As mentioned in patch 20 in this series the response of upstream QEMU
community to CXL device emulation has been underwhelming to date. Even
if that picked up it still results in a situation where new driver
features and new test capabilities for those features are split across
multiple repositories.
The "nfit_test" approach of mocking up platform resources via an
external test module continues to yield positive results catching
regressions early and often. Repeat that success with a "cxl_test"
module to inject custom crafted topologies and command responses into
the CXL subsystem's sysfs and ioctl UAPIs.
The first target for cxl_test to verify is the integration of CXL with
LIBNVDIMM and the new support for the CXL namespace label + region-label
format. The first 11 patches introduce support for the new label format.
The next 9 patches rework the CXL PCI driver and to move more common
infrastructure into the core for the unit test environment to reuse. The
largest change here is disconnecting the mailbox command processing
infrastructure from the PCI specific transport. The unit test
environment replaces the PCI transport with a custom backend with mocked
responses to command requests.
Patch 20 introduces just enough mocked functionality for the cxl_acpi
driver to load against cxl_test resources. Patch 21 fixes the first bug
discovered by this framework, namely that HDM decoder target list maps
were not being filled out.
Finally patches 22 and 23 introduce a cxl_test representation of memory
expander devices. In this initial implementation these memory expander
targets implement just enough command support to pass the basic driver
init sequence and enable label command passthrough to LIBNVDIMM.
The topology of cxl_test includes:
- (4) platform fixed memory windows. One each of a x1-volatile,
x4-volatile, x1-persistent, and x4-persistent.
- (4) Host bridges each with (2) root ports
- (8) CXL memory expanders, one for each root port
- Each memory expander device supports the GET_SUPPORTED_LOGS, GET_LOG,
IDENTIFY, GET_LSA, and SET_LSA commands.
Going forward the expectation is that where possible new UAPI visible
subsystem functionality comes with cxl_test emulation of the same.
The build process for cxl_test is:
make M=tools/testing/cxl
make M=tools/testing/cxl modules_install
The implementation methodology of the test module is the same as
nfit_test where the bulk of the emulation comes from replacing symbols
that cxl_acpi and the cxl_core import with mocked implementation of
those symbols. See the "--wrap=" lines in tools/testing/cxl/Kbuild. Some
symbols need to be replaced, but are local to the modules like
match_add_root_ports(). In those cases the local symbol is marked __weak
with a strong implementation coming from tools/testing/cxl/. The goal
being to be minimally invasive to production code paths.
---
Dan Williams (23):
libnvdimm/labels: Introduce getters for namespace label fields
libnvdimm/labels: Add isetcookie validation helper
libnvdimm/labels: Introduce label setter helpers
libnvdimm/labels: Add a checksum calculation helper
libnvdimm/labels: Add blk isetcookie set / validation helpers
libnvdimm/labels: Add blk special cases for nlabel and position helpers
libnvdimm/labels: Add type-guid helpers
libnvdimm/labels: Add claim class helpers
libnvdimm/labels: Add address-abstraction uuid definitions
libnvdimm/labels: Add uuid helpers
libnvdimm/labels: Introduce CXL labels
cxl/pci: Make 'struct cxl_mem' device type generic
cxl/mbox: Introduce the mbox_send operation
cxl/mbox: Move mailbox and other non-PCI specific infrastructure to the
core
cxl/pci: Use module_pci_driver
cxl/mbox: Convert 'enabled_cmds' to DECLARE_BITMAP
cxl/mbox: Add exclusive kernel command support
cxl/pmem: Translate NVDIMM label commands to CXL label commands
cxl/pmem: Add support for multiple nvdimm-bridge objects
tools/testing/cxl: Introduce a mocked-up CXL port hierarchy
cxl/bus: Populate the target list at decoder create
cxl/mbox: Move command definitions to common location
tools/testing/cxl: Introduce a mock memory device + driver
Documentation/driver-api/cxl/memory-devices.rst | 3
drivers/cxl/acpi.c | 65 +
drivers/cxl/core/Makefile | 1
drivers/cxl/core/bus.c | 69 +-
drivers/cxl/core/core.h | 8
drivers/cxl/core/mbox.c | 796 +++++++++++++++++
drivers/cxl/core/memdev.c | 84 ++
drivers/cxl/core/pmem.c | 32 +
drivers/cxl/cxl.h | 35 -
drivers/cxl/cxlmem.h | 186 ++++
drivers/cxl/pci.c | 1053 +----------------------
drivers/cxl/pmem.c | 162 +++-
drivers/nvdimm/btt.c | 11
drivers/nvdimm/btt.h | 4
drivers/nvdimm/btt_devs.c | 12
drivers/nvdimm/core.c | 40 -
drivers/nvdimm/label.c | 354 +++++---
drivers/nvdimm/label.h | 96 +-
drivers/nvdimm/namespace_devs.c | 194 ++--
drivers/nvdimm/nd-core.h | 5
drivers/nvdimm/nd.h | 263 ++++++
drivers/nvdimm/pfn_devs.c | 2
include/linux/nd.h | 4
tools/testing/cxl/Kbuild | 29 +
tools/testing/cxl/mock_acpi.c | 105 ++
tools/testing/cxl/mock_pmem.c | 24 +
tools/testing/cxl/test/Kbuild | 10
tools/testing/cxl/test/cxl.c | 587 +++++++++++++
tools/testing/cxl/test/mem.c | 255 ++++++
tools/testing/cxl/test/mock.c | 155 +++
tools/testing/cxl/test/mock.h | 27 +
31 files changed, 3234 insertions(+), 1437 deletions(-)
create mode 100644 drivers/cxl/core/mbox.c
create mode 100644 tools/testing/cxl/Kbuild
create mode 100644 tools/testing/cxl/mock_acpi.c
create mode 100644 tools/testing/cxl/mock_pmem.c
create mode 100644 tools/testing/cxl/test/Kbuild
create mode 100644 tools/testing/cxl/test/cxl.c
create mode 100644 tools/testing/cxl/test/mem.c
create mode 100644 tools/testing/cxl/test/mock.c
create mode 100644 tools/testing/cxl/test/mock.h
base-commit: 427832674f6e2413c21ca2271ec945a720608ff2
(cxl.git#pending as of August 9th, 2021)
