Changeset 92522 in vbox for trunk/src/VBox/VMM/VMMR3/NEMR3Native-linux.cpp

Timestamp:

Nov 20, 2021 2:41:05 AM (3 years ago)

Author:

vboxsync

Message:

VMM/NEM-linux: Make sure to flush pending IO or MMIO exits before returning from the inner RUN loop to the EM loops, otherwise weird stuff may happen if someone else (IEM,TRPM,EM,Debugger) modified the CPU state before we get back and do the next KVM_RUN. bugref:9044

File:

• trunk/src/VBox/VMM/VMMR3/NEMR3Native-linux.cpp (modified) (6 diffs)

trunk/src/VBox/VMM/VMMR3/NEMR3Native-linux.cpp

@@ -534 +534 @@
                         STAMR3RegisterF(pVM, &pNemCpu->StatImportPendingInterrupt, STAMTYPE_COUNTER, STAMVISIBILITY_ALWAYS, STAMUNIT_OCCURENCES, "Number of times an interrupt was pending when importing from KVM", "/NEM/CPU%u/ImportPendingInterrupt", idCpu);
                         STAMR3RegisterF(pVM, &pNemCpu->StatExportPendingInterrupt, STAMTYPE_COUNTER, STAMVISIBILITY_ALWAYS, STAMUNIT_OCCURENCES, "Number of times an interrupt was pending when exporting to KVM", "/NEM/CPU%u/ExportPendingInterrupt", idCpu);
+                        STAMR3RegisterF(pVM, &pNemCpu->StatFlushExitOnReturn,   STAMTYPE_COUNTER, STAMVISIBILITY_ALWAYS, STAMUNIT_OCCURENCES, "Number of times a KVM_EXIT_IO or KVM_EXIT_MMIO was flushed before returning to EM", "/NEM/CPU%u/FlushExitOnReturn", idCpu);
                         STAMR3RegisterF(pVM, &pNemCpu->StatQueryCpuTick,        STAMTYPE_COUNTER, STAMVISIBILITY_ALWAYS, STAMUNIT_OCCURENCES, "Number of TSC queries",                  "/NEM/CPU%u/QueryCpuTick", idCpu);
                         STAMR3RegisterF(pVM, &pNemCpu->StatExitTotal,           STAMTYPE_COUNTER, STAMVISIBILITY_ALWAYS, STAMUNIT_OCCURENCES, "All exits",                  "/NEM/CPU%u/Exit", idCpu);
@@ -2247 +2248 @@
 
 
-static VBOXSTRICTRC nemHCLnxHandleExit(PVMCC pVM, PVMCPUCC pVCpu, struct kvm_run *pRun)
+static VBOXSTRICTRC nemHCLnxHandleExit(PVMCC pVM, PVMCPUCC pVCpu, struct kvm_run *pRun, bool *pfStatefulExit)
 {
     STAM_REL_COUNTER_INC(&pVCpu->nem.s.StatExitTotal);
@@ -2258 +2259 @@
         case KVM_EXIT_IO:
             STAM_REL_COUNTER_INC(&pVCpu->nem.s.StatExitIo);
+            *pfStatefulExit = true;
             return nemHCLnxHandleExitIo(pVM, pVCpu, pRun);
 
         case KVM_EXIT_MMIO:
             STAM_REL_COUNTER_INC(&pVCpu->nem.s.StatExitMmio);
+            *pfStatefulExit = true;
             return nemHCLnxHandleExitMmio(pVM, pVCpu, pRun);
 
@@ -2411 +2414 @@
     const bool              fSingleStepping     = DBGFIsStepping(pVCpu);
     VBOXSTRICTRC            rcStrict            = VINF_SUCCESS;
+    bool                    fStatefulExit       = false;  /* For MMIO and IO exits. */
     for (unsigned iLoop = 0;; iLoop++)
     {
@@ -2491 +2495 @@
                 }
 #endif
+                fStatefulExit = false;
                 if (RT_LIKELY(rcLnx == 0 || errno == EINTR))
                 {
                     /*
-                     * Deal with the message.
+                     * Deal with the exit.
                      */
-                    rcStrict = nemHCLnxHandleExit(pVM, pVCpu, pRun);
+                    rcStrict = nemHCLnxHandleExit(pVM, pVCpu, pRun, &fStatefulExit);
                     if (rcStrict == VINF_SUCCESS)
                     { /* hopefully likely */ }
@@ -2539 +2544 @@
     } /* the run loop */
 
+
+    /*
+     * If the last exit was stateful, commit the state we provided before
+     * returning to the EM loop so we have a consistent state and can safely
+     * be rescheduled and whatnot.  (There is no 'ing way to reset the kernel
+     * side completion callback for these stateful i/o exits.)
+     */
+    if (fStatefulExit)
+    {
+        pRun->immediate_exit = 1;
+        int rcLnx = ioctl(pVCpu->nem.s.fdVCpu, KVM_RUN, 0UL);
+        pRun->immediate_exit = 0;
+        Log(("NEM/%u: Flushed stateful exit -> %d/%d exit_reason=%d\n", pVCpu->idCpu, rcLnx, errno, pRun->exit_reason));
+        STAM_REL_COUNTER_INC(&pVCpu->nem.s.StatFlushExitOnReturn);
+    }
 
     /*