linux-kernel - [PATCH v2 06/14] nvme: Rapid Path Failure Recovery read controller identify fields

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Message-ID: <20260130223531.2478849-7-mkhalfella@purestorage.com>
Date: Fri, 30 Jan 2026 14:34:10 -0800
From: Mohamed Khalfella <mkhalfella@...estorage.com>
To: Justin Tee <justin.tee@...adcom.com>,
	Naresh Gottumukkala <nareshgottumukkala83@...il.com>,
	Paul Ely <paul.ely@...adcom.com>,
	Chaitanya Kulkarni <kch@...dia.com>,
	Christoph Hellwig <hch@....de>,
	Jens Axboe <axboe@...nel.dk>,
	Keith Busch <kbusch@...nel.org>,
	Sagi Grimberg <sagi@...mberg.me>
Cc: Aaron Dailey <adailey@...estorage.com>,
	Randy Jennings <randyj@...estorage.com>,
	Dhaval Giani <dgiani@...estorage.com>,
	Hannes Reinecke <hare@...e.de>,
	linux-nvme@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	Mohamed Khalfella <mkhalfella@...estorage.com>
Subject: [PATCH v2 06/14] nvme: Rapid Path Failure Recovery read controller identify fields

TP8028 Rapid path failure added new fileds to controller identify
response. Read CIU (Controller Instance Uniquifier), CIRN (Controller
Instance Random Number), and CCRL (Cross-Controller Reset Limit) from
controller identify response. Expose CIU and CIRN as sysfs attributes
so the values can be used directrly by user if needed.

TP4129 KATO Corrections and Clarifications defined CQT (Command Quiesce
Time) which is used along with KATO (Keep Alive Timeout) to set an upper
limit for attempting Cross-Controller Recovery.

Signed-off-by: Mohamed Khalfella <mkhalfella@...estorage.com>
---
 drivers/nvme/host/core.c  |  5 +++++
 drivers/nvme/host/nvme.h  | 11 +++++++++++
 drivers/nvme/host/sysfs.c | 23 +++++++++++++++++++++++
 3 files changed, 39 insertions(+)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 7bf228df6001..8961d612ccb0 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -3571,6 +3571,11 @@ static int nvme_init_identify(struct nvme_ctrl *ctrl)
 	ctrl->crdt[1] = le16_to_cpu(id->crdt2);
 	ctrl->crdt[2] = le16_to_cpu(id->crdt3);
 
+	ctrl->ciu = id->ciu;
+	ctrl->cirn = le64_to_cpu(id->cirn);
+	atomic_set(&ctrl->ccr_limit, id->ccrl);
+	ctrl->cqt = le16_to_cpu(id->cqt);
+
 	ctrl->oacs = le16_to_cpu(id->oacs);
 	ctrl->oncs = le16_to_cpu(id->oncs);
 	ctrl->mtfa = le16_to_cpu(id->mtfa);
diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index 9a5f28c5103c..9dd9f179ad88 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -326,13 +326,17 @@ struct nvme_ctrl {
 	u32 max_zone_append;
 #endif
 	u16 crdt[3];
+	u16 cqt;
 	u16 oncs;
 	u8 dmrl;
+	u8 ciu;
 	u32 dmrsl;
+	u64 cirn;
 	u16 oacs;
 	u16 sqsize;
 	u32 max_namespaces;
 	atomic_t abort_limit;
+	atomic_t ccr_limit;
 	u8 vwc;
 	u32 vs;
 	u32 sgls;
@@ -1225,4 +1229,11 @@ static inline bool nvme_multi_css(struct nvme_ctrl *ctrl)
 	return (ctrl->ctrl_config & NVME_CC_CSS_MASK) == NVME_CC_CSS_CSI;
 }
 
+static inline unsigned long nvme_fence_timeout_ms(struct nvme_ctrl *ctrl)
+{
+	if (ctrl->ctratt & NVME_CTRL_ATTR_TBKAS)
+		return 3 * ctrl->kato * 1000 + ctrl->cqt;
+	return 2 * ctrl->kato * 1000 + ctrl->cqt;
+}
+
 #endif /* _NVME_H */
diff --git a/drivers/nvme/host/sysfs.c b/drivers/nvme/host/sysfs.c
index 29430949ce2f..f81bbb6ec768 100644
--- a/drivers/nvme/host/sysfs.c
+++ b/drivers/nvme/host/sysfs.c
@@ -388,6 +388,27 @@ nvme_show_int_function(queue_count);
 nvme_show_int_function(sqsize);
 nvme_show_int_function(kato);
 
+static ssize_t nvme_sysfs_ciu_show(struct device *dev,
+					  struct device_attribute *attr,
+					  char *buf)
+{
+	struct nvme_ctrl *ctrl = dev_get_drvdata(dev);
+
+	return sysfs_emit(buf, "%02x\n", ctrl->ciu);
+}
+static DEVICE_ATTR(ciu, S_IRUGO, nvme_sysfs_ciu_show, NULL);
+
+static ssize_t nvme_sysfs_cirn_show(struct device *dev,
+					  struct device_attribute *attr,
+					  char *buf)
+{
+	struct nvme_ctrl *ctrl = dev_get_drvdata(dev);
+
+	return sysfs_emit(buf, "%016llx\n", ctrl->cirn);
+}
+static DEVICE_ATTR(cirn, S_IRUGO, nvme_sysfs_cirn_show, NULL);
+
+
 static ssize_t nvme_sysfs_delete(struct device *dev,
 				struct device_attribute *attr, const char *buf,
 				size_t count)
@@ -734,6 +755,8 @@ static struct attribute *nvme_dev_attrs[] = {
 	&dev_attr_numa_node.attr,
 	&dev_attr_queue_count.attr,
 	&dev_attr_sqsize.attr,
+	&dev_attr_ciu.attr,
+	&dev_attr_cirn.attr,
 	&dev_attr_hostnqn.attr,
 	&dev_attr_hostid.attr,
 	&dev_attr_ctrl_loss_tmo.attr,
-- 
2.52.0