s390/time: LPAR offset handling

It is possible to specify a user offset for the TOD clock, e.g. +2 hours.
The TOD clock will carry this offset even if the clock is synchronized
with STP. This makes the time stamps acquired with get_sync_clock()
useless as another LPAR migth use a different TOD offset.

Use the PTFF instrution to get the TOD epoch difference and subtract
it from the TOD clock value to get a physical timestamp. As the epoch
difference contains the sync check delta as well the LPAR offset value
to the physical clock needs to be refreshed after each clock
synchronization.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/arch/s390/kernel/early.c b/arch/s390/kernel/early.c
index 4067dbe390ac..717b03aa16b5 100644
--- a/arch/s390/kernel/early.c
+++ b/arch/s390/kernel/early.c
@@ -467,6 +467,7 @@ void __init startup_init(void)
 	ipl_save_parameters();
 	rescue_initrd();
 	clear_bss_section();
+	ptff_init();
 	init_kernel_storage_key();
 	lockdep_off();
 	setup_lowcore_early();