[ipoib] Kill off the IPoIB pseudo-header

Some Infiniband cards will not be as accommodating as the Arbel and
Hermon cards in providing enough space for us to push a fake extra
header at the start of the received packet.  We must therefore make do
with squeezing enough information to identify source and destination
addresses into the two bytes of padding within a genuine IPoIB
link-layer header.

src/drivers/net/ipoib.c

@@ -85,49 +85,146 @@ struct ipoib_device {
 	int broadcast_attached;
 };
 
+/** TID half used to identify get path record replies */
+#define IPOIB_TID_GET_PATH_REC 0x11111111UL
+
+/** TID half used to identify multicast member record replies */
+#define IPOIB_TID_MC_MEMBER_REC 0x22222222UL
+
+/** IPoIB metadata TID */
+static uint32_t ipoib_meta_tid = 0;
+
+/** Broadcast QPN used in IPoIB MAC addresses
+ *
+ * This is a guaranteed invalid real QPN
+ */
+#define IPOIB_BROADCAST_QPN 0xffffffffUL
+
+/** Broadcast IPoIB address */
+static struct ipoib_mac ipoib_broadcast = {
+	.qpn = ntohl ( IPOIB_BROADCAST_QPN ),
+	.gid.u.bytes = 	{ 0xff, 0x12, 0x40, 0x1b, 0x00, 0x00, 0x00, 0x00,
+			  0x00, 0x00, 0x00, 0x00, 0xff, 0xff, 0xff, 0xff },
+};
+
+/****************************************************************************
+ *
+ * IPoIB peer cache
+ *
+ ****************************************************************************
+ */
+
 /**
- * IPoIB path cache entry
+ * IPoIB peer address
  *
  * This serves a similar role to the ARP cache for Ethernet.  (ARP
  * *is* used on IPoIB; we have two caches to maintain.)
  */
-struct ipoib_cached_path {
-	/** Destination GID */
-	struct ib_gid gid;
-	/** Destination LID */
-	unsigned int dlid;
+struct ipoib_peer {
+	/** Key */
+	uint8_t key;
+	/** MAC address */
+	struct ipoib_mac mac;
+	/** LID */
+	unsigned int lid;
 	/** Service level */
 	unsigned int sl;
 	/** Rate */
 	unsigned int rate;
 };
 
-/** Number of IPoIB path cache entries */
-#define IPOIB_NUM_CACHED_PATHS 2
+/** Number of IPoIB peer cache entries
+ *
+ * Must be a power of two.
+ */
+#define IPOIB_NUM_CACHED_PEERS 4
 
-/** IPoIB path cache */
-static struct ipoib_cached_path ipoib_path_cache[IPOIB_NUM_CACHED_PATHS];
+/** IPoIB peer address cache */
+static struct ipoib_peer ipoib_peer_cache[IPOIB_NUM_CACHED_PEERS];
 
-/** Oldest IPoIB path cache entry index */
-static unsigned int ipoib_path_cache_idx = 0;
+/** Oldest IPoIB peer cache entry index */
+static unsigned int ipoib_peer_cache_idx = 1;
 
-/** TID half used to identify get path record replies */
-#define IPOIB_TID_GET_PATH_REC 0x11111111UL
+/**
+ * Look up cached peer by key
+ *
+ * @v key		Peer cache key
+ * @ret peer		Peer cache entry, or NULL
+ */
+static struct ipoib_peer * ipoib_lookup_peer_by_key ( unsigned int key ) {
+	struct ipoib_peer *peer;
+	unsigned int i;
 
-/** TID half used to identify multicast member record replies */
-#define IPOIB_TID_MC_MEMBER_REC 0x22222222UL
+	for ( i = 0 ; i < IPOIB_NUM_CACHED_PEERS ; i++ ) {
+		peer = &ipoib_peer_cache[i];
+		if ( peer->key == key )
+			return peer;
+	}
 
-/** IPoIB metadata TID */
-static uint32_t ipoib_meta_tid = 0;
+	if ( key != 0 ) {
+		DBG ( "IPoIB warning: peer cache lost track of key %x while "
+		      "still in use\n", key );
+	}
+	return NULL;
+}
 
