linux-kernel - [tip: x86/bugs] x86/bugs: Add attack vector controls for TAA

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Message-ID: <175225018223.406.5657922974048706825.tip-bot2@tip-bot2>
Date: Fri, 11 Jul 2025 16:09:42 -0000
From: "tip-bot2 for David Kaplan" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: David Kaplan <david.kaplan@....com>,
 "Borislav Petkov (AMD)" <bp@...en8.de>, x86@...nel.org,
 linux-kernel@...r.kernel.org
Subject: [tip: x86/bugs] x86/bugs: Add attack vector controls for TAA

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

Commit-ID:     736565d4edcd8b6dad50fca0c0134e7918e3d61c
Gitweb:        https://git.kernel.org/tip/736565d4edcd8b6dad50fca0c0134e7918e3d61c
Author:        David Kaplan <david.kaplan@....com>
AuthorDate:    Mon, 07 Jul 2025 13:33:01 -05:00
Committer:     Borislav Petkov (AMD) <bp@...en8.de>
CommitterDate: Fri, 11 Jul 2025 17:56:40 +02:00

x86/bugs: Add attack vector controls for TAA

Use attack vector controls to determine if TAA mitigation is required.

Signed-off-by: David Kaplan <david.kaplan@....com>
Signed-off-by: Borislav Petkov (AMD) <bp@...en8.de>
Link: https://lore.kernel.org/20250707183316.1349127-7-david.kaplan@amd.com
---
 arch/x86/kernel/cpu/bugs.c | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 31e0cf8..438c482 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -538,12 +538,13 @@ static void __init taa_select_mitigation(void)
 		return;
 	}
 
-	if (cpu_mitigations_off())
-		taa_mitigation = TAA_MITIGATION_OFF;
-
 	/* Microcode will be checked in taa_update_mitigation(). */
-	if (taa_mitigation == TAA_MITIGATION_AUTO)
-		taa_mitigation = TAA_MITIGATION_VERW;
+	if (taa_mitigation == TAA_MITIGATION_AUTO) {
+		if (should_mitigate_vuln(X86_BUG_TAA))
+			taa_mitigation = TAA_MITIGATION_VERW;
+		else
+			taa_mitigation = TAA_MITIGATION_OFF;
+	}
 
 	if (taa_mitigation != TAA_MITIGATION_OFF)
 		verw_clear_cpu_buf_mitigation_selected = true;
@@ -551,7 +552,7 @@ static void __init taa_select_mitigation(void)
 
 static void __init taa_update_mitigation(void)
 {
-	if (!taa_vulnerable() || cpu_mitigations_off())
+	if (!taa_vulnerable())
 		return;
 
 	if (verw_clear_cpu_buf_mitigation_selected)
@@ -592,7 +593,7 @@ static void __init taa_apply_mitigation(void)
 		 */
 		setup_force_cpu_cap(X86_FEATURE_CLEAR_CPU_BUF);
 
-		if (taa_nosmt || cpu_mitigations_auto_nosmt())
+		if (taa_nosmt || smt_mitigations == SMT_MITIGATIONS_ON)
 			cpu_smt_disable(false);
 	}
 }