The CXL specification claims S3 support at a hardware level, but at a
system software level there are some missing pieces. Section 9.4 (CXL
2.0) rightly claims that "CXL mem adapters may need aux power to retain
memory context across S3", but there is no enumeration mechanism for the
OS to determine if a given adapter has that support. Moreover the save
state and resume image for the system may inadvertantly end up in a CXL
device that needs to be restored before the save state is recoverable.
I.e. a circular dependency that is not resolvable without a third party
save-area.
Arrange for the cxl_mem driver to fail S3 attempts. This still nominaly
allows for suspend, but requires unbinding all CXL memory devices before
the suspend to ensure the typical DRAM flow is taken. The cxl_mem unbind
flow is intended to also tear down all CXL memory regions associated
with a given cxl_memdev.
It is reasonable to assume that any device participating in a System RAM
range published in the EFI memory map is covered by aux power and
save-area outside the device itself. So this restriction can be
minimized in the future once pre-existing region enumeration support
arrives, and perhaps a spec update to clarify if the EFI memory map is
sufficent for determining the range of devices managed by
platform-firmware for S3 support.
Per Rafael, if the CXL configuration prevents suspend then it should
fail early before tasks are frozen, and mem_sleep should stop showing
'mem' as an option [1]. Effectively CXL augments the platform suspend
->valid() op since, for example, the ACPI ops are not aware of the CXL /
PCI dependencies. Given the split role of platform firmware vs OS
provisioned CXL memory it is up to the cxl_mem driver to determine if
the CXL configuration has elements that platform firmware may not be
prepared to restore.
Link: https://lore.kernel.org/r/CAJZ5v0hGVN_=3iU8OLpHY3Ak35T5+JcBM-qs8SbojKrpd0VXsA@mail.gmail.com [1]
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Len Brown <len.brown@intel.com>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Link: https://lore.kernel.org/r/165066828317.3907920.5690432272182042556.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
cxl_mem_probe() already emits a log message when HDM operation can not
be established. Delete the similar one in cxl_hdm_decode_init().
What is less obvious is why global_ctrl being enabled makes positive
values of info->ranges irrelevant, and the Linux behavior with respect
to the spec recommendation to mirror CXL Range registers with HDM
Decoder Base + Size registers.
Cc: Ben Widawsky <ben.widawsky@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Davidlohr Bueso <dave@stgolabs.net>
Link: https://lore.kernel.org/r/164944616743.454665.7055846627973202403.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
cxl_dvsec_decode_init() is tasked with checking whether legacy DVSEC
range based decode is in effect, or whether HDM can be enabled / already
is enabled. As such it either succeeds or fails and that result is the
return value. The @do_hdm_init variable is misleading in the case where
HDM operation is already found to be active, so just call it @retval.
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Davidlohr Bueso <dave@stgolabs.net>
Link: https://lore.kernel.org/r/164730736435.3806189.2537160791687837469.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
cxl_dvsec_ranges(), the helper for enumerating the presence of an active
legacy CXL.mem configuration on a CXL 2.0 Memory Expander, is not fatal
for cxl_pci because there is still value to enable mailbox operations
even if CXL.mem operation is disabled. Recall that the reason cxl_pci
does this initialization and not cxl_mem is to preserve the useful
property (for unit testing) that cxl_mem is cxl_memdev + mmio generic,
and does not require access to a 'struct pci_dev' to issue config
cycles.
Update 'struct cxl_endpoint_dvsec_info' to carry either a positive
number of non-zero size legacy CXL DVSEC ranges, or the negative error
code from __cxl_dvsec_ranges() in its @ranges member.
Reported-by: Krzysztof Zach <krzysztof.zach@intel.com>
Fixes: 560f785590 ("cxl/pci: Retrieve CXL DVSEC memory info")
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Davidlohr Bueso <dave@stgolabs.net>
Link: https://lore.kernel.org/r/164730735869.3806189.4032428192652531946.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
In preparation for the cxl_pci driver to continue operation after
cxl_dvsec_range() failure, update cxl_mem to check for negative error
codes in info->ranges. Treat that condition as fatal regardless of the
state of the HDM configuration since cxl_mem needs positive confirmation
that legacy ranges were not established by platform firmware or another
agent.
