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

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Message-ID: <175225018061.406.7548749218244696205.tip-bot2@tip-bot2>
Date: Fri, 11 Jul 2025 16:09:40 -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 RFDS

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

Commit-ID:     54b53dca650bb273655a9a9b5a5b5a3fced0bcc1
Gitweb:        https://git.kernel.org/tip/54b53dca650bb273655a9a9b5a5b5a3fced0bcc1
Author:        David Kaplan <david.kaplan@....com>
AuthorDate:    Mon, 07 Jul 2025 13:33:03 -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 RFDS

Use attack vector controls to determine if RFDS 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/20250707183316.1349127-9-david.kaplan@amd.com
---
 arch/x86/kernel/cpu/bugs.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 39ff556..a557d17 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -748,13 +748,17 @@ static inline bool __init verw_clears_cpu_reg_file(void)
 
 static void __init rfds_select_mitigation(void)
 {
-	if (!boot_cpu_has_bug(X86_BUG_RFDS) || cpu_mitigations_off()) {
+	if (!boot_cpu_has_bug(X86_BUG_RFDS)) {
 		rfds_mitigation = RFDS_MITIGATION_OFF;
 		return;
 	}
 
-	if (rfds_mitigation == RFDS_MITIGATION_AUTO)
-		rfds_mitigation = RFDS_MITIGATION_VERW;
+	if (rfds_mitigation == RFDS_MITIGATION_AUTO) {
+		if (should_mitigate_vuln(X86_BUG_RFDS))
+			rfds_mitigation = RFDS_MITIGATION_VERW;
+		else
+			rfds_mitigation = RFDS_MITIGATION_OFF;
+	}
 
 	if (rfds_mitigation == RFDS_MITIGATION_OFF)
 		return;
@@ -765,7 +769,7 @@ static void __init rfds_select_mitigation(void)
 
 static void __init rfds_update_mitigation(void)
 {
-	if (!boot_cpu_has_bug(X86_BUG_RFDS) || cpu_mitigations_off())
+	if (!boot_cpu_has_bug(X86_BUG_RFDS))
 		return;
 
 	if (verw_clear_cpu_buf_mitigation_selected)