linux-kernel - [PATCH v3 0/7] eIBRS fixes

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Message-ID: <20250522-eibrs-fix-v3-0-12704e291e1e@linux.intel.com>
Date: Thu, 22 May 2025 18:20:15 -0700
From: Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>
To: x86@...nel.org
Cc: David Kaplan <david.kaplan@....com>, linux-kernel@...r.kernel.org,
	"H. Peter Anvin" <hpa@...or.com>,
	Josh Poimboeuf <jpoimboe@...nel.org>,
	Borislav Petkov <bp@...en8.de>,
	Nikolay Borisov <nik.borisov@...e.com>
Subject: [PATCH v3 0/7] eIBRS fixes

v3:
- Get rid of AUTO check in retbleed mitigation. (Borislav)
- Update commit message to mention the preparatory patch. (Nikolay)
- Collected tags.

v2: https://lore.kernel.org/r/20250521-eibrs-fix-v2-0-70e2598e932c@linux.intel.com
- Split the ITS stuffing patch into smaller patches. (Borislav)
- Zap spectre_v2_in_retpoline_mode() helper. (Borislav)

v1: https://lore.kernel.org/r/20250520-eibrs-fix-v1-2-91bacd35ed09@linux.intel.com

tip/x86/core that has the restructured bugs.c including the recent ITS
mitigation has some disparities compared to upstream:

1. Spectre-v2 mitigation default is IBRS on eIBRS supported systems.
2. RSB stuffing mitigation for ITS is not allowed with eIBRS.

These couple of patches fixes the above issues.

---
Pawan Gupta (7):
      x86/retbleed: Avoid AUTO after the select step
      x86/retbleed: Simplify the =stuff checks
      x86/bugs: Exit early if return thunk is already set
      x86/its: Use switch/case to apply mitigation
      x86/retbleed: Introduce cdt_possible()
      x86/its: Remove =stuff dependency on retbleed
      x86/its: Allow stuffing in eIBRS+retpoline mode also

 arch/x86/kernel/cpu/bugs.c | 91 +++++++++++++++++++++++++++-------------------
 1 file changed, 53 insertions(+), 38 deletions(-)
---
base-commit: 6a7c3c2606105a41dde81002c0037420bc1ddf00
change-id: 20250520-eibrs-fix-6c452b697dbf

-- 
Thanks,
Pawan