[Qemu-devel] [PATCH v6 0/7] Allow hotplug of s390 CPUs

[Matthew Rosato]

Changes from v5->v6:

* Patch #5 - Remove unnecessary unplug handler (Igor)
* Patch #6 - New patch - move last_cpu to qom/cpu.h, rename one existing
  variable to 'cpu_last' to avoid conflicts. (Igor)
* Patch #7 - Move s390_cpu_hot_add to s390-virtio-ccw & make static. (Igor)

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

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 (7):
  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 CPU property links
  s390/virtio-ccw: Add hotplug handler
  cpu: Add a last_cpu macro
  s390x/cpu: Allow hotplug of CPUs

 hw/intc/openpic.c          | 12 ++++----
 hw/s390x/s390-virtio-ccw.c | 68 +++++++++++++++++++++++++++++++++++++++++++++-
 hw/s390x/s390-virtio.c     | 36 +++++++++++++-----------
 hw/s390x/s390-virtio.h     |  2 +-
 include/qom/cpu.h          |  1 +
 target-s390x/cpu.c         | 18 ++++++++++--
 6 files changed, 110 insertions(+), 27 deletions(-)

-- 
1.9.1