITIGATIONS=n kinda sorta missed
> that "cpu_mitigations" is completely generic, whereas
> SPECULATION_MITIGATIONS is x86 specific.
> 
> Rename x86's SPECULATIVE_MITIGATIONS instead of keeping both and have it
> select CPU_MITIGATIONS, as having two configs for the same thing is
> unnecessary and confusing.  This will also allow x86 to use the knob to
> manage mitigations that aren't strictly related to speculative execution.
> 
> Use another Kconfig to communicate to common code that CPU_MITIGATIONS is
> already defined instead of having x86's menu depend on the common
> CPU_MITIGATIONS.  This allows keeping a single point of contact for all of
> x86's mitigations, and it's not clear that other architectures *want* to
> allow disabling mitigations at compile-time.
> 
> Reported-by: Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx>
> Reported-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
> Reported-by: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
> Closes: https://lkml.kernel.org/r/20240413115324.53303a68%40canb.auug.org.au
> Fixes: f337a6a21e2f ("x86/cpu: Actually turn off mitigations by default for SPECULATION_MITIGATIONS=n")
> Cc: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
> Cc: Will Deacon <will@xxxxxxxxxx>
> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>

Acked-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>

-- 
Josh