Commit 0af3e137 authored by Andrea Parri's avatar Andrea Parri Committed by Daniel Lezcano
Browse files

clocksource/drivers/hyper-v: Untangle stimers and timesync from clocksources 



hyperv_timer.c exports hyperv_cs, which is used by stimers and the
timesync mechanism.  However, the clocksource dependency is not
needed: these mechanisms only depend on the partition reference
counter (which can be read via a MSR or via the TSC Reference Page).

Introduce the (function) pointer hv_read_reference_counter, as an
embodiment of the partition reference counter read, and export it
in place of the hyperv_cs pointer.  The latter can be removed.

This should clarify that there's no relationship between Hyper-V
stimers & timesync and the Linux clocksource abstractions.  No
functional or semantic change.

Suggested-by: default avatarMichael Kelley <mikelley@microsoft.com>
Signed-off-by: default avatarAndrea Parri <parri.andrea@gmail.com>
Reviewed-by: default avatarMichael Kelley <mikelley@microsoft.com>
Signed-off-by: default avatarDaniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20200109160650.16150-2-parri.andrea@gmail.com
parent b9c60a74

drivers/clocksource/hyperv_timer.c

+23 −13
Original line number Diff line number Diff line
@@ -66,7 +66,7 @@ static int hv_ce_set_next_event(unsigned long delta, 
{

	u64 current_tick;



	current_tick = hyperv_cs->read(NULL);

	current_tick = hv_read_reference_counter();

	current_tick += delta;

	hv_init_timer(0, current_tick);

	return 0;
@@ -304,8 +304,8 @@ EXPORT_SYMBOL_GPL(hv_stimer_global_cleanup); 
 * Hyper-V and 32-bit x86.  The TSC reference page version is preferred.

 */



struct clocksource *hyperv_cs;

EXPORT_SYMBOL_GPL(hyperv_cs);

u64 (*hv_read_reference_counter)(void);

EXPORT_SYMBOL_GPL(hv_read_reference_counter);



static union {

	struct ms_hyperv_tsc_page page;
@@ -318,7 +318,7 @@ struct ms_hyperv_tsc_page *hv_get_tsc_page(void) 
}

EXPORT_SYMBOL_GPL(hv_get_tsc_page);



static u64 notrace read_hv_clock_tsc(struct clocksource *arg)

static u64 notrace read_hv_clock_tsc(void)

{

	u64 current_tick = hv_read_tsc_page(hv_get_tsc_page());
@@ -328,9 +328,14 @@ static u64 notrace read_hv_clock_tsc(struct clocksource *arg) 
	return current_tick;

}



static u64 notrace read_hv_clock_tsc_cs(struct clocksource *arg)

{

	return read_hv_clock_tsc();

}



static u64 read_hv_sched_clock_tsc(void)

{

	return read_hv_clock_tsc(NULL) - hv_sched_clock_offset;

	return read_hv_clock_tsc() - hv_sched_clock_offset;

}



static void suspend_hv_clock_tsc(struct clocksource *arg)
@@ -359,14 +364,14 @@ static void resume_hv_clock_tsc(struct clocksource *arg) 
static struct clocksource hyperv_cs_tsc = {

	.name	= "hyperv_clocksource_tsc_page",

	.rating	= 400,

	.read	= read_hv_clock_tsc,

	.read	= read_hv_clock_tsc_cs,

	.mask	= CLOCKSOURCE_MASK(64),

	.flags	= CLOCK_SOURCE_IS_CONTINUOUS,

	.suspend= suspend_hv_clock_tsc,

	.resume	= resume_hv_clock_tsc,

};



static u64 notrace read_hv_clock_msr(struct clocksource *arg)

static u64 notrace read_hv_clock_msr(void)

{

	u64 current_tick;

	/*
@@ -378,15 +383,20 @@ static u64 notrace read_hv_clock_msr(struct clocksource *arg) 
	return current_tick;

}



static u64 notrace read_hv_clock_msr_cs(struct clocksource *arg)

{

	return read_hv_clock_msr();

}



static u64 read_hv_sched_clock_msr(void)

{

	return read_hv_clock_msr(NULL) - hv_sched_clock_offset;

	return read_hv_clock_msr() - hv_sched_clock_offset;

