diff -r 77dec8732cde xen/drivers/passthrough/vtd/dmar.c
--- a/xen/drivers/passthrough/vtd/dmar.c	Wed Apr 23 16:58:44 2008 +0100
+++ b/xen/drivers/passthrough/vtd/dmar.c	Thu Apr 24 15:19:20 2008 +0100
@@ -180,7 +180,12 @@
     return NULL;
 }
 
-static int scope_device_count(void *start, void *end)
+static u8 path_dev(u8 dev, int type)
+{
+    return (type == DMAR_TYPE) ? dev >> 3 : dev;
+}
+
+static int scope_device_count(void *start, void *end, int type)
 {
     struct acpi_dev_scope *scope;
     u16 bus, sub_bus, sec_bus;
@@ -206,7 +211,7 @@
         while ( --depth > 0 )
         {
             bus = pci_conf_read8(
-                bus, path->dev, path->fn, PCI_SECONDARY_BUS);
+                bus, path_dev(path->dev, type), path->fn, PCI_SECONDARY_BUS);
             path++;
         }
 
@@ -214,18 +219,18 @@
         {
             dprintk(XENLOG_INFO VTDPREFIX,
                     "found endpoint: bdf = %x:%x:%x\n",
-                    bus, path->dev, path->fn);
+                    bus, path_dev(path->dev, type), path->fn);
             count++;
         }
         else if ( scope->dev_type == ACPI_DEV_P2PBRIDGE )
         {
             dprintk(XENLOG_INFO VTDPREFIX,
                     "found bridge: bdf = %x:%x:%x\n",
-                    bus, path->dev, path->fn);
+                    bus, path_dev(path->dev, type), path->fn);
             sec_bus = pci_conf_read8(
-                bus, path->dev, path->fn, PCI_SECONDARY_BUS);
+                bus, path_dev(path->dev, type), path->fn, PCI_SECONDARY_BUS);
             sub_bus = pci_conf_read8(
-                bus, path->dev, path->fn, PCI_SUBORDINATE_BUS);
+                bus, path_dev(path->dev, type), path->fn, PCI_SUBORDINATE_BUS);
 
             while ( sec_bus <= sub_bus )
             {
@@ -252,14 +257,14 @@
         {
             dprintk(XENLOG_INFO VTDPREFIX,
                     "found IOAPIC: bdf = %x:%x:%x\n",
-                    bus, path->dev, path->fn);
+                    bus, path_dev(path->dev, type), path->fn);
             count++;
         }
         else
         {
             dprintk(XENLOG_INFO VTDPREFIX,
                     "found MSI HPET: bdf = %x:%x:%x\n",
-                    bus, path->dev, path->fn);
+                    bus, path_dev(path->dev, type), path->fn);
             count++;
         }
 
@@ -304,7 +309,7 @@
             dprintk(XENLOG_ERR VTDPREFIX, "invalid vt-d acpi entry type\n");
     }
 
-    *cnt = scope_device_count(start, end);
+    *cnt = scope_device_count(start, end, type);
     if ( *cnt == 0 )
     {
         dprintk(XENLOG_INFO VTDPREFIX, "acpi_parse_dev_scope: no device\n");
@@ -328,7 +333,7 @@
         while ( --depth > 0 )
         {
             bus = pci_conf_read8(
-                bus, path->dev, path->fn, PCI_SECONDARY_BUS);
+                bus, path_dev(path->dev, type), path->fn, PCI_SECONDARY_BUS);
             path++;
         }
 
@@ -336,20 +341,20 @@
         {
             dprintk(XENLOG_INFO VTDPREFIX,
                     "found endpoint: bdf = %x:%x:%x\n",
-                    bus, path->dev, path->fn);
+                    bus, path_dev(path->dev, type), path->fn);
             pdev->bus = bus;
-            pdev->devfn = PCI_DEVFN(path->dev, path->fn);
+            pdev->devfn = PCI_DEVFN(path_dev(path->dev, type), path->fn);
             pdev++;
         }
         else if ( scope->dev_type == ACPI_DEV_P2PBRIDGE )
         {
             dprintk(XENLOG_INFO VTDPREFIX,
                     "found bridge: bus = %x dev = %x func = %x\n",
-                    bus, path->dev, path->fn);
+                    bus, path_dev(path->dev, type), path->fn);
             sec_bus = pci_conf_read8(
-                bus, path->dev, path->fn, PCI_SECONDARY_BUS);
+                bus, path_dev(path->dev, type), path->fn, PCI_SECONDARY_BUS);
             sub_bus = pci_conf_read8(
-                bus, path->dev, path->fn, PCI_SUBORDINATE_BUS);
+                bus, path_dev(path->dev, type), path->fn, PCI_SUBORDINATE_BUS);
 
             while ( sec_bus <= sub_bus )
             {
@@ -382,17 +387,17 @@
                 return -ENOMEM;
             acpi_ioapic_unit->apic_id = scope->enum_id;
             acpi_ioapic_unit->ioapic.bdf.bus = bus;
-            acpi_ioapic_unit->ioapic.bdf.dev = path->dev;
+            acpi_ioapic_unit->ioapic.bdf.dev = path_dev(path->dev, type);
             acpi_ioapic_unit->ioapic.bdf.func = path->fn;
             list_add(&acpi_ioapic_unit->list, &dmaru->ioapic_list);
             dprintk(XENLOG_INFO VTDPREFIX,
                     "found IOAPIC: bus = %x dev = %x func = %x\n",
-                    bus, path->dev, path->fn);
+                    bus, path_dev(path->dev, type), path->fn);
         }
         else
             dprintk(XENLOG_INFO VTDPREFIX,
                     "found MSI HPET: bus = %x dev = %x func = %x\n",
-                    bus, path->dev, path->fn);
+                    bus, path_dev(path->dev, type), path->fn);
         start += scope->length;
     }