[PATCH 3/3] s390/time: LPAR offset handling
Tim Gardner
tim.gardner at canonical.com
Tue Nov 29 17:44:24 UTC 2016
From: Martin Schwidefsky <schwidefsky at de.ibm.com>
BugLink: http://bugs.launchpad.net/bugs/1644505
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 at de.ibm.com>
(cherry picked from commit 4027789192d149678262ad606b2d7e2a61bed0f2)
Signed-off-by: Tim Gardner <tim.gardner at canonical.com>
---
arch/s390/include/asm/timex.h | 15 +++++++++++++-
arch/s390/kernel/early.c | 1 +
arch/s390/kernel/time.c | 46 ++++++++++++++++++++++++++++++++++--------
drivers/s390/block/dasd_eckd.c | 4 ++--
4 files changed, 55 insertions(+), 11 deletions(-)
diff --git a/arch/s390/include/asm/timex.h b/arch/s390/include/asm/timex.h
index 920db0a..0f34db4 100644
--- a/arch/s390/include/asm/timex.h
+++ b/arch/s390/include/asm/timex.h
@@ -52,6 +52,11 @@ static inline void store_clock_comparator(__u64 *time)
void clock_comparator_work(void);
+void __init ptff_init(void);
+
+extern unsigned char ptff_function_mask[16];
+extern unsigned long lpar_offset;
+
/* Function codes for the ptff instruction. */
#define PTFF_QAF 0x00 /* query available functions */
#define PTFF_QTO 0x01 /* query tod offset */
@@ -69,6 +74,14 @@ struct ptff_qto {
unsigned long long tod_epoch_difference;
} __packed;
+static inline int ptff_query(unsigned int nr)
+{
+ unsigned char *ptr;
+
+ ptr = ptff_function_mask + (nr >> 3);
+ return (*ptr & (0x80 >> (nr & 7))) != 0;
+}
+
static inline int ptff(void *ptff_block, size_t len, unsigned int func)
{
typedef struct { char _[len]; } addrtype;
@@ -138,7 +151,7 @@ static inline cycles_t get_cycles(void)
return (cycles_t) get_tod_clock() >> 2;
}
-int get_sync_clock(unsigned long long *clock);
+int get_phys_clock(unsigned long long *clock);
void init_cpu_timer(void);
unsigned long long monotonic_clock(void);
diff --git a/arch/s390/kernel/early.c b/arch/s390/kernel/early.c
index 3c31609..f82bcab 100644
--- a/arch/s390/kernel/early.c
+++ b/arch/s390/kernel/early.c
@@ -439,6 +439,7 @@ void __init startup_init(void)
ipl_save_parameters();
rescue_initrd();
clear_bss_section();
+ ptff_init();
init_kernel_storage_key();
lockdep_init();
lockdep_off();
diff --git a/arch/s390/kernel/time.c b/arch/s390/kernel/time.c
index 1a94242..bc554e3 100644
--- a/arch/s390/kernel/time.c
+++ b/arch/s390/kernel/time.c
@@ -39,6 +39,7 @@
#include <linux/gfp.h>
#include <linux/kprobes.h>
#include <asm/uaccess.h>
+#include <asm/facility.h>
#include <asm/delay.h>
#include <asm/div64.h>
#include <asm/vdso.h>
@@ -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.
@@ -759,6 +779,7 @@ 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;
@@ -805,6 +826,10 @@ 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;
}
@@ -1539,6 +1564,7 @@ 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;
@@ -1564,6 +1590,10 @@ 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);
diff --git a/drivers/s390/block/dasd_eckd.c b/drivers/s390/block/dasd_eckd.c
index 9083247..4d4cfaf 100644
--- a/drivers/s390/block/dasd_eckd.c
+++ b/drivers/s390/block/dasd_eckd.c
@@ -223,7 +223,7 @@ check_XRC (struct ccw1 *de_ccw,
data->ga_extended |= 0x08; /* switch on 'Time Stamp Valid' */
data->ga_extended |= 0x02; /* switch on 'Extended Parameter' */
- rc = get_sync_clock(&data->ep_sys_time);
+ rc = get_phys_clock(&data->ep_sys_time);
/* Ignore return code if sync clock is switched off. */
if (rc == -EOPNOTSUPP || rc == -EACCES)
rc = 0;
@@ -334,7 +334,7 @@ static int check_XRC_on_prefix(struct PFX_eckd_data *pfxdata,
pfxdata->define_extent.ga_extended |= 0x02; /* 'Extended Parameter' */
pfxdata->validity.time_stamp = 1; /* 'Time Stamp Valid' */
- rc = get_sync_clock(&pfxdata->define_extent.ep_sys_time);
+ rc = get_phys_clock(&pfxdata->define_extent.ep_sys_time);
/* Ignore return code if sync clock is switched off. */
if (rc == -EOPNOTSUPP || rc == -EACCES)
rc = 0;
--
2.7.4
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