-/** IPv4 broadcast GID */
-static const struct ib_gid ipv4_broadcast_gid = {
-	{ { 0xff, 0x12, 0x40, 0x1b, 0x00, 0x00, 0x00, 0x00,
-	    0x00, 0x00, 0x00, 0x00, 0xff, 0xff, 0xff, 0xff } }
-};
+/**
+ * Look up cached peer by GID
+ *
+ * @v gid		Peer GID
+ * @ret peer		Peer cache entry, or NULL
+ */
+static struct ipoib_peer *
+ipoib_lookup_peer_by_gid ( const struct ib_gid *gid ) {
+	struct ipoib_peer *peer;
+	unsigned int i;
 
-/** Maximum time we will wait for the broadcast join to succeed */
-#define IPOIB_JOIN_MAX_DELAY_MS 1000
+	for ( i = 0 ; i < IPOIB_NUM_CACHED_PEERS ; i++ ) {
+		peer = &ipoib_peer_cache[i];
+		if ( memcmp ( &peer->mac.gid, gid,
+			      sizeof ( peer->mac.gid) ) == 0 ) {
+			return peer;
+		}
+	}
+
+	return NULL;
+}
+
+/**
+ * Store GID and QPN in peer cache
+ *
+ * @v gid		Peer GID
+ * @v qpn		Peer QPN
+ * @ret peer		Peer cache entry
+ */
+static struct ipoib_peer *
+ipoib_cache_peer ( const struct ib_gid *gid, unsigned long qpn ) {
+	struct ipoib_peer *peer;
+	unsigned int key;
+
+	/* Look for existing cache entry */
+	peer = ipoib_lookup_peer_by_gid ( gid );
+	if ( peer ) {
+		assert ( peer->mac.qpn = ntohl ( qpn ) );
+		return peer;
+	}
+
+	/* No entry found: create a new one */
+	key = ipoib_peer_cache_idx++;
+	peer = &ipoib_peer_cache[ key % IPOIB_NUM_CACHED_PEERS ];
+	if ( peer->key )
+		DBG ( "IPoIB peer %x evicted from cache\n", peer->key );
+
+	memset ( peer, 0, sizeof ( *peer ) );
+	peer->key = key;
+	peer->mac.qpn = htonl ( qpn );
+	memcpy ( &peer->mac.gid, gid, sizeof ( peer->mac.gid ) );
+	DBG ( "IPoIB peer %x has GID %08lx:%08lx:%08lx:%08lx and QPN %lx\n",
+	      peer->key, htonl ( gid->u.dwords[0] ),
+	      htonl ( gid->u.dwords[1] ), htonl ( gid->u.dwords[2] ),
+	      htonl ( gid->u.dwords[3] ), qpn );
+	return peer;
+}
 
 /****************************************************************************
  *
@@ -136,17 +233,6 @@ static const struct ib_gid ipv4_broadcast_gid = {
  ****************************************************************************
  */
 
-/** Broadcast QPN used in IPoIB MAC addresses
- *
- * This is a guaranteed invalid real QPN
- */
-#define IPOIB_BROADCAST_QPN 0xffffffffUL
-
-/** Broadcast IPoIB address */
-static struct ipoib_mac ipoib_broadcast = {
-	.qpn = ntohl ( IPOIB_BROADCAST_QPN ),
-};
-
 /**
  * Add IPoIB link-layer header
  *
@@ -160,12 +246,19 @@ static int ipoib_push ( struct io_buffer *iobuf, const void *ll_dest,
 			const void *ll_source __unused, uint16_t net_proto ) {
 	struct ipoib_hdr *ipoib_hdr =
 		iob_push ( iobuf, sizeof ( *ipoib_hdr ) );
+	const struct ipoib_mac *dest_mac = ll_dest;
+	const struct ipoib_mac *src_mac = ll_source;
+	struct ipoib_peer *dest;
+	struct ipoib_peer *src;
+
+	/* Add link-layer addresses to cache */
+	dest = ipoib_cache_peer ( &dest_mac->gid, ntohl ( dest_mac->qpn ) );
+	src = ipoib_cache_peer ( &src_mac->gid, ntohl ( src_mac->qpn ) );
 
 	/* Build IPoIB header */
-	memcpy ( &ipoib_hdr->pseudo.peer, ll_dest,
-		 sizeof ( ipoib_hdr->pseudo.peer ) );
-	ipoib_hdr->real.proto = net_proto;
-	ipoib_hdr->real.reserved = 0;
+	ipoib_hdr->proto = net_proto;
+	ipoib_hdr->u.peer.dest = dest->key;
+	ipoib_hdr->u.peer.src = src->key;
 
 	return 0;
 }
@@ -182,6 +275,8 @@ static int ipoib_push ( struct io_buffer *iobuf, const void *ll_dest,
 static int ipoib_pull ( struct io_buffer *iobuf, const void **ll_dest,
 			const void **ll_source, uint16_t *net_proto ) {
 	struct ipoib_hdr *ipoib_hdr = iobuf->data;
+	struct ipoib_peer *dest;
+	struct ipoib_peer *source;
 
