linux-kernel - Re: [PATCH 0/2] VERW based clean-up

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Message-ID: <963f9a3e-71f2-41ba-ba46-e27aa8fe991a@linux.intel.com>
Date: Mon, 28 Oct 2024 16:53:04 -0700
From: Daniel Sneddon <daniel.sneddon@...ux.intel.com>
To: Jonathan Corbet <corbet@....net>, Thomas Gleixner <tglx@...utronix.de>,
 Borislav Petkov <bp@...en8.de>, Peter Zijlstra <peterz@...radead.org>,
 Josh Poimboeuf <jpoimboe@...nel.org>, Ingo Molnar <mingo@...hat.com>,
 Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org
Cc: hpa@...or.com, linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
 pawan.kumar.gupta@...ux.intel.com
Subject: Re: [PATCH 0/2] VERW based clean-up

Of course it isn't until after I hit send to realize I missed the "-v2" flag
when I generated these patches! Sorry for the confusion!

On 10/28/24 16:50, Daniel Sneddon wrote:
> There are several mitigations that use the VERW instruction to clean
> up internal CPU buffers.  Currently, each of these mitigations is
> treated independently, but if VERW is needed for one of the
> mitigations, it's on for all of them. This can lead to some confusion
> if a user tries to disable one of the mitigations, but it is left
> enabled for one of the others. The user needs to disable all 4 VERW-
> based mitigations. Warn the user when one or more VERW mitigations are
> disabled but not all of them. While we're messing with VERW
> mitigations, might as well simplify them and remove the need to call
> each of them twice.
> 
> V2:
> Dropped the new knob previously introduced in the first patch (Borislav)
> Add warning if not all 4 mitigations states match (Borislav)
> Removed extra comment (Josh)
> Code clean-up (Josh)
> 
> 
> Daniel Sneddon (2):
>   x86/bugs: Check VERW mitigations for consistency
>   x86/bugs: Clean-up verw mitigations
> 
>  arch/x86/include/asm/processor.h |   2 +-
>  arch/x86/kernel/cpu/bugs.c       | 206 +++++++++++++------------------
>  2 files changed, 90 insertions(+), 118 deletions(-)
>