Index: /trunk/src/VBox/Runtime/r0drv/linux/mp-r0drv-linux.c
===================================================================
--- /trunk/src/VBox/Runtime/r0drv/linux/mp-r0drv-linux.c	(revision 52580)
+++ /trunk/src/VBox/Runtime/r0drv/linux/mp-r0drv-linux.c	(revision 52581)
@@ -187,5 +187,5 @@
 
 /**
- * Wrapper between the native linux per-cpu callbacks and PFNRTWORKER
+ * Wrapper between the native linux per-cpu callbacks and PFNRTWORKER.
  *
  * @param   pvInfo      Pointer to the RTMPARGS package.
@@ -199,31 +199,78 @@
 
 
+/**
+ * Wrapper between the native linux all-cpu callbacks and PFNRTWORKER.
+ *
+ * @param   pvInfo      Pointer to the RTMPARGS package.
+ */
+static void rtmpLinuxAllWrapper(void *pvInfo)
+{
+    PRTMPARGS  pArgs      = (PRTMPARGS)pvInfo;
+    PRTCPUSET  pWorkerSet = pArgs->pWorkerSet;
+    RTCPUID    idCpu      = RTMpCpuId();
+    Assert(!RTThreadPreemptIsEnabled(NIL_RTTHREAD));
+
+    if (RTCpuSetIsMember(pWorkerSet, idCpu))
+    {
+        pArgs->pfnWorker(idCpu, pArgs->pvUser1, pArgs->pvUser2);
+        RTCpuSetDel(pWorkerSet, idCpu);
+    }
+}
+
+
 RTDECL(int) RTMpOnAll(PFNRTMPWORKER pfnWorker, void *pvUser1, void *pvUser2)
 {
     int rc;
     RTMPARGS Args;
-
-#if LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 0)
+    RTCPUSET OnlineSet;
+    RTCPUID  idCpu;
+    uint32_t cLoops;
+
     RTTHREADPREEMPTSTATE PreemptState = RTTHREADPREEMPTSTATE_INITIALIZER;
-#endif
-    Args.pfnWorker = pfnWorker;
-    Args.pvUser1 = pvUser1;
-    Args.pvUser2 = pvUser2;
-    Args.idCpu = NIL_RTCPUID;
-    Args.cHits = 0;
-
+
+    Args.pfnWorker  = pfnWorker;
+    Args.pvUser1    = pvUser1;
+    Args.pvUser2    = pvUser2;
+    Args.idCpu      = NIL_RTCPUID;
+    Args.cHits      = 0;
+
+    RTThreadPreemptDisable(&PreemptState);
+    RTMpGetOnlineSet(&OnlineSet);
+    Args.pWorkerSet = &OnlineSet;
+    idCpu = RTMpCpuId();
+
+    if (RTCpuSetCount(&OnlineSet) > 1)
+    {
+        /* Fire the function on all other CPUs without waiting for completion. */
 #if LINUX_VERSION_CODE >= KERNEL_VERSION(2, 6, 27)
-    rc = on_each_cpu(rtmpLinuxWrapper, &Args, 1 /* wait */);
-#elif LINUX_VERSION_CODE >= KERNEL_VERSION(2, 6, 0)
-    rc = on_each_cpu(rtmpLinuxWrapper, &Args, 0 /* retry */, 1 /* wait */);
-#else /* older kernels */
-    RTThreadPreemptDisable(&PreemptState);
-    rc = smp_call_function(rtmpLinuxWrapper, &Args, 0 /* retry */, 1 /* wait */);
-    local_irq_disable();
-    rtmpLinuxWrapper(&Args);
-    local_irq_enable();
+        rc = smp_call_function(rtmpLinuxAllWrapper, &Args, 0 /* wait */);
+#else
+        rc = smp_call_function(rtmpLinuxAllWrapper, &Args, 0 /* retry */, 0 /* wait */);
+#endif
+        Assert(!rc); NOREF(rc);
+    }
+
+    /* Fire the function on this CPU. */
+    Args.pfnWorker(idCpu, Args.pvUser1, Args.pvUser2);
+    RTCpuSetDel(Args.pWorkerSet, idCpu);
+
+    /* Wait for all of them finish. */
+    cLoops = 64000;
+    while (!RTCpuSetIsEmpty(Args.pWorkerSet))
+    {
+        /* Periodically check if any CPU in the wait set has gone offline, if so update the wait set. */
+        if (!cLoops--)
+        {
+            RTCPUSET OnlineSetNow;
+            RTMpGetOnlineSet(&OnlineSetNow);
+            RTCpuSetAnd(Args.pWorkerSet, &OnlineSetNow);
+
+            cLoops = 64000;
+        }
+
+        ASMNopPause();
+    }
+
     RTThreadPreemptRestore(&PreemptState);
-#endif /* older kernels */
-    Assert(rc == 0); NOREF(rc);
     return VINF_SUCCESS;
 }
Index: /trunk/src/VBox/Runtime/r0drv/mp-r0drv.h
===================================================================
--- /trunk/src/VBox/Runtime/r0drv/mp-r0drv.h	(revision 52580)
+++ /trunk/src/VBox/Runtime/r0drv/mp-r0drv.h	(revision 52581)
@@ -54,4 +54,7 @@
     RTCPUID     idCpu;
     uint32_t volatile cHits;
+#ifdef RT_OS_LINUX
+    PRTCPUSET   pWorkerSet;
+#endif
 } RTMPARGS;
 /** Pointer to a RTMpOn* argument packet. */