Pull CXL (Compute Express Link) updates from Dan Williams:
 "This development cycle extends the subsystem to discover CXL resources
  throughout a CXL/PCIe switch topology and respond to hot add/remove
  events anywhere in that topology.

  This is more foundational infrastructure in preparation for dynamic
  memory region provisioning support. Recall that CXL memory regions, as
  the new "Theory of Operation" section of
  Documentation/driver-api/cxl/memory-devices.rst describes, bring
  storage volume striping semantics to memory.

  The hot add/remove behavior is validated with extensions to the
  cxl_test unit test environment and this test in the cxl-cli test
  suite:

      https://github.com/pmem/ndctl/blob/djbw/for-74/cxl/test/cxl-topology.sh

  Summary:

   - Add a driver for 'struct cxl_memdev' objects responsible for
     CXL.mem operation as distinct from 'cxl_pci' mailbox operations.

     Its primary responsibility is enumerating an endpoint 'struct
     cxl_port' and all the 'struct cxl_port' instances between an
     endpoint and the CXL platform root.

   - Add a driver for 'struct cxl_port' objects responsible for
     enumerating and operating all Host-managed Device Memory (HDM)
     decoder resources between the platform-level CXL memory
     description, all intervening host bridges / switches, and the HDM
     resources in endpoints.

   - Update the cxl_pci driver to validate CXL.mem operation precursors
     to HDM decoder operation like ready-polling, and legacy CXL 1.1
     DVSEC based CXL.mem configuration.

   - Add basic lockdep coverage for usage of device_lock() on CXL
     subsystem objects similar to what exists for LIBNVDIMM. Include a
     compile-time switch for which subsystem to validate at run-time.

   - Update cxl_test to emulate a one level switch topology.

   - Document a "Theory of Operation" for the subsystem.

   - Add 'numa_node' and 'serial' attributes to cxl_memdev sysfs

   - Include miscellaneous fixes for spec / QEMU CXL emulation
     compatibility and static analysis reports"

* tag 'cxl-for-5.18' of git://git.kernel.org/pub/scm/linux/kernel/git/cxl/cxl: (48 commits)
  cxl/core/port: Fix NULL but dereferenced coccicheck error
  cxl/port: Hold port reference until decoder release
  cxl/port: Fix endpoint refcount leak
  cxl/core: Fix cxl_device_lock() class detection
  cxl/core/port: Fix unregister_port() lock assertion
  cxl/regs: Fix size of CXL Capability Header Register
  cxl/core/port: Handle invalid decoders
  cxl/core/port: Fix / relax decoder target enumeration
  tools/testing/cxl: Add a physical_node link
  tools/testing/cxl: Enumerate mock decoders
  tools/testing/cxl: Mock one level of switches
  tools/testing/cxl: Fix root port to host bridge assignment
  tools/testing/cxl: Mock dvsec_ranges()
  cxl/core/port: Add endpoint decoders
  cxl/core: Move target_list out of base decoder attributes
  cxl/mem: Add the cxl_mem driver
  cxl/core/port: Add switch port enumeration
  cxl/memdev: Add numa_node attribute
  cxl/pci: Emit device serial number
  cxl/pci: Implement wait for media active
  ...