4 files changed, 85 insertions, 0 deletions

diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig
index cabfa97f4674..c1c8566c6840 100644
--- a/drivers/xen/Kconfig
+++ b/drivers/xen/Kconfig
@@ -180,6 +180,17 @@ config XEN_PRIVCMD
         depends on XEN
         default m
 
+config XEN_STUB
+        bool "Xen stub drivers"
+        depends on XEN && X86_64
+        default n
+        help
+          Allow kernel to install stub drivers, to reserve space for Xen drivers,
+          i.e. memory hotplug and cpu hotplug, and to block native drivers loaded,
+          so that real Xen drivers can be modular.
+
+          To enable Xen features like cpu and memory hotplug, select Y here.
+
 config XEN_ACPI_PROCESSOR
         tristate "Xen ACPI processor"
         depends on XEN && X86 && ACPI_PROCESSOR && CPU_FREQ
diff --git a/drivers/xen/Makefile b/drivers/xen/Makefile
index fb213cf81a7b..b63edd824ad4 100644
--- a/drivers/xen/Makefile
+++ b/drivers/xen/Makefile
@@ -30,6 +30,7 @@ obj-$(CONFIG_SWIOTLB_XEN)		+= swiotlb-xen.o
 obj-$(CONFIG_XEN_MCE_LOG)               += mcelog.o
 obj-$(CONFIG_XEN_PCIDEV_BACKEND)        += xen-pciback/
 obj-$(CONFIG_XEN_PRIVCMD)               += xen-privcmd.o
+obj-$(CONFIG_XEN_STUB)                  += xen-stub.o
 obj-$(CONFIG_XEN_ACPI_PROCESSOR)        += xen-acpi-processor.o
 xen-evtchn-y                            := evtchn.o
 xen-gntdev-y                            := gntdev.o
diff --git a/drivers/xen/xen-stub.c b/drivers/xen/xen-stub.c
new file mode 100644
index 000000000000..811152f67137
--- /dev/null
+++ b/drivers/xen/xen-stub.c
@@ -0,0 +1,66 @@
+/*
+ * xen-stub.c - stub drivers to reserve space for Xen
+ *
+ * Copyright (C) 2012 Intel Corporation
+ *    Author: Liu Jinsong <jinsong.liu@intel.com>
+ *    Author: Jiang Yunhong <yunhong.jiang@intel.com>
+ *
+ * Copyright (C) 2012 Oracle Inc
+ *    Author: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or (at
+ * your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
+ * NON INFRINGEMENT.  See the GNU General Public License for more
+ * details.
+ */
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/export.h>
+#include <linux/types.h>
+#include <linux/acpi.h>
+#include <acpi/acpi_drivers.h>
+#include <xen/acpi.h>
+
+/*--------------------------------------------
+        stub driver for Xen memory hotplug
+--------------------------------------------*/
+
+#ifdef CONFIG_ACPI
+
+static const struct acpi_device_id memory_device_ids[] = {
+        {ACPI_MEMORY_DEVICE_HID, 0},
+        {"", 0},
+};
+
+static struct acpi_driver xen_stub_memory_device_driver = {
+        /* same name as native memory driver to block native loaded */
+        .name = "acpi_memhotplug",
+        .class = ACPI_MEMORY_DEVICE_CLASS,
+        .ids = memory_device_ids,
+};
+
+int xen_stub_memory_device_init(void)
+{
+        if (!xen_initial_domain())
+                return -ENODEV;
+
+        /* just reserve space for Xen, block native driver loaded */
+        return acpi_bus_register_driver(&xen_stub_memory_device_driver);
+}
+EXPORT_SYMBOL_GPL(xen_stub_memory_device_init);
+subsys_initcall(xen_stub_memory_device_init);
+
+void xen_stub_memory_device_exit(void)
+{
+        acpi_bus_unregister_driver(&xen_stub_memory_device_driver);
+}
+EXPORT_SYMBOL_GPL(xen_stub_memory_device_exit);
+
+#endif
diff --git a/include/xen/acpi.h b/include/xen/acpi.h
index 48a9c0171b65..ce7e5264b320 100644
--- a/include/xen/acpi.h
+++ b/include/xen/acpi.h
@@ -40,6 +40,13 @@
 #include <xen/xen.h>
 #include <linux/acpi.h>
 
+#define ACPI_MEMORY_DEVICE_CLASS        "memory"
+#define ACPI_MEMORY_DEVICE_HID          "PNP0C80"
+#define ACPI_MEMORY_DEVICE_NAME         "Hotplug Mem Device"
+
+int xen_stub_memory_device_init(void);
+void xen_stub_memory_device_exit(void);
+
 int xen_acpi_notify_hypervisor_state(u8 sleep_state,
                                      u32 pm1a_cnt, u32 pm1b_cnd);