Commit 4f3498a0 authored Nov 08, 2017 by Joao Martins Committed by Greg Kroah-Hartman Jan 31, 2019

x86/xen/time: set pvclock flags on xen_time_init()



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@oracle.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 9a12f78a

arch/x86/xen/time.c

+9 −0

Original line number	Diff line number	Diff line
		@@ -373,6 +373,7 @@ static const struct pv_time_ops xen_time_ops __initconst = {

		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();