Changeset 72639 in vbox for trunk/src/VBox/Runtime

Timestamp:

Jun 21, 2018 1:51:44 PM (6 years ago)

Author:

vboxsync

Message:

IPRT,VMM: Try use KeShouldYieldProcessor to implement RTThreadPreemptIsPending on Windows. That'll save us a lot of pain with changing _KPRCB structures. bugref:5102

Location:

trunk/src/VBox/Runtime/r0drv/nt

Files:

• initterm-r0drv-nt.cpp (modified) (2 diffs)
• internal-r0drv-nt.h (modified) (1 diff)
• thread-r0drv-nt.cpp (modified) (2 diffs)

trunk/src/VBox/Runtime/r0drv/nt/initterm-r0drv-nt.cpp

@@ -95 +95 @@
 /** KeInitializeTimerEx - Introduced in NT 4. */
 decltype(KeInitializeTimerEx)          *g_pfnrtKeInitializeTimerEx;
+/** KeShouldYieldProcessor - Introduced in Windows 10. */
+PFNKESHOULDYIELDPROCESSOR               g_pfnrtKeShouldYieldProcessor;
 /** Pointer to the MmProtectMdlSystemAddress kernel function if it's available.
  * This API was introduced in XP. */
@@ -306 +308 @@
     GET_SYSTEM_ROUTINE(KeSetTargetProcessorDpc);
     GET_SYSTEM_ROUTINE(KeInitializeTimerEx);
+    GET_SYSTEM_ROUTINE_TYPE(KeShouldYieldProcessor, PFNKESHOULDYIELDPROCESSOR);
     GET_SYSTEM_ROUTINE(MmProtectMdlSystemAddress);
     GET_SYSTEM_ROUTINE(MmAllocatePagesForMdl);

trunk/src/VBox/Runtime/r0drv/nt/internal-r0drv-nt.h

@@ -85 +85 @@
 extern decltype(KeSetTargetProcessorDpc)      *g_pfnrtKeSetTargetProcessorDpc;
 extern decltype(KeInitializeTimerEx)          *g_pfnrtKeInitializeTimerEx;
+extern PFNKESHOULDYIELDPROCESSOR               g_pfnrtKeShouldYieldProcessor;
 extern decltype(MmProtectMdlSystemAddress)    *g_pfnrtMmProtectMdlSystemAddress;
 extern decltype(MmAllocatePagesForMdl)        *g_pfnrtMmAllocatePagesForMdl;

trunk/src/VBox/Runtime/r0drv/nt/thread-r0drv-nt.cpp

@@ -96 +96 @@
 
     /*
+     * The KeShouldYieldProcessor API introduced in Windows 10 looks like exactly
+     * what we want.  But of course there is a snag.  It may return with interrupts
+     * enabled when called with them disabled.  Let's just hope it doesn't get upset
+     * by disabled interrupts in other ways...
+     */
+    if (g_pfnrtKeShouldYieldProcessor)
+    {
+        RTCCUINTREG fSavedFlags = ASMGetFlags();
+        bool fReturn = g_pfnrtKeShouldYieldProcessor() != FALSE;
+        ASMSetFlags(fSavedFlags);
+        return fReturn;
+    }
+
+    /*
+     * Fallback approach for pre W10 kernels.
+     *
+     * If W10 is anything to go by, we should also check and yield when:
+     *      - pPrcb->NextThread != NULL && pPrcb->NextThread != pPrcb->CurrentThread
+     *        when QuantumEnd is zero.
+     *      - pPrcb->DpcRequestSummary & 1
+     *      - pPrcb->DpcRequestSummary & 0x1e
+     */
+
+    /*
      * Read the globals and check if they are useful.
      */
@@ -154 +178 @@
 RTDECL(bool) RTThreadPreemptIsPendingTrusty(void)
 {
+    if (g_pfnrtKeShouldYieldProcessor)
+        return true;
 #if 0 /** @todo RTThreadPreemptIsPending isn't good enough on w7 and possibly elsewhere. */
     /* RTThreadPreemptIsPending is only reliable if we've got both offsets and size. */