linux-kernel - [tip: x86/bugs] x86/bugs: Use the cpu_smt_possible() helper instead of open-coded code

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Message-ID: <174100326694.10177.17515354436837072065.tip-bot2@tip-bot2>
Date: Mon, 03 Mar 2025 12:01:06 -0000
From: "tip-bot2 for Breno Leitao" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Breno Leitao <leitao@...ian.org>, Ingo Molnar <mingo@...nel.org>,
 Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>,
 David Kaplan <David.Kaplan@....com>, x86@...nel.org,
 linux-kernel@...r.kernel.org
Subject: [tip: x86/bugs] x86/bugs: Use the cpu_smt_possible() helper instead
 of open-coded code

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

Commit-ID:     2a08b832712980b9eb0e913d64a42c74fc56319b
Gitweb:        https://git.kernel.org/tip/2a08b832712980b9eb0e913d64a42c74fc56319b
Author:        Breno Leitao <leitao@...ian.org>
AuthorDate:    Thu, 31 Oct 2024 04:06:16 -07:00
Committer:     Ingo Molnar <mingo@...nel.org>
CommitterDate: Mon, 03 Mar 2025 12:48:17 +01:00

x86/bugs: Use the cpu_smt_possible() helper instead of open-coded code

There is a helper function to check if SMT is available. Use this helper
instead of performing the check manually.

The helper function cpu_smt_possible() does exactly the same thing as
was being done manually inside spectre_v2_user_select_mitigation().
Specifically, it returns false if CONFIG_SMP is disabled, otherwise
it checks the cpu_smt_control global variable.

This change improves code consistency and reduces duplication.

No change in functionality intended.

Signed-off-by: Breno Leitao <leitao@...ian.org>
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Reviewed-by: Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>
Cc: David Kaplan <David.Kaplan@....com>
Link: https://lore.kernel.org/r/20241031-x86_bugs_last_v2-v2-1-b7ff1dab840e@debian.org
---
 arch/x86/kernel/cpu/bugs.c | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 93c437f..346bebf 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -1346,16 +1346,11 @@ static void __init
 spectre_v2_user_select_mitigation(void)
 {
 	enum spectre_v2_user_mitigation mode = SPECTRE_V2_USER_NONE;
-	bool smt_possible = IS_ENABLED(CONFIG_SMP);
 	enum spectre_v2_user_cmd cmd;
 
 	if (!boot_cpu_has(X86_FEATURE_IBPB) && !boot_cpu_has(X86_FEATURE_STIBP))
 		return;
 
-	if (cpu_smt_control == CPU_SMT_FORCE_DISABLED ||
-	    cpu_smt_control == CPU_SMT_NOT_SUPPORTED)
-		smt_possible = false;
-
 	cmd = spectre_v2_parse_user_cmdline();
 	switch (cmd) {
 	case SPECTRE_V2_USER_CMD_NONE:
@@ -1416,7 +1411,7 @@ spectre_v2_user_select_mitigation(void)
 	 * so allow for STIBP to be selected in those cases.
 	 */
 	if (!boot_cpu_has(X86_FEATURE_STIBP) ||
-	    !smt_possible ||
+	    !cpu_smt_possible() ||
 	    (spectre_v2_in_eibrs_mode(spectre_v2_enabled) &&
 	     !boot_cpu_has(X86_FEATURE_AUTOIBRS)))
 		return;