Commit 954e6da5 authored by Nathan Fontenot's avatar Nathan Fontenot Committed by Benjamin Herrenschmidt
Browse files

powerpc: Correct smt_enabled=X boot option for > 2 threads per core 



The 'smt_enabled=X' boot option does not handle values of X > 2.
For Power 7 processors with smt modes of 0,1,2,3, and 4 this does
not work.  This patch allows the smt_enabled option to be set to
any value limited to a max equal to the number of threads per
core.

Signed-off-by: default avatarNathan Fontenot <nfont@austin.ibm.com>
Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
parent 1afb56cf

arch/powerpc/kernel/setup_64.c

+36 −27
Original line number Diff line number Diff line
@@ -95,7 +95,7 @@ int ucache_bsize; 


#ifdef CONFIG_SMP



static int smt_enabled_cmdline;

static char *smt_enabled_cmdline;



/* Look for ibm,smt-enabled OF option */

static void check_smt_enabled(void)
@@ -103,37 +103,46 @@ static void check_smt_enabled(void) 
	struct device_node *dn;

	const char *smt_option;



	/* Default to enabling all threads */

	smt_enabled_at_boot = threads_per_core;



	/* Allow the command line to overrule the OF option */

	if (smt_enabled_cmdline)

		return;

	if (smt_enabled_cmdline) {

		if (!strcmp(smt_enabled_cmdline, "on"))

			smt_enabled_at_boot = threads_per_core;

		else if (!strcmp(smt_enabled_cmdline, "off"))

			smt_enabled_at_boot = 0;

		else {

			long smt;

			int rc;



			rc = strict_strtol(smt_enabled_cmdline, 10, &smt);

			if (!rc)

				smt_enabled_at_boot =

					min(threads_per_core, (int)smt);

		}

	} else {

		dn = of_find_node_by_path("/options");



		if (dn) {

		smt_option = of_get_property(dn, "ibm,smt-enabled", NULL);

			smt_option = of_get_property(dn, "ibm,smt-enabled",

						     NULL);



			if (smt_option) {

				if (!strcmp(smt_option, "on"))

				smt_enabled_at_boot = 1;

					smt_enabled_at_boot = threads_per_core;

				else if (!strcmp(smt_option, "off"))

					smt_enabled_at_boot = 0;

			}



			of_node_put(dn);

		}

	}

}



/* Look for smt-enabled= cmdline option */

static int __init early_smt_enabled(char *p)

{

	smt_enabled_cmdline = 1;



	if (!p)

		return 0;



	if (!strcmp(p, "on") || !strcmp(p, "1"))

		smt_enabled_at_boot = 1;

	else if (!strcmp(p, "off") || !strcmp(p, "0"))

		smt_enabled_at_boot = 0;



	smt_enabled_cmdline = p;

	return 0;

}

early_param("smt-enabled", early_smt_enabled);
@@ -380,8 +389,8 @@ void __init setup_system(void) 
	 */

	xmon_setup();



	check_smt_enabled();

	smp_setup_cpu_maps();

	check_smt_enabled();



#ifdef CONFIG_SMP

	/* Release secondary cpus out of their spinloops at 0x60 now that

arch/powerpc/platforms/pseries/smp.c

+7 −4
Original line number Diff line number Diff line
@@ -182,10 +182,13 @@ static int smp_pSeries_cpu_bootable(unsigned int nr) 
	/* Special case - we inhibit secondary thread startup

	 * during boot if the user requests it.

	 */

	if (system_state < SYSTEM_RUNNING &&

	    cpu_has_feature(CPU_FTR_SMT) &&

	    !smt_enabled_at_boot && cpu_thread_in_core(nr) != 0)

	if (system_state < SYSTEM_RUNNING && cpu_has_feature(CPU_FTR_SMT)) {

		if (!smt_enabled_at_boot && cpu_thread_in_core(nr) != 0)

			return 0;

		if (smt_enabled_at_boot

		    && cpu_thread_in_core(nr) >= smt_enabled_at_boot)

			return 0;

	}



	return 1;

}

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