Index: /trunk/include/VBox/vmm/cpum.h
===================================================================
--- /trunk/include/VBox/vmm/cpum.h	(revision 88289)
+++ /trunk/include/VBox/vmm/cpum.h	(revision 88290)
@@ -1481,4 +1481,5 @@
 VMMDECL(CPUMCPUVENDOR)  CPUMGetGuestCpuVendor(PVM pVM);
 VMMDECL(CPUMMICROARCH)  CPUMGetGuestMicroarch(PCVM pVM);
+VMMDECL(void)           CPUMGetGuestAddrWidths(PCVM pVM, uint8_t *pcPhysAddrWidth, uint8_t *pcLinearAddrWidth);
 VMMDECL(CPUMCPUVENDOR)  CPUMGetHostCpuVendor(PVM pVM);
 VMMDECL(CPUMMICROARCH)  CPUMGetHostMicroarch(PCVM pVM);
Index: /trunk/include/VBox/vmm/pdmdev.h
===================================================================
--- /trunk/include/VBox/vmm/pdmdev.h	(revision 88289)
+++ /trunk/include/VBox/vmm/pdmdev.h	(revision 88290)
@@ -2349,5 +2349,5 @@
 
 /** Current PDMDEVHLPR3 version number. */
-#define PDM_DEVHLPR3_VERSION                    PDM_VERSION_MAKE_PP(0xffe7, 46, 0)
+#define PDM_DEVHLPR3_VERSION                    PDM_VERSION_MAKE_PP(0xffe7, 47, 0)
 
 /**
@@ -4248,4 +4248,16 @@
     DECLR3CALLBACKMEMBER(CPUMMICROARCH, pfnCpuGetGuestMicroarch,(PPDMDEVINS pDevIns));
 
+    /**
+     * Get the number of physical and linear address bits supported by the guest.
+     *
+     * @param   pDevIns             The device instance.
+     * @param   pcPhysAddrWidth     Where to store the number of physical address bits
+     *                              supported by the guest.
+     * @param   pcLinearAddrWidth   Where to store the number of linear address bits
+     *                              supported by the guest.
+     */
+    DECLR3CALLBACKMEMBER(void, pfnCpuGetGuestAddrWidths,(PPDMDEVINS pDevIns, uint8_t *pcPhysAddrWidth,
+                                                         uint8_t *pcLinearAddrWidth));
+
     /** Space reserved for future members.
      * @{ */
@@ -6637,4 +6649,12 @@
 {
     return pDevIns->CTX_SUFF(pHlp)->pfnCpuGetGuestMicroarch(pDevIns);
+}
+
+/**
+ * @copydoc PDMDEVHLPR3::pfnCpuGetGuestAddrWidths
+ */
+DECLINLINE(void) PDMDevHlpCpuGetGuestAddrWidths(PPDMDEVINS pDevIns, uint8_t *pcPhysAddrWidth, uint8_t *pcLinearAddrWidth)
+{
+    pDevIns->CTX_SUFF(pHlp)->pfnCpuGetGuestAddrWidths(pDevIns, pcPhysAddrWidth, pcLinearAddrWidth);
 }
 
Index: /trunk/src/VBox/VMM/VMMAll/CPUMAllRegs.cpp
===================================================================
--- /trunk/src/VBox/VMM/VMMAll/CPUMAllRegs.cpp	(revision 88289)
+++ /trunk/src/VBox/VMM/VMMAll/CPUMAllRegs.cpp	(revision 88290)
@@ -1074,4 +1074,22 @@
 {
     return pVM->cpum.s.GuestFeatures.enmMicroarch;
+}
+
+
+/**
+ * Gets the maximum number of physical and linear address bits supported by the
+ * guest.
+ *
+ * @param   pVM                 The cross context VM structure.
+ * @param   pcPhysAddrWidth     Where to store the physical address width.
+ * @param   pcLinearAddrWidth   Where to store the linear address width.
+ */
+VMMDECL(void) CPUMGetGuestAddrWidths(PCVM pVM, uint8_t *pcPhysAddrWidth, uint8_t *pcLinearAddrWidth)
+{
+    AssertPtr(pVM);
+    AssertReturnVoid(pcPhysAddrWidth);
+    AssertReturnVoid(pcLinearAddrWidth);
+    *pcPhysAddrWidth   = pVM->cpum.s.GuestFeatures.cMaxPhysAddrWidth;
+    *pcLinearAddrWidth = pVM->cpum.s.GuestFeatures.cMaxLinearAddrWidth;
 }
 
Index: /trunk/src/VBox/VMM/VMMR3/PDMDevHlp.cpp
===================================================================
--- /trunk/src/VBox/VMM/VMMR3/PDMDevHlp.cpp	(revision 88289)
+++ /trunk/src/VBox/VMM/VMMR3/PDMDevHlp.cpp	(revision 88290)
@@ -973,4 +973,20 @@
     Log(("pdmR3DevHlp_CpuGetGuestMicroarch: caller='%s'/%d: returns %u\n", pDevIns->pReg->szName, pDevIns->iInstance, enmMicroarch));
     return enmMicroarch;
+}
+
+
+/** @interface_method_impl{PDMDEVHLPR3,pfnCpuGetGuestAddrWidths} */
+static DECLCALLBACK(void) pdmR3DevHlp_CpuGetGuestAddrWidths(PPDMDEVINS pDevIns, uint8_t *pcPhysAddrWidth,
+                                                            uint8_t *pcLinearAddrWidth)
+{
+    PDMDEV_ASSERT_DEVINS(pDevIns);
+    PVM pVM = pDevIns->Internal.s.pVMR3;
+    LogFlow(("pdmR3DevHlp_CpuGetGuestAddrWidths: caller='%s'/%d\n", pDevIns->pReg->szName, pDevIns->iInstance));
+    AssertPtrReturnVoid(pcPhysAddrWidth);
+    AssertPtrReturnVoid(pcLinearAddrWidth);
+
+    CPUMGetGuestAddrWidths(pVM, pcPhysAddrWidth, pcLinearAddrWidth);
+
+    Log(("pdmR3DevHlp_CpuGetGuestAddrWidths: caller='%s'/%d: returns void\n", pDevIns->pReg->szName, pDevIns->iInstance));
 }
 
@@ -4394,4 +4410,5 @@
     pdmR3DevHlp_PhysBulkReleasePageMappingLocks,
     pdmR3DevHlp_CpuGetGuestMicroarch,
+    pdmR3DevHlp_CpuGetGuestAddrWidths,
     0,
     0,
@@ -4741,4 +4758,5 @@
     pdmR3DevHlp_PhysBulkReleasePageMappingLocks,
     pdmR3DevHlp_CpuGetGuestMicroarch,
+    pdmR3DevHlp_CpuGetGuestAddrWidths,
     0,
     0,
@@ -5245,4 +5263,5 @@
     pdmR3DevHlp_PhysBulkReleasePageMappingLocks,
     pdmR3DevHlp_CpuGetGuestMicroarch,
+    pdmR3DevHlp_CpuGetGuestAddrWidths,
     0,
     0,