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, 16 insertions, 4 deletions

diff --git a/drivers/infiniband/ulp/ipoib/ipoib.h b/drivers/infiniband/ulp/ipoib/ipoib.h
index 73b2b176ad0e..f1f142dc64b1 100644
--- a/drivers/infiniband/ulp/ipoib/ipoib.h
+++ b/drivers/infiniband/ulp/ipoib/ipoib.h
@@ -56,11 +56,11 @@
 /* constants */
 
 enum {
-        IPOIB_PACKET_SIZE         = 2048,
-        IPOIB_BUF_SIZE            = IPOIB_PACKET_SIZE + IB_GRH_BYTES,
-
         IPOIB_ENCAP_LEN           = 4,
 
+        IPOIB_UD_HEAD_SIZE        = IB_GRH_BYTES + IPOIB_ENCAP_LEN,
+        IPOIB_UD_RX_SG            = 2, /* max buffer needed for 4K mtu */
+
         IPOIB_CM_MTU              = 0x10000 - 0x10, /* padding to align header to 16 */
         IPOIB_CM_BUF_SIZE         = IPOIB_CM_MTU  + IPOIB_ENCAP_LEN,
         IPOIB_CM_HEAD_SIZE        = IPOIB_CM_BUF_SIZE % PAGE_SIZE,
@@ -139,7 +139,7 @@ struct ipoib_mcast {
 
 struct ipoib_rx_buf {
         struct sk_buff *skb;
-        u64             mapping;
+        u64             mapping[IPOIB_UD_RX_SG];
 };
 
 struct ipoib_tx_buf {
@@ -294,6 +294,7 @@ struct ipoib_dev_priv {
 
         unsigned int admin_mtu;
         unsigned int mcast_mtu;
+        unsigned int max_ib_mtu;
 
         struct ipoib_rx_buf *rx_ring;
 
@@ -305,6 +306,9 @@ struct ipoib_dev_priv {
         struct ib_send_wr    tx_wr;
         unsigned             tx_outstanding;
 
+        struct ib_recv_wr    rx_wr;
+        struct ib_sge        rx_sge[IPOIB_UD_RX_SG];
+
         struct ib_wc ibwc[IPOIB_NUM_WC];
 
         struct list_head dead_ahs;
@@ -366,6 +370,14 @@ struct ipoib_neigh {
         struct list_head    list;
 };
 
+#define IPOIB_UD_MTU(ib_mtu)            (ib_mtu - IPOIB_ENCAP_LEN)
+#define IPOIB_UD_BUF_SIZE(ib_mtu)       (ib_mtu + IB_GRH_BYTES)
+
+static inline int ipoib_ud_need_sg(unsigned int ib_mtu)
+{
+        return IPOIB_UD_BUF_SIZE(ib_mtu) > PAGE_SIZE;
+}
+
 /*
  * We stash a pointer to our private neighbour information after our
  * hardware address in neigh->ha.  The ALIGN() expression here makes