linux/Documentation/ABI/testing/debugfs-cxl
Alison Schofield 591209c798 cxl/memdev: Replace ENXIO with EBUSY for inject poison limit reached
The CXL driver provides a debugfs interface offering users the
ability to inject and clear poison to a memdev. Once a user has
injected up to the devices limit further injection requests fail
with ENXIO until a clear poison is issued.

Users may not have device specs in hand or may want to intentionally
hit the limit and then clear. Replace the usual ENXIO return status
with EBUSY so users can recognize this failure.

Signed-off-by: Alison Schofield <alison.schofield@intel.com>
Tested-by: Xingtao Yao <yaoxt.fnst@fujitsu.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Davidlohr Bueso <dave@stgolabs.net>
Link: https://patch.msgid.link/825bd4c67fb55a4373c4182d999ad49d4e6b4fe7.1720316188.git.alison.schofield@intel.com
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
2024-07-10 17:12:42 -07:00

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What: /sys/kernel/debug/cxl/memX/inject_poison
Date: April, 2023
KernelVersion: v6.4
Contact: linux-cxl@vger.kernel.org
Description:
(WO) When a Device Physical Address (DPA) is written to this
attribute, the memdev driver sends an inject poison command to
the device for the specified address. The DPA must be 64-byte
aligned and the length of the injected poison is 64-bytes. If
successful, the device returns poison when the address is
accessed through the CXL.mem bus. Injecting poison adds the
address to the device's Poison List and the error source is set
to Injected. In addition, the device adds a poison creation
event to its internal Informational Event log, updates the
Event Status register, and if configured, interrupts the host.
It is not an error to inject poison into an address that
already has poison present and no error is returned. If the
device returns 'Inject Poison Limit Reached' an -EBUSY error
is returned to the user. The inject_poison attribute is only
visible for devices supporting the capability.
What: /sys/kernel/debug/memX/clear_poison
Date: April, 2023
KernelVersion: v6.4
Contact: linux-cxl@vger.kernel.org
Description:
(WO) When a Device Physical Address (DPA) is written to this
attribute, the memdev driver sends a clear poison command to
the device for the specified address. Clearing poison removes
the address from the device's Poison List and writes 0 (zero)
for 64 bytes starting at address. It is not an error to clear
poison from an address that does not have poison set. If the
device cannot clear poison from the address, -ENXIO is returned.
The clear_poison attribute is only visible for devices
supporting the capability.
What: /sys/kernel/debug/cxl/einj_types
Date: January, 2024
KernelVersion: v6.9
Contact: linux-cxl@vger.kernel.org
Description:
(RO) Prints the CXL protocol error types made available by
the platform in the format:
0x<error number> <error type>
The possible error types are (as of ACPI v6.5):
0x1000 CXL.cache Protocol Correctable
0x2000 CXL.cache Protocol Uncorrectable non-fatal
0x4000 CXL.cache Protocol Uncorrectable fatal
0x8000 CXL.mem Protocol Correctable
0x10000 CXL.mem Protocol Uncorrectable non-fatal
0x20000 CXL.mem Protocol Uncorrectable fatal
The <error number> can be written to einj_inject to inject
<error type> into a chosen dport.
What: /sys/kernel/debug/cxl/$dport_dev/einj_inject
Date: January, 2024
KernelVersion: v6.9
Contact: linux-cxl@vger.kernel.org
Description:
(WO) Writing an integer to this file injects the corresponding
CXL protocol error into $dport_dev ($dport_dev will be a device
name from /sys/bus/pci/devices). The integer to type mapping for
injection can be found by reading from einj_types. If the dport
was enumerated in RCH mode, a CXL 1.1 error is injected, otherwise
a CXL 2.0 error is injected.