Re: [PATCH v4 17/36] Documentation/x86: Document the new attack vector controls

[Josh Poimboeuf]

On Tue, Apr 15, 2025 at 02:59:32PM +0000, Kaplan, David wrote:
> > > > > +BHI                   X                           X
> > > > > +GDS                   X              X            X              X        (Note 1)
> > > > > +L1TF                  X                           X                       (Note 2)
> > > > > +MDS                   X              X            X              X        (Note 2)
> > > > > +MMIO                  X              X            X              X        (Note 2)
> > > > > +Meltdown              X
> > > > > +Retbleed              X                           X                       (Note 3)
> > > > > +RFDS                  X              X            X              X
> > > > > +Spectre_v1            X
> > > > > +Spectre_v2            X                           X
> > > > > +Spectre_v2_user                      X                           X        (Note 1)
> > > > > +SRBDS                 X              X            X              X
> > > > > +SRSO                  X                           X
> > > > > +SSB (Note 4)
> > > >
> > > > Any reason not to put the "Note 4" in the same column as the others?
> > > >
> > >
> > > The other notes are about cross-thread mitigation specifically and those notes
> > refer to the SMT aspects of those issues.
> > >
> > > Note 4 in this case is about the SSB vulnerability itself, explaining
> > > that by default there is no mitigation for any case.  I was concerned
> > > that including SSB but without any X's in any of the columns would be
> > > confusing, so the note attempted to explain that there were no default
> > > mitigations for SSB under any attack vector.
> >
> > Putting the note there makes it a lot harder to see it.  And I think the lack of X's is
> > accurate, no?
> >
> 
> It is, it's just rather unique compared to the other bugs.  I could
> remove the note entirely, but I was concerned that might look odd
> because it'd be the only bug that isn't mitigated under any of the
> attack vectors.  And that's really just because the current default is
> not to mitigate that one.

I think the note is helpful, it attempts to explain why there are no
X's.  I was just thinking that it seems more logical to put it in the
same column as the others.  And that would also help make it more clear
that yes, the X's are missing.  Which is indeed odd, but it's also the
reality.

-- 
Josh