[Qemu-devel] [PATCH v4 0/5] Allow hotplug of s390 CPUs

[Matthew Rosato <mjrosato@linux.vnet.ibm.com>]

Changes from v3-v4:
* Drop patches related to device_add / device_del
* Add patch to enable cpu_add for s390x.

**************

As discussed in the KVM call, we will go ahead with cpu_add for 
s390x to get cpu hotplug functionality in s390x now, until
architectures that require a more robust hotplug interface
settle on a design.

To configure a guest with 2 CPUs online at 
boot and 4 maximum:

qemu -smp 2,maxcpus=4

Or, when using libvirt:
  <domain>
    ...
    <vcpu current="2">4</vcpu>
    ...
  </domain> 


To subsequently hotplug a CPU:

Issue 'cpu-add <id>' from qemu monitor, or use virsh setvcpus --count <n> 
<domain>, where <n> is the total number of desired guest CPUs.

At this point, the guest must bring the CPU online for use -- This can be 
achieved via "echo 1 > /sys/devices/system/cpu/cpuX/online" or via a management 
tool like cpuplugd.

This patch set is based on work previously done by Jason Herne.


Matthew Rosato (5):
  s390x/cpu: Cleanup init in preparation for hotplug
  s390x/cpu: Set initial CPU state in common routine
  s390x/cpu: Move some CPU initialization into realize
  s390x/cpu: Add functions to register CPU state
  s390x/cpu: Allow hotplug of CPUs

 hw/s390x/s390-virtio-ccw.c |  3 ++-
 hw/s390x/s390-virtio.c     | 55 +++++++++++++++++++++++++++-----------
 hw/s390x/s390-virtio.h     |  2 +-
 target-s390x/cpu.c         | 66 +++++++++++++++++++++++++++++++++++++++++++---
 target-s390x/cpu.h         |  2 ++
 5 files changed, 107 insertions(+), 21 deletions(-)

-- 
1.9.1