[PATCH v4 1/3] nvme: add ABI documentation for host sysfs interfaces

[Guixin Liu <kanie@linux.alibaba.com>]

Add Documentation/ABI/stable/sysfs-nvme documenting all NVMe host
sysfs attributes, covering controller attributes under
/sys/class/nvme/nvmeX/, namespace attributes under
/sys/block/nvmeXnY/, and subsystem attributes under
/sys/class/nvme-subsystem/nvme-subsysX/.

Each entry has been traced to its original introducing commit to
provide accurate Date, KernelVersion, and Contact information.

Signed-off-by: Guixin Liu <kanie@linux.alibaba.com>
Reviewed-by: Hannes Reinecke <hare@kernel.org>
Reviewed-by: Daniel Wagner <dwagner@suse.de>
Reviewed-by: Nilay Shroff <nilay@linux.ibm.com>
---
 Documentation/ABI/stable/sysfs-nvme  | 453 +++++++++++++++++++++++++++
 Documentation/ABI/testing/sysfs-nvme |  13 -
 2 files changed, 453 insertions(+), 13 deletions(-)
 create mode 100644 Documentation/ABI/stable/sysfs-nvme
 delete mode 100644 Documentation/ABI/testing/sysfs-nvme

diff --git a/Documentation/ABI/stable/sysfs-nvme b/Documentation/ABI/stable/sysfs-nvme
new file mode 100644
index 000000000000..a2f5d0710db4
--- /dev/null
+++ b/Documentation/ABI/stable/sysfs-nvme
@@ -0,0 +1,453 @@
+What:		/sys/class/nvme/nvmeX/model
+What:		/sys/class/nvme/nvmeX/serial
+What:		/sys/class/nvme/nvmeX/firmware_rev
+Date:		January 2016
+KernelVersion:	4.5
+Contact:	Keith Busch <kbusch@kernel.org>
+Description:
+		Shows the model, serial number, or firmware revision string
+		of the NVMe controller, as reported in the Identify
+		Controller data structure.
+
+What:		/sys/class/nvme/nvmeX/cntlid
+Date:		February 2016
+KernelVersion:	4.6
+Contact:	Ming Lin <ming.l@ssi.samsung.com>
+Description:
+		Shows the controller identifier assigned by the NVMe
+		subsystem.
+
+What:		/sys/class/nvme/nvmeX/cntrltype
+What:		/sys/class/nvme/nvmeX/dctype
+Date:		February 2022
+KernelVersion:	5.18
+Contact:	Martin Belanger <martin.belanger@dell.com>
+Description:
+		cntrltype: Shows the controller type. Possible values: "io",
+		"discovery", "admin", "reserved".
+
+		dctype: Shows the discovery controller type. Possible values:
+		"none", "ddc", "cdc", "reserved".
+
+What:		/sys/class/nvme/nvmeX/reset_controller
+Date:		November 2015
+KernelVersion:	4.5
+Contact:	Christoph Hellwig <hch@lst.de>
+Description:
+		Write-only. Writing any value triggers a synchronous
+		controller reset.
+
+What:		/sys/class/nvme/nvmeX/rescan_controller
+Date:		April 2016
+KernelVersion:	4.7
+Contact:	Keith Busch <kbusch@kernel.org>
+Description:
+		Write-only. Writing any value triggers a namespace rescan
+		on this controller.
+
+What:		/sys/class/nvme/nvmeX/transport
+What:		/sys/class/nvme/nvmeX/subsysnqn
+What:		/sys/class/nvme/nvmeX/address
+What:		/sys/class/nvme/nvmeX/delete_controller
+What:		/sys/class/nvme/nvmeX/reconnect_delay
+What:		/sys/class/nvme/nvmeX/ctrl_loss_tmo
+Date:		June 2016
+KernelVersion:	4.8
+Contact:	Ming Lin <ming.l@ssi.samsung.com>
+Description:
+		Fabrics controller attributes added with NVMe-oF support.
+
+		transport: Shows the transport type string. Possible values:
+		"pcie", "tcp", "rdma", "fc", "loop".
+
+		subsysnqn: Shows the NVMe Qualified Name (NQN) of the
+		subsystem this controller belongs to.
