Commit d63285e9 authored by Marcelo Tosatti's avatar Marcelo Tosatti Committed by Gleb Natapov
Browse files

pvclock: detect watchdog reset at pvclock read 



Implement reset of kernel watchdogs at pvclock read time. This avoids
adding special code to every watchdog.

This is possible for watchdogs which measure time based on sched_clock() or
ktime_get() variants.

Suggested by Don Zickus.

Acked-by: default avatarDon Zickus <dzickus@redhat.com>
Acked-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: default avatarMarcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: default avatarGleb Natapov <gleb@redhat.com>
parent 01b71917

arch/x86/include/asm/pvclock.h

+2 −0
Original line number Diff line number Diff line
@@ -14,6 +14,8 @@ void pvclock_read_wallclock(struct pvclock_wall_clock *wall, 
			    struct timespec *ts);

void pvclock_resume(void);



void pvclock_touch_watchdogs(void);



/*

 * Scale a 64-bit delta by scaling and multiplying by a 32-bit fraction,

 * yielding a 64-bit result.

arch/x86/kernel/kvmclock.c

+1 −0
Original line number Diff line number Diff line
@@ -139,6 +139,7 @@ bool kvm_check_and_clear_guest_paused(void) 
	src = &hv_clock[cpu].pvti;

	if ((src->flags & PVCLOCK_GUEST_STOPPED) != 0) {

		src->flags &= ~PVCLOCK_GUEST_STOPPED;

		pvclock_touch_watchdogs();

		ret = true;

	}

arch/x86/kernel/pvclock.c

+12 −0
Original line number Diff line number Diff line
@@ -43,6 +43,13 @@ unsigned long pvclock_tsc_khz(struct pvclock_vcpu_time_info *src) 
	return pv_tsc_khz;

}



void pvclock_touch_watchdogs(void)

{

	touch_softlockup_watchdog_sync();

	clocksource_touch_watchdog();

	rcu_cpu_stall_reset();

}



static atomic64_t last_value = ATOMIC64_INIT(0);



void pvclock_resume(void)
@@ -74,6 +81,11 @@ cycle_t pvclock_clocksource_read(struct pvclock_vcpu_time_info *src) 
		version = __pvclock_read_cycles(src, &ret, &flags);

	} while ((src->version & 1) || version != src->version);



	if (unlikely((flags & PVCLOCK_GUEST_STOPPED) != 0)) {

		src->flags &= ~PVCLOCK_GUEST_STOPPED;

		pvclock_touch_watchdogs();

	}



	if ((valid_flags & PVCLOCK_TSC_STABLE_BIT) &&

		(flags & PVCLOCK_TSC_STABLE_BIT))

		return ret;