linux-kernel - [PATCH v2 26/35] x86/bugs: Add attack vector controls for srbds

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Message-ID: <20241105215455.359471-27-david.kaplan@amd.com>
Date: Tue, 5 Nov 2024 15:54:46 -0600
From: David Kaplan <david.kaplan@....com>
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>
CC: <linux-kernel@...r.kernel.org>
Subject: [PATCH v2 26/35] x86/bugs: Add attack vector controls for srbds

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

Signed-off-by: David Kaplan <david.kaplan@....com>
---
 arch/x86/kernel/cpu/bugs.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index ecf7046673b9..083452942264 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -834,8 +834,14 @@ static void __init srbds_select_mitigation(void)
 	if (!boot_cpu_has_bug(X86_BUG_SRBDS))
 		return;
 
-	if (srbds_mitigation == SRBDS_MITIGATION_AUTO)
-		srbds_mitigation = SRBDS_MITIGATION_FULL;
+	if (srbds_mitigation == SRBDS_MITIGATION_AUTO) {
+		if (should_mitigate_vuln(X86_BUG_SRBDS))
+			srbds_mitigation = SRBDS_MITIGATION_FULL;
+		else {
+			srbds_mitigation = SRBDS_MITIGATION_OFF;
+			return;
+		}
+	}
 
 	/*
 	 * Check to see if this is one of the MDS_NO systems supporting TSX that
-- 
2.34.1