Index: sys/conf/files.x86
===================================================================
--- sys/conf/files.x86
+++ sys/conf/files.x86
@@ -324,6 +324,7 @@
 x86/x86/tsc.c			standard
 x86/x86/ucode.c			standard
 x86/x86/delay.c			standard
+x86/xen/arch.c			optional	xenhvm
 x86/xen/hvm.c			optional	xenhvm
 x86/xen/xen_intr.c		optional	xenhvm
 x86/xen/xen_apic.c		optional	xenhvm
Index: sys/dev/xen/bus/xenpv.c
===================================================================
--- sys/dev/xen/bus/xenpv.c
+++ sys/dev/xen/bus/xenpv.c
@@ -48,22 +48,6 @@
 
 #include "xenmem_if.h"
 
-/*
- * Allocate unused physical memory above 4GB in order to map memory
- * from foreign domains. We use memory starting at 4GB in order to
- * prevent clashes with MMIO/ACPI regions.
- *
- * Since this is not possible on i386 just use any available memory
- * chunk above 1MB and hope we don't clash with anything else.
- */
-#ifdef __amd64__
-#define LOW_MEM_LIMIT	0x100000000ul
-#elif defined(__i386__)
-#define LOW_MEM_LIMIT	0x100000ul
-#else
-#error "Unsupported architecture"
-#endif
-
 static devclass_t xenpv_devclass;
 
 static void
@@ -119,8 +103,7 @@
 	void *virt_addr;
 	int error;
 
-	res = bus_alloc_resource(child, SYS_RES_MEMORY, res_id, LOW_MEM_LIMIT,
-	    ~0, size, RF_ACTIVE | RF_UNMAPPED);
+	res = xen_arch_alloc_addr(child, res_id, size);
 	if (res == NULL)
 		return (NULL);
 
@@ -128,7 +111,7 @@
 	error = vm_phys_fictitious_reg_range(phys_addr, phys_addr + size,
 	    VM_MEMATTR_XEN);
 	if (error) {
-		bus_release_resource(child, SYS_RES_MEMORY, *res_id, res);
+		xen_arch_release_addr(child, *res_id, res);
 		return (NULL);
 	}
 	virt_addr = pmap_mapdev_attr(phys_addr, size, VM_MEMATTR_XEN);
@@ -151,7 +134,7 @@
 
 	pmap_unmapdev(virt_addr, size);
 	vm_phys_fictitious_unreg_range(phys_addr, phys_addr + size);
-	return (bus_release_resource(child, SYS_RES_MEMORY, res_id, res));
+	return (xen_arch_release_addr(child, res_id, res));
 }
 
 static device_method_t xenpv_methods[] = {
Index: sys/x86/include/xen/xen-os.h
===================================================================
--- sys/x86/include/xen/xen-os.h
+++ sys/x86/include/xen/xen-os.h
@@ -39,6 +39,12 @@
 /* If non-zero, the hypervisor has been configured to use a direct vector */
 extern int xen_vector_callback_enabled;
 
+/* Function for allocating physical address resource to xenpv code */
+extern struct resource *xen_arch_alloc_addr(device_t, int *, size_t);
+
+/* Function for releasing physical address resource from xenpv code */
+int xen_arch_release_addr(device_t, int, struct resource *);
+
 #endif /* !__ASSEMBLY__ */
 
 #endif /* _MACHINE_X86_XEN_XEN_OS_H_ */
Index: sys/x86/xen/arch.c
===================================================================
--- /dev/null
+++ sys/x86/xen/arch.c
@@ -0,0 +1,73 @@
+/*
+ * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
+ *
+ * Copyright (c) 2021 Elliott Mitchell
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/param.h>
+#include <sys/systm.h>
+#include <sys/bus.h>
+#include <sys/rman.h>
+
+#include <xen/xen-os.h>
+
+/*
+ * Allocate unused physical memory above 4GB in order to map memory
+ * from foreign domains. We use memory starting at 4GB in order to
+ * prevent clashes with MMIO/ACPI regions.
+ * 
+ * Since this is not possible on i386 just use any available memory
+ * chunk above 1MB and hope we don't clash with anything else.
+ */
+
+#ifdef __amd64__
+#define LOW_MEM_LIMIT 0x100000000ul
+#elif defined(__i386__)
+#define LOW_MEM_LIMIT 0x100000ul
+#else
+#error "Unsupported architecture"
+#endif
+
+/*
+ * Function for allocating physical address resource to xenpv code
+ */
+struct resource *xen_arch_alloc_addr(device_t dev, int *res_id, size_t size)
+{
+
+	return bus_alloc_resource(dev, SYS_RES_MEMORY, res_id, LOW_MEM_LIMIT,
+~0, size, RF_ACTIVE | RF_UNMAPPED);
+}
+
+/*
+ * Function for releasing physical address resource from xenpv code
+ */
+int xen_arch_release_addr(device_t dev, int res_id, struct resource *res)
+{
+
+	return bus_release_resource(dev, SYS_RES_MEMORY, res_id, res);
+}