Re: [PATCH v2] x86/speculation: Add support for STIBP always-on preferred mode

Borislav Petkov
2018-12-12T09:59:50Z

On Tue, Dec 11, 2018 at 07:37:26PM -0800, Thomas Gleixner wrote:
> Hmmm. I've not seen the V1 of this (it's not in my inbox) but the v1->v2
> changes contain:

You're on CC:

https://lkml.kernel.org/r/20181211190959.28321.56433.stgit@tlendack-t1.amdoffice.net

>
> > > - Removed explicit SPECTRE_V2_USER_STRICT_PREFERRED mode
>
> Now I really have to ask why?
>
> Neither the extra variable nor the cpu feature check are pretty. An
> explicit mode is way better in terms of code clarity and you get the proper
> printout via spectre_v2_user_strings.

Actually, now that I've slept on it, I think we should do this just
like X86_FEATURE_IBRS_ENHANCED - as a modifier for SPECTRE_V2_CMD_AUTO
or _FORCE options.

And that has its own mode SPECTRE_V2_IBRS_ENHANCED.

Makes sense?

--
Regards/Gruss,
Boris.

Good mailing practices for 400: avoid top-posting and trim the reply.