[infiniband] Centralise assumption of 2048-byte payloads

IPoIB and the SMA have separate constants for the packet size to be
used to I/O buffer allocations.  Merge these into the single
IB_MAX_PAYLOAD_SIZE constant.

(Various other points in the Infiniband stack have hard-coded
assumptions of a 2048-byte payload; we don't currently support
variable MTUs.)

src/drivers/net/ipoib.c

 				     IPOIB_META_NUM_CQES, &ipoib_meta_cq_op,
 				     IPOIB_META_NUM_SEND_WQES,
 				     IPOIB_META_NUM_RECV_WQES,
-				     IPOIB_PKT_LEN, IB_GLOBAL_QKEY ) ) != 0 ) {
+				     IB_GLOBAL_QKEY ) ) != 0 ) {
 		DBGC ( ipoib, "IPoIB %p could not allocate metadata QP: %s\n",
 		       ipoib, strerror ( rc ) );
 		goto err_create_meta_qset;
 				     IPOIB_DATA_NUM_CQES, &ipoib_data_cq_op,
 				     IPOIB_DATA_NUM_SEND_WQES,
 				     IPOIB_DATA_NUM_RECV_WQES,
-				     IPOIB_PKT_LEN, IB_GLOBAL_QKEY ) ) != 0 ) {
+				     IB_GLOBAL_QKEY ) ) != 0 ) {
 		DBGC ( ipoib, "IPoIB %p could not allocate data QP: %s\n",
 		       ipoib, strerror ( rc ) );
 		goto err_create_data_qset;
 	if ( netdev ) {
 		netdev->ll_protocol = &ipoib_protocol;
 		netdev->ll_broadcast = ( uint8_t * ) &ipoib_broadcast;
-		netdev->max_pkt_len = IPOIB_PKT_LEN;
+		netdev->max_pkt_len = IB_MAX_PAYLOAD_SIZE;
 	}
 	return netdev;
 }

src/include/gpxe/ib_qset.h

 	struct ib_queue_pair *qp;
 	/** Receive work queue maximum fill level */
 	unsigned int recv_max_fill;
-	/** Receive packet length */
-	size_t recv_pkt_len;
 };
 
 extern int ib_create_qset ( struct ib_device *ibdev,
 			    struct ib_queue_set *qset, unsigned int num_cqes,
 			    struct ib_completion_queue_operations *cq_op,
 			    unsigned int num_send_wqes,
-			    unsigned int num_recv_wqes, size_t recv_pkt_len,
-			    unsigned long qkey );
+			    unsigned int num_recv_wqes, unsigned long qkey );
 extern void ib_qset_refill_recv ( struct ib_device *ibdev,
 				  struct ib_queue_set *qset );
 extern void ib_destroy_qset ( struct ib_device *ibdev,

src/include/gpxe/ib_sma.h

 	struct process poll;
 };
 
-/** SMA payload size allocated for received packets */
-#define IB_SMA_PAYLOAD_LEN 2048
-
 /** SMA number of send WQEs
  *
  * This is a policy decision.

src/include/gpxe/infiniband.h

 /** Subnet administrator queue key */
 #define IB_GLOBAL_QKEY 0x80010000UL
 
+/**
+ * Maximum payload size
+ *
+ * This is currently hard-coded in various places (drivers, subnet
+ * management agent, etc.) to 2048.
+ */
+#define IB_MAX_PAYLOAD_SIZE 2048
+
 struct ib_device;
 struct ib_queue_pair;
 struct ib_address_vector;

src/include/gpxe/ipoib.h

 
 #include <gpxe/infiniband.h>
 
-/** IPoIB packet length */
-#define IPOIB_PKT_LEN 2048
-
 /** IPoIB MAC address length */
 #define IPOIB_ALEN 20
 

src/net/infiniband.c

 		   struct io_buffer *iobuf ) {
 	int rc;
 
+	/* Check packet length */
+	if ( iob_tailroom ( iobuf ) < IB_MAX_PAYLOAD_SIZE ) {
+		DBGC ( ibdev, "IBDEV %p QPN %#lx wrong RX buffer size (%zd)\n",
+		       ibdev, qp->qpn, iob_tailroom ( iobuf ) );
+		return -EINVAL;
+	}
+
 	/* Check queue fill level */
 	if ( qp->recv.fill >= qp->recv.num_wqes ) {
 		DBGC ( ibdev, "IBDEV %p QPN %#lx receive queue full\n",

src/net/infiniband/ib_qset.c

  * @v cq_op		Completion queue operations
  * @v num_send_wqes	Number of send work queue entries
  * @v num_recv_wqes	Number of receive work queue entries
- * @v recv_pkt_len	Receive packet length
  * @v qkey		Queue key
  * @ret rc		Return status code
  */
 		     unsigned int num_cqes,
 		     struct ib_completion_queue_operations *cq_op,
 		     unsigned int num_send_wqes, unsigned int num_recv_wqes,
-		     size_t recv_pkt_len, unsigned long qkey ) {
+		     unsigned long qkey ) {
 	int rc;
 
 	/* Sanity check */
 
 	/* Store queue parameters */
 	qset->recv_max_fill = num_recv_wqes;
-	qset->recv_pkt_len = recv_pkt_len;
 
 	/* Allocate completion queue */
 	qset->cq = ib_create_cq ( ibdev, num_cqes, cq_op );
 	while ( qset->qp->recv.fill < qset->recv_max_fill ) {
 
 		/* Allocate I/O buffer */
-		iobuf = alloc_iob ( qset->recv_pkt_len );
+		iobuf = alloc_iob ( IB_MAX_PAYLOAD_SIZE );
 		if ( ! iobuf ) {
 			/* Non-fatal; we will refill on next attempt */
 			return;

src/net/infiniband/ib_sma.c

 	while ( sma->qp->recv.fill < IB_SMA_NUM_RECV_WQES ) {
 
 		/* Allocate I/O buffer */
-		iobuf = alloc_iob ( IB_SMA_PAYLOAD_LEN );
+		iobuf = alloc_iob ( IB_MAX_PAYLOAD_SIZE );
 		if ( ! iobuf ) {
 			/* Non-fatal; we will refill on next attempt */
 			return;