x86: Increase precision of x86_platform.get/set_wallclock()
All the virtualized platforms (KVM, lguest and Xen) have persistent
wallclocks that have more than one second of precision.
read_persistent_wallclock() and update_persistent_wallclock() allow
for nanosecond precision but their implementation on x86 with
x86_platform.get/set_wallclock() only allows for one second precision.
This means guests may see a wallclock time that is off by up to 1
second.
Make set_wallclock() and get_wallclock() take a struct timespec
parameter (which allows for nanosecond precision) so KVM and Xen
guests may start with a more accurate wallclock time and a Xen dom0
can maintain a more accurate wallclock for guests.
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
diff --git a/arch/x86/xen/time.c b/arch/x86/xen/time.c
index 3d88bfd..a1947ac 100644
--- a/arch/x86/xen/time.c
+++ b/arch/x86/xen/time.c
@@ -191,32 +191,25 @@
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(&ts);
- return ts.tv_sec;
+ xen_read_wallclock(now);
}
-static int xen_set_wallclock(unsigned long now)
+static int xen_set_wallclock(const struct timespec *now)
{
struct xen_platform_op op;
- int rc;
/* do nothing for domU */
if (!xen_initial_domain())
return -1;
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);
-
- return rc;
+ return HYPERVISOR_dom0_op(&op);
}
static struct clocksource xen_clocksource __read_mostly = {