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Commit 8dbe4385 authored by Pavel Tatashin's avatar Pavel Tatashin Committed by Thomas Gleixner
Browse files

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: default avatarPavel Tatashin <pasha.tatashin@oracle.com>
Signed-off-by: default avatarThomas 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
parent 03821f45

arch/x86/include/asm/tsc.h

+0 −1
Original line number Diff line number Diff line
@@ -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);

arch/x86/kernel/tsc.c

+19 −6
Original line number Diff line number Diff line
@@ -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);



	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;

arch/x86/kernel/x86_init.c

+1 −1
Original line number Diff line number Diff line
@@ -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,