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authorThomas Gleixner <tglx@linutronix.de>2016-11-19 16:47:33 +0300
committerThomas Gleixner <tglx@linutronix.de>2016-11-29 21:23:15 +0300
commit7b3d2f6e08ed5eb6bcf6912938f7a542405f8e8e (patch)
tree0e6940350eeba63f102e93b8fb34b6f7e47df97c /arch/x86/kernel/tsc.c
parent984fecebda3b9c8e3d75f8492593da71c58972b3 (diff)
downloadlinux-7b3d2f6e08ed5eb6bcf6912938f7a542405f8e8e.tar.xz
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 <tglx@linutronix.de> Reviewed-by: Ingo Molnar <mingo@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Yinghai Lu <yinghai@kernel.org> Cc: Borislav Petkov <bp@alien8.de> Link: http://lkml.kernel.org/r/20161119134017.483561692@linutronix.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'arch/x86/kernel/tsc.c')
-rw-r--r--arch/x86/kernel/tsc.c14
1 files 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);
}