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x86: Increase precision of x86_platform.get/set_wallclock()

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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>
This commit is contained in:
David Vrabel
2013-05-13 18:56:06 +01:00
committed by John Stultz
parent 0a0a7e66fa
commit 3565184ed0
8 changed files with 32 additions and 41 deletions
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4
arch/x86/lguest/boot.c
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@@ -882,9 +882,9 @@ int lguest_setup_irq(unsigned int irq)
* It would be far better for everyone if the Guest had its own clock, but
* until then the Host gives us the time on every interrupt.
*/
static unsigned long lguest_get_wallclock(void)
static void lguest_get_wallclock(struct timespec *now)
{
return lguest_data.time.tv_sec;
*now = lguest_data.time;
}
/*