lkml.org 
[lkml]   [2023]   [Mar]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
SubjectRe: [RFC PATCH 07/13] powerpc/dexcr: Add sysctl entry for SBHE system override
From
On Mon Nov 28, 2022 at 12:44 PM AEST, Benjamin Gray wrote:
> The DEXCR Speculative Branch Hint Enable (SBHE) aspect controls whether
> the hints provided by BO field of Branch instructions are obeyed during
> speculative execution.
>
> SBHE behaviour per ISA 3.1B:
>
> 0: The hints provided by BO field of Branch instructions may be
> ignored during speculative execution
>
> 1: The hints provided by BO field of Branch instructions are obeyed
> during speculative execution
>
> Add a sysctl entry to allow changing this aspect globally in the system
> at runtime:
>
> /proc/sys/kernel/speculative_branch_hint_enable
>
> Three values are supported:
>
> -1: Disable DEXCR SBHE sysctl override
> 0: Override and set DEXCR[SBHE] aspect to 0
> 1: Override and set DEXCR[SBHE] aspect to 1
>
> Internally, introduces a mechanism to apply arbitrary system wide
> overrides on top of the prctl() config.

Why have an override for this, and not others?

Thanks,
Nick

\
 
 \ /
  Last update: 2023-03-27 00:46    [W:0.182 / U:0.256 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site