Re: [PATCH 0/3] x86/cpu: Fix SPECULATIVE_MITIGATION=n kernels

From: Daniel Sneddon <daniel.sneddon@linux.intel.com>
To: Sean Christopherson <seanjc@google.com>,
	Jonathan Corbet <corbet@lwn.net>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	x86@kernel.org, Peter Zijlstra <peterz@infradead.org>,
	Josh Poimboeuf <jpoimboe@kernel.org>
Cc: linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
	Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Subject: Re: [PATCH 0/3] x86/cpu: Fix SPECULATIVE_MITIGATION=n kernels
Date: Tue, 9 Apr 2024 11:55:43 -0700	[thread overview]
Message-ID: <976c385e-2174-464e-9afd-de4cb46f63b8@linux.intel.com> (raw)
In-Reply-To: <20240409175108.1512861-1-seanjc@google.com>

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@linux.intel.com>