[tip:x86/timers] x86/xen/time: Output xen sched_clock time from 0
From: tip-bot for Pavel Tatashin
Date: Thu Jul 19 2018 - 18:28:22 EST
Commit-ID: 38669ba205d178d2d38bfd194a196d65a44d5af2
Gitweb: https://git.kernel.org/tip/38669ba205d178d2d38bfd194a196d65a44d5af2
Author: Pavel Tatashin <pasha.tatashin@xxxxxxxxxx>
AuthorDate: Thu, 19 Jul 2018 16:55:32 -0400
Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitDate: Fri, 20 Jul 2018 00:02:40 +0200
x86/xen/time: Output xen sched_clock time from 0
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@xxxxxxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: steven.sistare@xxxxxxxxxx
Cc: daniel.m.jordan@xxxxxxxxxx
Cc: linux@xxxxxxxxxxxxxxx
Cc: schwidefsky@xxxxxxxxxx
Cc: heiko.carstens@xxxxxxxxxx
Cc: john.stultz@xxxxxxxxxx
Cc: sboyd@xxxxxxxxxxxxxx
Cc: hpa@xxxxxxxxx
Cc: douly.fnst@xxxxxxxxxxxxxx
Cc: peterz@xxxxxxxxxxxxx
Cc: prarit@xxxxxxxxxx
Cc: feng.tang@xxxxxxxxx
Cc: pmladek@xxxxxxxx
Cc: gnomes@xxxxxxxxxxxxxxxxxxx
Cc: linux-s390@xxxxxxxxxxxxxxx
Cc: boris.ostrovsky@xxxxxxxxxx
Cc: jgross@xxxxxxxx
Cc: pbonzini@xxxxxxxxxx
Link: https://lkml.kernel.org/r/20180719205545.16512-14-pasha.tatashin@xxxxxxxxxx
---
arch/x86/xen/time.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)
diff --git a/arch/x86/xen/time.c b/arch/x86/xen/time.c
index 53bb7a8d10b5..c84f1e039d84 100644
--- a/arch/x86/xen/time.c
+++ b/arch/x86/xen/time.c
@@ -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;