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x86/tsc: Make use of tsc_calibrate_cpu_early() 

During early boot enable tsc_calibrate_cpu_early() and switch to
tsc_calibrate_cpu() only later. Do this unconditionally, because it is
unknown what methods other cpus will use to calibrate once they are
onlined.

If by the time tsc_init() is called tsc frequency is still unknown do only
pit_hpet_ptimer_calibrate_cpu() to calibrate, as this function contains the
only methods wich have not been called and tried earlier.

Signed-off-by: Pavel Tatashin <pasha.tatashin@oracle.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: steven.sistare@oracle.com
Cc: daniel.m.jordan@oracle.com
Cc: linux@armlinux.org.uk
Cc: schwidefsky@de.ibm.com
Cc: heiko.carstens@de.ibm.com
Cc: john.stultz@linaro.org
Cc: sboyd@codeaurora.org
Cc: hpa@zytor.com
Cc: douly.fnst@cn.fujitsu.com
Cc: peterz@infradead.org
Cc: prarit@redhat.com
Cc: feng.tang@intel.com
Cc: pmladek@suse.com
Cc: gnomes@lxorguk.ukuu.org.uk
Cc: linux-s390@vger.kernel.org
Cc: boris.ostrovsky@oracle.com
Cc: jgross@suse.com
Cc: pbonzini@redhat.com
Link: https://lkml.kernel.org/r/20180719205545.16512-27-pasha.tatashin@oracle.com
This commit is contained in:
Pavel Tatashin 2018-07-19 16:55:45 -04:00 committed by Thomas Gleixner
parent 03821f451d
commit 8dbe438589
3 changed files with 20 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
arch/x86/include/asm/tsc.h
View File

@ -39,7 +39,6 @@ extern void mark_tsc_unstable(char *reason);
extern int unsynchronized_tsc(void);
extern int check_tsc_unstable(void);
extern void mark_tsc_async_resets(char *reason);
extern unsigned long native_calibrate_cpu(void);
extern unsigned long native_calibrate_cpu_early(void);
extern unsigned long native_calibrate_tsc(void);
extern unsigned long long native_sched_clock_from_tsc(u64 tsc);

25
arch/x86/kernel/tsc.c
View File

@ -854,7 +854,7 @@ unsigned long native_calibrate_cpu_early(void)
/**
* native_calibrate_cpu - calibrate the cpu
*/
unsigned long native_calibrate_cpu(void)
static unsigned long native_calibrate_cpu(void)
{
unsigned long tsc_freq = native_calibrate_cpu_early();
@ -1374,13 +1374,19 @@ static int __init init_tsc_clocksource(void)
*/
device_initcall(init_tsc_clocksource);
static bool __init determine_cpu_tsc_frequencies(void)
static bool __init determine_cpu_tsc_frequencies(bool early)
{
/* Make sure that cpu and tsc are not already calibrated */
WARN_ON(cpu_khz || tsc_khz);
cpu_khz = x86_platform.calibrate_cpu();
tsc_khz = x86_platform.calibrate_tsc();
if (early) {
cpu_khz = x86_platform.calibrate_cpu();
tsc_khz = x86_platform.calibrate_tsc();
} else {
/* We should not be here with non-native cpu calibration */
WARN_ON(x86_platform.calibrate_cpu != native_calibrate_cpu);
cpu_khz = pit_hpet_ptimer_calibrate_cpu();
}
/*
* Trust non-zero tsc_khz as authorative,
@ -1419,7 +1425,7 @@ void __init tsc_early_init(void)
{
if (!boot_cpu_has(X86_FEATURE_TSC))
return;
if (!determine_cpu_tsc_frequencies())
if (!determine_cpu_tsc_frequencies(true))
return;
loops_per_jiffy = get_loops_per_jiffy();
@ -1431,6 +1437,13 @@ void __init tsc_early_init(void)
void __init tsc_init(void)
{
/*
* native_calibrate_cpu_early can only calibrate using methods that are
* available early in boot.
*/
if (x86_platform.calibrate_cpu == native_calibrate_cpu_early)
x86_platform.calibrate_cpu = native_calibrate_cpu;
if (!boot_cpu_has(X86_FEATURE_TSC)) {
setup_clear_cpu_cap(X86_FEATURE_TSC_DEADLINE_TIMER);
return;
@ -1438,7 +1451,7 @@ void __init tsc_init(void)
if (!tsc_khz) {
/* We failed to determine frequencies earlier, try again */
if (!determine_cpu_tsc_frequencies()) {
if (!determine_cpu_tsc_frequencies(false)) {
mark_tsc_unstable("could not calculate TSC khz");
setup_clear_cpu_cap(X86_FEATURE_TSC_DEADLINE_TIMER);
return;

2
arch/x86/kernel/x86_init.c
View File

@ -109,7 +109,7 @@ struct x86_cpuinit_ops x86_cpuinit = {
static void default_nmi_init(void) { };
struct x86_platform_ops x86_platform __ro_after_init = {
.calibrate_cpu = native_calibrate_cpu,
.calibrate_cpu = native_calibrate_cpu_early,
.calibrate_tsc = native_calibrate_tsc,
.get_wallclock = mach_get_cmos_time,
.set_wallclock = mach_set_rtc_mmss,