+
+		address: Shows the transport-specific address string. Only
+		available for fabrics controllers.
+
+		delete_controller: Write-only. Triggers deletion of this
+		fabrics controller.
+
+		reconnect_delay: Shows or sets the reconnect delay in
+		seconds. Reading returns the delay value, or "off" if
+		disabled.
+
+		ctrl_loss_tmo: Shows or sets the controller loss timeout in
+		seconds. Reading returns the timeout value, or "off" if
+		infinite reconnects are allowed. Writing a negative value
+		disables the timeout.
+
+What:		/sys/class/nvme/nvmeX/hostnqn
+What:		/sys/class/nvme/nvmeX/hostid
+Date:		February 2020
+KernelVersion:	5.7
+Contact:	Sagi Grimberg <sagi@grimberg.me>
+Description:
+		hostnqn: Shows the host NQN used by this fabrics controller.
+
+		hostid: Shows the host identifier (UUID format) used by this
+		fabrics controller.
+
+		Only available for fabrics controllers.
+
+What:		/sys/class/nvme/nvmeX/fast_io_fail_tmo
+Date:		November 2020
+KernelVersion:	5.11
+Contact:	Victor Gladkov <Victor.Gladkov@kioxia.com>
+Description:
+		Shows or sets the fast I/O fail timeout in seconds. Reading
+		returns the timeout value, or "off" if disabled. Writing a
+		negative value disables the fast I/O fail. Only available
+		for fabrics controllers.
+
+What:		/sys/class/nvme/nvmeX/kato
+Date:		April 2021
+KernelVersion:	5.13
+Contact:	Hannes Reinecke <hare@suse.de>
+Description:
+		Shows the Keep Alive Timeout value in milliseconds for
+		this controller.
+
+What:		/sys/class/nvme/nvmeX/cmb
+Date:		October 2016
+KernelVersion:	4.9
+Contact:	Stephen Bates <sbates@raithlin.com>
+Description:
+		Shows the Controller Memory Buffer (CMB) register values
+		in format "cmbloc : 0x%08x\ncmbsz  : 0x%08x\n". Only
+		visible when the controller has a CMB (cmbsz != 0).
+		PCI transport only.
+
+What:		/sys/class/nvme/nvmeX/cmbloc
+What:		/sys/class/nvme/nvmeX/cmbsz
+What:		/sys/class/nvme/nvmeX/hmb
+Date:		July 2021
+KernelVersion:	5.15
+Contact:	Keith Busch <kbusch@kernel.org>
+Description:
+		cmbloc: Shows the CMBLOC register value.
+
+		cmbsz: Shows the CMBSZ register value.
+
+		cmbloc and cmbsz are only visible when the controller has
+		a CMB. PCI transport only.
+
+		hmb: Shows or sets whether the Host Memory Buffer (HMB) is
+		enabled. Reading returns 1 (enabled) or 0 (disabled).
+		Writing 1 enables HMB; writing 0 disables it. Only
+		visible when the controller supports HMB (hmpre != 0).
+		PCI transport only.
+
+What:		/sys/class/nvme/nvmeX/state
+Date:		November 2016
+KernelVersion:	4.11
+Contact:	Sagi Grimberg <sagi@grimberg.me>
+Description:
+		Shows the current state of the controller. Possible values:
+		"new", "live", "resetting", "connecting", "deleting",
+		"deleting (no IO)", "dead".
+
+What:		/sys/class/nvme/nvmeX/numa_node
+Date:		November 2018
+KernelVersion:	5.0
+Contact:	Hannes Reinecke <hare@suse.de>
+Description:
+		Shows the NUMA node the controller is attached to.
+
+What:		/sys/class/nvme/nvmeX/queue_count
+What:		/sys/class/nvme/nvmeX/sqsize
+Date:		September 2019
+KernelVersion:	5.4
+Contact:	James Smart <jsmart2021@gmail.com>
+Description:
+		queue_count: Shows the total number of queues (admin + I/O)
+		for this controller.
+
+		sqsize: Shows the submission queue size for this controller.
