[ewg] [RFC][1/2] IPoIB UD 4K MTU support

[Shirley Ma]

This patch defines some parameters and creates a couple of APIs and  for UD RX S/G to be used later.

Signed-off-by: Shirley Ma <xma at us.ibm.com>
---

 drivers/infiniband/ulp/ipoib/ipoib.h |   48 ++++++++++++++++++++++++++++++++++
 1 files changed, 48 insertions(+), 0 deletions(-)

diff --git a/drivers/infiniband/ulp/ipoib/ipoib.h b/drivers/infiniband/ulp/ipoib/ipoib.h
index f9b7caa..73a8fe5 100644
--- a/drivers/infiniband/ulp/ipoib/ipoib.h
+++ b/drivers/infiniband/ulp/ipoib/ipoib.h
@@ -61,6 +61,10 @@ enum {
 
 	IPOIB_ENCAP_LEN		  = 4,
 
+	IPOIB_UD_MAX_PAYLOAD	  = 4096,
+	IPOIB_UD_HEAD_SIZE	  = IB_GRH_BYTES + IPOIB_ENCAP_LEN,
+	IPOIB_UD_RX_SG		  = (IPOIB_UD_MAX_PAYLOAD + IB_GRH_BYTES) / PAGE_SIZE,
+
 	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,
@@ -141,6 +145,11 @@ struct ipoib_rx_buf {
 	u64		mapping;
 };
 
+struct ipoib_ud_rx_buf {
+	struct sk_buff *skb;
+	u64		mapping[IPOIB_UD_RX_SG];
+};
+
 struct ipoib_tx_buf {
 	struct sk_buff *skb;
 	u64		mapping[MAX_SKB_FRAGS + 1];
@@ -289,6 +298,7 @@ struct ipoib_dev_priv {
 
 	unsigned int admin_mtu;
 	unsigned int mcast_mtu;
+	unsigned int max_ib_mtu;
 
 	struct ipoib_rx_buf *rx_ring;
 
@@ -359,6 +369,44 @@ 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) ? 1 : 0;
+}
+
+static inline void ipoib_ud_dma_unmap_rx(struct ipoib_dev_priv *priv,
+					 u64 mapping[IPOIB_UD_RX_SG])
+{
+	if (ipoib_ud_need_sg(priv->max_ib_mtu)) {
+		ib_dma_unmap_single(priv->ca, mapping[0], IPOIB_UD_HEAD_SIZE, DMA_FROM_DEVICE);
+		ib_dma_unmap_page(priv->ca, mapping[1], PAGE_SIZE, DMA_FROM_DEVICE);
+	} else
+		ib_dma_unmap_single(priv->ca, mapping[0], IPOIB_UD_BUF_SIZE(priv->max_ib_mtu), DMA_FROM_DEVICE);
+}
+
+static inline void ipoib_ud_skb_put_frags(struct ipoib_dev_priv *priv,
+					  struct sk_buff *skb,
+					  unsigned int length)
+{
+	if (ipoib_ud_need_sg(priv->max_ib_mtu)) {
+		skb_frag_t *frag = &skb_shinfo(skb)->frags[0];
+		/*
+		 * There is only two buffers needed for max_payload = 4K,
+		 * first buf size is IPOIB_UD_HEAD_SIZE
+		 */
+		skb->tail += IPOIB_UD_HEAD_SIZE;
+		frag->size = length - IPOIB_UD_HEAD_SIZE;
+		skb->data_len += frag->size;
+		skb->truesize += frag->size;
+		skb->len += length;
+	} else
+		skb_put(skb, length);
+
+}
+
 /*
  * We stash a pointer to our private neighbour information after our
  * hardware address in neigh->ha.  The ALIGN() expression here makes