From 954e6da54b2f3a5e2634312db800bc1395c509ee Mon Sep 17 00:00:00 2001 From: Nathan Fontenot Date: Thu, 5 Aug 2010 07:42:11 +0000 Subject: [PATCH] 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: Nathan Fontenot Signed-off-by: Benjamin Herrenschmidt --- arch/powerpc/kernel/setup_64.c | 63 ++++++++++++++++------------ arch/powerpc/platforms/pseries/smp.c | 11 +++-- 2 files changed, 43 insertions(+), 31 deletions(-) diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c index 1bee4b68fa45..e72690ec9b87 100644 --- a/arch/powerpc/kernel/setup_64.c +++ b/arch/powerpc/kernel/setup_64.c @@ -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; - /* Allow the command line to overrule the OF option */ - if (smt_enabled_cmdline) - return; - - dn = of_find_node_by_path("/options"); - - if (dn) { - smt_option = of_get_property(dn, "ibm,smt-enabled", NULL); + /* Default to enabling all threads */ + smt_enabled_at_boot = threads_per_core; - if (smt_option) { - if (!strcmp(smt_option, "on")) - smt_enabled_at_boot = 1; - else if (!strcmp(smt_option, "off")) - smt_enabled_at_boot = 0; - } - } + /* Allow the command line to overrule the OF option */ + 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); + + if (smt_option) { + if (!strcmp(smt_option, "on")) + 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 diff --git a/arch/powerpc/platforms/pseries/smp.c b/arch/powerpc/platforms/pseries/smp.c index 3b1bf61c45be..0317cce877c6 100644 --- a/arch/powerpc/platforms/pseries/smp.c +++ b/arch/powerpc/platforms/pseries/smp.c @@ -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) - return 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; } -- GitLab