4.14-stable review patch. If anyone has any objections, please let me know.
------------------
From: Joao Martins <joao.m.martins@xxxxxxxxxx>
commit b888808093113ae7d63d213272d01fea4b8329ed upstream.
Specifically check for PVCLOCK_TSC_STABLE_BIT and if this bit is set,
then set it too on pvclock flags. This allows Xen clocksource to use it
and thus speeding up xen_clocksource_read() callers (i.e. sched_clock())
Signed-off-by: Joao Martins <joao.m.martins@xxxxxxxxxx>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/xen/time.c | 9 +++++++++
1 file changed, 9 insertions(+)
--- a/arch/x86/xen/time.c
+++ b/arch/x86/xen/time.c
@@ -373,6 +373,7 @@ static const struct pv_time_ops xen_time
static void __init xen_time_init(void)
{
+ struct pvclock_vcpu_time_info *pvti;
int cpu = smp_processor_id();
struct timespec tp;
@@ -396,6 +397,14 @@ static void __init xen_time_init(void)
setup_force_cpu_cap(X86_FEATURE_TSC);
+ /*
+ * We check ahead on the primary time info if this
+ * bit is supported hence speeding up Xen clocksource.
+ */
+ pvti = &__this_cpu_read(xen_vcpu)->time;
+ if (pvti->flags & PVCLOCK_TSC_STABLE_BIT)
+ pvclock_set_flags(PVCLOCK_TSC_STABLE_BIT);
+
xen_setup_runstate_info(cpu);
xen_setup_timer(cpu);
xen_setup_cpu_clockevents();
