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[PATCH v4 10/10] kvmclock: implement the extended reading function

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This allows L2 guests to use masterclock, namely
provide KVM with ability to use masterclock while
running over kvmclock closksource in the cases when
it's possible.

This is the final part of the work of teaching KVM
to use masterclock when over kvmclock clocksource.

Signed-off-by: Denis Plotnikov <dplotnikov@virtuozzo.com>
---
 arch/x86/kernel/kvmclock.c | 19 +++++++++++++++++--
 1 file changed, 17 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/kvmclock.c b/arch/x86/kernel/kvmclock.c
index f692579..8c1008f 100644
--- a/arch/x86/kernel/kvmclock.c
+++ b/arch/x86/kernel/kvmclock.c
@@ -82,7 +82,7 @@ static int kvm_set_wallclock(const struct timespec *now)
 	return -1;
 }
 
-static u64 kvm_clock_read(void)
+static inline u64 __kvm_clock_read(u64 *cycles, u8 *flags)
 {
 	struct pvclock_vcpu_time_info *src;
 	u64 ret;
@@ -91,10 +91,14 @@ static u64 kvm_clock_read(void)
 	preempt_disable_notrace();
 	cpu = smp_processor_id();
 	src = &hv_clock[cpu].pvti;
-	ret = pvclock_clocksource_read(src, NULL, NULL);
+	ret = pvclock_clocksource_read(src, cycles, flags);
 	preempt_enable_notrace();
 	return ret;
 }
+static u64 kvm_clock_read(void)
+{
+	return __kvm_clock_read(NULL, NULL);
+}
 
 static u64 kvm_clock_get_cycles(struct clocksource *cs)
 {
@@ -177,9 +181,20 @@ bool kvm_check_and_clear_guest_paused(void)
 	return ret;
 }
 
+static bool kvm_clock_read_with_stamp(struct clocksource *cs,
+					u64 *cycles, u64 *cycles_stamp)
+{
+	u8 flags;
+
+	*cycles = __kvm_clock_read(cycles_stamp, &flags);
+
+	return (bool) flags & PVCLOCK_TSC_STABLE_BIT;
+}
+
 struct clocksource kvm_clock = {
 	.name = "kvm-clock",
 	.read = kvm_clock_get_cycles,
+	.read_with_stamp = kvm_clock_read_with_stamp,
 	.rating = 400,
 	.mask = CLOCKSOURCE_MASK(64),
 	.flags = CLOCK_SOURCE_IS_CONTINUOUS,
-- 
2.7.4

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[PATCH v4 00/10] make L2's kvm-clock stable, get rid of pvclock_gtod_copy in KVM Denis Plotnikov <dplotnikov@virtuozzo.com> - 2017-08-02 17:00 +0200
  [PATCH v4 10/10] kvmclock: implement the extended reading function Denis Plotnikov <dplotnikov@virtuozzo.com> - 2017-08-02 17:00 +0200
  [PATCH v4 07/10] KVM: x86: remove not used pvclock_gtod_copy Denis Plotnikov <dplotnikov@virtuozzo.com> - 2017-08-02 17:00 +0200
    Re: [PATCH v4 07/10] KVM: x86: remove not used pvclock_gtod_copy Marcelo Tosatti <mtosatti@redhat.com> - 2017-08-03 01:30 +0200
      Re: [PATCH v4 07/10] KVM: x86: remove not used pvclock_gtod_copy Paolo Bonzini <pbonzini@redhat.com> - 2017-08-03 14:40 +0200
  [PATCH v4 09/10] pvclock: add clocksource change notification on changing of tsc stable bit Denis Plotnikov <dplotnikov@virtuozzo.com> - 2017-08-02 17:00 +0200
    Re: [PATCH v4 09/10] pvclock: add clocksource change notification on  changing of tsc stable bit Marcelo Tosatti <mtosatti@redhat.com> - 2017-08-03 01:40 +0200
  [PATCH v4 06/10] timekeeper: add clocksource change notifier Denis Plotnikov <dplotnikov@virtuozzo.com> - 2017-08-02 17:00 +0200
  Re: [PATCH v4 00/10] make L2's kvm-clock stable, get rid of  pvclock_gtod_copy in KVM Paolo Bonzini <pbonzini@redhat.com> - 2017-08-02 18:20 +0200
  Re: [PATCH v4 00/10] make L2's kvm-clock stable, get rid of  pvclock_gtod_copy in KVM John Stultz <john.stultz@linaro.org> - 2017-08-02 18:50 +0200
    Re: [PATCH v4 00/10] make L2's kvm-clock stable, get rid of  pvclock_gtod_copy in KVM Paolo Bonzini <pbonzini@redhat.com> - 2017-08-02 19:20 +0200

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