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com.
Reviewed-by: Ben Widawsky <ben.widawsky@intel.com>
Reviewed-by: Davidlohr Bueso <dave@stgolabs.net>
Link: https://lore.kernel.org/r/164730735324.3806189.4167509857771192422.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
In preparation for not treating DVSEC range initialization failures as
fatal to cxl_pci_probe() add individual dev_dbg() statements for each of
the major failure reasons in cxl_dvsec_ranges().
The rationale for cxl_dvsec_ranges() failure not being fatal is that
there is still value for cxl_pci to enable mailbox operations even if
CXL.mem operation is disabled.
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Ben Widawsky <ben.widawsky@intel.com>
Reviewed-by: Davidlohr Bueso <dave@stgolabs.net>
Link: https://lore.kernel.org/r/164730734812.3806189.2726330688692684104.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
When the driver finds legacy DVSEC ranges active on a CXL Memory
Expander it indicates that platform firmware is not aware of, or is
deliberately disabling common CXL 2.0 operation. In this case Linux
generally has no choice, but to leave the device alone.
The driver attempts to validate that the DVSEC range is in the EFI
memory map. Remove that logic since there is no requirement that the
BIOS publish DVSEC ranges in the EFI Memory Map.
In the future the driver will want to permanently reserve this capacity
out of the available CFMWS capacity and hide it from
request_free_mem_region(), but it serves no purpose to warn about the
range not appearing in the EFI Memory Map.
Reviewed-by: Davidlohr Bueso <dave@stgolabs.net>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Ben Widawsky <ben.widawsky@intel.com>
Link: https://lore.kernel.org/r/164730734246.3806189.13995924771963139898.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Use the global cxl_mbox_cmd_rc table to improve debug messaging
in __cxl_pci_mbox_send_cmd() and allow cxl_mbox_send_cmd()
to map to proper kernel style errno codes - this patch
continues to use -ENXIO only so no change in semantics.
Signed-off-by: Davidlohr Bueso <dave@stgolabs.net>
Reviewed by: Adam Manzanares <a.manzanares@samsung.com>
Link: https://lore.kernel.org/r/20220404021216.66841-5-dave@stgolabs.net
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Upon a completed command the caller is still expected to check
the actual return_code register to ensure it succeed. This
adds, per the spec, the potential command return codes. It maps
the hardware return code with the kernel's errno style, and by
default continues to use -ENXIO (Command completed, but device
reported an error).
Signed-off-by: Davidlohr Bueso <dave@stgolabs.net>
Reviewed by: Adam Manzanares <a.manzanares@samsung.com>
Link: https://lore.kernel.org/r/20220404021216.66841-4-dave@stgolabs.net
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Also mention the need for the caller to check against any
errors from the hardware in return_code.
Signed-off-by: Davidlohr Bueso <dave@stgolabs.net>
Reviewed by: Adam Manzanares <a.manzanares@samsung.com>
Link: https://lore.kernel.org/r/20220404021216.66841-3-dave@stgolabs.net
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
... we have lockdep for this.
Signed-off-by: Davidlohr Bueso <dave@stgolabs.net>
Reviewed by: Adam Manzanares <a.manzanares@samsung.com>
Link: https://lore.kernel.org/r/20220404021216.66841-2-dave@stgolabs.net
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
With SET_PARTITION_INFO on the exclusive_cmds list for the CXL_PMEM
driver, userspace cannot execute a set-partition command without
first unbinding the pmem driver from the device.
When userspace requests a partition change to take effect on the
next reboot this unbind requirement is unnecessarily restrictive.
The driver does not need to enforce an unbind because partitions
will not change until the next reboot. Of course, userspace still
needs to be aware that changing the size of persistent capacity
on the next reboot will result in the loss of data stored. That
can happen regardless of whether it is presently bound at the time
of issuing the set-partition command.
When userspace requests a partition change to take effect immediately,
restrictions are needed. The CXL_MEM driver currently blocks the usage
of immediate mode, making the presence of SET_PARTITION_INFO, in this
exclusive commands list, redundant.
