[v8,00/46] CXl 2.0 emulation Support

Message

Jonathan Cameron March 18, 2022, 3:05 p.m. UTC

Changes since v7:
* Fixed and added comments for _OSC definition (Michael Tsirkin)
* Dropped the RFC patch that added memops to a hostmem backend
  and replaced with a per CXL type 3 device address space and use
  of address_space_read() / address_space_write(). (Mark Cave-Ayland)
* Added switch documentation as a new patch.

Note that I haven't added tracepoints as Mark suggested. That will
probably be the subject of a future patchset building on this support.

Posting now so that people can review it when then find time, but clearly
this will need to wait for the next cycle.

Series organized to allow it to be taken in stages if the maintainers
prefer that approach. Most sets end with the addition of appropriate
tests (TBD for switch support)

Patches 0-15 - CXL PXB
Patches 16-22 - Type 3 Device, Root Port
Patches 23-39 - ACPI, board elements and interleave decoding to enable x86 hosts
Patches 40-41 - arm64 support on virt.
Patch 42 - Initial documentation
Patches 43-46 - Switch support.

I'm resisting the urge to have this series continue to grow with
additional features on the basis it is already huge and what we have
here is useful + functional.

Updated background info:

Looking in particular for:
* Review of the PCI interactions
* x86 and ARM machine interactions (particularly the memory maps)
* Review of the interleaving approach - is the basic idea
  acceptable?  It has changed since v7!
* Review of the command line interface.
* CXL related review welcome but much of that got reviewed
  in earlier versions and hasn't changed substantially.

Big TODOs:

* Volatile memory devices (easy but it's more code so left for now).
* Hotplug?  May not need much but it's not tested yet!
* More tests and tighter verification that values written to hardware
  are actually valid - stuff that real hardware would check.
* Testing, testing and more testing.  I have been running a basic
  set of ARM and x86 tests on this, but there is always room for
  more tests and greater automation.
* CFMWS flags as requested by Ben.

Why do we want QEMU emulation of CXL?

As Ben stated in V3, QEMU support has been critical to getting OS
software written given lack of availability of hardware supporting the
latest CXL features (coupled with very high demand for support being
ready in a timely fashion). What has become clear since Ben's v3
is that situation is a continuous one. Whilst we can't talk about
them yet, CXL 3.0 features and OS support have been prototyped on
top of this support and a lot of the ongoing kernel work is being
tested against these patches. The kernel CXL mocking code allows
some forms of testing, but QEMU provides a more versatile and
exensible platform.

Other features on the qemu-list that build on these include PCI-DOE
/CDAT support from the Avery Design team further showing how this
code is useful. Whilst not directly related this is also the test
platform for work on PCI IDE/CMA + related DMTF SPDM as CXL both
utilizes and extends those technologies and is likely to be an early
adopter.
Refs:
CMA Kernel: https://lore.kernel.org/all/[e-mail]/
CMA Qemu: https://lore.kernel.org/qemu-devel/[e-mail]/
DOE Qemu: https://lore.kernel.org/qemu-devel/[e-mail]/

As can be seen there is non trivial interaction with other areas of
Qemu, particularly PCI and keeping this set up to date is proving
a burden we'd rather do without :)

Ben mentioned a few other good reasons in v3:
https://lore.kernel.org/qemu-devel/[e-mail]/

What we have here is about what you need for it to be useful for testing
currently kernel code.  Note the kernel code is moving fast so
since v4, some features have been introduced we don't yet support in
QEMU (e.g. use of the PCIe serial number extended capability).

All comments welcome.

Additional info that was here in v5 is now in the documentation patch.

