When an ACPI0016 Host Bridge device is present yet no corresponding
CEDT Host Bridge Structure (CHBS) exists, the ACPI probe method
fails.
Rather than fail, emit this warning and continue:
cxl_acpi ACPI0017:00: No CHBS found for Host Bridge: ACPI0016:02
This error may occur on systems that are not compliant with the
ACPI specification. Compliant systems include a CHBS entry for
every CXL host bridge that is present at boot.
Suggested-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Alison Schofield <alison.schofield@intel.com>
Tested-by: Vishal Verma <vishal.l.verma@intel.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Link: https://lore.kernel.org/r/20211007213426.392644-1-alison.schofield@intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
The kbuild robot reports:
drivers/cxl/core/bus.c:516:1: warning: stack frame size (1032) exceeds
limit (1024) in function 'devm_cxl_add_decoder'
It is also the case the devm_cxl_add_decoder() is unwieldy to use for
all the different decoder types. Fix the stack usage by splitting the
creation into alloc and add steps. This also allows for context
specific construction before adding.
With the split the caller is responsible for registering a devm callback
to trigger device_unregister() for the decoder rather than it being
implicit in the decoder registration. I.e. the routine that calls alloc
is responsible for calling put_device() if the "add" operation fails.
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Nathan Chancellor <nathan@kernel.org>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Ben Widawsky <ben.widawsky@intel.com>
Link: https://lore.kernel.org/r/163225205828.3038145.6831131648369404859.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
As found by cxl_test, the implementation populated the target_list for
the single dport exceptional case, it missed populating the target_list
for the typical multi-dport case. Root decoders always know their target
list at the beginning of time, and even switch-level decoders should
have a target list of one or more zeros by default, depending on the
interleave-ways setting.
Walk the hosting port's dport list and populate based on the passed in
map.
Move devm_cxl_add_passthrough_decoder() out of line now that it does the
work of generating a target_map.
Before:
$ cat /sys/bus/cxl/devices/root2/decoder*/target_list
0
0
After:
$ cat /sys/bus/cxl/devices/root2/decoder*/target_list
0
0,1,2,3
0
0,1,2,3
Where root2 is a CXL topology root object generated by 'cxl_test'.
Acked-by: Ben Widawsky <ben.widawsky@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/163116439000.2460985.11713777051267946018.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Create an environment for CXL plumbing unit tests. Especially when it
comes to an algorithm for HDM Decoder (Host-managed Device Memory
Decoder) programming, the availability of an in-kernel-tree emulation
environment for CXL configuration complexity and corner cases speeds
development and deters regressions.
The approach taken mirrors what was done for tools/testing/nvdimm/. I.e.
an external module, cxl_test.ko built out of the tools/testing/cxl/
directory, provides mock implementations of kernel APIs and kernel
objects to simulate a real world device hierarchy.
One feedback for the tools/testing/nvdimm/ proposal was "why not do this
in QEMU?". In fact, the CXL development community has developed a QEMU
model for CXL [1]. However, there are a few blocking issues that keep
QEMU from being a tight fit for topology + provisioning unit tests:
1/ The QEMU community has yet to show interest in merging any of this
support that has had patches on the list since November 2020. So,
testing CXL to date involves building custom QEMU with out-of-tree
patches.
2/ CXL mechanisms like cross-host-bridge interleave do not have a clear
path to be emulated by QEMU without major infrastructure work. This
is easier to achieve with the alloc_mock_res() approach taken in this
patch to shortcut-define emulated system physical address ranges with
interleave behavior.
The QEMU enabling has been critical to get the driver off the ground,
and may still move forward, but it does not address the ongoing needs of
a regression testing environment and test driven development.
This patch adds an ACPI CXL Platform definition with emulated CXL
multi-ported host-bridges. A follow on patch adds emulated memory
expander devices.
Acked-by: Ben Widawsky <ben.widawsky@intel.com>
Reported-by: Vishal Verma <vishal.l.verma@intel.com>
Link: https://lore.kernel.org/r/20210202005948.241655-1-ben.widawsky@intel.com [1]
Link: https://lore.kernel.org/r/163164680798.2831381.838684634806668012.stgit@dwillia2-desk3.amr.corp.intel.com
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
During CXL ACPI probe, host bridge ports are discovered by scanning
the ACPI0017 root port for ACPI0016 host bridge devices. The scan
matches on the hardware id of "ACPI0016". An issue occurs when an
ACPI0016 device is defined in the DSDT yet disabled on the platform.
Attempts by the cxl_acpi driver to add host bridge ports using a
disabled device fails, and the entire cxl_acpi probe fails.
The DSDT table includes an _STA method that sets the status and the
ACPI subsystem has checks available to examine it. One such check is
in the acpi_pci_find_root() path. Move the call to acpi_pci_find_root()
to the matching function to prevent this issue when adding either
upstream or downstream ports.
Suggested-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Alison Schofield <alison.schofield@intel.com>
Fixes: 7d4b5ca2e2 ("cxl/acpi: Add downstream port data to cxl_port instances")
Cc: <stable@vger.kernel.org>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/163072203957.2250120.2178685721061002124.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
The ACPI CXL Early Discovery Table (CEDT) includes a list of CXL memory
resources in CXL Fixed Memory Window Structures (CFMWS). Retrieve each
CFMWS in the CEDT and add a cxl_decoder object to the root port (root0)
for each memory resource.