In the future, when the CXL_MEM driver adds support for immediate
changes to device partitions it will ensure that the partition change
will not affect any active decode. That means the work will not fall
right back here, onto the CXL_PMEM driver.
Signed-off-by: Alison Schofield <alison.schofield@intel.com>
Link: https://lore.kernel.org/r/accc6abc878f0662093b81490a1a052f2ff6f06e.1648687552.git.alison.schofield@intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
User space may send the SET_PARTITION_INFO mailbox command using
the IOCTL interface. Inspect the input payload and fail if the
immediate flag is set.
This is the first instance of the driver inspecting an input payload
from user space. Assume there will be more such cases and implement
with an extensible helper.
In order for the kernel to react to an immediate partition change it
needs to assert that the change will not affect any active decode. At
a minimum this requires validating that the device is using HDM
decoders instead of the CXL DVSEC for decode, and that none of the
active HDM decoders are affected by the partition change. For now,
just fail until that support arrives.
Signed-off-by: Alison Schofield <alison.schofield@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Link: https://lore.kernel.org/r/241821186c363833980adbc389e2c547bc5a6395.1648687552.git.alison.schofield@intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
cxl_validate_command_from_user() is now the single point of validation
for mailbox commands coming from user space. Previously, it returned a
a cxl_mem_command, but that was not sufficient when validation of the
actual mailbox command became a requirement. Now, it returns a fully
validated cxl_mbox_cmd.
Remove the extraneous cxl_mem_command parameter. Define and use a
local version only.
Signed-off-by: Alison Schofield <alison.schofield@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Link: https://lore.kernel.org/r/c11a437896d914daf36f5ac8ec62f999c5ec2da7.1648687552.git.alison.schofield@intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Previously, handle_mailbox_cmd_from_user(), constructed the mailbox
command and dispatched it to the hardware. The construction work
has moved to the validation path.
handle_mailbox_cmd_from_user() now expects a fully validated
mbox param. Make it's caller, cxl_send_cmd(), deliver it. Update
the comments and dereferencing of the new mbox parameter.
Signed-off-by: Alison Schofield <alison.schofield@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Link: https://lore.kernel.org/r/77050ba512d6c30eccf7505467509e460dd325a0.1648687552.git.alison.schofield@intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
In preparation for removing access to struct cxl_mem_command,
change this debug message to use cxl_mbox_cmd fields instead.
Retrieve the pretty command name from cxl_mbox_cmd using a new
opcode to command name helper.
Signed-off-by: Alison Schofield <alison.schofield@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Link: https://lore.kernel.org/r/57265751d336a6e95f5ca31a9c77189408b05742.1648687552.git.alison.schofield@intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
This is a step in refactoring the handling of user space mailbox
commands. The intent is to have all the validation work originate
in cxl_validate_cmd_from_user().
Move the construction and validation of a mailbox command to the
validation path. Continue to pass both the out_cmd and the mbox_cmd
until handle_mbox_cmd_from_user() learns how to use a mbox_cmd param.
Signed-off-by: Alison Schofield <alison.schofield@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Link: https://lore.kernel.org/r/c9fbdad968a2b619f9108bb6c37cef1a853cdf5a.1648687552.git.alison.schofield@intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
This move serves two purposes: 1) Emit the warning in the raw
command validation path, and 2) Remove the dependency on the
struct cxl_mem_command in handle_mailbox_cmd_from_user() in
preparation for a refactor of that function.
Signed-off-by: Alison Schofield <alison.schofield@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Link: https://lore.kernel.org/r/df5f0e0ec8afa1f75299aa86b4226ab4479ef325.1648687552.git.alison.schofield@intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Sanitizing and constructing a cxl_mem_command from a userspace
command is part of the validation process prior to submitting
the command to a CXL device. Move this work to helper functions:
cxl_to_mem_cmd(), cxl_to_mem_cmd_raw().
This declutters cxl_validate_cmd_from_user() in preparation for
adding new validation steps.