Thanks,

Jonathan

Ben Widawsky (24):
  hw/pci/cxl: Add a CXL component type (interface)
  hw/cxl/component: Introduce CXL components (8.1.x, 8.2.5)
  hw/cxl/device: Introduce a CXL device (8.2.8)
  hw/cxl/device: Implement the CAP array (8.2.8.1-2)
  hw/cxl/device: Implement basic mailbox (8.2.8.4)
  hw/cxl/device: Add memory device utilities
  hw/cxl/device: Add cheap EVENTS implementation (8.2.9.1)
  hw/cxl/device: Timestamp implementation (8.2.9.3)
  hw/cxl/device: Add log commands (8.2.9.4) + CEL
  hw/pxb: Use a type for realizing expanders
  hw/pci/cxl: Create a CXL bus type
  hw/pxb: Allow creation of a CXL PXB (host bridge)
  hw/cxl/rp: Add a root port
  hw/cxl/device: Add a memory device (8.2.8.5)
  hw/cxl/device: Implement MMIO HDM decoding (8.2.5.12)
  hw/cxl/device: Add some trivial commands
  hw/cxl/device: Plumb real Label Storage Area (LSA) sizing
  hw/cxl/device: Implement get/set Label Storage Area (LSA)
  hw/cxl/component: Implement host bridge MMIO (8.2.5, table 142)
  acpi/cxl: Add _OSC implementation (9.14.2)
  acpi/cxl: Create the CEDT (9.14.1)
  acpi/cxl: Introduce CFMWS structures in CEDT
  hw/cxl/component Add a dumb HDM decoder handler
  qtest/cxl: Add more complex test cases with CFMWs

Jonathan Cameron (22):
  MAINTAINERS: Add entry for Compute Express Link Emulation
  cxl: Machine level control on whether CXL support is enabled
  qtest/cxl: Introduce initial test for pxb-cxl only.
  qtests/cxl: Add initial root port and CXL type3 tests
  hw/cxl/component: Add utils for interleave parameter encoding/decoding
  hw/cxl/host: Add support for CXL Fixed Memory Windows.
  hw/pci-host/gpex-acpi: Add support for dsdt construction for pxb-cxl
  pci/pcie_port: Add pci_find_port_by_pn()
  CXL/cxl_component: Add cxl_get_hb_cstate()
  mem/cxl_type3: Add read and write functions for associated hostmem.
  cxl/cxl-host: Add memops for CFMWS region.
  i386/pc: Enable CXL fixed memory windows
  tests/acpi: q35: Allow addition of a CXL test.
  qtests/bios-tables-test: Add a test for CXL emulation.
  tests/acpi: Add tables for CXL emulation.
  hw/arm/virt: Basic CXL enablement on pci_expander_bridge instances
    pxb-cxl
  qtest/cxl: Add aarch64 virt test for CXL
  docs/cxl: Add initial Compute eXpress Link (CXL) documentation.
  pci-bridge/cxl_upstream: Add a CXL switch upstream port
  pci-bridge/cxl_downstream: Add a CXL switch downstream port
  cxl/cxl-host: Support interleave decoding with one level of switches.
  docs/cxl: Add switch documentation

