[PATCH v4 30/47] x86/xen/time: NOP-ify x86_platform's sched_clock save/restore hooks

[Sean Christopherson]

NOP-ify the x86_platform sched_clock save/restore hooks when setting up
Xen's PV clock to make it somewhat obvious the hooks aren't used when
running as a Xen guest (Xen uses a paravirtualized suspend/resume flow).

Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
 arch/x86/xen/time.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/x86/xen/time.c b/arch/x86/xen/time.c
index 36d66abf5379..640b71d22d97 100644
--- a/arch/x86/xen/time.c
+++ b/arch/x86/xen/time.c
@@ -578,6 +578,12 @@ static void __init xen_init_time_common(void)
 	xen_sched_clock_offset = xen_clocksource_read();
 	static_call_update(pv_steal_clock, xen_steal_clock);
 	paravirt_set_sched_clock(xen_sched_clock);
+	/*
+	 * Xen has paravirtualized suspend/resume and so doesn't use the common
+	 * x86 sched_clock save/restore hooks.
+	 */
+	x86_platform.save_sched_clock_state = x86_init_noop;
+	x86_platform.restore_sched_clock_state = x86_init_noop;
 
 	x86_init.hyper.get_tsc_khz = xen_tsc_khz;
 	x86_platform.get_wallclock = xen_get_wallclock;
-- 
2.54.0.823.g6e5bcc1fc9-goog