diff options
| author | Jiri Kosina <jkosina@suse.cz> | 2018-07-13 16:23:23 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-08-15 17:37:30 +0200 |
| commit | 758b51878d9e6221e2ee04d00425cddbbb5efb6f (patch) | |
| tree | 6cd6b80c2db58604ab5e09ac59fd14c616f139c7 | |
| parent | fe30a30f5906c1bea13ee224fbe34f994cb42d5d (diff) | |
| download | linux-758b51878d9e6221e2ee04d00425cddbbb5efb6f.tar.gz | |
cpu/hotplug: Expose SMT control init function
commit 8e1b706b6e819bed215c0db16345568864660393 upstream.
The L1TF mitigation will gain a commend line parameter which allows to set
a combination of hypervisor mitigation and SMT control.
Expose cpu_smt_disable() so the command line parser can tweak SMT settings.
[ tglx: Split out of larger patch and made it preserve an already existing
force off state ]
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Jiri Kosina <jkosina@suse.cz>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/20180713142323.039715135@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | include/linux/cpu.h | 2 | ||||
| -rw-r--r-- | kernel/cpu.c | 16 |
2 files changed, 15 insertions, 3 deletions
diff --git a/include/linux/cpu.h b/include/linux/cpu.h index b79b3970e46b04..7fb6b4ddf4e247 100644 --- a/include/linux/cpu.h +++ b/include/linux/cpu.h @@ -177,8 +177,10 @@ enum cpuhp_smt_control { #if defined(CONFIG_SMP) && defined(CONFIG_HOTPLUG_SMT) extern enum cpuhp_smt_control cpu_smt_control; +extern void cpu_smt_disable(bool force); #else # define cpu_smt_control (CPU_SMT_ENABLED) +static inline void cpu_smt_disable(bool force) { } #endif #endif /* _LINUX_CPU_H_ */ diff --git a/kernel/cpu.c b/kernel/cpu.c index d0b4ba9a2058ee..bd43ca43c4a0af 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -347,13 +347,23 @@ EXPORT_SYMBOL_GPL(cpu_hotplug_enable); enum cpuhp_smt_control cpu_smt_control __read_mostly = CPU_SMT_ENABLED; EXPORT_SYMBOL_GPL(cpu_smt_control); -static int __init smt_cmdline_disable(char *str) +void __init cpu_smt_disable(bool force) { - cpu_smt_control = CPU_SMT_DISABLED; - if (str && !strcmp(str, "force")) { + if (cpu_smt_control == CPU_SMT_FORCE_DISABLED || + cpu_smt_control == CPU_SMT_NOT_SUPPORTED) + return; + + if (force) { pr_info("SMT: Force disabled\n"); cpu_smt_control = CPU_SMT_FORCE_DISABLED; + } else { + cpu_smt_control = CPU_SMT_DISABLED; } +} + +static int __init smt_cmdline_disable(char *str) +{ + cpu_smt_disable(str && !strcmp(str, "force")); return 0; } early_param("nosmt", smt_cmdline_disable); |