x86: paravirt: factor out cpu_khz to common code

KVM intends to use paravirt code to calibrate khz. Xen
current code will do just fine. So as a first step, factor out
code to pvclock.c.

Signed-off-by: Glauber Costa <gcosta@redhat.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>

1 files changed, 12 insertions, 0 deletions

diff --git a/arch/x86/kernel/pvclock.c b/arch/x86/kernel/pvclock.c
index 05fbe9a..1c54b5f 100644
--- a/arch/x86/kernel/pvclock.c
+++ b/arch/x86/kernel/pvclock.c
@@ -97,6 +97,18 @@ static unsigned pvclock_get_time_values(struct pvclock_shadow_time *dst,
 	return dst->version;
 }
 
+unsigned long pvclock_tsc_khz(struct pvclock_vcpu_time_info *src)
+{
+	u64 tsc_khz = 1000000ULL << 32;
+
+	do_div(tsc_khz, src->tsc_to_system_mul);
+	if (src->tsc_shift < 0)
+		tsc_khz <<= -src->tsc_shift;
+	else
+		tsc_khz >>= src->tsc_shift;
+	return tsc_khz;
+}
+
 cycle_t pvclock_clocksource_read(struct pvclock_vcpu_time_info *src)
 {
 	struct pvclock_shadow_time shadow;