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Subject[patch 1/8] 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>
---
arch/x86/kernel/tsc.c | 14 ++++++++------
1 file changed, 8 insertions(+), 6 deletions(-)

--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -1043,18 +1043,20 @@ 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);
}

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