Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel...

[mirror_ubuntu-zesty-kernel.git] / arch / x86 / kernel / tsc.c

diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index 3d743da828d38acff0013600ed582c8b14ef81b3..56380440d86229a41314487792decd6a04190fca 100644 (file)
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -43,6 +43,11 @@ static DEFINE_STATIC_KEY_FALSE(__use_tsc);
 
 int tsc_clocksource_reliable;
 
+static u32 art_to_tsc_numerator;
+static u32 art_to_tsc_denominator;
+static u64 art_to_tsc_offset;
+struct clocksource *art_related_clocksource;
+
 /*
  * Use a ring-buffer like data structure, where a writer advances the head by
  * writing a new data entry and a reader advances the tail when it observes a
@@ -964,6 +969,37 @@ core_initcall(cpufreq_tsc);
 
 #endif /* CONFIG_CPU_FREQ */
 
+#define ART_CPUID_LEAF (0x15)
+#define ART_MIN_DENOMINATOR (1)
+
+
+/*
+ * If ART is present detect the numerator:denominator to convert to TSC
+ */
+static void detect_art(void)
+{
+       unsigned int unused[2];
+
+       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 */
+       if (boot_cpu_has(X86_FEATURE_HYPERVISOR) ||
+           !boot_cpu_has(X86_FEATURE_NONSTOP_TSC) ||
+           art_to_tsc_denominator < ART_MIN_DENOMINATOR)
+               return;
+
+       if (rdmsrl_safe(MSR_IA32_TSC_ADJUST, &art_to_tsc_offset))
+               return;
+
+       /* Make this sticky over multiple CPU init calls */
+       setup_force_cpu_cap(X86_FEATURE_ART);
+}
+
+
 /* clocksource code */
 
 static struct clocksource clocksource_tsc;
@@ -1071,6 +1107,25 @@ int unsynchronized_tsc(void)
        return 0;
 }
 
+/*
+ * Convert ART to TSC given numerator/denominator found in detect_art()
+ */
+struct system_counterval_t convert_art_to_tsc(cycle_t art)
+{
+       u64 tmp, res, rem;
+
+       rem = do_div(art, art_to_tsc_denominator);
+
+       res = art * art_to_tsc_numerator;
+       tmp = rem * art_to_tsc_numerator;
+
+       do_div(tmp, art_to_tsc_denominator);
+       res += tmp + art_to_tsc_offset;
+
+       return (struct system_counterval_t) {.cs = art_related_clocksource,
+                       .cycles = res};
+}
+EXPORT_SYMBOL(convert_art_to_tsc);
 
 static void tsc_refine_calibration_work(struct work_struct *work);
 static DECLARE_DELAYED_WORK(tsc_irqwork, tsc_refine_calibration_work);
@@ -1142,6 +1197,8 @@ static void tsc_refine_calibration_work(struct work_struct *work)
                (unsigned long)tsc_khz % 1000);
 
 out:
+       if (boot_cpu_has(X86_FEATURE_ART))
+               art_related_clocksource = &clocksource_tsc;
        clocksource_register_khz(&clocksource_tsc, tsc_khz);
 }
 
@@ -1235,6 +1292,8 @@ void __init tsc_init(void)
                mark_tsc_unstable("TSCs unsynchronized");
 
        check_system_tsc_reliable();
+
+       detect_art();
 }
 
 #ifdef CONFIG_SMP
@@ -1246,14 +1305,14 @@ void __init tsc_init(void)
  */
 unsigned long calibrate_delay_is_known(void)
 {
-       int i, cpu = smp_processor_id();
+       int sibling, cpu = smp_processor_id();
 
        if (!tsc_disabled && !cpu_has(&cpu_data(cpu), X86_FEATURE_CONSTANT_TSC))
                return 0;
 
-       for_each_online_cpu(i)
-               if (cpu_data(i).phys_proc_id == cpu_data(cpu).phys_proc_id)
-                       return cpu_data(i).loops_per_jiffy;
+       sibling = cpumask_any_but(topology_core_cpumask(cpu), cpu);
+       if (sibling < nr_cpu_ids)
+               return cpu_data(sibling).loops_per_jiffy;
        return 0;
 }
 #endif