[PATCH] x86: Disable RTM on Skylake [BZ #27398]

[H.J. Lu]

On Sat, Mar 27, 2021 at 1:02 PM Florian Weimer <fw@deneb.enyo.de> wrote:
>
> * H. J. Lu:
>
> > On Sat, Mar 27, 2021 at 12:15 PM Florian Weimer <fw@deneb.enyo.de> wrote:
> >>
> >> * H. J. Lu via Libc-alpha:
> >>
> >> > Disable RTM explicitly on Skylake since CPUID may incorrectly report RTM
> >> > feature.
> >> > ---
> >> >  sysdeps/x86/cpu-features.c | 4 ++++
> >> >  1 file changed, 4 insertions(+)
> >> >
> >> > diff --git a/sysdeps/x86/cpu-features.c b/sysdeps/x86/cpu-features.c
> >> > index d7248cbb45..3641a48407 100644
> >> > --- a/sysdeps/x86/cpu-features.c
> >> > +++ b/sysdeps/x86/cpu-features.c
> >> > @@ -518,6 +518,10 @@ init_cpu_features (struct cpu_features *cpu_features)
> >> >                with stepping >= 4) to avoid TSX on kernels that weren't
> >> >                updated with the latest microcode package (which disables
> >> >                broken feature by default).  */
> >> > +         case 0x8e:
> >> > +         case 0x9e:
> >> > +           /* Disable RTM explicitly on Skylake since CPUID may report
> >> > +              RTM feature incorrectly [BZ #27398].  */
> >> >             CPU_FEATURE_UNSET (cpu_features, RTM);
> >> >             break;
> >> >           }
> >>
> >> Won't this affect the server parts as well?  I'm not sure if that's
> >> what our users want.
> >
> > No since Xeon has a different model number (0x55).
>
> Hmm.  Xeon E3-1240 v6 has model number 158 (0x9e), too.

Does it have RTM?

-- 
H.J.