LoongArch cpu hotplug is based on ACPI GED device, there is a little
change about ipi and extioi device, the value of num-cpu property is
maximum cpu number rather than present cpu number.

It can be verified with qemu command:
  qemu-system-loongarch64 -smp 2,maxcpus=16,sockets=4,cores=4,threads=1
and vcpu can be added or remove with hmp command:
  device_add la464-loongarch-cpu,socket-id=0,core-id=2,thread-id=0,id=cpu-2
  device_del cpu-2

---
v1 ... v2:
  1. Add new property hw-id, property hw-id is set for cold-added CPUs,
     and property socket-id/core-id/thread-id is set for hot-added CPUs.
     The two properties can be generated from each other.
  2. Use general hotplug api such as hotplug_handler_pre_plug etc
  3. Reorganize the patch order, split the patch set into 4 small
     patches.
---
Bibo Mao (4):
  hw/loongarch/virt: Add CPU topology support
  hw/loongarch/virt: Implement cpu plug interface
  hw/loongarch/virt: Update the ACPI table for hotplug cpu
  hw/loongarch/virt: Enable cpu hotplug feature on virt machine

 docs/system/loongarch/virt.rst |  31 ++++
 hw/loongarch/Kconfig           |   1 +
 hw/loongarch/acpi-build.c      |  35 +++-
 hw/loongarch/virt.c            | 293 +++++++++++++++++++++++++++++++--
 include/hw/loongarch/virt.h    |   3 +
 target/loongarch/cpu.c         |  25 +++
 target/loongarch/cpu.h         |  17 ++
 7 files changed, 385 insertions(+), 20 deletions(-)


base-commit: e67b7aef7c7f67ecd0282e903e0daff806d5d680
-- 
2.39.3