[PATCH v3 0/7] CPU unplug timeout/LMB unplug cleanup in DRC reconfiguration

[Daniel Henrique Barboza]

Hi,

This is marked as a v3 as it started as a result of discussions that
followed the v2 [1]. 

The idea with this series is to add CPU hotunplug timeout to avoid the
situations where the kernel refuses to release the CPU. The reasoning
for a timeout approach is described in patch 05.

While investigating putting a timeout in memory hotunplug, I have found
out that we have a way to determine, at least in some cases, when the kernel
refuses to release the DIMM during a memory hotunplug. This alleviate one
of the most common issues (at least AFAIK) with memory hotunplug and it
made me gave up attempting to put a timeout in memory hotunplug altogether.

At this point I didn't add timeouts for PCI hotunplug operations, but it
is trivial to do so if desirable.

The series goes as follows:

- Patches 1-4: DRC simplifications/cleanups. The idea with these
  cleanups were to trim the spapr_drc_detach use as much as possible,
  since the function would be used to start the timeout timer

- Patch 5: timeout timer infrastructure

- Patch 6: add cpu unplug timeout

- Patch 7: reset DIMM unplug state when the kernel reconfigures the DRC
  connector



v2 link: [1] https://lists.gnu.org/archive/html/qemu-devel/2021-01/msg04400.html


Daniel Henrique Barboza (7):
  spapr_drc.c: do not call spapr_drc_detach() in drc_isolate_logical()
  spapr_pci.c: simplify spapr_pci_unplug_request() function handling
  spapr_drc.c: use spapr_drc_release() in isolate_physical/set_unusable
  spapr: rename spapr_drc_detach() to spapr_drc_unplug_request()
  spapr_drc.c: introduce unplug_timeout_timer
  spapr_drc.c: add hotunplug timeout for CPUs
  spapr_drc.c: use DRC reconfiguration to cleanup DIMM unplug state

 hw/ppc/spapr.c             |  40 ++++++++++++-
 hw/ppc/spapr_drc.c         | 116 +++++++++++++++++++++++++++----------
 hw/ppc/spapr_pci.c         |  44 +++++---------
 hw/ppc/trace-events        |   2 +-
 include/hw/ppc/spapr.h     |   2 +
 include/hw/ppc/spapr_drc.h |   7 ++-
 6 files changed, 147 insertions(+), 64 deletions(-)

-- 
2.29.2