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Commit 40277891 authored by Martin Schwidefsky's avatar Martin Schwidefsky
Browse files

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: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 9dc06ccf

arch/s390/include/asm/timex.h

+14 −1
Original line number Diff line number Diff line
@@ -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);

arch/s390/kernel/early.c

+1 −0
Original line number Diff line number Diff line
@@ -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();

arch/s390/kernel/time.c

+38 −8
Original line number Diff line number Diff line
@@ -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.
@@ -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);

drivers/s390/block/dasd_eckd.c

+2 −2
Original line number Diff line number Diff line
@@ -228,7 +228,7 @@ 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;
@@ -339,7 +339,7 @@ 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;