linux-kernel - [PATCH v2 0/2] x86/bugs: default spectre_v2_user

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Message-Id: <20241031-x86_bugs_last_v2-v2-0-b7ff1dab840e@debian.org>
Date: Thu, 31 Oct 2024 04:06:15 -0700
From: Breno Leitao <leitao@...ian.org>
To: Thomas Gleixner <tglx@...utronix.de>, Borislav Petkov <bp@...en8.de>, 
 Peter Zijlstra <peterz@...radead.org>, Josh Poimboeuf <jpoimboe@...nel.org>, 
 Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>, 
 Ingo Molnar <mingo@...hat.com>, Dave Hansen <dave.hansen@...ux.intel.com>, 
 x86@...nel.org, "H. Peter Anvin" <hpa@...or.com>, 
 Jonathan Corbet <corbet@....net>
Cc: linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org, 
 Breno Leitao <leitao@...ian.org>
Subject: [PATCH v2 0/2] x86/bugs: default spectre_v2_user_cmd depends on
 Kconfig

This series contains two patches that improve the handling of Spectre v2
user mitigations in the x86 architecture:

1. Make spectre_v2_user_cmd default depend on Kconfig
2. Simplify spectre_v2_user_select_mitigation() using cpu_smt_possible()

The first patch was originally part of a larger patchset [1] but was
removed in version 3 [2] to simplify the revision process. Now that the
original patchset has been merged, I am resubmitting this patch
separately.

This patch aligns the default configuration of spectre_v2_user_cmd with
CONFIG_MITIGATION_SPECTRE_V2, consistent with other user-selectable
mitigations.

The other patch is a simple optimization that leverages the
cpu_smt_possible() helper function to simplify the code in
spectre_v2_user_select_mitigation().

Together, these changes improve code consistency and simplify the
configuration and selection of Spectre v2 user mitigations.

[1] https://lore.kernel.org/all/20240118173213.2008115-4-leitao@debian.org/
[2] https://lore.kernel.org/all/20240422165830.2142904-1-leitao@debian.org/

Changelog:
 v2:
   * Added the documentation bits in kernel-parameters.txt, as suggested
     by Pawan.
 v1:
   * https://lore.kernel.org/all/20241015105107.496105-1-leitao@debian.org/#r

Signed-off-by: Breno Leitao <leitao@...ian.org>
---
Breno Leitao (2):
      x86/bugs: Use cpu_smt_possible helper
      x86/bugs: spectre user default must depend on MITIGATION_SPECTRE_V2

 Documentation/admin-guide/kernel-parameters.txt |  2 ++
 arch/x86/kernel/cpu/bugs.c                      | 17 ++++++++---------
 2 files changed, 10 insertions(+), 9 deletions(-)
---
base-commit: 81983758430957d9a5cb3333fe324fd70cf63e7e
change-id: 20241031-x86_bugs_last_v2-adf8f107fd1e

Best regards,
-- 
Breno Leitao <leitao@...ian.org>