[PATCH v3 -qemu 0/5] hw/cxl: Support Back-Invalidate

[Davidlohr Bueso <dave@stgolabs.net>]

Hello,

The following allows support for component basic back invalidation discovery
and config, by exposing the BI routing table and decoder registers. Instead
of going the type2[0] route, this series proposes adding support for type3
hdm-db, which allows a more direct way of supporting BI in qemu.

Changes from v2 (https://lore.kernel.org/linux-cxl/20250811033405.332295-1-dave@stgolabs.net/):
  o Renamed 256b-flit to x-256b-flit (mst)
  o Added a brief description of flit mode in patch 1 changelog (Markus)
  o Added missing hdm-db parameter which went missing in v2.
  o Replaced the new CXL3_TYPE3_DEVICE with passing 'bi' params. (Jonathan)
  o Fixed writemask bits in patch 4. (Jonathan)
  o Misc cleanups in patch 4. (Jonathan)
  o New patch 5 to remove register special_ops read() cb. (Jonathan)

Changes from v1 (https://lore.kernel.org/qemu-devel/20250806055708.196851-1-dave@stgolabs.net/):
  o Further lnk training in patch 1. (Jonathan)
  o Flit parameter changed to bool in patch 1. (Jonathan)
  o Do not set 68B in component Flexbus Port when in flitmode in patch 1.
  o Doc build fixlet in patch 3.
  o Pass the exact type3 type in cxl_component_create_dvsec() - unused, but better
    for keeping track, in patch 4.
  o Change doc example to volatile device in patch 4.

Changes from rfc (https://lore.kernel.org/qemu-devel/20250729165441.1898150-1-dave@stgolabs.net/):
  o Added 256b-flit parameter, per Jonathan.
  o Added window restrictions changes.
  o Dropped rfc tag.

Patch 1 introduces the flit mode parameter.
Patch 2 is lifted from Ira's series with some small (but non-trivial) changes.
Patch 3 updates the cfmw restrictions option.
Patch 4 adds BI decoder/rt register support to enable type3 HDM-DB.
Patch 5 is a small cleanup.

Testing wise, this has passed relevant kernel side BI register IO flows for
BI-ID setup and deallocation.

The next step for this would be to add UIO support to qemu.

Applies against branch 'origin/cxl-2025-07-03' from Jonathan's repository.

Thanks!

Davidlohr Bueso (4):
  hw/pcie: Support enabling flit mode
  hw/cxl: Allow BI by default in Window restrictions
  hw/cxl: Support type3 HDM-DB
  hw/cxl: Remove register special_ops->read()

Ira Weiny (1):
  hw/cxl: Refactor component register initialization

 docs/system/devices/cxl.rst               |  23 +++
 hw/cxl/cxl-component-utils.c              | 214 ++++++++++++++++------
 hw/cxl/cxl-host.c                         |   2 +-
 hw/mem/cxl_type3.c                        |  18 +-
 hw/pci-bridge/cxl_downstream.c            |  13 +-
 hw/pci-bridge/cxl_root_port.c             |  14 +-
 hw/pci-bridge/cxl_upstream.c              |  21 ++-
 hw/pci-bridge/gen_pcie_root_port.c        |   1 +
 hw/pci-bridge/pci_expander_bridge.c       |   2 +-
 hw/pci/pcie.c                             |  23 ++-
 include/hw/cxl/cxl_component.h            |  87 +++++++--
 include/hw/cxl/cxl_device.h               |   4 +
 include/hw/pci-bridge/cxl_upstream_port.h |   1 +
 include/hw/pci/pcie.h                     |   2 +-
 include/hw/pci/pcie_port.h                |   1 +
 qapi/machine.json                         |   3 +-
 qemu-options.hx                           |   4 +-
 17 files changed, 329 insertions(+), 104 deletions(-)

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2.39.5