Commit f3d7eab7 authored by Thomas Gleixner's avatar Thomas Gleixner Committed by Borislav Petkov (AMD)
Browse files

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: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarBorislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20240229142248.455616019@linutronix.de
parent 0ab56287

arch/x86/kernel/process.c

+7 −17
Original line number Diff line number Diff line
@@ -857,8 +857,8 @@ static int prefer_mwait_c1_over_halt(const struct cpuinfo_x86 *c) 
{

	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 */
@@ -976,24 +976,14 @@ 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;

}