Signed-off-by: Alison Schofield <alison.schofield@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Link: https://lore.kernel.org/r/7d9b826f29262e3a484cb4bb7b63872134d60bd7.1648687552.git.alison.schofield@intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Fix the following coccicheck warning:
./drivers/cxl/core/port.c:913:21-24: ERROR: port is NULL but dereferenced.
The put_device() is only relevent in the is_cxl_root() case.
Fixes: 2703c16c75 ("cxl/core/port: Add switch port enumeration")
Signed-off-by: Wan Jiabing <wanjiabing@vivo.com>
Link: https://lore.kernel.org/r/20220307094158.404882-1-wanjiabing@vivo.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
KASAN + DEBUG_KOBJECT_RELEASE reports a potential use-after-free in
cxl_decoder_release() where it goes to reference its parent, a cxl_port,
to free its id back to port->decoder_ida.
BUG: KASAN: use-after-free in to_cxl_port+0x18/0x90 [cxl_core]
Read of size 8 at addr ffff888119270908 by task kworker/35:2/379
CPU: 35 PID: 379 Comm: kworker/35:2 Tainted: G OE 5.17.0-rc2+ #198
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
Workqueue: events kobject_delayed_cleanup
Call Trace:
<TASK>
dump_stack_lvl+0x59/0x73
print_address_description.constprop.0+0x1f/0x150
? to_cxl_port+0x18/0x90 [cxl_core]
kasan_report.cold+0x83/0xdf
? to_cxl_port+0x18/0x90 [cxl_core]
to_cxl_port+0x18/0x90 [cxl_core]
cxl_decoder_release+0x2a/0x60 [cxl_core]
device_release+0x5f/0x100
kobject_cleanup+0x80/0x1c0
The device core only guarantees parent lifetime until all children are
unregistered. If a child needs a parent to complete its ->release()
callback that child needs to hold a reference to extend the lifetime of
the parent.
Fixes: 40ba17afdf ("cxl/acpi: Introduce cxl_decoder objects")
Reported-by: Ben Widawsky <ben.widawsky@intel.com>
Tested-by: Ben Widawsky <ben.widawsky@intel.com>
Reviewed-by: Ben Widawsky <ben.widawsky@intel.com>
Link: https://lore.kernel.org/r/164505751190.4175768.13324905271463416712.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
An endpoint can be unregistered via two paths. Either its parent port is
unregistered, or the memdev that registered the endpoint is removed. The
memdev remove path is responsible for synchronizing against the parent
->remove() event and if the memdev remove path wins, manually trigger
unregister_port() via devm_release_action(). Until that race is resolved
the memdev remove path holds a reference on the endpoint.
If the parent port for the endpoint can not be found that is an
indication that the endpoint has already been registered. Be sure to
drop the reference in all exit paths from delete_endpoint().
Fixes: 8dd2bc0f8e ("cxl/mem: Add the cxl_mem driver")
Link: https://lore.kernel.org/r/164454148209.3429624.12905500880311609053.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
If cxl_device_lock() is used on a non-CXL device the expectation is that
the lock class will fall back to CXL_ANON_LOCK. Instead it crashes when
trying to determine if the device is a 'decoder'. Specifically when the
device has a NULL type pointer. Just check for NULL before
de-referencing ->release.
Fixes: 3c5b903955 ("cxl: Prove CXL locking")
Reported-by: Ben Widawsky <ben.widawsky@intel.com>
Reviewed-by: Ben Widawsky <ben.widawsky@intel.com>
Link: https://lore.kernel.org/r/164439225406.2941117.3927102269866914339.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
The device_lock_assert() in unregister_port() fails to pick the right
device leading to splats like the following from:
echo "ACPI0017:00" > /sys/bus/platform/drivers/cxl_acpi/unbind
WARNING: CPU: 32 PID: 1147 at include/linux/device.h:787 unregister_port+0x49/0x50 [cxl_c
[..]
RIP: 0010:unregister_port+0x49/0x50 [cxl_core]
[..]
Call Trace:
<TASK>
release_nodes+0x63/0x80
devres_release_all+0x8b/0xc0
__device_release_driver+0x190/0x240
device_driver_detach+0x3e/0xa0
unbind_store+0x113/0x130
Fix it up to assert on the device_lock() for ACPI0017 for root and 1st
level ports, and parent ports for all the rest.
