[PATCH v3 0/9] perf/cxlpmu: Misc sashiko raised issues fixes

[Dave Jiang <dave.jiang@intel.com>]

Teed off of Davidlohr's misc cxlpmu series [1]. I had Claude pick up all
the sashiko raised issues and then continued multiple internal review
iterations to pick up a number of fixes. I'm no CXL PMU or perf expert,
but the fixes look reasonable to me AFAICT.

Since v2:
- 1/9: check event_idx alongside counter_idx (Jonathan).
- 2/9: use FIELD_MODIFY() rather than mask-then-OR, for the four fields
  that can carry a stale value (Jonathan).
- 3/9: rewrite the rationale, no code change (Jonathan).
- 4/9: new patch, split the MSI vector out of info->irq (Robin, Jonathan).
- 5/9: was 4/9, now tests info->msi_vec. Fix unchanged.
- 6/9: was 5/9, retitled. Drop IRQF_SHARED as well as adding
  IRQF_NOBALANCING (Jonathan, Robin). Review tags dropped as the patch
  grew.
- 7/9: was 6/9. Don't unfreeze if the PMU has been disabled meanwhile
  (Robin, Jonathan). Review tag dropped as the patch grew a hunk.
- 8/9: was 7/9, unchanged.
- 9/9: was 8/9, retitled. Drop the cxl_pmu_offline_cpu() hunk, and clear
  the overflow status at probe so a stale bit from firmware cannot reach
  the handler (Robin). Ack dropped as the patch grew a hunk.
- dropped: the old 9/9 (cpumask_of(-1) guard).

Since v1:
- Updated 3/9 to address sashiko issue.
- No other changes as sashiko only raised issue with pre-existing.

Two follow-ups this series does not attempt. cxl_pmu_read() relies on
local64_t being same-CPU, which is the only reason the interrupt has to be
pinned at all; moving prev_count and event->count off local64_t would make
that moot and Robin may have a view on whether it is worth it. And the
on_cpu transient plus dead branch above want the same patch, possibly on
top of the generic PMU hotplug rework Jonathan pointed at [2].

[1]: https://lore.kernel.org/linux-cxl/20260715191454.459673-1-dave@stgolabs.net/
[2]: https://lore.kernel.org/linux-arm-kernel/cover.1784911757.git.robin.murphy@arm.com/

Dave Jiang (9):
  perf/cxl: Program the requested event group on configurable counters
  perf/cxl: Clear stale event fields before reprogramming a counter
  perf/cxl: Fix the counter overflow delta fixup
  perf/cxl: Split the MSI vector out of info->irq
  perf/cxl: Accept an overflow interrupt on MSI message number 0
  perf/cxl: Don't share the overflow interrupt, and keep it pinned
  perf/cxl: Unfreeze counters after handling an overflow interrupt
  perf/cxl: Validate the hardware-reported counter width
  perf/cxl: Don't log through pmu.dev in the overflow interrupt handler

 drivers/perf/cxl_pmu.c | 88 +++++++++++++++++++++++++++++++-----------
 1 file changed, 65 insertions(+), 23 deletions(-)


base-commit: f5098b6bae761e346ebcd9da7f95622c04733cff
-- 
2.55.0