svn commit: r298056 - head/sys/x86/x86

[Konstantin Belousov]

Author: kib
Date: Fri Apr 15 14:36:38 2016
New Revision: 298056
URL: https://svnweb.freebsd.org/changeset/base/298056

Log:
  Always calculate divisor for the counter mode of LAPIC timer.  Even if
  initially configured in the TSC deadline mode, eventtimer subsystem
  can be switched to periodic, and then DCR register is loaded with
  unitialized value.
  
  Reset the LAPIC eventtimer frequency and min/max periods when changing
  between deadline and counted periodic modes.
  
  Reported and tested by:	Vladimir Zakharov <zakharov.vv at gmail.com>
  Sponsored by:	The FreeBSD Foundation

Modified:
  head/sys/x86/x86/local_apic.c

Modified: head/sys/x86/x86/local_apic.c
==============================================================================
--- head/sys/x86/x86/local_apic.c	Fri Apr 15 14:30:40 2016	(r298055)
+++ head/sys/x86/x86/local_apic.c	Fri Apr 15 14:36:38 2016	(r298056)
@@ -170,7 +170,7 @@ vm_paddr_t lapic_paddr;
 int x2apic_mode;
 int lapic_eoi_suppression;
 static int lapic_timer_tsc_deadline;
-static u_long lapic_timer_divisor;
+static u_long lapic_timer_divisor, count_freq;
 static struct eventtimer lapic_et;
 #ifdef SMP
 static uint64_t lapic_ipi_wait_mult;
@@ -814,20 +814,46 @@ lapic_calibrate_initcount(struct eventti
 		printf("lapic: Divisor %lu, Frequency %lu Hz\n",
 		    lapic_timer_divisor, value);
 	}
-	et->et_frequency = value;
+	count_freq = value;
 }
 
 static void
 lapic_calibrate_deadline(struct eventtimer *et, struct lapic *la __unused)
 {
 
-	et->et_frequency = tsc_freq;
 	if (bootverbose) {
 		printf("lapic: deadline tsc mode, Frequency %ju Hz\n",
-		    (uintmax_t)et->et_frequency);
+		    (uintmax_t)tsc_freq);
 	}
 }
 
+static void
+lapic_change_mode(struct eventtimer *et, struct lapic *la,
+    enum lat_timer_mode newmode)
+{
+
+	if (la->la_timer_mode == newmode)
+		return;
+	switch (newmode) {
+	case LAT_MODE_PERIODIC:
+		lapic_timer_set_divisor(lapic_timer_divisor);
+		et->et_frequency = count_freq;
+		break;
+	case LAT_MODE_DEADLINE:
+		et->et_frequency = tsc_freq;
+		break;
+	case LAT_MODE_ONESHOT:
+		lapic_timer_set_divisor(lapic_timer_divisor);
+		et->et_frequency = count_freq;
+		break;
+	default:
+		panic("lapic_change_mode %d", newmode);
+	}
+	la->la_timer_mode = newmode;
+	et->et_min_period = (0x00000002LLU << 32) / et->et_frequency;
+	et->et_max_period = (0xfffffffeLLU << 32) / et->et_frequency;
+}
+
 static int
 lapic_et_start(struct eventtimer *et, sbintime_t first, sbintime_t period)
 {
@@ -835,28 +861,21 @@ lapic_et_start(struct eventtimer *et, sb
 
 	la = &lapics[PCPU_GET(apic_id)];
 	if (et->et_frequency == 0) {
+		lapic_calibrate_initcount(et, la);
 		if (lapic_timer_tsc_deadline)
 			lapic_calibrate_deadline(et, la);
-		else
-			lapic_calibrate_initcount(et, la);
-		et->et_min_period = (0x00000002LLU << 32) / et->et_frequency;
-		et->et_max_period = (0xfffffffeLLU << 32) / et->et_frequency;
 	}
 	if (period != 0) {
-		if (la->la_timer_mode == LAT_MODE_UNDEF)
-			lapic_timer_set_divisor(lapic_timer_divisor);
-		la->la_timer_mode = LAT_MODE_PERIODIC;
+		lapic_change_mode(et, la, LAT_MODE_PERIODIC);
 		la->la_timer_period = ((uint32_t)et->et_frequency * period) >>
 		    32;
 		lapic_timer_periodic(la);
 	} else if (lapic_timer_tsc_deadline) {
-		la->la_timer_mode = LAT_MODE_DEADLINE;
+		lapic_change_mode(et, la, LAT_MODE_DEADLINE);
 		la->la_timer_period = (et->et_frequency * first) >> 32;
 		lapic_timer_deadline(la);
 	} else {
-		if (la->la_timer_mode == LAT_MODE_UNDEF)
-			lapic_timer_set_divisor(lapic_timer_divisor);
-		la->la_timer_mode = LAT_MODE_ONESHOT;
+		lapic_change_mode(et, la, LAT_MODE_ONESHOT);
 		la->la_timer_period = ((uint32_t)et->et_frequency * first) >>
 		    32;
 		lapic_timer_oneshot(la);