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

[Noah Goldstein <goldstein.w.n@gmail.com>]

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.