Merge tag 'iio-fixes-for-3.11b' of git://git.kernel.org/pub/scm/linux/kernel/git...

[~andy/linux] / arch / x86 / xen / time.c

diff --git a/arch/x86/xen/time.c b/arch/x86/xen/time.c
index a690868be837ad99407d050a1c0229d9a237adc5..ee365895b06bb431a2f56e1f940119a9c0cc5ef1 100644 (file)
--- a/arch/x86/xen/time.c
+++ b/arch/x86/xen/time.c
@@ -15,6 +15,7 @@
 #include <linux/math64.h>
 #include <linux/gfp.h>
 #include <linux/slab.h>
+#include <linux/pvclock_gtod.h>
 
 #include <asm/pvclock.h>
 #include <asm/xen/hypervisor.h>
@@ -179,34 +180,56 @@ static void xen_read_wallclock(struct timespec *ts)
        put_cpu_var(xen_vcpu);
 }
 
-static unsigned long xen_get_wallclock(void)
+static void xen_get_wallclock(struct timespec *now)
 {
-       struct timespec ts;
+       xen_read_wallclock(now);
+}
 
-       xen_read_wallclock(&ts);
-       return ts.tv_sec;
+static int xen_set_wallclock(const struct timespec *now)
+{
+       return -1;
 }
 
-static int xen_set_wallclock(unsigned long now)
+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 timespec next_sync;
+
        struct xen_platform_op op;
-       int rc;
+       struct timespec now;
 
-       /* do nothing for domU */
-       if (!xen_initial_domain())
-               return -1;
+       now = __current_kernel_time();
+
+       /*
+        * We only take the expensive HV call when the clock was set
+        * or when the 11 minutes RTC synchronization time elapsed.
+        */
+       if (!was_set && timespec_compare(&now, &next_sync) < 0)
+               return NOTIFY_OK;
 
        op.cmd = XENPF_settime;
-       op.u.settime.secs = now;
-       op.u.settime.nsecs = 0;
+       op.u.settime.secs = now.tv_sec;
+       op.u.settime.nsecs = now.tv_nsec;
        op.u.settime.system_time = xen_clocksource_read();
 
-       rc = HYPERVISOR_dom0_op(&op);
-       WARN(rc != 0, "XENPF_settime failed: now=%ld\n", now);
+       (void)HYPERVISOR_dom0_op(&op);
 
-       return rc;
+       /*
+        * 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 struct clocksource xen_clocksource __read_mostly = {
        .name = "xen",
        .rating = 400,
@@ -482,6 +505,9 @@ static void __init xen_time_init(void)
        xen_setup_runstate_info(cpu);
        xen_setup_timer(cpu);
        xen_setup_cpu_clockevents();
+
+       if (xen_initial_domain())
+               pvclock_gtod_register_notifier(&xen_pvclock_gtod_notifier);
 }
 
 void __init xen_init_time_ops(void)
@@ -494,7 +520,9 @@ void __init xen_init_time_ops(void)
 
        x86_platform.calibrate_tsc = xen_tsc_khz;
        x86_platform.get_wallclock = xen_get_wallclock;
-       x86_platform.set_wallclock = xen_set_wallclock;
+       /* Dom0 uses the native method to set the hardware RTC. */
+       if (!xen_initial_domain())
+               x86_platform.set_wallclock = xen_set_wallclock;
 }
 
 #ifdef CONFIG_XEN_PVHVM