+
+What:		/sys/class/nvme/nvmeX/dhchap_secret
+What:		/sys/class/nvme/nvmeX/dhchap_ctrl_secret
+Date:		June 2022
+KernelVersion:	6.0
+Contact:	Hannes Reinecke <hare@suse.de>
+Description:
+		dhchap_secret: Shows or sets the host DH-HMAC-CHAP secret
+		for this controller. Reading returns "none" if not set.
+		Writing must use the "DHHC-1:" key format and triggers
+		re-authentication.
+
+		dhchap_ctrl_secret: Shows or sets the controller
+		DH-HMAC-CHAP secret for bidirectional authentication.
+		Same format as dhchap_secret.
+
+		Only available when CONFIG_NVME_HOST_AUTH is enabled and
+		for fabrics controllers.
+
+What:		/sys/class/nvme/nvmeX/tls_key
+Date:		August 2023
+KernelVersion:	6.7
+Contact:	Hannes Reinecke <hare@suse.de>
+Description:
+		Shows the serial of the currently active TLS PSK as hex.
+		Returns empty if no TLS key is active. Only available for
+		TCP controllers with TLS or secure concatenation enabled
+		(CONFIG_NVME_TCP_TLS).
+
+What:		/sys/class/nvme/nvmeX/tls_configured_key
+Date:		July 2024
+KernelVersion:	6.12
+Contact:	Hannes Reinecke <hare@kernel.org>
+Description:
+		Shows the serial of the configured TLS key. Writing 0
+		triggers a PSK reauthentication (REPLACETLSPSK) with
+		the target. After reauthentication the returned serial
+		will be the new key. Only available for TCP controllers
+		with secure concatenation enabled (CONFIG_NVME_TCP_TLS).
+
+What:		/sys/class/nvme/nvmeX/tls_keyring
+Date:		July 2024
+KernelVersion:	6.12
+Contact:	Hannes Reinecke <hare@kernel.org>
+Description:
+		Shows the TLS keyring description. Only available for TCP
+		controllers with a keyring configured (CONFIG_NVME_TCP_TLS).
+
+What:		/sys/class/nvme/nvmeX/tls_mode
+Date:		April 2026
+KernelVersion:	7.1
+Contact:	Daniel Wagner <wagi@kernel.org>
+Description:
+		Shows the TLS mode: "tls" for direct TLS or "concat" for
+		secure concatenation. Only available for TCP controllers
+		with TLS or secure concatenation enabled
+		(CONFIG_NVME_TCP_TLS).
+
+What:		/sys/class/nvme/nvmeX/passthru_err_log_enabled
+Date:		January 2024
+KernelVersion:	6.8
+Contact:	Alan Adamson <alan.adamson@oracle.com>
+Description:
+		Shows or sets whether admin passthrough error logging is
+		enabled for this controller. Reading returns "on" or "off".
+		Writing accepts a boolean value.
+
+What:		/sys/class/nvme/nvmeX/quirks
+Date:		November 2025
+KernelVersion:	7.0
+Contact:	Maurizio Lombardi <mlombard@redhat.com>
+Description:
+		Shows the active quirk names for this controller, one per
+		line. Shows "none" if no quirks are active.
+
+What:		/sys/class/nvme/nvmeX/admin_timeout
+What:		/sys/class/nvme/nvmeX/io_timeout
+Date:		May 2026
+KernelVersion:	7.2
+Contact:	Maurizio Lombardi <mlombard@redhat.com>
+Description:
+		admin_timeout: Shows or sets the admin command timeout in
+		milliseconds.
+
+		io_timeout: Shows or sets the I/O command timeout in
+		milliseconds. Changes are propagated to all namespace
+		request queues.
+
+		The value must be nonzero. Only writable after the
+		controller has been started at least once.
+
+What:		/sys/block/nvmeXnY/uuid
+What:		/sys/block/nvmeXnY/eui
+What:		/sys/block/nvmeXnY/nsid
+Date:		December 2015
+KernelVersion:	4.5
+Contact:	Keith Busch <kbusch@kernel.org>
+Description:
+		Namespace identification attributes.
+
+		uuid: Shows the UUID for this namespace. Falls back to
+		showing the NGUID for backward compatibility. Hidden if
+		both are all zeros.
+
+		eui: Shows the IEEE Extended Unique Identifier (EUI-64).
