diff options
Diffstat (limited to 'arch/x86/xen/time.c')
| -rw-r--r-- | arch/x86/xen/time.c | 58 |
1 files changed, 43 insertions, 15 deletions
diff --git a/arch/x86/xen/time.c b/arch/x86/xen/time.c index a690868be837..ee365895b06b 100644 --- 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 |