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x86/xen/time: Output xen sched_clock time from 0

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It is expected for sched_clock() to output data from 0, when system boots.

Add an offset xen_sched_clock_offset (similarly how it is done in other
hypervisors i.e. kvm_sched_clock_offset) to count sched_clock() from 0,
when time is first initialized.

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/20180719205545.16512-14-pasha.tatashin@oracle.com
This commit is contained in:
Pavel Tatashin 2018-07-19 16:55:32 -04:00 committed by Thomas Gleixner
parent 7b25b9cb0d
commit 38669ba205
1 changed files with 10 additions and 1 deletions
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11
arch/x86/xen/time.c
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@ -31,6 +31,8 @@
/* Xen may fire a timer up to this many ns early */
#define TIMER_SLOP 100000
static u64 xen_sched_clock_offset __read_mostly;
/* Get the TSC speed from Xen */
static unsigned long xen_tsc_khz(void)
{
@ -57,6 +59,11 @@ static u64 xen_clocksource_get_cycles(struct clocksource *cs)
return xen_clocksource_read();
}
static u64 xen_sched_clock(void)
{
return xen_clocksource_read() - xen_sched_clock_offset;
}
static void xen_read_wallclock(struct timespec64 *ts)
{
struct shared_info *s = HYPERVISOR_shared_info;
@ -367,7 +374,7 @@ void xen_timer_resume(void)
}
static const struct pv_time_ops xen_time_ops __initconst = {
.sched_clock = xen_clocksource_read,
.sched_clock = xen_sched_clock,
.steal_clock = xen_steal_clock,
};
@ -505,6 +512,7 @@ static void __init xen_time_init(void)
void __init xen_init_time_ops(void)
{
xen_sched_clock_offset = xen_clocksource_read();
pv_time_ops = xen_time_ops;
x86_init.timers.timer_init = xen_time_init;
@ -546,6 +554,7 @@ void __init xen_hvm_init_time_ops(void)
return;
}
xen_sched_clock_offset = xen_clocksource_read();
pv_time_ops = xen_time_ops;
x86_init.timers.setup_percpu_clockev = xen_time_init;
x86_cpuinit.setup_percpu_clockev = xen_hvm_setup_cpu_clockevents;