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-rw-r--r--arch/x86/kernel/tsc.c117
1 files changed, 95 insertions, 22 deletions
diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index 6e1a368d21d..cd982f48e23 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -17,6 +17,8 @@
#include <asm/time.h>
#include <asm/delay.h>
#include <asm/hypervisor.h>
+#include <asm/nmi.h>
+#include <asm/x86_init.h>
unsigned int __read_mostly cpu_khz; /* TSC clocks / usec, not used here */
EXPORT_SYMBOL(cpu_khz);
@@ -275,15 +277,20 @@ static unsigned long pit_calibrate_tsc(u32 latch, unsigned long ms, int loopmin)
* use the TSC value at the transitions to calculate a pretty
* good value for the TSC frequencty.
*/
+static inline int pit_verify_msb(unsigned char val)
+{
+ /* Ignore LSB */
+ inb(0x42);
+ return inb(0x42) == val;
+}
+
static inline int pit_expect_msb(unsigned char val, u64 *tscp, unsigned long *deltap)
{
int count;
u64 tsc = 0;
for (count = 0; count < 50000; count++) {
- /* Ignore LSB */
- inb(0x42);
- if (inb(0x42) != val)
+ if (!pit_verify_msb(val))
break;
tsc = get_cycles();
}
@@ -336,8 +343,7 @@ static unsigned long quick_pit_calibrate(void)
* to do that is to just read back the 16-bit counter
* once from the PIT.
*/
- inb(0x42);
- inb(0x42);
+ pit_verify_msb(0);
if (pit_expect_msb(0xff, &tsc, &d1)) {
for (i = 1; i <= MAX_QUICK_PIT_ITERATIONS; i++) {
@@ -348,8 +354,19 @@ static unsigned long quick_pit_calibrate(void)
* Iterate until the error is less than 500 ppm
*/
delta -= tsc;
- if (d1+d2 < delta >> 11)
- goto success;
+ if (d1+d2 >= delta >> 11)
+ continue;
+
+ /*
+ * Check the PIT one more time to verify that
+ * all TSC reads were stable wrt the PIT.
+ *
+ * This also guarantees serialization of the
+ * last cycle read ('d2') in pit_expect_msb.
+ */
+ if (!pit_verify_msb(0xfe - i))
+ break;
+ goto success;
}
}
printk("Fast TSC calibration failed\n");
@@ -385,15 +402,9 @@ unsigned long native_calibrate_tsc(void)
{
u64 tsc1, tsc2, delta, ref1, ref2;
unsigned long tsc_pit_min = ULONG_MAX, tsc_ref_min = ULONG_MAX;
- unsigned long flags, latch, ms, fast_calibrate, hv_tsc_khz;
+ unsigned long flags, latch, ms, fast_calibrate;
int hpet = is_hpet_enabled(), i, loopmin;
- hv_tsc_khz = get_hypervisor_tsc_freq();
- if (hv_tsc_khz) {
- printk(KERN_INFO "TSC: Frequency read from the hypervisor\n");
- return hv_tsc_khz;
- }
-
local_irq_save(flags);
fast_calibrate = quick_pit_calibrate();
local_irq_restore(flags);
@@ -551,7 +562,7 @@ int recalibrate_cpu_khz(void)
unsigned long cpu_khz_old = cpu_khz;
if (cpu_has_tsc) {
- tsc_khz = calibrate_tsc();
+ tsc_khz = x86_platform.calibrate_tsc();
cpu_khz = tsc_khz;
cpu_data(0).loops_per_jiffy =
cpufreq_scale(cpu_data(0).loops_per_jiffy,
@@ -655,7 +666,7 @@ static int time_cpufreq_notifier(struct notifier_block *nb, unsigned long val,
if ((val == CPUFREQ_PRECHANGE && freq->old < freq->new) ||
(val == CPUFREQ_POSTCHANGE && freq->old > freq->new) ||
(val == CPUFREQ_RESUMECHANGE)) {
- *lpj = cpufreq_scale(loops_per_jiffy_ref, ref_freq, freq->new);
+ *lpj = cpufreq_scale(loops_per_jiffy_ref, ref_freq, freq->new);
