[PATCH v6 0/7] mshv: Debugfs interface for mshv_root

[Nuno Das Neves <nunodasneves@linux.microsoft.com>]

Expose hypervisor, logical processor, partition, and virtual processor
statistics via debugfs. These are provided by mapping 'stats' pages via
hypercall.

Patch #1: Update hv_call_map_stats_page() to return success when
          HV_STATS_AREA_PARENT is unavailable, which is the case on some
          hypervisor versions, where it can fall back to HV_STATS_AREA_SELF
Patch #2: Use struct hv_stats_page pointers instead of void *
Patch #3: Make mshv_vp_stats_map/unmap() more flexible to use with debugfs
          code
Patch #4: Always map vp stats page regardless of scheduler, to reuse in
          debugfs
Patch #5: Change to hv_stats_page definition and
          VpRootDispatchThreadBlocked
Patch #6: Introduce the definitions needed for the various stats pages
Patch #7: Add mshv_debugfs.c, and integrate it with the mshv_root driver to
          expose the partition and VP stats.

---
Changes in v6:
- Fix whitespace and other checkpatch issues [Michael]

Changes in v5:
- Rename hv_counters.c to mshv_debugfs_counters.c [Michael]
- Clarify unusual inclusion of mshv_debugfs_counters.c with comment. After
  discussion it is still included directly to keep things simple. Including
  arrays with unspecified size via a header means sizeof() cannot be used on
  the array.
- Error if mshv_debugfs_counters.c is included elsewhere than mshv_debugfs.c
- Use array index as stats page index to save space [Stanislav]
- Enforce HV_STATS_AREA_PARENT and SELF fit in NUM_STATS_AREAS with
  static_assert and clarify with comment [Michael]
- Return to using lp count from hv stats page for mshv_lps_count [Michael]
- Use nr_cpu_ids instead of num_possible_cpus() [Michael]
- Set mshv_lps_stats[idx] and the array itself to NULL on unmap and cleanup
  [Michael]
- Rename HvLogicalProcessors and VpRootDispatchThreadBlocked to Linux style
- Translate Linux cpu index to vp index via hv_vp_index on partition destroy
  [Michael]
- Minor formatting cleanups [Michael]

Changes in v4:
- Put the counters definitions in static arrays in hv_counters.c, instead of
  as enums in hvhdk.h [Michael]
- Due to the above, add an additional patch (#5) to simplify hv_stats_page,
  and retain the enum definition at the top of mshv_root_main.c for use with
  VpRootDispatchThreadBlocked. That is the only remaining use of the counter
  enum.
- Due to the above, use num_present_cpus() as the number of LPs to map stats
  pages for - this number shouldn't change at runtime because the hypervisor
  doesn't support hotplug for root partition.

Changes in v3:
- Add 3 small refactor/cleanup patches (patches 2,3,4) from Stanislav. These
  simplify some of the debugfs code, and fix issues with mapping VP stats on
  L1VH.
- Fix cleanup of parent stats dentries on module removal (via squashing some
  internal patches into patch #6) [Praveen]
- Remove unused goto label [Stanislav, kernel bot]
- Use struct hv_stats_page * instead of void * in mshv_debugfs.c [Stanislav]
- Remove some redundant variables [Stanislav]
- Rename debugfs dentry fields for brevity [Stanislav]
- Use ERR_CAST() for the dentry error pointer returned from
  lp_debugfs_stats_create() [Stanislav]
- Fix leak of pages allocated for lp stats mappings by storing them in an array
  [Michael]
- Add comments to clarify PARENT vs SELF usage and edge cases [Michael]
- Add VpLoadAvg for x86 and print the stat [Michael]
- Add NUM_STATS_AREAS for array sizing in mshv_debugfs.c [Michael]

Changes in v2:
- Remove unnecessary pr_debug_once() in patch 1 [Stanislav Kinsburskii]
- CONFIG_X86 -> CONFIG_X86_64 in patch 2 [Stanislav Kinsburskii]

---
Nuno Das Neves (3):
  mshv: Update hv_stats_page definitions
  mshv: Add data for printing stats page counters
  mshv: Add debugfs to view hypervisor statistics

Purna Pavan Chandra Aekkaladevi (1):
  mshv: Ignore second stats page map result failure

Stanislav Kinsburskii (3):
  mshv: Use typed hv_stats_page pointers
  mshv: Improve mshv_vp_stats_map/unmap(), add them to mshv_root.h
  mshv: Always map child vp stats pages regardless of scheduler type

 drivers/hv/Makefile                |   1 +
 drivers/hv/mshv_debugfs.c          | 726 +++++++++++++++++++++++++++++
 drivers/hv/mshv_debugfs_counters.c | 490 +++++++++++++++++++
 drivers/hv/mshv_root.h             |  49 +-
 drivers/hv/mshv_root_hv_call.c     |  64 ++-
 drivers/hv/mshv_root_main.c        | 140 +++---
 include/hyperv/hvhdk.h             |   7 +
 7 files changed, 1412 insertions(+), 65 deletions(-)
 create mode 100644 drivers/hv/mshv_debugfs.c
 create mode 100644 drivers/hv/mshv_debugfs_counters.c

-- 
2.34.1