 	/* Sanity check */
 	if ( iob_len ( iobuf ) < sizeof ( *ipoib_hdr ) ) {
@@ -193,10 +288,17 @@ static int ipoib_pull ( struct io_buffer *iobuf, const void **ll_dest,
 	/* Strip off IPoIB header */
 	iob_pull ( iobuf, sizeof ( *ipoib_hdr ) );
 
+	/* Identify source and destination addresses, and clear
+	 * reserved word in IPoIB header
+	 */
+	dest = ipoib_lookup_peer_by_key ( ipoib_hdr->u.peer.dest );
+	source = ipoib_lookup_peer_by_key ( ipoib_hdr->u.peer.src );
+	ipoib_hdr->u.reserved = 0;
+
 	/* Fill in required fields */
-	*ll_dest = &ipoib_broadcast; /* Doesn't really exist in packet */
-	*ll_source = &ipoib_hdr->pseudo.peer;
-	*net_proto = ipoib_hdr->real.proto;
+	*ll_dest = ( dest ? &dest->mac : &ipoib_broadcast );
+	*ll_source = ( source ? &source->mac : &ipoib_broadcast );
+	*net_proto = ipoib_hdr->proto;
 
 	return 0;
 }
@@ -327,28 +429,6 @@ static int ipoib_create_qset ( struct ipoib_device *ipoib,
 	return rc;
 }
 
-/**
- * Find path cache entry by GID
- *
- * @v gid		GID
- * @ret entry		Path cache entry, or NULL
- */
-static struct ipoib_cached_path *
-ipoib_find_cached_path ( struct ib_gid *gid ) {
-	struct ipoib_cached_path *path;
-	unsigned int i;
-
-	for ( i = 0 ; i < IPOIB_NUM_CACHED_PATHS ; i++ ) {
-		path = &ipoib_path_cache[i];
-		if ( memcmp ( &path->gid, gid, sizeof ( *gid ) ) == 0 )
-			return path;
-	}
-	DBG ( "IPoIB %08lx:%08lx:%08lx:%08lx cache miss\n",
-	      htonl ( gid->u.dwords[0] ), htonl ( gid->u.dwords[1] ),
-	      htonl ( gid->u.dwords[2] ), htonl ( gid->u.dwords[3] ) );
-	return NULL;
-}
-
 /**
  * Transmit path record request
  *
@@ -477,18 +557,17 @@ static int ipoib_transmit ( struct net_device *netdev,
 			    struct io_buffer *iobuf ) {
 	struct ipoib_device *ipoib = netdev->priv;
 	struct ib_device *ibdev = ipoib->ibdev;
-	struct ipoib_pseudo_hdr *ipoib_pshdr = iobuf->data;
+	struct ipoib_hdr *ipoib_hdr;
+	struct ipoib_peer *dest;
 	struct ib_address_vector av;
 	struct ib_gid *gid;
-	struct ipoib_cached_path *path;
-	int rc;
 
 	/* Sanity check */
-	if ( iob_len ( iobuf ) < sizeof ( *ipoib_pshdr ) ) {
+	if ( iob_len ( iobuf ) < sizeof ( *ipoib_hdr ) ) {
 		DBGC ( ipoib, "IPoIB %p buffer too short\n", ipoib );
 		return -EINVAL;
 	}
-	iob_pull ( iobuf, ( sizeof ( *ipoib_pshdr ) ) );
+	ipoib_hdr = iobuf->data;
 
 	/* Attempting transmission while link is down will put the
 	 * queue pair into an error state, so don't try it.
@@ -496,30 +575,33 @@ static int ipoib_transmit ( struct net_device *netdev,
 	if ( ! ib_link_ok ( ibdev ) )
 		return -ENETUNREACH;
 
