s390/qeth: use diag26c to get MAC address on L2

When a s390 guest runs on a z/VM host that's part of a SSI cluster,
it can be migrated to a different host. In this case, the MAC address
it originally obtained on the old host may be re-assigned to a new
guest. This would result in address conflicts between the two guests.

When running as z/VM guest, use the diag26c MAC Service to obtain
a hypervisor-managed MAC address. The MAC Service is SSI-aware, and
won't re-assign the address after the guest is migrated to a new host.

This patch adds support for the z/VM MAC Service on L2 devices.

Signed-off-by: Julian Wiedmann <jwi@linux.vnet.ibm.com>
Acked-by: Ursula Braun <ubraun@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 61 insertions, 0 deletions

diff --git a/drivers/s390/net/qeth_core_main.c b/drivers/s390/net/qeth_core_main.c
index 13a55f1dee7a..3b657d5b7e49 100644
--- a/drivers/s390/net/qeth_core_main.c
+++ b/drivers/s390/net/qeth_core_main.c
@@ -27,6 +27,9 @@
 #include <asm/io.h>
 #include <asm/sysinfo.h>
 #include <asm/compat.h>
+#include <asm/diag.h>
+#include <asm/cio.h>
+#include <asm/ccwdev.h>
 
 #include "qeth_core.h"
 
@@ -4773,6 +4776,64 @@ static int qeth_query_card_info(struct qeth_card *card,
 					(void *)carrier_info);
 }
 
+/**
+ * qeth_vm_request_mac() - Request a hypervisor-managed MAC address
+ * @card: pointer to a qeth_card
+ *
+ * Returns
+ *	0, if a MAC address has been set for the card's netdevice
+ *	a return code, for various error conditions
+ */
+int qeth_vm_request_mac(struct qeth_card *card)
+{
+	struct diag26c_mac_resp *response;
+	struct diag26c_mac_req *request;
+	struct ccw_dev_id id;
+	int rc;
+
+	QETH_DBF_TEXT(SETUP, 2, "vmreqmac");
+
+	if (!card->dev)
+		return -ENODEV;
+
+	request = kzalloc(sizeof(*request), GFP_KERNEL | GFP_DMA);
+	response = kzalloc(sizeof(*response), GFP_KERNEL | GFP_DMA);
+	if (!request || !response) {
+		rc = -ENOMEM;
+		goto out;
+	}
+
+	ccw_device_get_id(CARD_DDEV(card), &id);
+	request->resp_buf_len = sizeof(*response);
+	request->resp_version = DIAG26C_VERSION2;
+	request->op_code = DIAG26C_GET_MAC;
+	request->devno = id.devno;
+
+	rc = diag26c(request, response, DIAG26C_MAC_SERVICES);
+	if (rc)
+		goto out;
+
+	if (request->resp_buf_len < sizeof(*response) ||
+	    response->version != request->resp_version) {
+		rc = -EIO;
+		QETH_DBF_TEXT(SETUP, 2, "badresp");
+		QETH_DBF_HEX(SETUP, 2, &request->resp_buf_len,
+			     sizeof(request->resp_buf_len));
+	} else if (!is_valid_ether_addr(response->mac)) {
+		rc = -EINVAL;
+		QETH_DBF_TEXT(SETUP, 2, "badmac");
+		QETH_DBF_HEX(SETUP, 2, response->mac, ETH_ALEN);
+	} else {
+		ether_addr_copy(card->dev->dev_addr, response->mac);
+	}
+
+out:
+	kfree(response);
+	kfree(request);
+	return rc;
+}
+EXPORT_SYMBOL_GPL(qeth_vm_request_mac);
+
 static inline int qeth_get_qdio_q_format(struct qeth_card *card)
 {
 	if (card->info.type == QETH_CARD_TYPE_IQD)