[PATCH v15 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

v14: https://lore.kernel.org/linux-cxl/20260918203049.7273-1-anisa.su@xxxxxxxxxxx/T/#m0b6ade9da2d4fefa8aab3bb7db7c29516bc3f955

v14 -> v15 Changes:
===================
The first and only supported DC partition's DPA resource name is still
dynamic_ram_1 because the partition's sysfs directory comes from the DPA
resource name. So it would show up as /sys/bus/.../dynamic_ram_1/
No sysfs patches are in this series, those come later.

 - Patch 1: cxl/mbox: Flag support for Dynamic Capacity Devices (DCD)
        - No change.

 - Patch 2: cxl/mem: Read dynamic capacity configuration from the device
        - Renamed partition mode from CXL_PARTMODE_DYNAMIC_RAM_1 to
	  CXL_PARTMODE_DYNAMIC_RAM.
	  The mode should only describe the capacity type, not the number of
	  the partition. The _1 looks to be an artifact from v8 to v9, when we
	  went from supporting all 8 partitions down to limiting to 1.
	  The first and only supported DC partition's DPA resource name is still
	  dynamic_ram_1 because the partition's sysfs directory comes from the DPA
	  resource name. So it would show up as /sys/bus/.../dynamic_ram_1/
	  when the sysfs patches from the rest of the series are added.

 - Patch 3: cxl/cdat: Gather DSMAS data for DCD partitions
        - Disable DCD when the DC partition has no valid DSMAS entry:
          no CDAT, CDAT parse failure, or no entry matching the
          partition. A DCD shall describe its DC partition in a DSMAS
          (CXL r4.0 9.13.3), so rather than run with unknown attributes
          the device keeps its static capacity and loses DCD (Richard,
          Dave).
        - DSLBIS is optional. cxl_cdat_endpoint_process() treated zero
          DSLBIS entries as a parse failure, which with the change above
          would have disabled DCD on a device with a perfectly valid
          DSMAS. An empty DSLBIS no longer fails the parse, and
          cxl_port_perf_data_calculate() skips DSMAS entries that have
          no DSLBIS coordinates so the QTG _DSM is never evaluated with
          zero bandwidth
        - cxl_memdev_apply_dsmas() takes an enum cxl_dsmas_apply
          (FLAGS / FLAGS_PERF) instead of a bool so the call sites say
          what is applied (Dave).
        - The DSMAS read-only flag (CDAT 1.04, Flags bit 6) is recorded
          on the partition alongside shareable. (Jonathan)

 - Patch 4: cxl/events: Split event msgnum configuration from irq setup
        - No code change.

 - Patch 5: cxl/pci: Factor out interrupt policy check
        - No code change.

 - Patch 6: cxl/mem: Configure dynamic capacity interrupts
        - CXLDEV_EVENT_STATUS_STANDARD_LOGS names the four standard
          logs (INFO | WARN | FAIL | FATAL) that cxl_event_drain_mask()
          and the cxl_test mock's probe-time drain spelled out long-hand
          (Dave/Jonathan)
        - On platforms where BIOS owns the event logs, a failed Get or
          Set Event Interrupt Policy now disables DCD instead of failing
          the memdev probe. Before this series that path never reached
          the mailbox on such a platform; DCD is now the only reason it
          does, so a failure there costs DCD, not the device. With OS
          owned logs the commands remain fatal to probe as before
          (Sashiko).

 - Patch 7: cxl/core: Enforce partition order/simplify partition calls
        - No change.

 - Patch 8: Documentation/cxl: Document DPA partition layout and
   ordering rules
        - No change.

Review status
=============
Dropped all tested-by tags for patches 1-8

Patch 2: Dropped all Review tags.

Patch 3: Dropped all Review tags.

Patch 6: Dropped all Review tags.

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:
Waiting on results from partner team.

cxl_test:
ndctl's cxl suite against cxl_test (7.3.0-rc6, CXL as modules)
16 of 17 pass, cxl-features.sh skips for lack of FWCTL, and
cxl-dcd.sh passes.

QEMU:
Tested extent add/release and DAX device create/destroy.
Tested that expected errors are printed from malformed Get DC Configuration
payload.

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                       |  97 +++++-
 drivers/cxl/core/hdm.c                        |  24 +-
 drivers/cxl/core/mbox.c                       | 285 ++++++++++++++++++
 drivers/cxl/core/memdev.c                     |  94 ++++--
 drivers/cxl/cxl.h                             |  14 +-
 drivers/cxl/cxlmem.h                          |  88 +++++-
 drivers/cxl/mem.c                             |   2 +-
 drivers/cxl/pci.c                             | 176 +++++++++--
 include/cxl/cxl.h                             |  29 +-
 tools/testing/cxl/test/mem.c                  |   2 +-
 12 files changed, 761 insertions(+), 89 deletions(-)


base-commit: a90ee4305c4a5df72c11b31dacfdc76e00fcf78a
-- 
2.43.0