At this point the subsystem can enumerate all CXL ports (CXL.mem decode
resources in upstream switch ports and host bridges) in a system. The
last mile is connecting those ports to endpoints.
The cxl_mem driver connects an endpoint device to the platform CXL.mem
protoctol decode-topology. At ->probe() time it walks its
device-topology-ancestry and adds a CXL Port object at every Upstream
Port hop until it gets to CXL root. The CXL root object is only present
after a platform firmware driver registers platform CXL resources. For
ACPI based platform this is managed by the ACPI0017 device and the
cxl_acpi driver.
The ports are registered such that disabling a given port automatically
unregisters all descendant ports, and the chain can only be registered
after the root is established.
Given ACPI device scanning may run asynchronously compared to PCI device
scanning the root driver is tasked with rescanning the bus after the
root successfully probes.
Conversely if any ports in a chain between the root and an endpoint
becomes disconnected it subsequently triggers the endpoint to
unregister. Given lock depenedencies the endpoint unregistration happens
in a workqueue asynchronously. If userspace cares about synchronizing
delayed work after port events the /sys/bus/cxl/flush attribute is
available for that purpose.
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Ben Widawsky <ben.widawsky@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
[djbw: clarify changelog, rework hotplug support]
Link: https://lore.kernel.org/r/164398782997.903003.9725273241627693186.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
So far the platorm level CXL resources have been enumerated by the
cxl_acpi driver, and cxl_pci has gathered all the pre-requisite
information it needs to fire up a cxl_mem driver. However, the first
thing the cxl_mem driver will be tasked to do is validate that all the
PCIe Switches in its ancestry also have CXL capabilities and an CXL.mem
link established.
Provide a common mechanism for a CXL.mem endpoint driver to enumerate
all the ancestor CXL ports in the topology and validate CXL.mem
connectivity.
Multiple endpoints may end up racing to establish a shared port in the
topology. This race is resolved via taking the device-lock on a parent
CXL Port before establishing a new child. The winner of the race
establishes the port, the loser simply registers its interest in the
port via 'struct cxl_ep' place-holder reference.
At endpoint teardown the same parent port lock is taken as 'struct
cxl_ep' references are deleted. Last endpoint to drop its reference
unregisters the port.
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/164398731146.902644.1029761300481366248.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Now that dport and decoder enumeration is centralized in the port
driver, the @host argument for these helpers can be made implicit. For
the root port the host is the port's uport device (ACPI0017 for
cxl_acpi), and for all other descendant ports the devm context is the
parent of @port.
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Ben Widawsky <ben.widawsky@intel.com>
Link: https://lore.kernel.org/r/164375043390.484143.17617734732003230076.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
The need for a CXL port driver and a dedicated cxl_bus_type is driven by
a need to simultaneously support 2 independent physical memory decode
domains (cache coherent CXL.mem and uncached PCI.mmio) that also
intersect at a single PCIe device node. A CXL Port is a device that
advertises a CXL Component Register block with an "HDM Decoder
Capability Structure".
>From Documentation/driver-api/cxl/memory-devices.rst:
Similar to how a RAID driver takes disk objects and assembles them into
a new logical device, the CXL subsystem is tasked to take PCIe and ACPI
objects and assemble them into a CXL.mem decode topology. The need for
runtime configuration of the CXL.mem topology is also similar to RAID in
that different environments with the same hardware configuration may
decide to assemble the topology in contrasting ways. One may choose
performance (RAID0) striping memory across multiple Host Bridges and
endpoints while another may opt for fault tolerance and disable any
striping in the CXL.mem topology.
The port driver identifies whether an endpoint Memory Expander is
connected to a CXL topology. If an active (bound to the 'cxl_port'
driver) CXL Port is not found at every PCIe Switch Upstream port and an
active "root" CXL Port then the device is just a plain PCIe endpoint
only capable of participating in PCI.mmio and DMA cycles, not CXL.mem
coherent interleave sets.
