linux-kernel - [PATCH v4 33/36] x86/bugs: Add attack vector controls for srso

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Message-ID: <20250310164023.779191-34-david.kaplan@amd.com>
Date: Mon, 10 Mar 2025 11:40:20 -0500
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>, Brendan Jackman <jackmanb@...gle.com>,
	Derek Manwaring <derekmn@...zon.com>
Subject: [PATCH v4 33/36] x86/bugs: Add attack vector controls for srso

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

Signed-off-by: David Kaplan <david.kaplan@....com>
---
 arch/x86/kernel/cpu/bugs.c | 17 +++++++++++------
 1 file changed, 11 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index e38529f3022b..4e1fc1468870 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -2858,14 +2858,19 @@ static void __init srso_select_mitigation(void)
 {
 	bool has_microcode = boot_cpu_has(X86_FEATURE_IBPB_BRTYPE);
 
-	if (!boot_cpu_has_bug(X86_BUG_SRSO) || cpu_mitigations_off())
+	if (!boot_cpu_has_bug(X86_BUG_SRSO)) {
 		srso_mitigation = SRSO_MITIGATION_NONE;
-
-	if (srso_mitigation == SRSO_MITIGATION_NONE)
 		return;
+	}
 
-	if (srso_mitigation == SRSO_MITIGATION_AUTO)
-		srso_mitigation = SRSO_MITIGATION_SAFE_RET;
+	if (srso_mitigation == SRSO_MITIGATION_AUTO) {
+		if (should_mitigate_vuln(X86_BUG_SRSO))
+			srso_mitigation = SRSO_MITIGATION_SAFE_RET;
+		else {
+			srso_mitigation = SRSO_MITIGATION_NONE;
+			return;
+		}
+	}
 
 	if (has_microcode) {
 		/*
@@ -2921,7 +2926,7 @@ static void __init srso_update_mitigation(void)
 	    boot_cpu_has(X86_FEATURE_IBPB_BRTYPE))
 		srso_mitigation = SRSO_MITIGATION_IBPB;
 
-	if (boot_cpu_has_bug(X86_BUG_SRSO) && !cpu_mitigations_off())
+	if (boot_cpu_has_bug(X86_BUG_SRSO))
 		pr_info("%s\n", srso_strings[srso_mitigation]);
 }
 
-- 
2.34.1