[Qemu-devel] [PATCH v3 0/6] spapr: dedicated hotplug events and memory unplug support

[Michael Roth <mdroth@linux.vnet.ibm.com>]

This series is based on David's ppc-for-2.8 branch, and is also available from:

  https://github.com/mdroth/qemu/commits/spapr-hotplug-event-update

Changes since v2:
  * Rebased on latest ppc-for-2.8
  * Fix silly screw up with Reviewed-by attributions

Changes since v1:
  * Rebased on latest ppc-for-2.8
  * Dropped patches relating to option vector manipulation (now merged)
  * Moved patch introducing modern-hotplug-events option to come after
    that actual implementation of modern-hotplug-events support. (David)
  * Removed uneeded source name string from sPAPREventSource in favor of
    manual lookup of the name when creating DT. (David)
  * Don't split function return signatures across lines (David)
  * Add comment to clarify hotplug events being enabled regardless
    of CAS-negotiation.
  * Avoid unecessary initialization of hotplug_ctrl in
    spapr_lmb_release. (David)

Changes since RFC:
  * Rebased on latest ppc-for-2.8 (with DT refactoring)
  * Submitting as v1 now that PAPR Hotplug ACR is committed
  * address Patchew warnings
  * add comments to clarify spapr->ov5/ov5_cas usage. (David)
  * revise comment to clarify intent when setting spapr->ov5
    OV5_HP_EVT bit. (Bharata)
  * drop internal usage of spapr_ovec_from_bitmap() in favor of
    directly assigning bitmap to sPAPROptionVector instances. (David)
  * standardize meaning of 'vector_len' variable through spapr_ovec_*
    functions to be the byte-wise length of option vectors entries,
    and not including the preceeding length byte itself. (David)
  * fix spapr_ovec_populate_dt() to parse up to OV_MAXBITS bits
    rather than OV_MAXBITS - 1. (David)
  * fix spapr_ovec_populate_dt() encode the minimum of 1 option
    vector byte instead of the max of OV_MAXBYTES in cases where
    no option bits are set. (David)
  * add some comments to spapr_ovec_populate_dt() to clarify what
    is being encoded into length byte of ibm,architecture-vec-5
  * switch 'legacy-hotplug-events' option to
    'modern-hotplug-events' (David)
  * modify rtas_event_log_to_source() to check for OV5_HP_EVT
    option rather than relying on whether the hotplug source is
    specifically enabled. Assert the latter in cases where
    OV5_HP_EVT is set. (Bharata)
  * drop global EventSource list in favor of an sPAPREventSource
    list field within sPAPRMachineState (David)
  * add CPU unplug hook in mc->unplug_request (Bharata)

Patches 1-4 add support for an updated event format for hotplug events,
which includes a new way to specify a range of DRCs/LMBs to hotplug/unplug
using a starting position and count, which is necessary for memory unplug.

Patches 5-6 add support for memory unplug using the new event format.

In addition to kernel 4.8 or later, there are a number of patches required
to enable support on the guest kernel side. I've including the minimum set
of patches in my branch here:

   https://github.com/mdroth/linux/commits/spapr-hotplug-event-update

   *powerpc/pseries: advertise Hot Plug Event support to firmware
   powerpc/pseries: Implement indexed-count hotplug memory remove
   powerpc/pseries: Implement indexed-count hotplug memory add

Note that there is currently an issue that arises when attempting to
offline an LMB that was onlined using a guest kernel's auto-onlining
mechanism, which can prevent full completion of memory unplug requests.
This is being investigated, but for the purposes of testing this can
be worked around currently by disabling auto-onlining in guests via:

  "echo offline >/sys/devices/system/memory/auto_online_blocks"

and instead onlining the blocks manually or via udev.

 docs/specs/ppc-spapr-hotplug.txt |  55 +++++++++++++++++++++-----
 hw/ppc/spapr.c                   | 178 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++----
 hw/ppc/spapr_drc.c               |  17 ++++++++
 hw/ppc/spapr_events.c            | 278 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-------------------------
 include/hw/ppc/spapr.h           |  10 ++++-
 include/hw/ppc/spapr_ovec.h      |   1 +
 6 files changed, 469 insertions(+), 70 deletions(-)