[Qemu-devel] Enable x86 linux guest with cpu hotplug feature.

[pingfank]

From: Liu Ping Fan <address@hidden>

A bunch of patches, which are applied separately for kernel and qemu-kvm,
and make x86 based linux guest with cpu hotplug feature.

For kernel:
0001-ACPI-Call-ACPI-remove-handler-when-handling-ACPI-eje.patch
--call acpi eject event handler in acpi_bus_notify()

For qemu-kvm:
0001-ACPI-Update-cpu-hotplug-event-for-guest.patch
--trigger acpi cpu hotplug event for guest, so qemu-kvm can bring present cpu
  to online state
0002-LAPIC-make-lapic-support-cpu-hotplug.patch
--make qemu-kvm support to bring possible cpu to present state.

After applying these patches, we can bring possible cpu online 
by the following step.
1.Boot up qemu-kvm with the param "-smp 1,maxcpu=4", 
2.Use "cpu_set 2 online" cmd in qemu monitor to bring possible cpu 
  to present state. 
3.In guest,echo 1 > cpu2/online to bring the present cpu to online 
  state.