The 'cxl_port' driver lets the CXL subsystem leverage driver-core
infrastructure for setup and teardown of register resources and
communicating device activation status to userspace. The cxl_bus_type
can rendezvous the async arrival of platform level CXL resources (via
the 'cxl_acpi' driver) with the asynchronous enumeration of Memory
Expander endpoints, while also implementing a hierarchical locking model
independent of the associated 'struct pci_dev' locking model. The
locking for dport and decoder enumeration is now handled in the core
rather than callers.
For now the port driver only enumerates and registers CXL resources
(downstream port metadata and decoder resources) later it will be used
to take action on its decoders in response to CXL.mem region
provisioning requests.
Note1: cxlpci.h has long depended on pci.h, but port.c was the first to
not include pci.h. Carry that dependency in cxlpci.h.
Note2: cxl port enumeration and probing complicates CXL subsystem init
to the point that it helps to have centralized debug logging of probe
events in cxl_bus_probe().
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Ben Widawsky <ben.widawsky@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Co-developed-by: Dan Williams <dan.j.williams@intel.com>
Link: https://lore.kernel.org/r/164374948116.464348.1772618057599155408.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Unlike the decoder enumeration for "root decoders" described by platform
firmware, standard decoders can be enumerated from the component
registers space once the base address has been identified (via PCI,
ACPI, or another mechanism).
Add common infrastructure for HDM (Host-managed-Device-Memory) Decoder
enumeration and share it between host-bridge, upstream switch port, and
cxl_test defined decoders.
The locking model for switch level decoders is to hold the port lock
over the enumeration. This facilitates moving the dport and decoder
enumeration to a 'port' driver. For now, the only enumerator of decoder
resources is the cxl_acpi root driver.
Co-developed-by: Ben Widawsky <ben.widawsky@intel.com>
Signed-off-by: Ben Widawsky <ben.widawsky@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/164374688404.395335.9239248252443123526.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
The core houses infrastructure for decoder resources. A CXL port's
dports are more closely related to decoder infrastructure than topology
enumeration. Implement generic PCI based dport enumeration in the core,
i.e. arrange for existing root port enumeration from cxl_acpi to share
code with switch port enumeration which just amounts to a small
difference in a pci_walk_bus() invocation once the appropriate 'struct
pci_bus' has been retrieved.
Set the convention that decoder objects are registered after all dports
are enumerated. This enables userspace to know when the CXL core is
finished establishing 'dportX' links underneath the 'portX' object.
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/164368114191.354031.5270501846455462665.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Similar to the mem.h rename, if the core wants to reuse definitions from
drivers/cxl/pci.h it is unable to use <pci.h> as that collides with
archs that have an arch/$arch/include/asm/pci.h, like MIPS.
Reported-by: kernel test robot <lkp@intel.com>
Acked-by: Ben Widawsky <ben.widawsky@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/164298422510.3018233.14693126572756675563.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Add a helper for converting a PCI enumerated cxl_port into the pci_bus
that hosts its dports. For switch ports this is trivial, but for root
ports there is no generic way to go from a platform defined host bridge
device, like ACPI0016 to its corresponding pci_bus. Rather than spill
ACPI goop outside of the cxl_acpi driver, just arrange for it to
register an xarray translation from the uport device to the
corresponding pci_bus.
This is in preparation for centralizing dport enumeration in the core.
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Ben Widawsky <ben.widawsky@intel.com>
Link: https://lore.kernel.org/r/164364745633.85488.9744017377155103992.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
When CONFIG_PROVE_LOCKING is enabled the 'struct device' definition gets
an additional mutex that is not clobbered by
lockdep_set_novalidate_class() like the typical device_lock(). This
allows for local annotation of subsystem locks with mutex_lock_nested()
per the subsystem's object/lock hierarchy. For CXL, this primarily needs
the ability to lock ports by depth and child objects of ports by their
parent parent-port lock.
