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xen/arm: introduce xen_read_wallclock 

Read the wallclock from the shared info page at boot time.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
This commit is contained in:
Stefano Stabellini 2015-11-23 10:40:12 +00:00 committed by David Vrabel
parent ab76078a3d
commit e709fba132
1 changed files with 27 additions and 0 deletions
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27
arch/arm/xen/enlighten.c
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@ -26,6 +26,7 @@
#include <linux/cpufreq.h>
#include <linux/cpu.h>
#include <linux/console.h>
#include <linux/timekeeping.h>
#include <linux/mm.h>
@ -93,6 +94,27 @@ static unsigned long long xen_stolen_accounting(int cpu)
return state.time[RUNSTATE_runnable] + state.time[RUNSTATE_offline];
}
static void xen_read_wallclock(struct timespec64 *ts)
{
u32 version;
struct timespec64 now, ts_monotonic;
struct shared_info *s = HYPERVISOR_shared_info;
struct pvclock_wall_clock *wall_clock = &(s->wc);
/* get wallclock at system boot */
do {
version = wall_clock->version;
rmb(); /* fetch version before time */
now.tv_sec = ((uint64_t)wall_clock->sec_hi << 32) | wall_clock->sec;
now.tv_nsec = wall_clock->nsec;
rmb(); /* fetch time before checking version */
} while ((wall_clock->version & 1) || (version != wall_clock->version));
/* time since system boot */
ktime_get_ts64(&ts_monotonic);
*ts = timespec64_add(now, ts_monotonic);
}
static void xen_percpu_init(void)
{
struct vcpu_register_vcpu_info info;
@ -301,6 +323,11 @@ static int __init xen_pm_init(void)
pm_power_off = xen_power_off;
arm_pm_restart = xen_restart;
if (!xen_initial_domain()) {
struct timespec64 ts;
xen_read_wallclock(&ts);
do_settimeofday64(&ts);
}
return 0;
}