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authorPavel Tatashin <pasha.tatashin@oracle.com>2018-07-19 23:55:45 +0300
committerThomas Gleixner <tglx@linutronix.de>2018-07-20 01:02:44 +0300
commit8dbe438589f373544a1af8b4a859e4da853c0f90 (patch)
treed5677d86892654b28d3db26bae192b3ece2637b3 /arch/x86/kernel/tsc.c
parent03821f451d2d2d7599061244734245be139014ea (diff)
downloadlinux-8dbe438589f373544a1af8b4a859e4da853c0f90.tar.xz
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
Diffstat (limited to 'arch/x86/kernel/tsc.c')
-rw-r--r--arch/x86/kernel/tsc.c25
1 files changed, 19 insertions, 6 deletions
diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index 60586779b02c..02e416b87ac1 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -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 @@ unreg:
*/
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;