[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH v4 5/7] xen/arm: introduce xen_read_wallclock
Read the wallclock from the shared info page at boot time. Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx> --- Changes in v4: - simplify xen_read_wallclock Changes in v3: - use ktime_get_ns instead of calling into the arch_timer functions directly - read the wallclock from the late_initcall Changes in v2: - properly convert arch_timer ticker to nsec - use timespec64 interfaces - use sec_hi to get a 64-bit seconds value --- arch/arm/xen/enlighten.c | 27 +++++++++++++++++++++++++++ 1 file changed, 27 insertions(+) diff --git a/arch/arm/xen/enlighten.c b/arch/arm/xen/enlighten.c index 2f57ba3..6ae4ef5 100644 --- a/arch/arm/xen/enlighten.c +++ b/arch/arm/xen/enlighten.c @@ -28,6 +28,7 @@ #include <linux/cpufreq.h> #include <linux/cpu.h> #include <linux/console.h> +#include <linux/timekeeping.h> #include <linux/mm.h> @@ -95,6 +96,27 @@ 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; @@ -303,6 +325,11 @@ 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; } -- 1.7.10.4 _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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