Re: [Qemu-devel] [PATCH v3 00/10] Allow hotplug of s390 CPUs

[Christian Borntraeger <borntraeger@de.ibm.com>]

On 01/27/2016 05:53 PM, Matthew Rosato wrote:
> Changes from v2->v3:
> 
> * Call cpu_remove_sync rather than cpu_remove().
> * Pull latest version of patches from pseries set (v6).  Trivial change to 
>   "Reclaim VCPU objects" to fix checkpatch error.
> * Add object_unparent during s390_cpu_release to accomodate changes in 
>   Patch 4 "Reclaim VCPU objects."
> * Remove a cleanup patch in favor of 2 patches from pseries set.
> 
> **************
> 
> The following patchset enables hotplug of s390 CPUs.
> 
> The standard interface is used -- to configure a guest with 2 CPUs online at 
> boot and 4 maximum:
> 
> qemu -smp 2,maxcpus=4
> 
> To subsequently hotplug a CPU:
> 
> Issue 'device_add s390-cpu,id=<id>' from monitor.
> 
> 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.
> 
> Hot unplug support is provided via 'device_del <id>', however s390 does not have
> a mechanism for gracefully handling a CPU that has been removed, so this event
> triggers a reset of the guest in order to force recognition.  
> 
> This patch set is based on work previously done by Jason Herne.
> 
> Bharata B Rao (3):
>   exec: Remove cpu from cpus list during cpu_exec_exit()
>   exec: Do vmstate unregistration from cpu_exec_exit()
>   cpu: Add a sync version of cpu_remove()
> 
> Gu Zheng (1):
>   cpu: Reclaim vCPU objects
> 
> Matthew Rosato (6):
>   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 (un)register CPU state
>   s390/virtio-ccw: Add hotplug handler and prepare for unplug
>   s390x/cpu: Allow hot plug/unplug of CPUs
> 
>  cpus.c                     | 50 +++++++++++++++++++++++++++++++++
>  exec.c                     | 30 ++++++++++++++++++++
>  hw/s390x/s390-virtio-ccw.c | 30 +++++++++++++++++++-
>  hw/s390x/s390-virtio.c     | 64 +++++++++++++++++++++++++++++++-----------
>  hw/s390x/s390-virtio.h     |  2 +-
>  include/qom/cpu.h          | 18 ++++++++++++
>  include/sysemu/kvm.h       |  1 +
>  kvm-all.c                  | 57 ++++++++++++++++++++++++++++++++++++-
>  kvm-stub.c                 |  5 ++++
>  target-s390x/cpu.c         | 70 +++++++++++++++++++++++++++++++++++++++++++---
>  target-s390x/cpu.h         |  4 +++
>  11 files changed, 308 insertions(+), 23 deletions(-)


Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>


Alexander, if you are too busy at the moment, we could carry
these patches via the s390/kvm tree?

We want these patches merged, since we have to libvirt as well to
use device_add instead of cpu_add (sigh).

Christian