Fixes: 54cdbf845c ("cxl/port: Add a driver for 'struct cxl_port' objects")
Reported-by: Ben Widawsky <ben.widawsky@intel.com>
Reviewed-by: Ben Widawsky <ben.widawsky@intel.com>
Link: https://lore.kernel.org/r/164439224893.2941117.18331456248117887720.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
In CXL 2.0, 8.2.5.1 CXL Capability Header Register: this register
is given as 32 bits.
8.2.3 which covers the CXL 2.0 Component registers, including the
CXL Capability Header Register states that access restrictions
specified in Section 8.2.2 apply.
8.2.2 includes:
* A 32 bit register shall be accessed as a 4 Byte quantity.
...
If these rules are not followed, the behavior is undefined.
Discovered during review of CXL QEMU emulation. Alex Bennée pointed
out there was a comment saying that 4 byte registers must be read
with a 4 byte read, but 8 byte reads were being emulated.
https://lore.kernel.org/qemu-devel/87bkzyd3c7.fsf@linaro.org/
Fixing that, led to this code failing. Whilst a given hardware
implementation 'might' work with an 8 byte read, it should not be relied
upon. The QEMU emulation v5 will return 0 and log the wrong access width.
The code moved, so one fixes tag for where this will directly apply and
also a reference to the earlier introduction of the code for backports.
Fixes: 0f06157e01 ("cxl/core: Move register mapping infrastructure")
Fixes: 08422378c4 ("cxl/pci: Add HDM decoder capabilities")
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Ben Widawsky <ben.widawsky@intel.com>
Link: https://lore.kernel.org/r/20220201153437.2873-1-Jonathan.Cameron@huawei.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
In case init_hdm_decoder() finds invalid settings, skip to the next
valid decoder. Only fail port enumeration if zero valid decoders are
found. This protects the driver init against broken hardware and / or
future interleave capabilities.
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/164317464918.3438644.12371149695618136198.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Recall that a CXL Port is any object that publishes a CXL HDM Decoder
Capability structure. That is Host Bridge and Switches that have been
enabled so far. Now, add decoder support to the 'endpoint' CXL Ports
registered by the cxl_mem driver. They mostly share the same enumeration
as Bridges and Switches, but witout a target list. The target of
endpoint decode is device-internal DPA space, not another downstream
port.
Signed-off-by: Ben Widawsky <ben.widawsky@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
[djbw: clarify changelog, hookup enumeration in the port driver]
Link: https://lore.kernel.org/r/164386092069.765089.14895687988217608642.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
In preparation for introducing endpoint decoder objects, move the
target_list attribute out of the common set since it has no meaning for
endpoint decoders.
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Ben Widawsky <ben.widawsky@intel.com>
Link: https://lore.kernel.org/r/164298430100.3018233.4715072508880290970.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
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>
Per the CXL specification (8.1.12.2 Memory Device PCIe Capabilities and
Extended Capabilities) the Device Serial Number capability is mandatory.
Emit it for user tooling to identify devices.
It is reasonable to ask whether the attribute should be added to the
list of PCI sysfs device attributes. The PCI layer can optionally emit
it too, but the CXL subsystem is aiming to preserve its independence and
the possibility of CXL topologies with non-PCI devices in it. To date
that has only proven useful for the 'cxl_test' model, but as can be seen
with seen with ACPI0016 devices, sometimes all that is needed is a
platform firmware table to point to CXL Component Registers in MMIO
space to define a "CXL" device.
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/164366608838.196598.16856227191534267098.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
CXL 2.0 8.1.3.8.2 states:
Memory_Active: When set, indicates that the CXL Range 1 memory is
fully initialized and available for software use. Must be set within
Range 1. Memory_Active_Timeout of deassertion of reset to CXL device
if CXL.mem HwInit Mode=1
Unfortunately, Memory_Active can take quite a long time depending on
media size (up to 256s per 2.0 spec). Provide a callback for the
eventual establishment of CXL.mem operations via the 'cxl_mem' driver
the 'struct cxl_memdev'. The implementation waits for 60s by default for
now and can be overridden by the mbox_ready_time module parameter.