+		Hidden if all zeros.
+
+		nsid: Shows the namespace identifier (NSID).
+
+What:		/sys/block/nvmeXnY/wwid
+Date:		February 2016
+KernelVersion:	4.6
+Contact:	Keith Busch <kbusch@kernel.org>
+Description:
+		Shows the World Wide Identifier for this namespace. The
+		format depends on available identifiers (in priority
+		order): "uuid.{UUID}", "eui.{NGUID}", "eui.{EUI64}", or
+		"nvme.{VID}-{SERIAL}-{MODEL}-{NSID}".
+
+What:		/sys/block/nvmeXnY/nguid
+Date:		June 2017
+KernelVersion:	4.13
+Contact:	Johannes Thumshirn <jthumshirn@suse.de>
+Description:
+		Shows the Namespace Globally Unique Identifier (NGUID).
+		Hidden if the NGUID is all zeros.
+
+What:		/sys/block/nvmeXcYnZ/ana_grpid
+What:		/sys/block/nvmeXcYnZ/ana_state
+Date:		May 2018
+KernelVersion:	4.19
+Contact:	Christoph Hellwig <hch@lst.de>
+Description:
+		ana_grpid: Shows the ANA Group ID for this namespace
+		path device.
+
+		ana_state: Shows the ANA state. Possible values:
+		"optimized", "non-optimized", "inaccessible",
+		"persistent-loss", "change".
+
+		Only visible when the controller supports ANA.
+		Requires CONFIG_NVME_MULTIPATH.
+
+What:		/sys/block/nvmeXcYnZ/queue_depth
+Date:		June 2024
+KernelVersion:	6.11
+Contact:	Thomas Song <tsong@purestorage.com>
+Description:
+		Shows the current active I/O count on this path's
+		controller. Returns empty if iopolicy is not "queue-depth".
+		Requires CONFIG_NVME_MULTIPATH.
+
+What:		/sys/block/nvmeXcYnZ/numa_nodes
+Date:		January 2025
+KernelVersion:	6.15
+Contact:	Nilay Shroff <nilay@linux.ibm.com>
+Description:
+		Shows the NUMA node mask for which this path is the
+		currently selected path. Returns empty if iopolicy is not
+		"numa". Requires CONFIG_NVME_MULTIPATH.
+
+What:		/sys/block/nvmeXnY/delayed_removal_secs
+Date:		May 2025
+KernelVersion:	6.16
+Contact:	Nilay Shroff <nilay@linux.ibm.com>
+Description:
+		Shows or sets the delayed removal timeout in seconds for
+		the multipath head device. When nonzero, I/O is queued
+		instead of failed when all paths are gone, and head removal
+		is deferred. Only visible on multipath head devices.
+		Requires CONFIG_NVME_MULTIPATH.
+
+What:		/sys/block/nvmeXnY/csi
+What:		/sys/block/nvmeXnY/metadata_bytes
+What:		/sys/block/nvmeXnY/nuse
+Date:		December 2023
+KernelVersion:	6.8
+Contact:	Daniel Wagner <dwagner@suse.de>
+Description:
+		csi: Shows the Command Set Identifier for this namespace.
+
+		metadata_bytes: Shows the metadata size in bytes.
+
+		nuse: Shows the Namespace Utilization (NUSE) value. Reading
+		triggers an Identify Namespace command to refresh the
+		value (rate-limited to avoid excessive commands).
+
+What:		/sys/block/nvmeXnY/passthru_err_log_enabled
+Date:		January 2024
+KernelVersion:	6.8
+Contact:	Alan Adamson <alan.adamson@oracle.com>
+Description:
+		Shows or sets whether I/O passthrough error logging is
+		enabled for this namespace. Reading returns "on" or "off".
+		Writing accepts a boolean value.
+
+What:		/sys/class/nvme/nvmeX/diag/command_error_count
+What:		/sys/class/nvme/nvmeX/diag/reset_count
+What:		/sys/class/nvme/nvmeX/diag/reconnect_count
+Date:		May 2026
+KernelVersion:	7.2
+Contact:	Nilay Shroff <nilay@linux.ibm.com>
+Description:
+		Controller diagnostic counters.
