KVM: PPC: Use exported tb_to_ns() function in decrementer emulation

This changes the KVM code that emulates the decrementer function to do
the conversion of decrementer values to time intervals in nanoseconds
by calling the tb_to_ns() function exported by the powerpc timer code,
in preference to open-coded arithmetic using values from the
decrementer_clockevent struct.  Similarly, the HV-KVM code that did
the same conversion using arithmetic on tb_ticks_per_sec also now
uses tb_to_ns().

Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index 3e3a715..a6d948b 100644 (file)
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -2160,8 +2160,7 @@ static void kvmppc_set_timer(struct kvm_vcpu *vcpu)
                kvmppc_core_prepare_to_enter(vcpu);
                return;
        }
-       dec_nsec = (vcpu->arch.dec_expires - now) * NSEC_PER_SEC
-                  / tb_ticks_per_sec;
+       dec_nsec = tb_to_ns(vcpu->arch.dec_expires - now);
        hrtimer_start(&vcpu->arch.dec_timer, dec_nsec, HRTIMER_MODE_REL);
        vcpu->arch.timer_running = 1;
 }

diff --git a/arch/powerpc/kvm/emulate.c b/arch/powerpc/kvm/emulate.c
index fa888bf..9f5b8c0 100644 (file)
--- a/arch/powerpc/kvm/emulate.c
+++ b/arch/powerpc/kvm/emulate.c
@@ -61,11 +61,10 @@ void kvmppc_emulate_dec(struct kvm_vcpu *vcpu)
 
        dec_time = vcpu->arch.dec;
        /*
-        * Guest timebase ticks at the same frequency as host decrementer.
-        * So use the host decrementer calculations for decrementer emulation.
+        * Guest timebase ticks at the same frequency as host timebase.
+        * So use the host timebase calculations for decrementer emulation.
         */
-       dec_time = dec_time << decrementer_clockevent.shift;
-       do_div(dec_time, decrementer_clockevent.mult);
+       dec_time = tb_to_ns(dec_time);
        dec_nsec = do_div(dec_time, NSEC_PER_SEC);
        hrtimer_start(&vcpu->arch.dec_timer,
                ktime_set(dec_time, dec_nsec), HRTIMER_MODE_REL);