[Qemu-devel] [PATCH v9 0/7] Allow hotplug of s390 CPUs

[Matthew Rosato]

Changes from v8->v9:

* Patch 4: fix bug introduced during split, only init smp_cpus (David)
* Patch 6: 
     * nit change to error_propagate handling in realizefn (David)
     * scc->next_cpu_id++ (David)
     * s/s390_cpu_set_id/s390x_cpu_set_id/ (David) 
     * s/s390_new_cpu/s390x_new_cpu/ (David)
     * Put id getter back in (David)
     * Move linux-user next_cpu_id into s390_cpux_init (David)
* Patch 7: nit change to error_propagate handling (David)

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

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: Get rid of side effects when creating a vcpu
  s390x/cpu: Tolerate max_cpus
  s390x/cpu: Add CPU property links
  s390x/cpu: Add error handling to cpu creation
  s390x/cpu: Allow hotplug of CPUs

 hw/s390x/s390-virtio-ccw.c | 46 +++++++++++++++++++++-
 hw/s390x/s390-virtio.c     | 36 +++++++++--------
 hw/s390x/s390-virtio.h     |  2 +-
 target-s390x/cpu-qom.h     |  3 ++
 target-s390x/cpu.c         | 96 +++++++++++++++++++++++++++++++++++++++++++---
 target-s390x/cpu.h         |  2 +
 target-s390x/helper.c      | 41 +++++++++++++++++++-
 7 files changed, 200 insertions(+), 26 deletions(-)

-- 
1.9.1