Re: [PATCH] x86/bugs: Qualify RETBLEED_INTEL_MSG

[Pawan Gupta <pawan.kumar.gupta@linux.intel.com>]

On Fri, Oct 10, 2025 at 12:19:12PM -0700, Josh Poimboeuf wrote:
> On Fri, Oct 10, 2025 at 11:47:25AM -0700, Pawan Gupta wrote:
> > > Instead, CONFIG_MITIGATION_SPECTRE_V2 could enable a submenu which then
> > > allows the user to enable retpoline, IBRS on entry, etc, with each
> > > having help text describing what generations of CPUs it would be the
> > > default for, to help guide the user to choose sane defaults depending on
> > > their CPU:
> > > 
> > >   * CONFIG_MITIGATION_SPECTRE_V2
> > >     * CONFIG_MITIGATION_SPECTRE_V2_RETPOLINE
> > >       select CONFIG_BUILD_INDIRECT_THUNKS
> > >     * CONFIG_MITIGATION_SPECTRE_V2_IBRS
> > >       select CONFIG_BUILD_IBRS_ENTRY
> > 
> > That would be good if a kernel is built for certain specific CPU(s). This
> > may not be ideal for distro kernels.
> 
> Why not?  A distro can just enable everything:

Ahh, right.

>   CONFIG_MITIGATION_SPECTRE_V2=y
>   CONFIG_MITIGATION_SPECTRE_V2_RETPOLINE=y
>   CONFIG_MITIGATION_SPECTRE_V2_IBRS=y
> 
> and then if/when some older HW ages out of being supported by the
> distro, they can start disabling things.

Yup, that makes sense.