nvme-sysfs: add 'tls_configured_key' sysfs attribute

There is a difference between the negotiated TLS key (which is
always present for a TLS encrypted connection) and the configured
TLS key (which is specified with the --tls_key command line option).
To differentate between these two add a new sysfs attribute
'tls_configured_key' to hold the specified on the command line.
Signed-off-by: Hannes Reinecke <hare@kernel.org>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Keith Busch <kbusch@kernel.org>

drivers/nvme/host/sysfs.c

@@ -743,8 +743,19 @@ static ssize_t tls_key_show(struct device *dev,
 }
 static DEVICE_ATTR_RO(tls_key);
 
+static ssize_t tls_configured_key_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct nvme_ctrl *ctrl = dev_get_drvdata(dev);
+	struct key *key = ctrl->opts->tls_key;
+
+	return sysfs_emit(buf, "%08x\n", key_serial(key));
+}
+static DEVICE_ATTR_RO(tls_configured_key);
+
 static struct attribute *nvme_tls_attrs[] = {
 	&dev_attr_tls_key.attr,
+	&dev_attr_tls_configured_key.attr,
 };
 
 static umode_t nvme_tls_attrs_are_visible(struct kobject *kobj,
@@ -759,6 +770,9 @@ static umode_t nvme_tls_attrs_are_visible(struct kobject *kobj,
 	if (a == &dev_attr_tls_key.attr &&
 	    !ctrl->opts->tls)
 		return 0;
+	if (a == &dev_attr_tls_configured_key.attr &&
+	    !ctrl->opts->tls_key)
+		return 0;
 
 	return a->mode;
 }