[PATCH net] s390/qeth: allow bridgeport queries despite OS_MISMATCH

[Nagamani PV <nagamani@linux.ibm.com>]

When HiperSockets interfaces on the same VCHID span different OS
families, reads of the sysfs attributes bridge_role and bridge_state
fail with -EPERM if bridge port ownership belongs to another OS family.

As a result, userspace tools such as 'lszdev -ii' cannot retrieve
bridge_role and bridge_state, even though firmware returns valid bridge
port data for QUERY_BRIDGE_PORTS requests.

The firmware reports IPA_RC_SBP_IQD_OS_MISMATCH (0x0010) to indicate
that bridge port ownership belongs to a different OS family. For
QUERY_BRIDGE_PORTS operations, firmware still returns valid bridge port
data (role=none, state=inactive) together with a primary return code of
0x0000 (success).

Allow QUERY_BRIDGE_PORTS requests to return the bridge port data
provided by the firmware despite OS_MISMATCH. To make the OS family
mismatch visible to userspace, represent the firmware-reported role
"none" as "none (OS family mismatch)" while preserving the reported
bridge_state.

The behavior for non-QUERY bridge port commands is unchanged; SET
operations continue to return -EPERM when another OS family owns the
bridge port.

This restores readability of bridge_role and bridge_state.

Fixes: 1b05cf6285c1 ("qeth: Include error message for "OS Mismatch"")
Cc: stable@vger.kernel.org
Suggested-by: Halil Pasic <pasic@linux.ibm.com>
Reviewed-by: Alexandra Winter <wintera@linux.ibm.com>
Signed-off-by: Nagamani PV <nagamani@linux.ibm.com>
---
 drivers/s390/net/qeth_l2.h      |  3 ++-
 drivers/s390/net/qeth_l2_main.c | 26 ++++++++++++++++++++++----
 drivers/s390/net/qeth_l2_sys.c  |  7 ++++++-
 3 files changed, 30 insertions(+), 6 deletions(-)

diff --git a/drivers/s390/net/qeth_l2.h b/drivers/s390/net/qeth_l2.h
index 7c646e2fed7e..f94975e970ca 100644
--- a/drivers/s390/net/qeth_l2.h
+++ b/drivers/s390/net/qeth_l2.h
@@ -13,7 +13,8 @@ extern const struct attribute_group *qeth_l2_attr_groups[];
 
 int qeth_bridgeport_query_ports(struct qeth_card *card,
 				enum qeth_sbp_roles *role,
-				enum qeth_sbp_states *state);
+				enum qeth_sbp_states *state,
+				bool *os_mismatch);
 int qeth_bridgeport_setrole(struct qeth_card *card, enum qeth_sbp_roles role);
 int qeth_bridgeport_an_set(struct qeth_card *card, int enable);
 
diff --git a/drivers/s390/net/qeth_l2_main.c b/drivers/s390/net/qeth_l2_main.c
index a9e7d1d637a2..2935c2ecc314 100644
--- a/drivers/s390/net/qeth_l2_main.c
+++ b/drivers/s390/net/qeth_l2_main.c
@@ -1158,7 +1158,7 @@ static void qeth_l2_setup_bridgeport_attrs(struct qeth_card *card)
 		qeth_bridgeport_setrole(card, card->options.sbp.role);
 		/* Let the callback function refresh the stored role value. */
 		qeth_bridgeport_query_ports(card, &card->options.sbp.role,
-					    NULL);
+					    NULL, NULL);
 	}
 	if (card->options.sbp.hostnotification) {
 		if (qeth_bridgeport_an_set(card, 1))
@@ -1545,6 +1545,7 @@ struct _qeth_sbp_cbctl {
 		struct {
 			enum qeth_sbp_roles *role;
 			enum qeth_sbp_states *state;
+			bool *os_mismatch;
 		} qports;
 	} data;
 };
@@ -1721,10 +1722,19 @@ static int qeth_bridgeport_query_ports_cb(struct qeth_card *card,
 	struct qeth_ipa_cmd *cmd = (struct qeth_ipa_cmd *) data;
 	struct _qeth_sbp_cbctl *cbctl = (struct _qeth_sbp_cbctl *)reply->param;
 	struct qeth_sbp_port_data *qports;
+	u16 sbp_rc;
 	int rc;
 
