Re: [PATCH v2] x86: Black list more Intel CPUs for TSX [BZ #27398]

["H.J. Lu" <hjl.tools@gmail.com>]

On Tue, Jan 18, 2022 at 1:51 PM Noah Goldstein <goldstein.w.n@gmail.com> wrote:
>
> On Tue, Jan 18, 2022 at 3:29 PM H.J. Lu <hjl.tools@gmail.com> wrote:
> >
> > Disable TSX and enable RTM_ALWAYS_ABORT for Intel CPUs listed in:
> >
> > https://www.intel.com/content/www/us/en/support/articles/000059422/processors.html
> >
> > This fixes BZ #27398.
> > ---
> >  sysdeps/x86/cpu-features.c | 34 +++++++++++++++++++++++++++++++---
> >  1 file changed, 31 insertions(+), 3 deletions(-)
> >
> > diff --git a/sysdeps/x86/cpu-features.c b/sysdeps/x86/cpu-features.c
> > index 772ccf8e91..514226b378 100644
> > --- a/sysdeps/x86/cpu-features.c
> > +++ b/sysdeps/x86/cpu-features.c
> > @@ -507,11 +507,39 @@ init_cpu_features (struct cpu_features *cpu_features)
> >               break;
> >             }
> >
> > -        /* Disable TSX on some Haswell processors to avoid TSX on kernels that
> > -           weren't updated with the latest microcode package (which disables
> > -           broken feature by default).  */
> > +        /* Disable TSX on some processors to avoid TSX on kernels that
> > +           weren't updated with the latest microcode package (which
> > +           disables broken feature by default).  */
> >          switch (model)
> >             {
> > +           case 0x55:
> > +             if (stepping <= 5)
> > +               goto disable_tsx;
> > +             break;
> > +           case 0x8e:
> > +             /* NB: Although the errata documents that for model == 0x8e,
> > +                only 0xb stepping or lower are impacted, the intention of
> > +                the errata was to disable TSX on all client processors on
> > +                all steppings.  Include 0xc stepping which is an Intel
> > +                Core i7-8665U, a client mobile processor.  */
> > +           case 0x9e:
> > +             if (stepping > 0xc)
> > +               break;
> > +             /* Fall through.  */
> > +           case 0x4e:
> > +           case 0x5e:
> > +             {
> > +               /* Disable Intel TSX and enable RTM_ALWAYS_ABORT for
> > +                  processors listed in:
> > +
> > +https://www.intel.com/content/www/us/en/support/articles/000059422/processors.html
> > +                */
> > +disable_tsx:
> > +               CPU_FEATURE_UNSET (cpu_features, HLE);
> > +               CPU_FEATURE_UNSET (cpu_features, RTM);
> > +               CPU_FEATURE_SET (cpu_features, RTM_ALWAYS_ABORT);
> > +             }
> > +             break;
> >             case 0x3f:
> >               /* Xeon E7 v3 with stepping >= 4 has working TSX.  */
> >               if (stepping >= 4)
> > --
> > 2.34.1
> >
>
> LGTM.

I am backporting this to release branches.

-- 
H.J.