linux-kernel - [patch 4/6] x86/idle: Cleanup idle

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20240229142248.455616019@linutronix.de>
Date: Thu, 29 Feb 2024 15:23:40 +0100 (CET)
From: Thomas Gleixner <tglx@...utronix.de>
To: LKML <linux-kernel@...r.kernel.org>
Cc: x86@...nel.org,
 Steven Rostedt <rostedt@...dmis.org>,
 "Paul E. McKenney" <paulmck@...nel.org>
Subject: [patch 4/6] x86/idle: Cleanup idle_setup()

Updating the static call for x86_idle() from idle_setup() is counter
intuitive.

Let select_idle_routine() handle it like the other idle choices, which
allows to simplify the idle selection later on.

While at it rewrite comments and return a proper error code and not -1.

Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
---
 arch/x86/kernel/process.c |   24 +++++++-----------------
 1 file changed, 7 insertions(+), 17 deletions(-)

--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -857,8 +857,8 @@ static int prefer_mwait_c1_over_halt(con
 {
 	u32 eax, ebx, ecx, edx;
 
-	/* User has disallowed the use of MWAIT. Fallback to HALT */
-	if (boot_option_idle_override == IDLE_NOMWAIT)
+	/* If override is enforced on the command line, fall back to HALT. */
+	if (boot_option_idle_override != IDLE_NO_OVERRIDE)
 		return 0;
 
 	/* MWAIT is not supported on this platform. Fallback to HALT */
@@ -975,24 +975,14 @@ static int __init idle_setup(char *str)
 		boot_option_idle_override = IDLE_POLL;
 		cpu_idle_poll_ctrl(true);
 	} else if (!strcmp(str, "halt")) {
-		/*
-		 * When the boot option of idle=halt is added, halt is
-		 * forced to be used for CPU idle. In such case CPU C2/C3
-		 * won't be used again.
-		 * To continue to load the CPU idle driver, don't touch
-		 * the boot_option_idle_override.
-		 */
-		static_call_update(x86_idle, default_idle);
+		/* 'idle=halt' HALT for idle. C-states are disabled. */
 		boot_option_idle_override = IDLE_HALT;
 	} else if (!strcmp(str, "nomwait")) {
-		/*
-		 * If the boot option of "idle=nomwait" is added,
-		 * it means that mwait will be disabled for CPU C1/C2/C3
-		 * states.
-		 */
+		/* 'idle=nomwait' disables MWAIT for idle */
 		boot_option_idle_override = IDLE_NOMWAIT;
-	} else
-		return -1;
+	} else {
+		return -EINVAL;
+	}
 
 	return 0;
 }