+
+		command_error_count: Admin command error counter.
+
+		reset_count: Controller reset counter.
+
+		reconnect_count: Accumulated reconnect counter. Only
+		available for fabrics controllers.
+
+		All counters can be reset by writing a value.
+
+What:		/sys/block/nvmeXnY/diag/command_retries_count
+What:		/sys/block/nvmeXnY/diag/command_error_count
+Date:		May 2026
+KernelVersion:	7.2
+Contact:	Nilay Shroff <nilay@linux.ibm.com>
+Description:
+		Namespace diagnostic counters for non-multipath
+		configurations (when CONFIG_NVME_MULTIPATH is not
+		configured).
+
+		command_retries_count: I/O command retry counter.
+
+		command_error_count: I/O command error counter.
+
+		All counters can be reset by writing any value.
+
+What:		/sys/block/nvmeXcYnZ/diag/command_retries_count
+What:		/sys/block/nvmeXcYnZ/diag/command_error_count
+What:		/sys/block/nvmeXcYnZ/diag/multipath_failover_count
+What:		/sys/block/nvmeXnY/diag/io_requeue_no_usable_path_count
+What:		/sys/block/nvmeXnY/diag/io_fail_no_available_path_count
+Date:		May 2026
+KernelVersion:	7.2
+Contact:	Nilay Shroff <nilay@linux.ibm.com>
+Description:
+		Namespace diagnostic counters for multipath
+		configurations (when CONFIG_NVME_MULTIPATH is
+		configured).
+
+		command_retries_count: I/O command retry counter.
+
+		command_error_count: I/O command error counter.
+
+		multipath_failover_count: Multipath failover counter.
+
+		io_requeue_no_usable_path_count: Counter of I/Os
+		requeued because no usable path was available.
+
+		io_fail_no_available_path_count: Counter of I/Os
+		failed because no available path existed.
+
+		All counters can be reset by writing any value.
+
+What:		/sys/class/nvme-subsystem/nvme-subsysX/model
+What:		/sys/class/nvme-subsystem/nvme-subsysX/serial
+What:		/sys/class/nvme-subsystem/nvme-subsysX/firmware_rev
+What:		/sys/class/nvme-subsystem/nvme-subsysX/subsysnqn
+Date:		November 2017
+KernelVersion:	4.15
+Contact:	Hannes Reinecke <hare@suse.de>
+Description:
+		Shows the model, serial number, firmware revision, or NQN
+		of the NVMe subsystem.
+
+What:		/sys/class/nvme-subsystem/nvme-subsysX/iopolicy
+Date:		February 2019
+KernelVersion:	5.1
+Contact:	Hannes Reinecke <hare@suse.de>
+Description:
+		Shows or sets the multipath I/O path selection policy for
+		this subsystem. Accepted values: "numa", "round-robin",
+		"queue-depth". Changing the policy clears all current path
+		selections. Only available when CONFIG_NVME_MULTIPATH is
+		enabled.
+
+What:		/sys/class/nvme-subsystem/nvme-subsysX/subsystype
+Date:		September 2021
+KernelVersion:	5.16
+Contact:	Hannes Reinecke <hare@suse.de>
+Description:
+		Shows the subsystem type. Possible values: "discovery",
+		"nvm", "reserved".
diff --git a/Documentation/ABI/testing/sysfs-nvme b/Documentation/ABI/testing/sysfs-nvme
deleted file mode 100644
index 499d5f843cd4..000000000000
--- a/Documentation/ABI/testing/sysfs-nvme
+++ /dev/null
@@ -1,13 +0,0 @@
-What:		/sys/devices/virtual/nvme-fabrics/ctl/.../tls_configured_key
-Date:		November 2025
-KernelVersion:	6.19
-Contact:	Linux NVMe mailing list <linux-nvme@lists.infradead.org>
-Description:
-		The file is avaliable when using a secure concatanation
-		connection to a NVMe target. Reading the file will return
-		the serial of the currently negotiated key.
-
-		Writing 0 to the file will trigger a PSK reauthentication
-		(REPLACETLSPSK) with the target. After a reauthentication
-		the value returned by tls_configured_key will be the new
-		serial.
-- 
2.43.7