linux-kernel - [tip: x86/core] x86/bugs: Fix spectre

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Message-ID: <174782181894.406.10038998736172191302.tip-bot2@tip-bot2>
Date: Wed, 21 May 2025 10:03:38 -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>, x86@...nel.org,
 linux-kernel@...r.kernel.org
Subject: [tip: x86/core] x86/bugs: Fix spectre_v2 mitigation default on Intel

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

Commit-ID:     6a7c3c2606105a41dde81002c0037420bc1ddf00
Gitweb:        https://git.kernel.org/tip/6a7c3c2606105a41dde81002c0037420bc1ddf00
Author:        Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>
AuthorDate:    Tue, 20 May 2025 22:35:20 -07:00
Committer:     Borislav Petkov (AMD) <bp@...en8.de>
CommitterDate: Wed, 21 May 2025 11:51:32 +02:00

x86/bugs: Fix spectre_v2 mitigation default on Intel

Commit

  480e803dacf8 ("x86/bugs: Restructure spectre_v2 mitigation")

inadvertently changed the spectre-v2 mitigation default from eIBRS to IBRS on
Intel. While splitting the spectre_v2 mitigation in select/update/apply
functions, eIBRS and IBRS selection logic was separated in select and update.

This caused IBRS selection to not consider that eIBRS mitigation is already
selected, fix it.

Fixes: 480e803dacf8 ("x86/bugs: Restructure spectre_v2 mitigation")
Signed-off-by: Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>
Signed-off-by: Borislav Petkov (AMD) <bp@...en8.de>
Link: https://lore.kernel.org/20250520-eibrs-fix-v1-1-91bacd35ed09@linux.intel.com
---
 arch/x86/kernel/cpu/bugs.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 3d5796d..7f94e6a 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -2105,7 +2105,8 @@ static void __init spectre_v2_select_mitigation(void)
 
 static void __init spectre_v2_update_mitigation(void)
 {
-	if (spectre_v2_cmd == SPECTRE_V2_CMD_AUTO) {
+	if (spectre_v2_cmd == SPECTRE_V2_CMD_AUTO &&
+	    !spectre_v2_in_eibrs_mode(spectre_v2_enabled)) {
 		if (IS_ENABLED(CONFIG_MITIGATION_IBRS_ENTRY) &&
 		    boot_cpu_has_bug(X86_BUG_RETBLEED) &&
 		    retbleed_mitigation != RETBLEED_MITIGATION_NONE &&