diff --git a/xen/arch/arm/include/asm/time.h b/xen/arch/arm/include/asm/time.h
index 49ad8c1a6d..c194dbb9f5 100644
--- a/xen/arch/arm/include/asm/time.h
+++ b/xen/arch/arm/include/asm/time.h
@@ -101,9 +101,6 @@ extern void init_timer_interrupt(void);
 /* Counter value at boot time */
 extern uint64_t boot_count;
 
-extern s_time_t ticks_to_ns(uint64_t ticks);
-extern uint64_t ns_to_ticks(s_time_t ns);
-
 void preinit_xen_time(void);
 
 void force_update_vcpu_system_time(struct vcpu *v);
diff --git a/xen/arch/arm/time.c b/xen/arch/arm/time.c
index cc3fcf47b6..a12912a106 100644
--- a/xen/arch/arm/time.c
+++ b/xen/arch/arm/time.c
@@ -27,7 +27,6 @@
 #include <asm/cpufeature.h>
 #include <asm/platform.h>
 #include <asm/system.h>
-#include <asm/time.h>
 #include <asm/vgic.h>
 
 uint64_t __read_mostly boot_count;
@@ -47,16 +46,6 @@ unsigned int timer_get_irq(enum timer_ppi ppi)
     return timer_irq[ppi];
 }
 
-/*static inline*/ s_time_t ticks_to_ns(uint64_t ticks)
-{
-    return muldiv64(ticks, SECONDS(1), 1000 * cpu_khz);
-}
-
-/*static inline*/ uint64_t ns_to_ticks(s_time_t ns)
-{
-    return muldiv64(ns, 1000 * cpu_khz, SECONDS(1));
-}
-
 static __initdata struct dt_device_node *timer;
 
 #ifdef CONFIG_ACPI
diff --git a/xen/arch/arm/vtimer.c b/xen/arch/arm/vtimer.c
index d2124b1755..2e85ff2b6e 100644
--- a/xen/arch/arm/vtimer.c
+++ b/xen/arch/arm/vtimer.c
@@ -12,13 +12,13 @@
 #include <xen/lib.h>
 #include <xen/perfc.h>
 #include <xen/sched.h>
+#include <xen/time.h>
 #include <xen/timer.h>
 
 #include <asm/cpregs.h>
 #include <asm/div64.h>
 #include <asm/irq.h>
 #include <asm/regs.h>
-#include <asm/time.h>
 #include <asm/vgic.h>
 #include <asm/vreg.h>
 #include <asm/vtimer.h>
diff --git a/xen/arch/riscv/include/asm/time.h b/xen/arch/riscv/include/asm/time.h
index 1e7801e2ea..be3875b998 100644
--- a/xen/arch/riscv/include/asm/time.h
+++ b/xen/arch/riscv/include/asm/time.h
@@ -24,11 +24,6 @@ static inline cycles_t get_cycles(void)
     return csr_read(CSR_TIME);
 }
 
-static inline s_time_t ticks_to_ns(uint64_t ticks)
-{
-    return muldiv64(ticks, MILLISECS(1), cpu_khz);
-}
-
 void preinit_xen_time(void);
 
 #endif /* ASM__RISCV__TIME_H */
diff --git a/xen/arch/riscv/time.c b/xen/arch/riscv/time.c
index e962f8518d..2c7af0a5d6 100644
--- a/xen/arch/riscv/time.c
+++ b/xen/arch/riscv/time.c
@@ -4,6 +4,7 @@
 #include <xen/init.h>
 #include <xen/lib.h>
 #include <xen/sections.h>
+#include <xen/time.h>
 #include <xen/types.h>
 
 unsigned long __ro_after_init cpu_khz; /* CPU clock frequency in kHz. */
diff --git a/xen/include/xen/time.h b/xen/include/xen/time.h
index fe0d7a578a..2185dd26a4 100644
--- a/xen/include/xen/time.h
+++ b/xen/include/xen/time.h
@@ -8,6 +8,7 @@
 #ifndef __XEN_TIME_H__
 #define __XEN_TIME_H__
 
+#include <xen/muldiv64.h>
 #include <xen/types.h>
 #include <public/xen.h>
 
@@ -75,6 +76,16 @@ extern void send_timer_event(struct vcpu *v);
 
 void domain_set_time_offset(struct domain *d, int64_t time_offset_seconds);
 
+static inline s_time_t ticks_to_ns(uint64_t ticks)
+{
+    return muldiv64(ticks, MILLISECS(1), cpu_khz);
+}
+
+static inline uint64_t ns_to_ticks(s_time_t ns)
+{
+    return muldiv64(ns, cpu_khz, MILLISECS(1));
+}
+
 #include <asm/time.h>
 
 #endif /* __XEN_TIME_H__ */