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Ben Widawsky <ben.widawsky@intel.com>
Link: https://lore.kernel.org/r/164365853422.99383.1052399160445197427.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Unused CXL decoders, or ports which use a passthrough decoder (no HDM
decoder registers) are expected to be initialized in a specific way.
Since upcoming drivers will want the same initialization, and it was
already a requirement to have consumers of the API configure the decoder
specific to their needs, initialize to this passthrough state by
default.
Signed-off-by: Ben Widawsky <ben.widawsky@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/164298418778.3018233.13573986275832546547.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Add wrappers for the creation of decoder objects at the root level and
switch level, and keep the core helper private to cxl/core/port.c. Root
decoders are static descriptors conveyed from platform firmware (e.g.
ACPI CFMWS). Switch decoders are CXL standard decoders enumerated via
the HDM decoder capability structure. The base address for the HDM
decoder capability structure may be conveyed either by PCIe or platform
firmware (ACPI CEDT.CHBS).
Additionally, the kdoc descriptions for these helpers and their
dependencies is updated.
Signed-off-by: Ben Widawsky <ben.widawsky@intel.com>
[djbw: fixup changelog, clarify kdoc]
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/164366463014.111117.9714595404002687111.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
CXL decoders manage address ranges in a hierarchical fashion whereby a
leaf is a unique subregion of its parent decoder (midlevel or root). It
therefore makes sense to use the resource API for handling this.
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> (v1)
Signed-off-by: Ben Widawsky <ben.widawsky@intel.com>
Link: https://lore.kernel.org/r/164298417191.3018233.5201055578165414714.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
This implements the TODO in cxl_acpi for mapping component registers.
cxl_acpi becomes the second consumer of CXL register block enumeration
(cxl_pci being the first). Moving the functionality to cxl_core allows
both of these drivers to use the functionality. Equally importantly it
allows cxl_core to use the functionality in the future.
CXL 2.0 root ports are similar to CXL 2.0 Downstream Ports with the main
distinction being they're a part of the CXL 2.0 host bridge. While
mapping their component registers is not immediately useful for the CXL
drivers, the movement of register block enumeration into core is a vital
step towards HDM decoder programming.
Signed-off-by: Ben Widawsky <ben.widawsky@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
[djbw: fix cxl_regmap_to_base() failure cases]
Link: https://lore.kernel.org/r/164298415080.3018233.14694957480228676592.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
During NUMA init, CXL memory defined in the SRAT Memory Affinity
subtable may be assigned to a NUMA node. Since there is no
requirement that the SRAT be comprehensive for CXL memory another
mechanism is needed to assign NUMA nodes to CXL memory not identified
in the SRAT.
Use the CXL Fixed Memory Window Structure (CFMWS) of the ACPI CXL
Early Discovery Table (CEDT) to find all CXL memory ranges.
Create a NUMA node for each CFMWS that is not already assigned to
a NUMA node. Add a memblk attaching its host physical address
range to the node.
Note that these ranges may not actually map any memory at boot time.
They may describe persistent capacity or may be present to enable
hot-plug.
Consumers can use phys_to_target_node() to discover the NUMA node.
Signed-off-by: Alison Schofield <alison.schofield@intel.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Link: https://lore.kernel.org/r/163553711933.2509508.2203471175679990.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Now that cxl_acpi has been converted to use the core ACPI CEDT sub-table
parser, update cxl_test to inject CFMWS and CHBS data directly into
cxl_acpi's handlers.
Cc: Alison Schofield <alison.schofield@intel.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Link: https://lore.kernel.org/r/163553711363.2509508.17428994087868269952.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
The cxl_acpi driver originally open-coded its table parsing since the
ACPI subtable helpers were marked __init and only used in early NUMA
initialization. Now that those helpers have been exported for driver
usage replace the open-coded solution with the common one.
Cc: Alison Schofield <alison.schofield@intel.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Link: https://lore.kernel.org/r/163553710810.2509508.14686373989517930921.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
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>
Dan Williams
Ben Widawsky
Alison Schofield