+	/* Identify destination address */
+	dest = ipoib_lookup_peer_by_key ( ipoib_hdr->u.peer.dest );
+	if ( ! dest )
+		return -ENXIO;
+	ipoib_hdr->u.reserved = 0;
+
 	/* Construct address vector */
 	memset ( &av, 0, sizeof ( av ) );
-	av.qkey = IB_GLOBAL_QKEY;
+	av.qkey = ipoib->data_qkey;
 	av.gid_present = 1;
-	if ( ipoib_pshdr->peer.qpn == htonl ( IPOIB_BROADCAST_QPN ) ) {
-		/* Broadcast address */
+	if ( dest->mac.qpn == htonl ( IPOIB_BROADCAST_QPN ) ) {
+		/* Broadcast */
 		av.qpn = IB_BROADCAST_QPN;
 		av.lid = ipoib->broadcast_lid;
 		gid = &ipoib->broadcast_gid;
 	} else {
-		/* Unicast - look in path cache */
-		path = ipoib_find_cached_path ( &ipoib_pshdr->peer.gid );
-		if ( ! path ) {
-			/* No path entry - get path record */
-			rc = ipoib_get_path_record ( ipoib,
-						     &ipoib_pshdr->peer.gid );
-			netdev_tx_complete ( netdev, iobuf );
-			return rc;
+		/* Unicast */
+		if ( ! dest->lid ) {
+			/* No LID yet - get path record to fetch LID */
+			ipoib_get_path_record ( ipoib, &dest->mac.gid );
+			return -ENOENT;
 		}
-		av.qpn = ntohl ( ipoib_pshdr->peer.qpn );
-		av.lid = path->dlid;
-		av.rate = path->rate;
-		av.sl = path->sl;
-		gid = &ipoib_pshdr->peer.gid;
+		av.qpn = ntohl ( dest->mac.qpn );
+		av.lid = dest->lid;
+		av.rate = dest->rate;
+		av.sl = dest->sl;
+		gid = &dest->mac.gid;
 	}
 	memcpy ( &av.gid, gid, sizeof ( av.gid ) );
 
@@ -553,28 +635,35 @@ static void ipoib_data_complete_send ( struct ib_device *ibdev __unused,
  */
 static void ipoib_data_complete_recv ( struct ib_device *ibdev __unused,
 				       struct ib_queue_pair *qp,
-				       struct ib_address_vector *av __unused,
+				       struct ib_address_vector *av,
 				       struct io_buffer *iobuf, int rc ) {
 	struct net_device *netdev = ib_qp_get_ownerdata ( qp );
 	struct ipoib_device *ipoib = netdev->priv;
-	struct ipoib_pseudo_hdr *ipoib_pshdr;
+	struct ipoib_hdr *ipoib_hdr;
+	struct ipoib_peer *src;
 
 	if ( rc != 0 ) {
 		netdev_rx_err ( netdev, iobuf, rc );
 		return;
 	}
 
-	if ( iob_len ( iobuf ) < sizeof ( struct ipoib_real_hdr ) ) {
+	/* Sanity check */
+	if ( iob_len ( iobuf ) < sizeof ( struct ipoib_hdr ) ) {
 		DBGC ( ipoib, "IPoIB %p received data packet too short to "
 		       "contain IPoIB header\n", ipoib );
 		DBGC_HD ( ipoib, iobuf->data, iob_len ( iobuf ) );
 		netdev_rx_err ( netdev, iobuf, -EIO );
 		return;
 	}
+	ipoib_hdr = iobuf->data;
 
-	ipoib_pshdr = iob_push ( iobuf, sizeof ( *ipoib_pshdr ) );
-	/* FIXME: fill in a MAC address for the sake of AoE! */
+	/* Parse source address */
+	if ( av->gid_present ) {
+		src = ipoib_cache_peer ( &av->gid, av->qpn );
+		ipoib_hdr->u.peer.src = src->key;
+	}
 
+	/* Hand off to network layer */
 	netdev_rx ( netdev, iobuf );
 }
 
@@ -611,26 +700,25 @@ static void ipoib_meta_complete_send ( struct ib_device *ibdev __unused,
  * @v ipoib		IPoIB device
  * @v path_record	Path record
  */
-static void ipoib_recv_path_record ( struct ipoib_device *ipoib __unused,
+static void ipoib_recv_path_record ( struct ipoib_device *ipoib,
 				     struct ib_mad_path_record *path_record ) {
-	struct ipoib_cached_path *path;
+	struct ipoib_peer *peer;
+
+	/* Locate peer cache entry */
+	peer = ipoib_lookup_peer_by_gid ( &path_record->dgid );
+	if ( ! peer ) {
+		DBGC ( ipoib, "IPoIB %p received unsolicited path record\n",
+		       ipoib );
+		return;
+	}
 
