[PATCH v6 16/18] nvmet: Add support for CQT to nvme target

[Mohamed Khalfella <mkhalfella@purestorage.com>]

TP4129 KATO Corrections and Clarifications defined CQT (Command Quiesce
Time) which is used along with KATO (Keep Alive Timeout) to set an upper
time limit for attempting Cross-Controller Recovery. CQT is added as a
subsystem attribute that defaults to 0 to maintain the current behavior.

Signed-off-by: Mohamed Khalfella <mkhalfella@purestorage.com>
Reviewed-by: Hannes Reinecke <hare@kernel.org>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
---
 drivers/nvme/target/admin-cmd.c |  1 +
 drivers/nvme/target/configfs.c  | 36 +++++++++++++++++++++++++++++++++
 drivers/nvme/target/core.c      |  3 +++
 drivers/nvme/target/nvmet.h     |  2 ++
 include/linux/nvme.h            |  5 ++++-
 5 files changed, 46 insertions(+), 1 deletion(-)

diff --git a/drivers/nvme/target/admin-cmd.c b/drivers/nvme/target/admin-cmd.c
index a60b2f271e98..c0cd233048eb 100644
--- a/drivers/nvme/target/admin-cmd.c
+++ b/drivers/nvme/target/admin-cmd.c
@@ -739,6 +739,7 @@ static void nvmet_execute_identify_ctrl(struct nvmet_req *req)
 	id->cntlid = cpu_to_le16(ctrl->cntlid);
 	id->ver = cpu_to_le32(ctrl->subsys->ver);
 	if (!nvmet_is_disc_subsys(ctrl->subsys)) {
+		id->cqt = cpu_to_le16(ctrl->cqt);
 		id->ciu = ctrl->ciu;
 		id->cirn = cpu_to_le64(ctrl->cirn);
 		id->ccrl = NVMF_CCR_LIMIT;
diff --git a/drivers/nvme/target/configfs.c b/drivers/nvme/target/configfs.c
index 6286e38436dd..88a59ac1e93a 100644
--- a/drivers/nvme/target/configfs.c
+++ b/drivers/nvme/target/configfs.c
@@ -1663,6 +1663,41 @@ static ssize_t nvmet_subsys_attr_pi_enable_store(struct config_item *item,
 CONFIGFS_ATTR(nvmet_subsys_, attr_pi_enable);
 #endif
 
+static ssize_t nvmet_subsys_attr_cqt_show(struct config_item *item,
+					  char *page)
+{
+	return snprintf(page, PAGE_SIZE, "%u\n", to_subsys(item)->cqt);
+}
+
+static ssize_t nvmet_subsys_attr_cqt_store(struct config_item *item,
+					   const char *page, size_t cnt)
+{
+	struct nvmet_subsys *subsys = to_subsys(item);
+	struct nvmet_ctrl *ctrl;
+	u16 cqt;
+
+	if (nvmet_is_disc_subsys(subsys))
+		return -EINVAL;
+
+	if (sscanf(page, "%hu\n", &cqt) != 1)
+		return -EINVAL;
+
+	down_write(&nvmet_config_sem);
+	mutex_lock(&subsys->lock);
+	if (subsys->cqt == cqt)
+		goto out;
+
+	subsys->cqt = cqt;
+	/* Force reconnect */
+	list_for_each_entry(ctrl, &subsys->ctrls, subsys_entry)
+		ctrl->ops->delete_ctrl(ctrl);
+out:
+	mutex_unlock(&subsys->lock);
+	up_write(&nvmet_config_sem);
+	return cnt;
+}
+CONFIGFS_ATTR(nvmet_subsys_, attr_cqt);
+
 static ssize_t nvmet_subsys_attr_qid_max_show(struct config_item *item,
 					      char *page)
 {
@@ -1703,6 +1738,7 @@ static struct configfs_attribute *nvmet_subsys_attrs[] = {
 	&nvmet_subsys_attr_attr_vendor_id,
 	&nvmet_subsys_attr_attr_subsys_vendor_id,
 	&nvmet_subsys_attr_attr_model,
+	&nvmet_subsys_attr_attr_cqt,
 	&nvmet_subsys_attr_attr_qid_max,
 	&nvmet_subsys_attr_attr_ieee_oui,
 	&nvmet_subsys_attr_attr_firmware,
diff --git a/drivers/nvme/target/core.c b/drivers/nvme/target/core.c
index 69491e8e52ba..a93cf7e3a704 100644
--- a/drivers/nvme/target/core.c
+++ b/drivers/nvme/target/core.c
@@ -1753,6 +1753,7 @@ struct nvmet_ctrl *nvmet_alloc_ctrl(struct nvmet_alloc_ctrl_args *args)
 	ctrl->cntlid = ret;
 
 	if (!nvmet_is_disc_subsys(ctrl->subsys)) {
+		ctrl->cqt = subsys->cqt;
 		ctrl->ciu = get_random_u8() ? : 1;
 		ctrl->cirn = get_random_u64();
 	}
@@ -1980,10 +1981,12 @@ struct nvmet_subsys *nvmet_subsys_alloc(const char *subsysnqn,
 
 	switch (type) {
 	case NVME_NQN_NVME:
+		subsys->cqt = NVMF_CQT_MS;
 		subsys->max_qid = NVMET_NR_QUEUES;
 		break;
 	case NVME_NQN_DISC:
 	case NVME_NQN_CURR:
+		subsys->cqt = 0;
 		subsys->max_qid = 0;
 		break;
 	default:
diff --git a/drivers/nvme/target/nvmet.h b/drivers/nvme/target/nvmet.h
index 88fa11aa0587..ddf88c772938 100644
--- a/drivers/nvme/target/nvmet.h
+++ b/drivers/nvme/target/nvmet.h
@@ -270,6 +270,7 @@ struct nvmet_ctrl {
 	uuid_t			hostid;
 	u16			cntlid;
 	u16			max_qid;
+	u16			cqt;
 	u8			ciu;
 	u32			kato;
 	u64			cirn;
@@ -347,6 +348,7 @@ struct nvmet_subsys {
 #ifdef CONFIG_NVME_TARGET_DEBUGFS
 	struct dentry		*debugfs_dir;
 #endif
+	u16			cqt;
 	u16			max_qid;
 
 	u64			ver;
diff --git a/include/linux/nvme.h b/include/linux/nvme.h
index 3757d11ffea3..0b69ed53f347 100644
--- a/include/linux/nvme.h
+++ b/include/linux/nvme.h
@@ -21,6 +21,7 @@
 #define NVMF_TRADDR_SIZE	256
 #define NVMF_TSAS_SIZE		256
 
+#define NVMF_CQT_MS		0
 #define NVMF_CCR_LIMIT		4
 #define NVMF_CCR_PER_PAGE	511
 
@@ -368,7 +369,9 @@ struct nvme_id_ctrl {
 	__u8			anacap;
 	__le32			anagrpmax;
 	__le32			nanagrpid;
-	__u8			rsvd352[160];
+	__u8			rsvd352[34];
+	__le16			cqt;
+	__u8			rsvd388[124];
 	__u8			sqes;
 	__u8			cqes;
 	__le16			maxcmd;
-- 
2.55.0