timer: add cpu_icount_to_ns function.

This adds cpu_icount_to_ns function which is needed for reverse execution.

It returns the time for a specific instruction.
Signed-off-by: NKONRAD Frederic <fred.konrad@greensocs.com>
Reviewed-by: NPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

cpus.c

@@ -146,7 +146,7 @@ static int64_t cpu_get_icount_locked(void)
         }
         icount -= (cpu->icount_decr.u16.low + cpu->icount_extra);
     }
-    return timers_state.qemu_icount_bias + (icount << icount_time_shift);
+    return timers_state.qemu_icount_bias + cpu_icount_to_ns(icount);
 }
 
 int64_t cpu_get_icount(void)
@@ -162,6 +162,11 @@ int64_t cpu_get_icount(void)
     return icount;
 }
 
+int64_t cpu_icount_to_ns(int64_t icount)
+{
+    return icount << icount_time_shift;
+}
+
 /* return the host CPU cycle counter and handle stop/restart */
 /* Caller must hold the BQL */
 int64_t cpu_get_ticks(void)

include/qemu/timer.h

@@ -745,6 +745,7 @@ static inline int64_t get_clock(void)
 /* icount */
 int64_t cpu_get_icount(void);
 int64_t cpu_get_clock(void);
+int64_t cpu_icount_to_ns(int64_t icount);
 
 /*******************************************/
 /* host CPU ticks (if available) */