Changeset 61703 in vbox for trunk/src/VBox/VMM

Timestamp:

Jun 15, 2016 9:24:43 AM (9 years ago)

Author:

vboxsync

Message:

VMX: Keep using 64-bit switcher to preserve guest CPU state on 32-bit hosts, bugref:8432 (undoing r108051).

Location:

trunk/src/VBox/VMM

Files:

• VMMR0/HMR0A.asm (modified) (1 diff)
• VMMR0/HMVMXR0.cpp (modified) (4 diffs)
• VMMR3/HM.cpp (modified) (1 diff)
• include/HMInternal.h (modified) (1 diff)

trunk/src/VBox/VMM/VMMR0/HMR0A.asm

@@ -1207 +1207 @@
     dec     xCX
     mov     eax, [ss:xDX + VMCSCACHE.Read.aField + xCX * 4]
+    ; Note! This leaves the high 32 bits of the cache entry unmodified!!
     vmread  [ss:xDX + VMCSCACHE.Read.aFieldVal + xCX * 8], xAX
-    mov     dword [ss:xDX + VMCSCACHE.Read.aFieldVal + xCX * 8 + 4], 0
     cmp     xCX, 0
     jnz     %%cached_read32

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

@@ -3315 +3315 @@
         Log4(("Load[%RU32]: VMX_VMCS_CTRL_EXIT_HOST_ADDR_SPACE_SIZE\n", pVCpu->idCpu));
 #else
-        if (CPUMIsGuestInLongModeEx(pMixedCtx))
+        Assert(   pVCpu->hm.s.vmx.pfnStartVM == VMXR0SwitcherStartVM64
+               || pVCpu->hm.s.vmx.pfnStartVM == VMXR0StartVM32);
+        /* Set the host address-space size based on the switcher, not guest state. See @bugref{8432}. */
+        if (pVCpu->hm.s.vmx.pfnStartVM == VMXR0SwitcherStartVM64)
         {
             /* The switcher returns to long mode, EFER is managed by the switcher. */
@@ -4846 +4849 @@
             }
             pVCpu->hm.s.vmx.pfnStartVM = VMXR0SwitcherStartVM64;
+
+            /* Mark that we've switched to 64-bit handler, we can't safely switch back to 32-bit for
+               the rest of the VM run (until VM reset). See @bugref{8432#c7}. */
+            pVCpu->hm.s.vmx.fSwitchedTo64on32 = true;
         }
 #else
@@ -4856 +4863 @@
         /* Guest is not in long mode, use the 32-bit handler. */
 #if HC_ARCH_BITS == 32
-        if (   pVCpu->hm.s.vmx.pfnStartVM != VMXR0StartVM32
-            && pVCpu->hm.s.vmx.pfnStartVM != NULL) /* Very first entry would have saved host-state already, ignore it. */
+        if (    pVCpu->hm.s.vmx.pfnStartVM != VMXR0StartVM32
+            && !pVCpu->hm.s.vmx.fSwitchedTo64on32   /* If set, guest mode change does not imply switcher change. */
+            &&  pVCpu->hm.s.vmx.pfnStartVM != NULL) /* Very first entry would have saved host-state already, ignore it. */
         {
             /* Currently, all mode changes sends us back to ring-3, so these should be set. See @bugref{6944}. */
@@ -4864 +4872 @@
                                              | HM_CHANGED_GUEST_EFER_MSR), ("flags=%#x\n", HMCPU_CF_VALUE(pVCpu)));
         }
+# ifdef VBOX_ENABLE_64_BITS_GUESTS
+        /* Keep using the 64-bit switcher even though we're in 32-bit because of bad Intel design. See @bugref{8432#c7}. */
+        if (!pVCpu->hm.s.vmx.fSwitchedTo64on32)
+            pVCpu->hm.s.vmx.pfnStartVM = VMXR0StartVM32;
+        else
+            Assert(pVCpu->hm.s.vmx.pfnStartVM == VMXR0SwitcherStartVM64);
+# else
+        pVCpu->hm.s.vmx.pfnStartVM = VMXR0StartVM32;
+# endif
+#else
+        pVCpu->hm.s.vmx.pfnStartVM = VMXR0StartVM32;
 #endif
-        pVCpu->hm.s.vmx.pfnStartVM = VMXR0StartVM32;
     }
     Assert(pVCpu->hm.s.vmx.pfnStartVM);

trunk/src/VBox/VMM/VMMR3/HM.cpp

@@ -1861 +1861 @@
     HMCPU_CF_RESET_TO(pVCpu, HM_CHANGED_HOST_CONTEXT | HM_CHANGED_ALL_GUEST);
 
-    pVCpu->hm.s.vmx.u32CR0Mask     = 0;
-    pVCpu->hm.s.vmx.u32CR4Mask     = 0;
-    pVCpu->hm.s.fActive            = false;
-    pVCpu->hm.s.Event.fPending     = false;
-    pVCpu->hm.s.vmx.fWasInRealMode = true;
-    pVCpu->hm.s.vmx.u64MsrApicBase = 0;
+    pVCpu->hm.s.vmx.u32CR0Mask        = 0;
+    pVCpu->hm.s.vmx.u32CR4Mask        = 0;
+    pVCpu->hm.s.fActive               = false;
+    pVCpu->hm.s.Event.fPending        = false;
+    pVCpu->hm.s.vmx.fWasInRealMode    = true;
+    pVCpu->hm.s.vmx.u64MsrApicBase    = 0;
+    pVCpu->hm.s.vmx.fSwitchedTo64on32 = false;
+
+
 
     /* Reset the contents of the read cache. */

trunk/src/VBox/VMM/include/HMInternal.h

@@ -809 +809 @@
         /** Set if guest was executing in real mode (extra checks). */
         bool                        fWasInRealMode;
-        uint8_t                     u8Alignment1[7];
+        /** Set if guest switched to 64-bit mode on a 32-bit host. */
+        bool                        fSwitchedTo64on32;
+
+        uint8_t                     u8Alignment1[6];
     } vmx;