Re: [Xen-devel] [PATCH v4 6/7] xen/arm: set the system time in Xen via the XENPF_settime64 hypercall

[Julien Grall <julien.grall@xxxxxxxxxx>]

On 12/11/15 17:30, Stefano Stabellini wrote:
> +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.interface_version = XENPF_INTERFACE_VERSION;
> +     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);
> +     printk("GTOD: Setting to %llu.%09u at %llu\n",
> +            op.u.settime64.secs,
> +            op.u.settime64.nsecs,
> +            op.u.settime64.system_time);

Is this printk really useful?

> +     (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;
> @@ -313,7 +364,9 @@ 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);
> + 

I think, you've introduced a trailing whitespace.

>       return 0;
>  }
>  early_initcall(xen_guest_init);
> 

Regards,


-- 
Julien Grall

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel