4.17-stable review patch. If anyone has any objections, please let me know.
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From: Julian Wiedmann jwi@linux.ibm.com
[ Upstream commit 4664610537d398d55be19432f9cd9c29c831e159 ]
This reverts commit b7493e91c11a757cf0f8ab26989642ee4bb2c642.
On its own, querying RDEV for a MAC address works fine. But when upgrading from a qeth that previously queried DDEV on a z/VM NIC (ie. any kernel with commit ec61bd2fd2a2), the RDEV query now returns a _different_ MAC address than the DDEV query.
If the NIC is configured with MACPROTECT, z/VM apparently requires us to use the MAC that was initially returned (on DDEV) and registered. So after upgrading to a kernel that uses RDEV, the SETVMAC registration cmd for the new MAC address fails and we end up with a non-operabel interface.
To avoid regressions on upgrade, switch back to using DDEV for the MAC address query. The downgrade path (first RDEV, later DDEV) is fine, in this case both queries return the same MAC address.
Fixes: b7493e91c11a ("s390/qeth: use Read device to query hypervisor for MAC") Reported-by: Michal Kubecek mkubecek@suse.com Tested-by: Karsten Graul kgraul@linux.ibm.com Signed-off-by: Julian Wiedmann jwi@linux.ibm.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/s390/net/qeth_core_main.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/s390/net/qeth_core_main.c +++ b/drivers/s390/net/qeth_core_main.c @@ -4845,7 +4845,7 @@ int qeth_vm_request_mac(struct qeth_card goto out; }
- ccw_device_get_id(CARD_RDEV(card), &id); + 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;