RDMA: Introduce and use GID attr helper to read RoCE L2 fields

Instead of RoCE drivers figuring out vlan, smac fields while working on
QP/AH, provide a helper routine to read the L2 fields such as vlan_id and
source mac address.

This moves logic from mlx5 driver to core for wider usage for RoCE ports.

This is a preparation patch to allow detaching netdev in subsequent patch.

Signed-off-by: Parav Pandit <parav@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

drivers/infiniband/hw/hns/hns_roce_ah.c

@@ -49,20 +49,22 @@ int hns_roce_create_ah(struct ib_ah *ibah, struct rdma_ah_attr *ah_attr,
 	u16 vlan_tag = 0xffff;
 	const struct ib_global_route *grh = rdma_ah_read_grh(ah_attr);
 	bool vlan_en = false;
+	int ret;
+
+	gid_attr = ah_attr->grh.sgid_attr;
+	ret = rdma_read_gid_l2_fields(gid_attr, &vlan_tag, NULL);
+	if (ret)
+		return ret;
 
 	/* Get mac address */
 	memcpy(ah->av.mac, ah_attr->roce.dmac, ETH_ALEN);
 
-	gid_attr = ah_attr->grh.sgid_attr;
-	if (is_vlan_dev(gid_attr->ndev)) {
-		vlan_tag = vlan_dev_vlan_id(gid_attr->ndev);
+	if (vlan_tag < VLAN_CFI_MASK) {
 		vlan_en = true;
-	}
-
-	if (vlan_tag < 0x1000)
 		vlan_tag |= (rdma_ah_get_sl(ah_attr) &
 			     HNS_ROCE_VLAN_SL_BIT_MASK) <<
 			     HNS_ROCE_VLAN_SL_SHIFT;
+	}
 
 	ah->av.port_pd = cpu_to_le32(to_hr_pd(ibah->pd)->pdn |
 				     (rdma_ah_get_port_num(ah_attr) <<

drivers/infiniband/hw/hns/hns_roce_hw_v2.c

@@ -37,6 +37,7 @@
 #include <linux/types.h>
 #include <net/addrconf.h>
 #include <rdma/ib_addr.h>
+#include <rdma/ib_cache.h>
 #include <rdma/ib_umem.h>
 #include <rdma/uverbs_ioctl.h>
 
@@ -3984,10 +3985,12 @@ static int hns_roce_v2_modify_qp(struct ib_qp *ibqp,
 
 		if (is_roce_protocol) {
 			gid_attr = attr->ah_attr.grh.sgid_attr;
-			vlan = rdma_vlan_dev_vlan_id(gid_attr->ndev);
+			ret = rdma_read_gid_l2_fields(gid_attr, &vlan, NULL);
+			if (ret)
+				goto out;
 		}
 
-		if (is_vlan_dev(gid_attr->ndev)) {
+		if (vlan < VLAN_CFI_MASK) {
 			roce_set_bit(context->byte_76_srqn_op_en,
 				     V2_QPC_BYTE_76_RQ_VLAN_EN_S, 1);
 			roce_set_bit(qpc_mask->byte_76_srqn_op_en,