From 4027789192d149678262ad606b2d7e2a61bed0f2 Mon Sep 17 00:00:00 2001 From: Martin Schwidefsky Date: Tue, 31 May 2016 10:16:24 +0200 Subject: 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 --- arch/s390/kernel/time.c | 46 ++++++++++++++++++++++++++++++++++++++-------- 1 file changed, 38 insertions(+), 8 deletions(-) (limited to 'arch/s390/kernel/time.c') diff --git a/arch/s390/kernel/time.c b/arch/s390/kernel/time.c index a725fd1c4315..d71623639997 100644 --- a/arch/s390/kernel/time.c +++ b/arch/s390/kernel/time.c @@ -39,6 +39,7 @@ #include #include #include +#include #include #include #include @@ -61,6 +62,25 @@ static DEFINE_PER_CPU(struct clock_event_device, comparators); ATOMIC_NOTIFIER_HEAD(s390_epoch_delta_notifier); EXPORT_SYMBOL(s390_epoch_delta_notifier); +unsigned char ptff_function_mask[16]; +unsigned long lpar_offset; + +/* + * Get time offsets with PTFF + */ +void __init ptff_init(void) +{ + struct ptff_qto qto; + + if (!test_facility(28)) + return; + ptff(&ptff_function_mask, sizeof(ptff_function_mask), PTFF_QAF); + + /* get LPAR offset */ + if (ptff_query(PTFF_QTO) && ptff(&qto, sizeof(qto), PTFF_QTO) == 0) + lpar_offset = qto.tod_epoch_difference; +} + /* * Scheduler clock - returns current time in nanosec units. */ @@ -337,20 +357,20 @@ static unsigned long clock_sync_flags; #define CLOCK_SYNC_STP 3 /* - * The synchronous get_clock function. It will write the current clock - * value to the clock pointer and return 0 if the clock is in sync with - * the external time source. If the clock mode is local it will return - * -EOPNOTSUPP and -EAGAIN if the clock is not in sync with the external - * reference. + * The get_clock function for the physical clock. It will get the current + * TOD clock, subtract the LPAR offset and write the result to *clock. + * The function returns 0 if the clock is in sync with the external time + * source. If the clock mode is local it will return -EOPNOTSUPP and + * -EAGAIN if the clock is not in sync with the external reference. */ -int get_sync_clock(unsigned long long *clock) +int get_phys_clock(unsigned long long *clock) { atomic_t *sw_ptr; unsigned int sw0, sw1; sw_ptr = &get_cpu_var(clock_sync_word); sw0 = atomic_read(sw_ptr); - *clock = get_tod_clock(); + *clock = get_tod_clock() - lpar_offset; sw1 = atomic_read(sw_ptr); put_cpu_var(clock_sync_word); if (sw0 == sw1 && (sw0 & 0x80000000U)) @@ -364,7 +384,7 @@ int get_sync_clock(unsigned long long *clock) return -EACCES; return -EAGAIN; } -EXPORT_SYMBOL(get_sync_clock); +EXPORT_SYMBOL(get_phys_clock); /* * Make get_sync_clock return -EAGAIN. @@ -758,6 +778,7 @@ static int etr_sync_clock(void *data) unsigned long long clock, old_clock, clock_delta, delay, delta; struct clock_sync_data *etr_sync; struct etr_aib *sync_port, *aib; + struct ptff_qto qto; int port; int rc; @@ -804,6 +825,10 @@ static int etr_sync_clock(void *data) etr_sync->in_sync = -EAGAIN; rc = -EAGAIN; } else { + if (ptff_query(PTFF_QTO) && + ptff(&qto, sizeof(qto), PTFF_QTO) == 0) + /* Update LPAR offset */ + lpar_offset = qto.tod_epoch_difference; etr_sync->in_sync = 1; rc = 0; } @@ -1533,6 +1558,7 @@ static int stp_sync_clock(void *data) static int first; unsigned long long old_clock, delta, new_clock, clock_delta; struct clock_sync_data *stp_sync; + struct ptff_qto qto; int rc; stp_sync = data; @@ -1558,6 +1584,10 @@ static int stp_sync_clock(void *data) if (rc == 0) { new_clock = old_clock + clock_delta; delta = adjust_time(old_clock, new_clock, 0); + if (ptff_query(PTFF_QTO) && + ptff(&qto, sizeof(qto), PTFF_QTO) == 0) + /* Update LPAR offset */ + lpar_offset = qto.tod_epoch_difference; atomic_notifier_call_chain(&s390_epoch_delta_notifier, 0, &clock_delta); fixup_clock_comparator(delta); -- cgit v1.2.3-55-g7522