IPoIB: Handle 4K IB MTU for UD (datagram) mode

This patch enables IPoIB to use 4K UD messages (when the underlying
device and fabrics support a 4K MTU) by using two scatter buffers when
PAGE_SIZE is less than or equal to thhe HCA IB MTU size.  The first
buffer is for IPoIB header + GRH header, and the second buffer is the
IPoIB payload, which is 4K-4.

Signed-off-by: Shirley Ma <xma@us.ibm.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

1 files changed, 14 insertions, 1 deletions

diff --git a/drivers/infiniband/ulp/ipoib/ipoib_verbs.c b/drivers/infiniband/ulp/ipoib/ipoib_verbs.c
index 8a20e3742c43..07c03f178a49 100644
--- a/drivers/infiniband/ulp/ipoib/ipoib_verbs.c
+++ b/drivers/infiniband/ulp/ipoib/ipoib_verbs.c
@@ -150,7 +150,7 @@ int ipoib_transport_dev_init(struct net_device *dev, struct ib_device *ca)
                         .max_send_wr  = ipoib_sendq_size,
                         .max_recv_wr  = ipoib_recvq_size,
                         .max_send_sge = 1,
-                        .max_recv_sge = 1
+                        .max_recv_sge = IPOIB_UD_RX_SG
                 },
                 .sq_sig_type = IB_SIGNAL_ALL_WR,
                 .qp_type     = IB_QPT_UD
@@ -215,6 +215,19 @@ int ipoib_transport_dev_init(struct net_device *dev, struct ib_device *ca)
         priv->tx_wr.sg_list     = priv->tx_sge;
         priv->tx_wr.send_flags  = IB_SEND_SIGNALED;
 
+        priv->rx_sge[0].lkey = priv->mr->lkey;
+        if (ipoib_ud_need_sg(priv->max_ib_mtu)) {
+                priv->rx_sge[0].length = IPOIB_UD_HEAD_SIZE;
+                priv->rx_sge[1].length = PAGE_SIZE;
+                priv->rx_sge[1].lkey = priv->mr->lkey;
+                priv->rx_wr.num_sge = IPOIB_UD_RX_SG;
+        } else {
+                priv->rx_sge[0].length = IPOIB_UD_BUF_SIZE(priv->max_ib_mtu);
+                priv->rx_wr.num_sge = 1;
+        }
+        priv->rx_wr.next = NULL;
+        priv->rx_wr.sg_list = priv->rx_sge;
+
         return 0;
 
 out_free_cq: