Index: sys/amd64/include/vmm.h
===================================================================
--- sys/amd64/include/vmm.h	(revision 261451)
+++ sys/amd64/include/vmm.h	(working copy)
@@ -100,7 +100,8 @@
 void vm_destroy(struct vm *vm);
 const char *vm_name(struct vm *vm);
 int vm_malloc(struct vm *vm, vm_paddr_t gpa, size_t len);
-int vm_map_mmio(struct vm *vm, vm_paddr_t gpa, size_t len, vm_paddr_t hpa);
+int vm_map_mmio(struct vm *vm, vm_paddr_t gpa, size_t len, vm_paddr_t hpa,
+    vm_memattr_t memattr);
 int vm_unmap_mmio(struct vm *vm, vm_paddr_t gpa, size_t len);
 void *vm_gpa_hold(struct vm *, vm_paddr_t gpa, size_t len, int prot,
 		  void **cookie);
Index: sys/amd64/vmm/intel/vmx.c
===================================================================
--- sys/amd64/vmm/intel/vmx.c	(revision 261453)
+++ sys/amd64/vmm/intel/vmx.c	(working copy)
@@ -833,7 +833,7 @@
 
 	if (virtual_interrupt_delivery) {
 		error = vm_map_mmio(vm, DEFAULT_APIC_BASE, PAGE_SIZE,
-		    APIC_ACCESS_ADDRESS);
+		    APIC_ACCESS_ADDRESS, VM_MEMATTR_WRITE_BACK);
 		/* XXX this should really return an error to the caller */
 		KASSERT(error == 0, ("vm_map_mmio(apicbase) error %d", error));
 	}
Index: sys/amd64/vmm/io/ppt.c
===================================================================
--- sys/amd64/vmm/io/ppt.c	(revision 261451)
+++ sys/amd64/vmm/io/ppt.c	(working copy)
@@ -44,6 +44,7 @@
 #include <dev/pci/pcireg.h>
 
 #include <machine/resource.h>
+#include <machine/vm.h>
 
 #include <machine/vmm.h>
 #include <machine/vmm_dev.h>
@@ -409,7 +410,8 @@
 		for (i = 0; i < MAX_MMIOSEGS; i++) {
 			seg = &ppt->mmio[i];
 			if (seg->len == 0) {
-				error = vm_map_mmio(vm, gpa, len, hpa);
+				error = vm_map_mmio(vm, gpa, len, hpa,
+				    VM_MEMATTR_UNCACHEABLE);
 				if (error == 0) {
 					seg->gpa = gpa;
 					seg->len = len;
Index: sys/amd64/vmm/vmm.c
===================================================================
--- sys/amd64/vmm/vmm.c	(revision 261451)
+++ sys/amd64/vmm/vmm.c	(working copy)
@@ -400,11 +400,12 @@
 }
 
 int
-vm_map_mmio(struct vm *vm, vm_paddr_t gpa, size_t len, vm_paddr_t hpa)
+vm_map_mmio(struct vm *vm, vm_paddr_t gpa, size_t len, vm_paddr_t hpa,
+    vm_memattr_t attr)
 {
 	vm_object_t obj;
 
-	if ((obj = vmm_mmio_alloc(vm->vmspace, gpa, len, hpa)) == NULL)
+	if ((obj = vmm_mmio_alloc(vm->vmspace, gpa, len, hpa, attr)) == NULL)
 		return (ENOMEM);
 	else
 		return (0);
Index: sys/amd64/vmm/vmm_mem.c
===================================================================
--- sys/amd64/vmm/vmm_mem.c	(revision 261451)
+++ sys/amd64/vmm/vmm_mem.c	(working copy)
@@ -57,7 +57,7 @@
 
 vm_object_t
 vmm_mmio_alloc(struct vmspace *vmspace, vm_paddr_t gpa, size_t len,
-	       vm_paddr_t hpa)
+	       vm_paddr_t hpa, vm_memattr_t memattr)
 {
 	int error;
 	vm_object_t obj;
@@ -77,7 +77,7 @@
 		 * this object to be mapped as uncacheable.
 		 */
 		VM_OBJECT_WLOCK(obj);
-		error = vm_object_set_memattr(obj, VM_MEMATTR_UNCACHEABLE);
+		error = vm_object_set_memattr(obj, memattr);
 		VM_OBJECT_WUNLOCK(obj);
 		if (error != KERN_SUCCESS) {
 			panic("vmm_mmio_alloc: vm_object_set_memattr error %d",
Index: sys/amd64/vmm/vmm_mem.h
===================================================================
--- sys/amd64/vmm/vmm_mem.h	(revision 261451)
+++ sys/amd64/vmm/vmm_mem.h	(working copy)
@@ -35,7 +35,7 @@
 int		vmm_mem_init(void);
 struct vm_object *vmm_mem_alloc(struct vmspace *, vm_paddr_t gpa, size_t size);
 struct vm_object *vmm_mmio_alloc(struct vmspace *, vm_paddr_t gpa, size_t len,
-				 vm_paddr_t hpa);
+				 vm_paddr_t hpa, vm_memattr_t attr);
 void		vmm_mem_free(struct vmspace *, vm_paddr_t gpa, size_t size);
 void		vmm_mmio_free(struct vmspace *, vm_paddr_t gpa, size_t size);
 vm_paddr_t	vmm_mem_maxaddr(void);