 	/* Update path cache entry */
-	path = &ipoib_path_cache[ipoib_path_cache_idx];
-	memcpy ( &path->gid, &path_record->dgid, sizeof ( path->gid ) );
-	path->dlid = ntohs ( path_record->dlid );
-	path->sl = ( path_record->reserved__sl & 0x0f );
-	path->rate = ( path_record->rate_selector__rate & 0x3f );
-
-	DBG ( "IPoIB %08lx:%08lx:%08lx:%08lx dlid %x sl %x rate %x\n",
-	      htonl ( path->gid.u.dwords[0] ), htonl ( path->gid.u.dwords[1] ),
-	      htonl ( path->gid.u.dwords[2] ), htonl ( path->gid.u.dwords[3] ),
-	      path->dlid, path->sl, path->rate );
-	
-	/* Update path cache index */
-	ipoib_path_cache_idx++;
-	if ( ipoib_path_cache_idx == IPOIB_NUM_CACHED_PATHS )
-		ipoib_path_cache_idx = 0;
+	peer->lid = ntohs ( path_record->dlid );
+	peer->sl = ( path_record->reserved__sl & 0x0f );
+	peer->rate = ( path_record->rate_selector__rate & 0x3f );
+
+	DBG ( "IPoIB peer %x has dlid %x sl %x rate %x\n",
+	      peer->key, peer->lid, peer->sl, peer->rate );
 }
 
 /**
@@ -933,7 +1021,7 @@ static void ipoib_set_ib_params ( struct ipoib_device *ipoib ) {
 	memcpy ( &mac->gid, &ibdev->gid, sizeof ( mac->gid ) );
 
 	/* Calculate broadcast GID based on partition key */
-	memcpy ( &ipoib->broadcast_gid, &ipv4_broadcast_gid,
+	memcpy ( &ipoib->broadcast_gid, &ipoib_broadcast.gid,
 		 sizeof ( ipoib->broadcast_gid ) );
 	ipoib->broadcast_gid.u.words[2] = htons ( ibdev->pkey );
 

src/include/gpxe/ipoib.h

@@ -26,33 +26,30 @@ struct ipoib_mac {
 } __attribute__ (( packed ));
 
 /** IPoIB link-layer header length */
-#define IPOIB_HLEN 24
+#define IPOIB_HLEN 4
 
-/**
- * IPoIB link-layer header pseudo portion
- *
- * This part doesn't actually exist on the wire, but it provides a
- * convenient way to fit into the typical network device model.
- */
-struct ipoib_pseudo_hdr {
-	/** Peer address */
-	struct ipoib_mac peer;
-} __attribute__ (( packed ));
-
-/** IPoIB link-layer header real portion */
-struct ipoib_real_hdr {
+/** IPoIB link-layer header */
+struct ipoib_hdr {
 	/** Network-layer protocol */
 	uint16_t proto;
 	/** Reserved, must be zero */
-	uint16_t reserved;
-} __attribute__ (( packed ));
-
-/** An IPoIB link-layer header */
-struct ipoib_hdr {
-	/** Pseudo portion */
-	struct ipoib_pseudo_hdr pseudo;
-	/** Real portion */
-	struct ipoib_real_hdr real;
+	union {
+		/** Reserved, must be zero */
+		uint16_t reserved;
+		/** Peer addresses
+		 *
+		 * We use these fields internally to represent the
+		 * peer addresses using a lookup key.  There simply
+		 * isn't enough room in the IPoIB header to store
+		 * literal source or destination MAC addresses.
+		 */
+		struct {
+			/** Destination address key */
+			uint8_t dest;
+			/** Source address key */
+			uint8_t src;
+		} __attribute__ (( packed )) peer;
+	} __attribute__ (( packed )) u;
 } __attribute__ (( packed ));
 
 extern struct ll_protocol ipoib_protocol;

src/include/gpxe/netdevice.h

@@ -23,7 +23,7 @@ struct device;
 #define MAX_LL_ADDR_LEN 20
 
 /** Maximum length of a link-layer header */
-#define MAX_LL_HEADER_LEN 32
+#define MAX_LL_HEADER_LEN 6
 
 /** Maximum length of a network-layer address */
 #define MAX_NET_ADDR_LEN 4