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

[Florian Weimer <fw@deneb.enyo.de>]

* 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.

We need to report the kernel bug properly, it got stalled because we
initially suspected it might be a security bug.