tsc_khz = cpufreq_scale(tsc_khz_ref, ref_freq, freq->new);
if (!(freq->flags & CPUFREQ_CONST_LOOPS))
@@ -729,10 +740,16 @@ static cycle_t __vsyscall_fn vread_tsc(void)
}
#endif
+static void resume_tsc(void)
+{
+ clocksource_tsc.cycle_last = 0;
+}
+
static struct clocksource clocksource_tsc = {
.name = "tsc",
.rating = 300,
.read = read_tsc,
+ .resume = resume_tsc,
.mask = CLOCKSOURCE_MASK(64),
.shift = 22,
.flags = CLOCK_SOURCE_IS_CONTINUOUS |
@@ -746,12 +763,14 @@ void mark_tsc_unstable(char *reason)
{
if (!tsc_unstable) {
tsc_unstable = 1;
- printk("Marking TSC unstable due to %s\n", reason);
+ printk(KERN_INFO "Marking TSC unstable due to %s\n", reason);
/* Change only the rating, when not registered */
if (clocksource_tsc.mult)
- clocksource_change_rating(&clocksource_tsc, 0);
- else
+ clocksource_mark_unstable(&clocksource_tsc);
+ else {
+ clocksource_tsc.flags |= CLOCK_SOURCE_UNSTABLE;
clocksource_tsc.rating = 0;
+ }
}
}
@@ -837,15 +856,71 @@ static void __init init_tsc_clocksource(void)
clocksource_register(&clocksource_tsc);
}
+#ifdef CONFIG_X86_64
+/*
+ * calibrate_cpu is used on systems with fixed rate TSCs to determine
+ * processor frequency
+ */
+#define TICK_COUNT 100000000
+static unsigned long __init calibrate_cpu(void)
+{
+ int tsc_start, tsc_now;
+ int i, no_ctr_free;
+ unsigned long evntsel3 = 0, pmc3 = 0, pmc_now = 0;
+ unsigned long flags;
+
+ for (i = 0; i < 4; i++)
+ if (avail_to_resrv_perfctr_nmi_bit(i))
+ break;
+ no_ctr_free = (i == 4);
+ if (no_ctr_free) {
+ WARN(1, KERN_WARNING "Warning: AMD perfctrs busy ... "
+ "cpu_khz value may be incorrect.\n");
+ i = 3;
+ rdmsrl(MSR_K7_EVNTSEL3, evntsel3);
+ wrmsrl(MSR_K7_EVNTSEL3, 0);
+ rdmsrl(MSR_K7_PERFCTR3, pmc3);
+ } else {
+ reserve_perfctr_nmi(MSR_K7_PERFCTR0 + i);
+ reserve_evntsel_nmi(MSR_K7_EVNTSEL0 + i);
+ }
+ local_irq_save(flags);
+ /* start measuring cycles, incrementing from 0 */
+ wrmsrl(MSR_K7_PERFCTR0 + i, 0);
+ wrmsrl(MSR_K7_EVNTSEL0 + i, 1 << 22 | 3 << 16 | 0x76);
+ rdtscl(tsc_start);
+ do {
+ rdmsrl(MSR_K7_PERFCTR0 + i, pmc_now);
+ tsc_now = get_cycles();
+ } while ((tsc_now - tsc_start) < TICK_COUNT);
+
+ local_irq_restore(flags);
+ if (no_ctr_free) {
+ wrmsrl(MSR_K7_EVNTSEL3, 0);
+ wrmsrl(MSR_K7_PERFCTR3, pmc3);
+ wrmsrl(MSR_K7_EVNTSEL3, evntsel3);
+ } else {
+ release_perfctr_nmi(MSR_K7_PERFCTR0 + i);
+ release_evntsel_nmi(MSR_K7_EVNTSEL0 + i);
+ }
+
+ return pmc_now * tsc_khz / (tsc_now - tsc_start);
+}
+#else
+static inline unsigned long calibrate_cpu(void) { return cpu_khz; }
+#endif
+
void __init tsc_init(void)
{
u64 lpj;
int cpu;
+ x86_init.timers.tsc_pre_init();
+
if (!cpu_has_tsc)
return;
- tsc_khz = calibrate_tsc();
+ tsc_khz = x86_platform.calibrate_tsc();
cpu_khz = tsc_khz;
if (!tsc_khz) {
@@ -853,11 +928,9 @@ void __init tsc_init(void)
return;
}
-#ifdef CONFIG_X86_64
if (cpu_has(&boot_cpu_data, X86_FEATURE_CONSTANT_TSC) &&
(boot_cpu_data.x86_vendor == X86_VENDOR_AMD))
cpu_khz = calibrate_cpu();
-#endif
printk("Detected %lu.%03lu MHz processor.\n",
(unsigned long)cpu_khz / 1000,
generated by cgit v1.2.3-70-g09d2 (git 2.46.0) at 2025-02-03 09:04:57 +0000