Commit 7d5f6f81 authored by Stefano Stabellini's avatar Stefano Stabellini Committed by David Vrabel
Browse files

xen/arm: set the system time in Xen via the XENPF_settime64 hypercall 



If Linux is running as dom0, call XENPF_settime64 to update the system
time in Xen on pvclock_gtod notifications.

Signed-off-by: default avatarStefano Stabellini <stefano.stabellini@eu.citrix.com>
Acked-by: default avatarArnd Bergmann <arnd@arndb.de>
parent e709fba1

arch/arm/xen/enlighten.c

+48 −0
Original line number Diff line number Diff line
@@ -26,7 +26,10 @@ 
#include <linux/cpufreq.h>

#include <linux/cpu.h>

#include <linux/console.h>

#include <linux/pvclock_gtod.h>

#include <linux/time64.h>

#include <linux/timekeeping.h>

#include <linux/timekeeper_internal.h>



#include <linux/mm.h>
@@ -115,6 +118,49 @@ static void xen_read_wallclock(struct timespec64 *ts) 
	*ts = timespec64_add(now, ts_monotonic);

}



static int xen_pvclock_gtod_notify(struct notifier_block *nb,

				   unsigned long was_set, void *priv)

{

	/* Protected by the calling core code serialization */

	static struct timespec64 next_sync;



	struct xen_platform_op op;

	struct timespec64 now, system_time;

	struct timekeeper *tk = priv;



	now.tv_sec = tk->xtime_sec;

	now.tv_nsec = (long)(tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift);

	system_time = timespec64_add(now, tk->wall_to_monotonic);



	/*

	 * We only take the expensive HV call when the clock was set

	 * or when the 11 minutes RTC synchronization time elapsed.

	 */

	if (!was_set && timespec64_compare(&now, &next_sync) < 0)

		return NOTIFY_OK;



	op.cmd = XENPF_settime64;

	op.u.settime64.mbz = 0;

	op.u.settime64.secs = now.tv_sec;

	op.u.settime64.nsecs = now.tv_nsec;

	op.u.settime64.system_time = timespec64_to_ns(&system_time);

	(void)HYPERVISOR_platform_op(&op);



	/*

	 * Move the next drift compensation time 11 minutes

	 * ahead. That's emulating the sync_cmos_clock() update for

	 * the hardware RTC.

	 */

	next_sync = now;

	next_sync.tv_sec += 11 * 60;



	return NOTIFY_OK;

}



static struct notifier_block xen_pvclock_gtod_notifier = {

	.notifier_call = xen_pvclock_gtod_notify,

};



static void xen_percpu_init(void)

{

	struct vcpu_register_vcpu_info info;
@@ -311,6 +357,8 @@ static int __init xen_guest_init(void) 


	pv_time_ops.steal_clock = xen_stolen_accounting;

	static_key_slow_inc(&paravirt_steal_enabled);

	if (xen_initial_domain())

		pvclock_gtod_register_notifier(&xen_pvclock_gtod_notifier);



	return 0;

}