3 files changed, 10 insertions, 3 deletions

diff --git a/arch/powerpc/include/asm/time.h b/arch/powerpc/include/asm/time.h
index 2136f58a54e8..3b4b4a8da922 100644
--- a/arch/powerpc/include/asm/time.h
+++ b/arch/powerpc/include/asm/time.h
@@ -23,6 +23,7 @@
 extern unsigned long tb_ticks_per_jiffy;
 extern unsigned long tb_ticks_per_usec;
 extern unsigned long tb_ticks_per_sec;
+extern struct clock_event_device decrementer_clockevent;
 
 struct rtc_time;
 extern void to_tm(int tim, struct rtc_time * tm);
diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c
index 2c42cd72d0f5..99a995c2a3f2 100644
--- a/arch/powerpc/kernel/time.c
+++ b/arch/powerpc/kernel/time.c
@@ -100,7 +100,7 @@ static int decrementer_set_next_event(unsigned long evt,
 static void decrementer_set_mode(enum clock_event_mode mode,
                                  struct clock_event_device *dev);
 
-static struct clock_event_device decrementer_clockevent = {
+struct clock_event_device decrementer_clockevent = {
         .name           = "decrementer",
         .rating         = 200,
         .irq            = 0,
@@ -108,6 +108,7 @@ static struct clock_event_device decrementer_clockevent = {
         .set_mode       = decrementer_set_mode,
         .features       = CLOCK_EVT_FEAT_ONESHOT,
 };
+EXPORT_SYMBOL(decrementer_clockevent);
 
 DEFINE_PER_CPU(u64, decrementers_next_tb);
 static DEFINE_PER_CPU(struct clock_event_device, decrementers);
diff --git a/arch/powerpc/kvm/emulate.c b/arch/powerpc/kvm/emulate.c
index afc9154f1aef..b5872f61a213 100644
--- a/arch/powerpc/kvm/emulate.c
+++ b/arch/powerpc/kvm/emulate.c
@@ -23,6 +23,7 @@
 #include <linux/types.h>
 #include <linux/string.h>
 #include <linux/kvm_host.h>
+#include <linux/clockchips.h>
 
 #include <asm/reg.h>
 #include <asm/time.h>
@@ -104,8 +105,12 @@ void kvmppc_emulate_dec(struct kvm_vcpu *vcpu)
          */
 
         dec_time = vcpu->arch.dec;
-        dec_time *= 1000;
-        do_div(dec_time, tb_ticks_per_usec);
+        /*
+         * Guest timebase ticks at the same frequency as host decrementer.
+         * So use the host decrementer calculations for decrementer emulation.
+         */
+        dec_time = dec_time << decrementer_clockevent.shift;
+        do_div(dec_time, decrementer_clockevent.mult);
         dec_nsec = do_div(dec_time, NSEC_PER_SEC);
         hrtimer_start(&vcpu->arch.dec_timer,
                 ktime_set(dec_time, dec_nsec), HRTIMER_MODE_REL);