Signed-off-by: Ben Widawsky <ben.widawsky@intel.com>
[djbw: switch to sleeping wait]
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/164298427373.3018233.9309741847039301834.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Before CXL 2.0 HDM Decoder Capability mechanisms can be utilized in a
device the driver must determine that the device is ready for CXL.mem
operation and that platform firmware, or some other agent, has
established an active decode via the legacy CXL 1.1 decoder mechanism.
This legacy mechanism is defined in the CXL DVSEC as a set of range
registers and status bits that take time to settle after a reset.
Validate the CXL memory decode setup via the DVSEC and cache it for
later consideration by the cxl_mem driver (to be added). Failure to
validate is not fatal to the cxl_pci driver since that is only providing
CXL command support over PCI.mmio, and might be needed to rectify CXL
DVSEC validation problems.
Any potential ranges that the device is already claiming via DVSEC need
to be reconciled with the dynamic provisioning ranges provided by
platform firmware (like ACPI CEDT.CFMWS). Leave that reconciliation to
the cxl_mem driver.
[djbw: shorten defines]
[djbw: change precise spin wait to generous msleep]
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Ben Widawsky <ben.widawsky@intel.com>
[djbw: clarify changelog]
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/164375911821.559935.7375160041663453400.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
The PCIe device DVSEC, defined in the CXL 2.0 spec, 8.1.3 is required to
be implemented by CXL 2.0 endpoint devices. In preparation for consuming
this information in a new cxl_mem driver, retrieve the CXL DVSEC
position and warn about the implications of not finding it. Allow for
mailbox operation even if the CXL DVSEC is missing.
Signed-off-by: Ben Widawsky <ben.widawsky@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/164375309615.513620.7874131241128599893.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
In preparation for defining a cxl_port object to represent the decoder
resources of a memory expander capture the component register base
address.
The port driver uses the component register base to enumerate the HDM
Decoder Capability structure. Unlike other cxl_port objects the endpoint
port decodes from upstream SPA to downstream DPA rather than upstream
port to downstream port.
Signed-off-by: Ben Widawsky <ben.widawsky@intel.com>
Reported-by: kernel test robot <lkp@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
[djbw: clarify changelog]
Link: https://lore.kernel.org/r/164375084181.484304.3919737667590006795.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>
In preparation for switch port enumeration while also preserving the
potential for multi-domain / multi-root CXL topologies. Introduce a
'struct device' generic mechanism for retrieving a root CXL port, if one
is registered. Note that the only known multi-domain CXL configurations
are running the cxl_test unit test on a system that also publishes an
ACPI0017 device.
With this in hand the nvdimm-bridge lookup can be with
device_find_child() instead of bus_find_device() + custom mocked lookup
infrastructure in cxl_test.
The mechanism looks for a 2nd level port since the root level topology
is platform-firmware specific and the 2nd level down follows standard
PCIe topology expectations. The cxl_acpi 2nd level is associated with a
PCIe Root Port.
Reported-by: Ben Widawsky <ben.widawsky@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/164367562182.225521.9488555616768096049.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>
Lockdep reports:
======================================================
WARNING: possible circular locking dependency detected
5.16.0-rc1+ #142 Tainted: G OE
------------------------------------------------------
cxl/1220 is trying to acquire lock:
ffff979b85475460 (kn->active#144){++++}-{0:0}, at: __kernfs_remove+0x1ab/0x1e0
but task is already holding lock:
ffff979b87ab38e8 (&dev->lockdep_mutex#2/4){+.+.}-{3:3}, at: cxl_remove_ep+0x50c/0x5c0 [cxl_core]
...where cxl_remove_ep() is a helper that wants to delete ports while
holding a lock on the host device for that port. That sets up a lockdep
violation whereby target_list_show() can not rely holding the decoder's
device lock while walking the target_list. Switch to a dedicated seqlock
for this purpose.
Reported-by: Ben Widawsky <ben.widawsky@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/164367209095.208169.1171673319121271280.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>
