linux-kernel - Re: [PATCH 0/3] x86/cpu: Fix SPECULATIVE

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Date: Tue, 9 Apr 2024 11:55:43 -0700
From: Daniel Sneddon <daniel.sneddon@...ux.intel.com>
To: Sean Christopherson <seanjc@...gle.com>, Jonathan Corbet
 <corbet@....net>, Thomas Gleixner <tglx@...utronix.de>,
 Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
 Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
 Peter Zijlstra <peterz@...radead.org>, Josh Poimboeuf <jpoimboe@...nel.org>
Cc: linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
 Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>
Subject: Re: [PATCH 0/3] x86/cpu: Fix SPECULATIVE_MITIGATION=n kernels

On 4/9/24 10:51, Sean Christopherson wrote:
> Fix the handling of SPECULATION_MITIGATIONS=n so that it actually does
> what it says it does: disable any and all mitigations.
> 
> And because I don't see a way to provide sane behavior for overriding
> SPECULATION_MITIGATIONS=n at runtime, explicitly disallow doing so via
> the "mitigations" kernel parameter, e.g. so that the user at least knows
> that their system is still likely vulnerable to a variety of issues.
> 
> Sean Christopherson (3):
>   x86/cpu: Actually turn off mitigations by default for
>     SPECULATION_MITIGATIONS=n
>   x86/cpu: Disable BHI mitigation by default when
>     SPECULATION_MITIGATIONS=n
>   x86/cpu: Ignore "mitigations" kernel parameter if
>     SPECULATION_MITIGATIONS=n
> 
>  Documentation/admin-guide/kernel-parameters.txt |  3 +++
>  arch/x86/Kconfig                                | 10 +++++++---
>  arch/x86/kernel/cpu/bugs.c                      |  6 +++---
>  kernel/cpu.c                                    |  5 ++++-
>  4 files changed, 17 insertions(+), 7 deletions(-)
> 
> 
> base-commit: 2c71fdf02a95b3dd425b42f28fd47fb2b1d22702

Reviewed-by: Daniel Sneddon <daniel.sneddon@...ux.intel.com>