[RFC PATCH] powerpc/fsl: Add barrier_nospec implementation for NXP PowerPC Book E

[Michael Ellerman]

Scott Wood <oss at buserror.net> writes:

> On Thu, 2018-05-31 at 14:35 +0000, Diana Madalina Craciun wrote:
>> On 5/31/2018 5:21 PM, Michael Ellerman wrote:
>> > 
>> > We can add a nospectre_v1 command line option if necessary.
>> 
>> What about nobarrier_nospec (or similar) instead of nospectre_v1 command
>> line? We are not disabling all the v1 mitigations, the masking part will
>> remain unchanged.
>
> I think nospectre_v1 makes more sense as it's about the user's intentions
> rather than the implementation.  The user is giving the kernel permission to
> not defend against spectre v1, and it's up to the implementation which
> mitigations (if any) to disable in response to that, same as any other
> optimization.

Yeah I agree. We also have `nospectre_v2` on x86/s390 so I think keeping
consistency with that is a must.

cheers