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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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10
arch/x86/platform/efi/efi.c
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@@ -352,8 +352,9 @@ static efi_status_t __init phys_efi_get_time(efi_time_t *tm,
return status;
}
int efi_set_rtc_mmss(unsigned long nowtime)
int efi_set_rtc_mmss(const struct timespec *now)
{
unsigned long nowtime = now->tv_sec;
efi_status_t status;
efi_time_t eft;
efi_time_cap_t cap;
@@ -388,7 +389,7 @@ int efi_set_rtc_mmss(unsigned long nowtime)
return 0;
}
unsigned long efi_get_time(void)
void efi_get_time(struct timespec *now)
{
efi_status_t status;
efi_time_t eft;
@@ -398,8 +399,9 @@ unsigned long efi_get_time(void)
if (status != EFI_SUCCESS)
pr_err("Oops: efitime: can't read time!\n");
return mktime(eft.year, eft.month, eft.day, eft.hour,
eft.minute, eft.second);
now->tv_sec = mktime(eft.year, eft.month, eft.day, eft.hour,
eft.minute, eft.second);
now->tv_nsec = 0;
}
/*