 	QETH_CARD_TEXT(card, 2, "brqprtcb");
-	rc = qeth_bridgeport_makerc(card, cmd);
+	sbp_rc = cmd->data.sbp.hdr.return_code;
+
+	/* on OS family mismatch, query still returns valid port data;
+	 * treat as success
+	 */
+	if (sbp_rc == IPA_RC_SBP_IQD_OS_MISMATCH && !cmd->hdr.return_code)
+		rc = 0;
+	else
+		rc = qeth_bridgeport_makerc(card, cmd);
 	if (rc)
 		return rc;
 
@@ -1740,6 +1750,9 @@ static int qeth_bridgeport_query_ports_cb(struct qeth_card *card,
 		if (cbctl->data.qports.state)
 			*cbctl->data.qports.state = qports->entry[0].state;
 	}
+	if (cbctl->data.qports.os_mismatch)
+		*cbctl->data.qports.os_mismatch =
+			(sbp_rc == IPA_RC_SBP_IQD_OS_MISMATCH);
 	return 0;
 }
 
@@ -1748,13 +1761,17 @@ static int qeth_bridgeport_query_ports_cb(struct qeth_card *card,
  * @card:			   qeth_card structure pointer.
  * @role:   Role of the port: 0-none, 1-primary, 2-secondary.
  * @state:  State of the port: 0-inactive, 1-standby, 2-active.
+ * @os_mismatch: if non-NULL, set to true when firmware reports
+ *		 OS family mismatch.
  *
  * Returns negative errno-compatible error indication or 0 on success.
  *
- * 'role' and 'state' are not updated in case of hardware operation failure.
+ * 'role', 'state' and 'os_mismatch' are not updated in case of
+ * hardware operation failure.
  */
 int qeth_bridgeport_query_ports(struct qeth_card *card,
-	enum qeth_sbp_roles *role, enum qeth_sbp_states *state)
+	enum qeth_sbp_roles *role, enum qeth_sbp_states *state,
+	bool *os_mismatch)
 {
 	struct qeth_cmd_buffer *iob;
 	struct _qeth_sbp_cbctl cbctl = {
@@ -1762,6 +1779,7 @@ int qeth_bridgeport_query_ports(struct qeth_card *card,
 			.qports = {
 				.role = role,
 				.state = state,
+				.os_mismatch = os_mismatch,
 			},
 		},
 	};
diff --git a/drivers/s390/net/qeth_l2_sys.c b/drivers/s390/net/qeth_l2_sys.c
index 7f592f912517..7101be62eb1d 100644
--- a/drivers/s390/net/qeth_l2_sys.c
+++ b/drivers/s390/net/qeth_l2_sys.c
@@ -15,6 +15,7 @@ static ssize_t qeth_bridge_port_role_state_show(struct device *dev,
 {
 	struct qeth_card *card = dev_get_drvdata(dev);
 	enum qeth_sbp_states state = QETH_SBP_STATE_INACTIVE;
+	bool os_mismatch = false;
 	int rc = 0;
 	char *word;
 
@@ -25,7 +26,7 @@ static ssize_t qeth_bridge_port_role_state_show(struct device *dev,
 	if (qeth_card_hw_is_reachable(card) &&
 					card->options.sbp.supported_funcs)
 		rc = qeth_bridgeport_query_ports(card,
-			&card->options.sbp.role, &state);
+			&card->options.sbp.role, &state, &os_mismatch);
 	if (!rc) {
 		if (show_state)
 			switch (state) {
@@ -52,6 +53,10 @@ static ssize_t qeth_bridge_port_role_state_show(struct device *dev,
 		if (rc)
 			QETH_CARD_TEXT_(card, 2, "SBP%02x:%02x",
 				card->options.sbp.role, state);
+		else if (!show_state &&
+			 card->options.sbp.role == QETH_SBP_ROLE_NONE &&
+			 os_mismatch)
+			rc = sysfs_emit(buf, "%s (OS family mismatch)\n", word);
 		else
 			rc = sysfs_emit(buf, "%s\n", word);
 	}
-- 
2.53.0