[PATCH v16 0/8] DCD Prep Series

[Anisa Su]

These are the first eight patches of the Dynamic Capacity Device (DCD)
series. They set up: DCD enumeration, CDAT handling for DC partitions,
the event interrupt plumbing, a preparatory refactor, and
documentation of the DPA partition layout. They stand alone and keep DCD
disabled. They are not dependent on the rest of the series.
Patch 1 detects the 48h command set and then leaves mds->dcd_supported
false. The flag is only turned on by the series that adds DCD event
handling, so every DCD specific path added here is shut off at runtime:
cxl_configure_dcd() never runs, no DC partition is created, no DCD
interrupt is armed, and the CXL_PARTMODE_DYNAMIC_RAM paths are
unreachable. The intent is to land the enumeration and plumbing while
the extent to DAX pipeline is still under review.

Based on v7.3-rc6
v15: https://lore.kernel.org/linux-cxl/20261007201828.952-1-anisa.su@xxxxxxxxxxx/

v15 -> v16 Changes:
===================
A quick respin:

 - Patch 2: cxl_configure_dcd() took Identify Total Capacity as the end
   of static capacity, but Total Capacity is only required to be >=
   ram + pmem. The static end now comes from the last static partition's end dpa
   +1 instead of info->size. Check that DC starts from there. (Richard).

 - Patch 3: dsmas_entry.qos_class initialized as CXL_QOS_CLASS_INVALID, so a
   DSMAS entry that is skipped for lack of DSLBIS, or whose QTG lookup
   fails, no longer reaches update_perf_entry() with qos_class 0, which
   is a valid class. (Sashiko).
   
   The DSMAD handle check now checks handle > U8_MAX instead of
   handle & ~0xFF (Dave).

 - Patch 6: when the DCD vector cannot be requested, tell the device
   not to use the vector: dcd_settings is cleared with
   Set Event Interrupt Policy, so a device does not keep signalling a
   vector with no handler while the
   host considers DCD off.  The Set command is re-factored into a new helper
   cxl_event_set_int_policy() (Richard).
   
All other patches are unchanged.
I kept the review tags on patch 3, since the changes are minimal and
dropped tags from 2 and 6.

Patch organization
==================
 1-3: enumerate DCD command support, read the DC configuration, and pick
      up DSMAS data for DC partitions.
 4-6: split event msgnum configuration from irq setup, factor out the
      interrupt policy check, then configure the DCD event interrupt.
   7: preparatory refactor -- enforce partition order while collapsing
      the ram/pmem specific partition helpers into one.
   8: document the DPA partition layout the previous patches enforce,
      and where Linux is stricter than the specification.

Testing
=======
This series leaves mds->dcd_supported false on purpose, so
cxl_configure_dcd(), cxl_dev_dc_identify() and cxl_dc_check() are
unreachable at runtime as posted. The tests below are done with the rest
of the series on top, otherwise testing would not yield any meaningful
results.

HW:
Tested add and release of one 2G tagged extent on a DCD with a sharable
partition, driven from the system's BMC with FM-API Initiate Dynamic
Capacity Add / Release over MCTP, to confirm the DCD interrupt
configuration and the DSMAS attributes are read properly. The device
is sharable, so an add without a tag and sequence number is refused.


cxl_test:
ndctl cxl test suite
16 of 17 pass, cxl-features.sh skips for lack of FWCTL

Anisa Su (1):
  Documentation/cxl: Document DPA partition layout and ordering rules

Ira Weiny (7):
  cxl/mbox: Flag support for Dynamic Capacity Devices (DCD)
  cxl/mem: Read dynamic capacity configuration from the device
  cxl/cdat: Gather DSMAS data for DCD partitions
  cxl/events: Split event msgnum configuration from irq setup
  cxl/pci: Factor out interrupt policy check
  cxl/mem: Configure dynamic capacity interrupts
  cxl/core: Enforce partition order/simplify partition calls

 .../driver-api/cxl/linux/cxl-driver.rst       |  35 +++
 Documentation/driver-api/cxl/maturity-map.rst |   4 +
 drivers/cxl/core/cdat.c                       |  99 +++++-
 drivers/cxl/core/hdm.c                        |  24 +-
 drivers/cxl/core/mbox.c                       | 285 ++++++++++++++++++
 drivers/cxl/core/memdev.c                     | 100 ++++--
 drivers/cxl/cxl.h                             |  14 +-
 drivers/cxl/cxlmem.h                          |  88 +++++-
 drivers/cxl/mem.c                             |   2 +-
 drivers/cxl/pci.c                             | 207 ++++++++++---
 include/cxl/cxl.h                             |  29 +-
 tools/testing/cxl/test/mem.c                  |   2 +-
 12 files changed, 792 insertions(+), 97 deletions(-)


base-commit: a90ee4305c4a5df72c11b31dacfdc76e00fcf78a
-- 
2.43.0