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

[Josh Poimboeuf]

On Mon, Apr 14, 2025 at 09:15:54PM +0000, Kaplan, David wrote:
> [AMD Official Use Only - AMD Internal Distribution Only]
> 
> > -----Original Message-----
> > From: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
> > Sent: Thursday, April 10, 2025 1:15 PM
> > To: Kaplan, David <David.Kaplan@xxxxxxx>
> > Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>; Borislav Petkov <bp@xxxxxxxxx>;
> > Peter Zijlstra <peterz@xxxxxxxxxxxxx>; Pawan Gupta
> > <pawan.kumar.gupta@xxxxxxxxxxxxxxx>; Ingo Molnar <mingo@xxxxxxxxxx>; Dave
> > Hansen <dave.hansen@xxxxxxxxxxxxxxx>; x86@xxxxxxxxxx; H . Peter Anvin
> > <hpa@xxxxxxxxx>; linux-kernel@xxxxxxxxxxxxxxx; Brendan Jackman
> > <jackmanb@xxxxxxxxxx>; Derek Manwaring <derekmn@xxxxxxxxxx>
> > Subject: Re: [PATCH v4 17/36] Documentation/x86: Document the new attack
> > vector controls
> >
> > Caution: This message originated from an External Source. Use proper caution
> > when opening attachments, clicking links, or responding.
> >
> >
> > On Mon, Mar 10, 2025 at 11:40:04AM -0500, David Kaplan wrote:
> > > +=============== ============== ============ =============
> > ============== ============
> > > +Vulnerability   User-to-Kernel User-to-User Guest-to-Host Guest-to-Guest
> > Cross-Thread
> > > +=============== ============== ============ =============
> > ============== ============
> > > +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?

-- 
Josh