Use clock_gettime(CLOCK_VIRTUAL,...) for QEMU_CLOCK_VIRTUAL.

This change uses clock_gettime(CLOCK_VIRTUAL,...) if it is available
for QEMU_CLOCK_VIRTUAL timers. It also backs out the 578c23d change
which cause problems booting CheriBSD.

cpus.c

@@ -211,7 +211,7 @@ static int64_t cpu_get_clock_locked(void)
 
     ticks = timers_state.cpu_clock_offset;
     if (timers_state.cpu_ticks_enabled) {
-        ticks += get_clock();
+        ticks += get_virtual_clock();
     }
 
     return ticks;

include/qemu/timer.h

@@ -825,6 +825,11 @@ static inline int64_t get_clock(void)
     return muldiv64(ti.QuadPart, get_ticks_per_sec(), clock_freq);
 }
 
+static inline int64_t get_virtual_clock(void)
+{
+    return get_clock();
+}
+
 #else
 
 extern int use_rt_clock;
@@ -844,6 +849,19 @@ static inline int64_t get_clock(void)
         return get_clock_realtime();
     }
 }
+
+static inline int64_t get_virtual_clock(void)
+{
+#ifdef CLOCK_VIRTUAL
+    struct timespec ts;
+
+    clock_gettime(CLOCK_VIRTUAL, &ts);
+    return ts.tv_sec * 1000000000LL + ts.tv_nsec;
+#else
+    return get_clock();
+#endif
+}
+
 #endif
 
 /* icount */

qemu-timer.c

@@ -565,7 +565,7 @@ int64_t qemu_clock_get_ns(QEMUClockType type)
     default:
     case QEMU_CLOCK_VIRTUAL:
         if (use_icount) {
-            return (cpu_get_icount() << 4) | (cpu_get_clock() & 0xful);
+            return cpu_get_icount();
         } else {
             return cpu_get_clock();
         }