xen/acpi: ACPI memory hotplug

This patch implements real Xen acpi memory hotplug driver as module.
When loaded, it replaces Xen stub driver.

When an acpi memory device hotadd event occurs, it notifies OS and
invokes notification callback, adding related memory device and parsing
memory information, finally hypercall to xen hypervisor to add memory.

Signed-off-by: Liu Jinsong <jinsong.liu@intel.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

drivers/xen/Kconfig

@@ -191,6 +191,17 @@ config XEN_STUB
 
 	  To enable Xen features like cpu and memory hotplug, select Y here.
 
+config XEN_ACPI_HOTPLUG_MEMORY
+	tristate "Xen ACPI memory hotplug"
+	depends on XEN_DOM0 && XEN_STUB && ACPI
+	default n
+	help
+	  This is Xen ACPI memory hotplug.
+
+	  Currently Xen only support ACPI memory hot-add. If you want
+	  to hot-add memory at runtime (the hot-added memory cannot be
+	  removed until machine stop), select Y/M here, otherwise select N.
+
 config XEN_ACPI_PROCESSOR
 	tristate "Xen ACPI processor"
 	depends on XEN && X86 && ACPI_PROCESSOR && CPU_FREQ

drivers/xen/Makefile

@@ -31,6 +31,7 @@ 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-$(CONFIG_XEN_ACPI_HOTPLUG_MEMORY)	+= xen-acpi-memhotplug.o
 obj-$(CONFIG_XEN_ACPI_PROCESSOR)	+= xen-acpi-processor.o
 xen-evtchn-y				:= evtchn.o
 xen-gntdev-y				:= gntdev.o