From 7b3d2f6e08ed5eb6bcf6912938f7a542405f8e8e Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Sat, 19 Nov 2016 13:47:33 +0000 Subject: [PATCH] x86/tsc: Use X86_FEATURE_TSC_ADJUST in detect_art() The art detection uses rdmsrl_safe() to detect the availablity of the TSC_ADJUST MSR. That's pointless because we have a feature bit for this. Use it. Signed-off-by: Thomas Gleixner Reviewed-by: Ingo Molnar Cc: Peter Zijlstra Cc: Yinghai Lu Cc: Borislav Petkov Link: http://lkml.kernel.org/r/20161119134017.483561692@linutronix.de Signed-off-by: Thomas Gleixner --- arch/x86/kernel/tsc.c | 14 ++++++++------ 1 file changed, 8 insertions(+), 6 deletions(-) diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c index 0ff1ec61d1e4..2b27c5ae9d1f 100644 --- a/arch/x86/kernel/tsc.c +++ b/arch/x86/kernel/tsc.c @@ -1057,18 +1057,20 @@ static void detect_art(void) if (boot_cpu_data.cpuid_level < ART_CPUID_LEAF) return; - cpuid(ART_CPUID_LEAF, &art_to_tsc_denominator, - &art_to_tsc_numerator, unused, unused+1); - - /* Don't enable ART in a VM, non-stop TSC required */ + /* Don't enable ART in a VM, non-stop TSC and TSC_ADJUST required */ if (boot_cpu_has(X86_FEATURE_HYPERVISOR) || !boot_cpu_has(X86_FEATURE_NONSTOP_TSC) || - art_to_tsc_denominator < ART_MIN_DENOMINATOR) + !boot_cpu_has(X86_FEATURE_TSC_ADJUST)) return; - if (rdmsrl_safe(MSR_IA32_TSC_ADJUST, &art_to_tsc_offset)) + cpuid(ART_CPUID_LEAF, &art_to_tsc_denominator, + &art_to_tsc_numerator, unused, unused+1); + + if (art_to_tsc_denominator < ART_MIN_DENOMINATOR) return; + rdmsrl(MSR_IA32_TSC_ADJUST, art_to_tsc_offset); + /* Make this sticky over multiple CPU init calls */ setup_force_cpu_cap(X86_FEATURE_ART); } -- 2.39.5