[PATCH 0/7] powerpc/numa: Enable coregroup support for shared LPARs

[Srikar Dronamraju]

Coregroup topology is currently disabled for shared LPARs even when
coregroup information is available through the associativity hierarchy.

The associativity hierarchy differs between shared and dedicated LPARs.
For dedicated LPARs, a coregroup level is present when the hierarchy
extends beyond primary_domain_index + 1. For shared LPARs, the hierarchy
has one fewer level and coregroup information is available when it
extends beyond primary_domain_index.

The processor sharing mode is not known when NUMA properties are
initially parsed. It is determined later in pSeries_setup_arch().
CPU associativity therefore initially uses the dedicated-LPAR
interpretation. Once shared processor mode is known, reprocess CPU
associativity to detect the coregroup level using the shared-LPAR
hierarchy.

The series also separates coregroup discovery from NUMA enablement.
CPU associativity is processed even with numa=disabled, while NUMA node,
memory and PCI processing remain disabled.

Patches 1-3 prepare the coregroup detection code by removing redundant
coregroup detection, consolidating the VPHN associativity lookup, and
factoring out the coregroup-level check.

Patches 4-6 allow coregroup discovery with NUMA disabled and restructure
CPU associativity processing so that it can be reused after processor
sharing mode is known.

Patch 7 accounts for the shared-LPAR associativity hierarchy and
reprocesses CPU associativity after shared processor mode has been
identified.

Testing
-------

Tested on:
  - Dedicated LPAR
  - Shared LPAR
  - numa=disabled
  - CPU hotplug
  - Memory hotplug

On a shared LPAR, /proc/schedstat did not contain an MC domain before
the series:

  domain0 SMT 00000000,00000000,00000055 ...
  domain1 PKG 000000ff,000000ff,000000ff ...
  domain2 NUMA ffffffff,ffffffff,ffffffff ...

After the series, an MC domain is present between SMT and PKG:

  domain0 SMT 00000000,00000000,00000055 ...
  domain1 MC 00000000,00000000,000000ff ...
  domain2 PKG 000000ff,000000ff,000000ff ...
  domain3 NUMA ffffffff,ffffffff,ffffffff ...


Srikar Dronamraju (7):
  powerpc/numa: Remove redundant coregroup enablement
  powerpc/numa: Consolidate VPHN associativity lookup
  powerpc/numa: Factor out coregroup availability check
  powerpc/numa: Allow coregroup detection when NUMA is disabled
  powerpc/numa: Consolidate associativity lookup in parse_numa_properties
  powerpc/numa: Extract CPU associativity processing into separate function
  powerpc/numa: Enable coregroup support for shared LPARs

 arch/powerpc/include/asm/topology.h    |   2 +
 arch/powerpc/kernel/smp.c              |   4 -
 arch/powerpc/mm/numa.c                 | 176 +++++++++++--------------
 arch/powerpc/platforms/pseries/setup.c |   6 +
 4 files changed, 83 insertions(+), 105 deletions(-)

-- 
2.47.1