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Diffstat (limited to 'Documentation/ABI/testing/debugfs-cxl')
| -rw-r--r-- | Documentation/ABI/testing/debugfs-cxl | 157 |
1 files changed, 157 insertions, 0 deletions
diff --git a/Documentation/ABI/testing/debugfs-cxl b/Documentation/ABI/testing/debugfs-cxl new file mode 100644 index 000000000000..2989d4da96c1 --- /dev/null +++ b/Documentation/ABI/testing/debugfs-cxl @@ -0,0 +1,157 @@ +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. + + TEST-ONLY INTERFACE: This interface is intended for testing + and validation purposes only. It is not a data repair mechanism + and should never be used on production systems or live data. + + DATA LOSS RISK: For CXL persistent memory (PMEM) devices, + poison injection can result in permanent data loss. Injected + poison may render data permanently inaccessible even after + clearing, as the clear operation writes zeros and does not + recover original data. + + SYSTEM STABILITY RISK: For volatile memory, poison injection + can cause kernel crashes, system instability, or unpredictable + behavior if the poisoned addresses are accessed by running code + or critical kernel structures. + +What: /sys/kernel/debug/cxl/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. + + TEST-ONLY INTERFACE: This interface is intended for testing + and validation purposes only. It is not a data repair mechanism + and should never be used on production systems or live data. + + CLEAR IS NOT DATA RECOVERY: This operation writes zeros to the + specified address range and removes the address from the poison + list. It does NOT recover or restore original data that may have + been present before poison injection. Any original data at the + cleared address is permanently lost and replaced with zeros. + + CLEAR IS NOT A REPAIR MECHANISM: This interface is for testing + purposes only and should not be used as a data repair tool. + Clearing poison is fundamentally different from data recovery + or error correction. + +What: /sys/kernel/debug/cxl/regionX/inject_poison +Date: August, 2025 +Contact: linux-cxl@vger.kernel.org +Description: + (WO) When a Host Physical Address (HPA) is written to this + attribute, the region driver translates it to a Device + Physical Address (DPA) and identifies the corresponding + memdev. It then sends an inject poison command to that memdev + at the translated DPA. Refer to the memdev ABI entry at: + /sys/kernel/debug/cxl/memX/inject_poison for the detailed + behavior. This attribute is only visible if all memdevs + participating in the region support both inject and clear + poison commands. + + TEST-ONLY INTERFACE: This interface is intended for testing + and validation purposes only. It is not a data repair mechanism + and should never be used on production systems or live data. + + DATA LOSS RISK: For CXL persistent memory (PMEM) devices, + poison injection can result in permanent data loss. Injected + poison may render data permanently inaccessible even after + clearing, as the clear operation writes zeros and does not + recover original data. + + SYSTEM STABILITY RISK: For volatile memory, poison injection + can cause kernel crashes, system instability, or unpredictable + behavior if the poisoned addresses are accessed by running code + or critical kernel structures. + +What: /sys/kernel/debug/cxl/regionX/clear_poison +Date: August, 2025 +Contact: linux-cxl@vger.kernel.org +Description: + (WO) When a Host Physical Address (HPA) is written to this + attribute, the region driver translates it to a Device + Physical Address (DPA) and identifies the corresponding + memdev. It then sends a clear poison command to that memdev + at the translated DPA. Refer to the memdev ABI entry at: + /sys/kernel/debug/cxl/memX/clear_poison for the detailed + behavior. This attribute is only visible if all memdevs + participating in the region support both inject and clear + poison commands. + + TEST-ONLY INTERFACE: This interface is intended for testing + and validation purposes only. It is not a data repair mechanism + and should never be used on production systems or live data. + + CLEAR IS NOT DATA RECOVERY: This operation writes zeros to the + specified address range and removes the address from the poison + list. It does NOT recover or restore original data that may have + been present before poison injection. Any original data at the + cleared address is permanently lost and replaced with zeros. + + CLEAR IS NOT A REPAIR MECHANISM: This interface is for testing + purposes only and should not be used as a data repair tool. + Clearing poison is fundamentally different from data recovery + or error correction. + +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. |