Signed-off-by: Alison Schofield <alison.schofield@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Ben Widawsky <ben.widawsky@intel.com>
Link: https://lore.kernel.org/r/d2b73eecfb7ea22e1103f1894b271a89958b4c41.1623968958.git.alison.schofield@intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
The base address for the Host Bridge port component registers is located
in the CXL Host Bridge Structure (CHBS) of the ACPI CXL Early Discovery
Table (CEDT). Retrieve the CHBS for each Host Bridge (ACPI0016 device)
and include that base address in the port object.
Co-developed-by: Vishal Verma <vishal.l.verma@intel.com>
Signed-off-by: Vishal Verma <vishal.l.verma@intel.com>
Signed-off-by: Alison Schofield <alison.schofield@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Ben Widawsky <ben.widawsky@intel.com>
Link: https://lore.kernel.org/r/a475ce137b899bc7ae5ba9550b5f198cb29ccbfd.1623968958.git.alison.schofield@intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Register an 'nvdimm-bridge' device to act as an anchor for a libnvdimm
bus hierarchy. Also, flesh out the cxl_bus definition to allow a
cxl_nvdimm_bridge_driver to attach to the bridge and trigger the
nvdimm-bus registration.
The creation of the bridge is gated on the detection of a PMEM capable
address space registered to the root. The bridge indirection allows the
libnvdimm module to remain unloaded on platforms without PMEM support.
Given that the probing of ACPI0017 is asynchronous to CXL endpoint
devices, and the expectation that CXL endpoint devices register other
PMEM resources on the 'CXL' nvdimm bus, a workqueue is added. The
workqueue is needed to run bus_rescan_devices() outside of the
device_lock() of the nvdimm-bridge device to rendezvous nvdimm resources
as they arrive. For now only the bus is taken online/offline in the
workqueue.
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/162379909706.2993820.14051258608641140169.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
A cxl_decoder is a child of a cxl_port. It represents a hardware decoder
configuration of an upstream port to one or more of its downstream
ports. The decoder is either represented in CXL standard HDM decoder
registers (see CXL 2.0 section 8.2.5.12 CXL HDM Decoder Capability
Structure), or it is a static decode configuration communicated by
platform firmware (see the CXL Early Discovery Table: Fixed Memory
Window Structure).
The firmware described and hardware described decoders differ slightly
leading to 2 different sub-types of decoders, cxl_decoder_root and
cxl_decoder_switch. At the root level the decode capabilities restrict
what can be mapped beneath them. Mid-level switch decoders are
configured for either acclerator (type-2) or memory-expander (type-3)
operation, but they are otherwise agnostic to the type of memory
(volatile vs persistent) being mapped.
Here is an example topology from a single-ported host-bridge environment
without CFMWS decodes enumerated.
/sys/bus/cxl/devices/root0
├── devtype
├── dport0 -> ../../../LNXSYSTM:00/LNXSYBUS:00/ACPI0016:00
├── port1
│ ├── decoder1.0
│ │ ├── devtype
│ │ ├── locked
│ │ ├── size
│ │ ├── start
│ │ ├── subsystem -> ../../../../../../bus/cxl
│ │ ├── target_list
│ │ ├── target_type
│ │ └── uevent
│ ├── devtype
│ ├── dport0 -> ../../../../pci0000:34/0000:34:00.0
│ ├── subsystem -> ../../../../../bus/cxl
│ ├── uevent
│ └── uport -> ../../../../LNXSYSTM:00/LNXSYBUS:00/ACPI0016:00
├── subsystem -> ../../../../bus/cxl
├── uevent
└── uport -> ../../ACPI0017:00
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/162325695128.2293823.17519927266014762694.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
While the resources enumerated by the CEDT.CFMWS identify a cxl_port
with host bridges as downstream ports, host bridges themselves are
upstream ports that decode to downstream ports represented by PCIe Root
Ports. Walk the PCIe Root Ports connected to a CXL Host Bridge,
identified by the ACPI0016 _HID, and add each one as a cxl_dport of the
host bridge cxl_port.
For now, component registers are not enumerated, only the first order
uport / dport relationships.
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/162325451145.2293126.10149150938788969381.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
In preparation for infrastructure that enumerates and configures the CXL
decode mechanism of an upstream port to its downstream ports, add a
representation of a CXL downstream port.
On ACPI systems the top-most logical downstream ports in the hierarchy
are the host bridges (ACPI0016 devices) that decode the memory windows
described by the CXL Early Discovery Table Fixed Memory Window
Structures (CEDT.CFMWS).
Reviewed-by: Alison Schofield <alison.schofield@intel.com>
Link: https://lore.kernel.org/r/162325450624.2293126.3533006409920271718.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
While CXL builds upon the PCI software model for enumeration and
endpoint control, a static platform component is required to bootstrap
the CXL memory layout. Similar to how ACPI identifies root-level PCI
memory resources, ACPI data enumerates the address space and interleave
configuration for CXL Memory.
In addition to identifying host bridges, ACPI is responsible for
enumerating the CXL memory space that can be addressed by downstream
decoders. This is similar to the requirement for ACPI to publish
resources via the _CRS method for PCI host bridges. Specifically, ACPI
publishes a table, CXL Early Discovery Table (CEDT), which includes a
list of CXL Memory resources, CXL Fixed Memory Window Structures
(CFMWS).
For now, introduce the core infrastructure for a cxl_port hierarchy
starting with a root level anchor represented by the ACPI0017 device.
Follow on changes model support for the configurable decode capabilities
of cxl_port instances, i.e. CXL switch support.
Co-developed-by: Alison Schofield <alison.schofield@intel.com>
Signed-off-by: Alison Schofield <alison.schofield@intel.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/162325449515.2293126.15303270193010154608.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Alison Schofield