1 files changed, 16 insertions, 14 deletions

diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index e9f777bfed40..3fae23834069 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -297,15 +297,16 @@ static int __init tsc_setup(char *str)
 
 __setup("tsc=", tsc_setup);
 
-#define MAX_RETRIES     5
-#define SMI_TRESHOLD    50000
+#define MAX_RETRIES             5
+#define TSC_DEFAULT_THRESHOLD   0x20000
 
 /*
- * Read TSC and the reference counters. Take care of SMI disturbance
+ * Read TSC and the reference counters. Take care of any disturbances
  */
 static u64 tsc_read_refs(u64 *p, int hpet)
 {
         u64 t1, t2;
+        u64 thresh = tsc_khz ? tsc_khz >> 5 : TSC_DEFAULT_THRESHOLD;
         int i;
 
         for (i = 0; i < MAX_RETRIES; i++) {
@@ -315,7 +316,7 @@ static u64 tsc_read_refs(u64 *p, int hpet)
                 else
                         *p = acpi_pm_read_early();
                 t2 = get_cycles();
-                if ((t2 - t1) < SMI_TRESHOLD)
+                if ((t2 - t1) < thresh)
                         return t2;
         }
         return ULLONG_MAX;
@@ -703,15 +704,15 @@ static unsigned long pit_hpet_ptimer_calibrate_cpu(void)
          * zero. In each wait loop iteration we read the TSC and check
          * the delta to the previous read. We keep track of the min
          * and max values of that delta. The delta is mostly defined
-         * by the IO time of the PIT access, so we can detect when a
-         * SMI/SMM disturbance happened between the two reads. If the
+         * by the IO time of the PIT access, so we can detect when
+         * any disturbance happened between the two reads. If the
          * maximum time is significantly larger than the minimum time,
          * then we discard the result and have another try.
          *
          * 2) Reference counter. If available we use the HPET or the
          * PMTIMER as a reference to check the sanity of that value.
          * We use separate TSC readouts and check inside of the
-         * reference read for a SMI/SMM disturbance. We dicard
+         * reference read for any possible disturbance. We dicard
          * disturbed values here as well. We do that around the PIT
          * calibration delay loop as we have to wait for a certain
          * amount of time anyway.
@@ -744,7 +745,7 @@ static unsigned long pit_hpet_ptimer_calibrate_cpu(void)
                 if (ref1 == ref2)
                         continue;
 
-                /* Check, whether the sampling was disturbed by an SMI */
+                /* Check, whether the sampling was disturbed */
                 if (tsc1 == ULLONG_MAX || tsc2 == ULLONG_MAX)
                         continue;
 
@@ -1268,7 +1269,7 @@ static DECLARE_DELAYED_WORK(tsc_irqwork, tsc_refine_calibration_work);
  */
 static void tsc_refine_calibration_work(struct work_struct *work)
 {
-        static u64 tsc_start = -1, ref_start;
+        static u64 tsc_start = ULLONG_MAX, ref_start;
         static int hpet;
         u64 tsc_stop, ref_stop, delta;
         unsigned long freq;
@@ -1283,14 +1284,15 @@ static void tsc_refine_calibration_work(struct work_struct *work)
          * delayed the first time we expire. So set the workqueue
          * again once we know timers are working.
          */
-        if (tsc_start == -1) {
+        if (tsc_start == ULLONG_MAX) {
+restart:
                 /*
                  * Only set hpet once, to avoid mixing hardware
                  * if the hpet becomes enabled later.
                  */
                 hpet = is_hpet_enabled();
-                schedule_delayed_work(&tsc_irqwork, HZ);
                 tsc_start = tsc_read_refs(&ref_start, hpet);
+                schedule_delayed_work(&tsc_irqwork, HZ);
                 return;
         }
 
@@ -1300,9 +1302,9 @@ static void tsc_refine_calibration_work(struct work_struct *work)
         if (ref_start == ref_stop)
                 goto out;
 
-        /* Check, whether the sampling was disturbed by an SMI */
-        if (tsc_start == ULLONG_MAX || tsc_stop == ULLONG_MAX)
-                goto out;
+        /* Check, whether the sampling was disturbed */
+        if (tsc_stop == ULLONG_MAX)
+                goto restart;
 
         delta = tsc_stop - tsc_start;
         delta *= 1000000LL;