Changeset 65251 in vbox for trunk/src/VBox/VMM

Timestamp:

Jan 12, 2017 7:30:01 AM (8 years ago)

Author:

vboxsync

Message:

VMM/HMVMXR0: Adjustments to fix in r112756 and comment update.

File:

• trunk/src/VBox/VMM/VMMR0/HMVMXR0.cpp (modified) (9 diffs)

trunk/src/VBox/VMM/VMMR0/HMVMXR0.cpp

@@ -3404 +3404 @@
  *                      before using them.
  *
- * @remarks Can cause longjumps!!!
+ * @remarks No-long-jump zone!!!
  */
 DECLINLINE(int) hmR0VmxLoadGuestApicState(PVMCPU pVCpu, PCPUMCTX pMixedCtx)
@@ -8373 +8373 @@
     HMVMX_ASSERT_PREEMPT_SAFE();
 
-    VMMRZCallRing3Disable(pVCpu);
-    Assert(VMMR0IsLogFlushDisabled(pVCpu));
-
     LogFlowFunc(("pVM=%p pVCpu=%p\n", pVM, pVCpu));
 
@@ -8442 +8439 @@
     HMCPU_CF_CLEAR(pVCpu, HM_CHANGED_GUEST_CR2);
 
-    VMMRZCallRing3Enable(pVCpu);
-
     STAM_PROFILE_ADV_STOP(&pVCpu->hm.s.StatLoadGuestState, x);
     return rc;
@@ -8524 +8519 @@
 {
     HMVMX_ASSERT_PREEMPT_SAFE();
+    Assert(!VMMRZCallRing3IsEnabled(pVCpu));
+    Assert(VMMR0IsLogFlushDisabled(pVCpu));
 
     Log5(("LoadFlags=%#RX32\n", HMCPU_CF_VALUE(pVCpu)));
@@ -8530 +8527 @@
 #endif
 
+    /*
+     * RIP is what changes the most often and hence if it's the only bit needing to be
+     * updated, we shall handle it early for performance reasons.
+     */
     VBOXSTRICTRC rcStrict = VINF_SUCCESS;
     if (HMCPU_CF_IS_SET_ONLY(pVCpu, HM_CHANGED_GUEST_RIP))
@@ -8626 +8627 @@
         && PDMHasApic(pVM))
     {
-        uint64_t u64MsrApicBase = APICGetBaseMsrNoCheck(pVCpu);
+        uint64_t const u64MsrApicBase = APICGetBaseMsrNoCheck(pVCpu);
         Assert(u64MsrApicBase);
         Assert(pVM->hm.s.vmx.HCPhysApicAccess);
 
-        /* We only care about the APIC base MSR address and not the other bits. */
-        RTGCPHYS GCPhysApicBase;
-        GCPhysApicBase  = u64MsrApicBase;
-        GCPhysApicBase &= PAGE_BASE_GC_MASK;
+        RTGCPHYS const GCPhysApicBase = u64MsrApicBase & PAGE_BASE_GC_MASK;
 
         /* Unalias any existing mapping. */
@@ -8640 +8638 @@
 
         /* Map the HC APIC-access page in place of the MMIO page, also updates the shadow page tables if necessary. */
-        LogRel(("HM: VCPU%u: Mapped HC APIC-access page GCPhysApicBase=%#RGp\n", pVCpu->idCpu, GCPhysApicBase));
+        LogRel(("hmR0VmxPreRunGuest: VCPU%u: Mapped HC APIC-access page at %#RGp\n", pVCpu->idCpu, GCPhysApicBase));
         rc = IOMMMIOMapMMIOHCPage(pVM, pVCpu, GCPhysApicBase, pVM->hm.s.vmx.HCPhysApicAccess, X86_PTE_RW | X86_PTE_P);
         AssertRCReturn(rc, rc);
@@ -8668 +8666 @@
 
     /*
-     * Load the guest state bits, we can handle longjmps/getting preempted here.
+     * No longjmps to ring-3 from this point on!!!
+     * Asserts() will still longjmp to ring-3 (but won't return), which is intentional, better than a kernel panic.
+     * This also disables flushing of the R0-logger instance (if any).
+     */
+    VMMRZCallRing3Disable(pVCpu);
+
+    /*
+     * Load the guest state bits.
+     *
+     * We cannot perform longjmps while loading the guest state because we do not preserve the
+     * host/guest state (although the VMCS will be preserved) across longjmps which can cause
+     * CPU migration.
      *
      * If we are injecting events to a real-on-v86 mode guest, we will have to update
      * RIP and some segment registers, i.e. hmR0VmxInjectPendingEvent()->hmR0VmxInjectEventVmcs().
-     * Hence, this needs to be done -after- injection of events.
+     * Hence, loading of the guest state needs to be done -after- injection of events.
      */
     rcStrict = hmR0VmxLoadGuestStateOptimal(pVM, pVCpu, pMixedCtx);
@@ -8678 +8687 @@
     { /* likely */ }
     else
+    {
+        VMMRZCallRing3Enable(pVCpu);
         return rcStrict;
-
-    /*
-     * No longjmps to ring-3 from this point on!!!
-     * Asserts() will still longjmp to ring-3 (but won't return), which is intentional, better than a kernel panic.
-     * This also disables flushing of the R0-logger instance (if any).
-     */
-    VMMRZCallRing3Disable(pVCpu);
+    }
 
     /*