 MAINTAINERS                         |   7 +
 docs/system/device-emulation.rst    |   1 +
 docs/system/devices/cxl.rst         | 386 ++++++++++++++++++++++
 hw/Kconfig                          |   1 +
 hw/acpi/Kconfig                     |   5 +
 hw/acpi/cxl-stub.c                  |  12 +
 hw/acpi/cxl.c                       | 257 +++++++++++++++
 hw/acpi/meson.build                 |   4 +-
 hw/arm/Kconfig                      |   1 +
 hw/arm/virt-acpi-build.c            |  33 ++
 hw/arm/virt.c                       |  40 ++-
 hw/core/machine.c                   |  28 ++
 hw/cxl/Kconfig                      |   3 +
 hw/cxl/cxl-component-utils.c        | 284 ++++++++++++++++
 hw/cxl/cxl-device-utils.c           | 265 +++++++++++++++
 hw/cxl/cxl-host-stubs.c             |  16 +
 hw/cxl/cxl-host.c                   | 262 +++++++++++++++
 hw/cxl/cxl-mailbox-utils.c          | 485 ++++++++++++++++++++++++++++
 hw/cxl/meson.build                  |  12 +
 hw/i386/acpi-build.c                |  57 +++-
 hw/i386/pc.c                        |  57 +++-
 hw/mem/Kconfig                      |   5 +
 hw/mem/cxl_type3.c                  | 359 ++++++++++++++++++++
 hw/mem/meson.build                  |   1 +
 hw/meson.build                      |   1 +
 hw/pci-bridge/Kconfig               |   5 +
 hw/pci-bridge/cxl_downstream.c      | 229 +++++++++++++
 hw/pci-bridge/cxl_root_port.c       | 231 +++++++++++++
 hw/pci-bridge/cxl_upstream.c        | 205 ++++++++++++
 hw/pci-bridge/meson.build           |   1 +
 hw/pci-bridge/pci_expander_bridge.c | 172 +++++++++-
 hw/pci-bridge/pcie_root_port.c      |   6 +-
 hw/pci-host/gpex-acpi.c             |  20 +-
 hw/pci/pci.c                        |  21 +-
 hw/pci/pcie_port.c                  |  25 ++
 include/hw/acpi/cxl.h               |  28 ++
 include/hw/arm/virt.h               |   1 +
 include/hw/boards.h                 |   2 +
 include/hw/cxl/cxl.h                |  54 ++++
 include/hw/cxl/cxl_component.h      | 207 ++++++++++++
 include/hw/cxl/cxl_device.h         | 271 ++++++++++++++++
 include/hw/cxl/cxl_pci.h            | 156 +++++++++
 include/hw/pci/pci.h                |  14 +
 include/hw/pci/pci_bridge.h         |  20 ++
 include/hw/pci/pci_bus.h            |   7 +
 include/hw/pci/pci_ids.h            |   1 +
 include/hw/pci/pcie_port.h          |   2 +
 qapi/machine.json                   |  18 ++
 qemu-options.hx                     |  38 +++
 scripts/device-crash-test           |   1 +
 softmmu/vl.c                        |  44 +++
 tests/data/acpi/q35/CEDT.cxl        | Bin 0 -> 184 bytes
 tests/data/acpi/q35/DSDT.cxl        | Bin 0 -> 9615 bytes
 tests/qtest/bios-tables-test.c      |  44 +++
 tests/qtest/cxl-test.c              | 181 +++++++++++
 tests/qtest/meson.build             |   5 +
 56 files changed, 4566 insertions(+), 25 deletions(-)
 create mode 100644 docs/system/devices/cxl.rst
 create mode 100644 hw/acpi/cxl-stub.c
 create mode 100644 hw/acpi/cxl.c
 create mode 100644 hw/cxl/Kconfig
 create mode 100644 hw/cxl/cxl-component-utils.c
 create mode 100644 hw/cxl/cxl-device-utils.c
 create mode 100644 hw/cxl/cxl-host-stubs.c
 create mode 100644 hw/cxl/cxl-host.c
 create mode 100644 hw/cxl/cxl-mailbox-utils.c
 create mode 100644 hw/cxl/meson.build
 create mode 100644 hw/mem/cxl_type3.c
 create mode 100644 hw/pci-bridge/cxl_downstream.c
 create mode 100644 hw/pci-bridge/cxl_root_port.c
 create mode 100644 hw/pci-bridge/cxl_upstream.c
 create mode 100644 include/hw/acpi/cxl.h
 create mode 100644 include/hw/cxl/cxl.h
 create mode 100644 include/hw/cxl/cxl_component.h
 create mode 100644 include/hw/cxl/cxl_device.h
 create mode 100644 include/hw/cxl/cxl_pci.h
 create mode 100644 tests/data/acpi/q35/CEDT.cxl
 create mode 100644 tests/data/acpi/q35/DSDT.cxl
 create mode 100644 tests/qtest/cxl-test.c