4.14-stable review patch. If anyone has any objections, please let me know.
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From: Pavel Tatashin pasha.tatashin@oracle.com
commit 38669ba205d178d2d38bfd194a196d65a44d5af2 upstream.
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 Signed-off-by: Juergen Gross jgross@suse.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- arch/x86/xen/time.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-)
--- 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(st return xen_clocksource_read(); }
+static u64 xen_sched_clock(void) +{ + return xen_clocksource_read() - xen_sched_clock_offset; +} + static void xen_read_wallclock(struct timespec *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 __ref 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; @@ -547,6 +555,7 @@ 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;