Index: /trunk/src/VBox/Devices/Storage/DevAHCI.cpp
===================================================================
--- /trunk/src/VBox/Devices/Storage/DevAHCI.cpp	(revision 54087)
+++ /trunk/src/VBox/Devices/Storage/DevAHCI.cpp	(revision 54088)
@@ -6638,4 +6638,12 @@
         ASMAtomicIncU32(&pAhci->cThreadsActive);
 
+        /* Check whether the thread should be suspended. */
+        if (pAhci->fSignalIdle)
+        {
+            if (!ASMAtomicDecU32(&pAhci->cThreadsActive))
+                PDMDevHlpAsyncNotificationCompleted(pAhciPort->pDevInsR3);
+            continue;
+        }
+
         /*
          * Check whether the global host controller bit is set and go to sleep immediately again