[PATCH v4 06/15] nvme: Rapid Path Failure Recovery read controller identify fields

From: Mohamed Khalfella

Date: Fri Mar 27 2026 - 20:50:50 EST


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.

Signed-off-by: Mohamed Khalfella <mkhalfella@xxxxxxxxxxxxxxx>
Reviewed-by: Hannes Reinecke <hare@xxxxxxx>
Reviewed-by: Sagi Grimberg <sagi@xxxxxxxxxxx>
---
drivers/nvme/host/core.c | 4 ++++
drivers/nvme/host/nvme.h | 10 ++++++++++
drivers/nvme/host/sysfs.c | 23 +++++++++++++++++++++++
3 files changed, 37 insertions(+)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 766e9cc4ffca..7a07c23aefdb 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -3567,6 +3567,10 @@ 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->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 9971045dbc05..234f3872a212 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -382,11 +382,14 @@ struct nvme_ctrl {
u16 crdt[3];
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;
@@ -1280,4 +1283,11 @@ 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;
+ return 2 * ctrl->kato * 1000;
+}
+
#endif /* _NVME_H */
diff --git a/drivers/nvme/host/sysfs.c b/drivers/nvme/host/sysfs.c
index 16c6fea4b2db..f182a26b38b0 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_IRUSR, 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_IRUSR, nvme_sysfs_cirn_show, NULL);
+
+
static ssize_t nvme_sysfs_delete(struct device *dev,
struct device_attribute *attr, const char *buf,
size_t count)
@@ -756,6 +777,8 @@ 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