linux-kernel - [PATCH AUTOSEL 5.18 22/54] x86/bugs: Do IBPB fallback check only once

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20220720011031.1023305-22-sashal@kernel.org>
Date:   Tue, 19 Jul 2022 21:09:59 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Josh Poimboeuf <jpoimboe@...nel.org>, Borislav Petkov <bp@...e.de>,
        Sasha Levin <sashal@...nel.org>, tglx@...utronix.de,
        mingo@...hat.com, bp@...en8.de, dave.hansen@...ux.intel.com,
        x86@...nel.org, peterz@...radead.org,
        pawan.kumar.gupta@...ux.intel.com, alexandre.chartre@...cle.com,
        kim.phillips@....com, sblbir@...zon.com
Subject: [PATCH AUTOSEL 5.18 22/54] x86/bugs: Do IBPB fallback check only once

From: Josh Poimboeuf <jpoimboe@...nel.org>

[ Upstream commit 0fe4aeea9c01baabecc8c3afc7889c809d939bc2 ]

When booting with retbleed=auto, if the kernel wasn't built with
CONFIG_CC_HAS_RETURN_THUNK, the mitigation falls back to IBPB.  Make
sure a warning is printed in that case.  The IBPB fallback check is done
twice, but it really only needs to be done once.

Signed-off-by: Josh Poimboeuf <jpoimboe@...nel.org>
Signed-off-by: Borislav Petkov <bp@...e.de>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 arch/x86/kernel/cpu/bugs.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index ca5f90375a7d..99c45cf27ae6 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -871,8 +871,9 @@ static void __init retbleed_select_mitigation(void)
 			retbleed_mitigation = RETBLEED_MITIGATION_UNRET;
 
 		/*
-		 * The Intel mitigation (IBRS) was already selected in
-		 * spectre_v2_select_mitigation().
+		 * The Intel mitigation (IBRS or eIBRS) was already selected in
+		 * spectre_v2_select_mitigation().  'retbleed_mitigation' will
+		 * be set accordingly below.
 		 */
 
 		break;
-- 
2.35.1