linux-kernel - [tip: x86/bugs] x86/bugs: Simplify the retbleed=stuff checks

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Message-ID: <175075954943.406.17585422913122991240.tip-bot2@tip-bot2>
Date: Tue, 24 Jun 2025 10:05:49 -0000
From: "tip-bot2 for Pawan Gupta" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>,
 "Borislav Petkov (AMD)" <bp@...en8.de>,
 Nikolay Borisov <nik.borisov@...e.com>, x86@...nel.org,
 linux-kernel@...r.kernel.org
Subject: [tip: x86/bugs] x86/bugs: Simplify the retbleed=stuff checks

The following commit has been merged into the x86/bugs branch of tip:

Commit-ID:     530e80648bff083e1d19ad7248c0540812a9a35f
Gitweb:        https://git.kernel.org/tip/530e80648bff083e1d19ad7248c0540812a9a35f
Author:        Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>
AuthorDate:    Wed, 11 Jun 2025 10:29:15 -07:00
Committer:     Borislav Petkov (AMD) <bp@...en8.de>
CommitterDate: Mon, 23 Jun 2025 12:16:30 +02:00

x86/bugs: Simplify the retbleed=stuff checks

Simplify the nested checks, remove redundant print and comment.

Signed-off-by: Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>
Signed-off-by: Borislav Petkov (AMD) <bp@...en8.de>
Reviewed-by: Nikolay Borisov <nik.borisov@...e.com>
Acked-by: Borislav Petkov (AMD) <bp@...en8.de>
Link: https://lore.kernel.org/20250611-eibrs-fix-v4-2-5ff86cac6c61@linux.intel.com
---
 arch/x86/kernel/cpu/bugs.c | 24 ++++++++----------------
 1 file changed, 8 insertions(+), 16 deletions(-)

diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 53649df..94d0de3 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -1263,24 +1263,16 @@ static void __init retbleed_update_mitigation(void)
 	if (!boot_cpu_has_bug(X86_BUG_RETBLEED) || cpu_mitigations_off())
 		return;
 
-	/*
-	 * retbleed=stuff is only allowed on Intel.  If stuffing can't be used
-	 * then a different mitigation will be selected below.
-	 *
-	 * its=stuff will also attempt to enable stuffing.
-	 */
-	if (retbleed_mitigation == RETBLEED_MITIGATION_STUFF ||
-	    its_mitigation == ITS_MITIGATION_RETPOLINE_STUFF) {
-		if (spectre_v2_enabled != SPECTRE_V2_RETPOLINE) {
-			pr_err("WARNING: retbleed=stuff depends on spectre_v2=retpoline\n");
-			retbleed_mitigation = RETBLEED_MITIGATION_NONE;
-		} else {
-			if (retbleed_mitigation != RETBLEED_MITIGATION_STUFF)
-				pr_info("Retbleed mitigation updated to stuffing\n");
+	 /* ITS can also enable stuffing */
+	if (its_mitigation == ITS_MITIGATION_RETPOLINE_STUFF)
+		retbleed_mitigation = RETBLEED_MITIGATION_STUFF;
 
-			retbleed_mitigation = RETBLEED_MITIGATION_STUFF;
-		}
+	if (retbleed_mitigation == RETBLEED_MITIGATION_STUFF &&
+	    spectre_v2_enabled != SPECTRE_V2_RETPOLINE) {
+		pr_err("WARNING: retbleed=stuff depends on spectre_v2=retpoline\n");
+		retbleed_mitigation = RETBLEED_MITIGATION_NONE;
 	}
+
 	/*
 	 * Let IBRS trump all on Intel without affecting the effects of the
 	 * retbleed= cmdline option except for call depth based stuffing