}



static struct clocksource hyperv_cs_msr = {

	.name	= "hyperv_clocksource_msr",

	.rating	= 400,

	.read	= read_hv_clock_msr,

	.read	= read_hv_clock_msr_cs,

	.mask	= CLOCKSOURCE_MASK(64),

	.flags	= CLOCK_SOURCE_IS_CONTINUOUS,

};
@@ -399,7 +409,7 @@ static bool __init hv_init_tsc_clocksource(void) 
	if (!(ms_hyperv.features & HV_MSR_REFERENCE_TSC_AVAILABLE))

		return false;



	hyperv_cs = &hyperv_cs_tsc;

	hv_read_reference_counter = read_hv_clock_tsc;

	phys_addr = virt_to_phys(hv_get_tsc_page());



	/*
@@ -417,7 +427,7 @@ static bool __init hv_init_tsc_clocksource(void) 
	hv_set_clocksource_vdso(hyperv_cs_tsc);

	clocksource_register_hz(&hyperv_cs_tsc, NSEC_PER_SEC/100);



	hv_sched_clock_offset = hyperv_cs->read(hyperv_cs);

	hv_sched_clock_offset = hv_read_reference_counter();

	hv_setup_sched_clock(read_hv_sched_clock_tsc);



	return true;
@@ -439,10 +449,10 @@ void __init hv_init_clocksource(void) 
	if (!(ms_hyperv.features & HV_MSR_TIME_REF_COUNT_AVAILABLE))

		return;



	hyperv_cs = &hyperv_cs_msr;

	hv_read_reference_counter = read_hv_clock_msr;

	clocksource_register_hz(&hyperv_cs_msr, NSEC_PER_SEC/100);



	hv_sched_clock_offset = hyperv_cs->read(hyperv_cs);

	hv_sched_clock_offset = hv_read_reference_counter();

	hv_setup_sched_clock(read_hv_sched_clock_msr);

}

EXPORT_SYMBOL_GPL(hv_init_clocksource);

drivers/hv/hv_util.c

+4 −4
Original line number Diff line number Diff line
@@ -211,7 +211,7 @@ static struct timespec64 hv_get_adj_host_time(void) 
	unsigned long flags;



	spin_lock_irqsave(&host_ts.lock, flags);

	reftime = hyperv_cs->read(hyperv_cs);

	reftime = hv_read_reference_counter();

	newtime = host_ts.host_time + (reftime - host_ts.ref_time);

	ts = ns_to_timespec64((newtime - WLTIMEDELTA) * 100);

	spin_unlock_irqrestore(&host_ts.lock, flags);
@@ -250,7 +250,7 @@ static inline void adj_guesttime(u64 hosttime, u64 reftime, u8 adj_flags) 
	 */

	spin_lock_irqsave(&host_ts.lock, flags);



	cur_reftime = hyperv_cs->read(hyperv_cs);

	cur_reftime = hv_read_reference_counter();

	host_ts.host_time = hosttime;

	host_ts.ref_time = cur_reftime;
@@ -315,7 +315,7 @@ static void timesync_onchannelcallback(void *context) 
					sizeof(struct vmbuspipe_hdr) +

					sizeof(struct icmsg_hdr)];

				adj_guesttime(timedatap->parenttime,

					      hyperv_cs->read(hyperv_cs),

					      hv_read_reference_counter(),

					      timedatap->flags);

			}

		}
@@ -524,7 +524,7 @@ static struct ptp_clock *hv_ptp_clock; 
static int hv_timesync_init(struct hv_util_service *srv)

{

	/* TimeSync requires Hyper-V clocksource. */

	if (!hyperv_cs)

	if (!hv_read_reference_counter)

		return -ENODEV;



	spin_lock_init(&host_ts.lock);

include/clocksource/hyperv_timer.h

+1 −1
Original line number Diff line number Diff line
@@ -30,7 +30,7 @@ extern void hv_stimer_global_cleanup(void); 
extern void hv_stimer0_isr(void);



#ifdef CONFIG_HYPERV_TIMER

extern struct clocksource *hyperv_cs;

extern u64 (*hv_read_reference_counter)(void);

extern void hv_init_clocksource(void);



extern struct ms_hyperv_tsc_page *hv_get_tsc_page(void);

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