IB/rdmavt: Add post receive to rdmavt

This patch adds the simple post receive verbs call to rdmavt. The actual
interrupt handling and packet processing is still done in the low level
driver.

Reviewed-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Reviewed-by: Harish Chegondi <harish.chegondi@intel.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/sw/rdmavt/qp.c

@@ -1244,14 +1244,47 @@ int rvt_query_qp(struct ib_qp *ibqp, struct ib_qp_attr *attr,
 int rvt_post_recv(struct ib_qp *ibqp, struct ib_recv_wr *wr,
 		  struct ib_recv_wr **bad_wr)
 {
-	/*
-	 * When a packet arrives the driver needs to call up to rvt to process
-	 * the packet. The UD, RC, UC processing will be done in rvt, however
-	 * the driver should be able to override this if it so choses. Perhaps a
-	 * set of function pointers set up at registration time.
-	 */
+	struct rvt_qp *qp = ibqp_to_rvtqp(ibqp);
+	struct rvt_rwq *wq = qp->r_rq.wq;
+	unsigned long flags;
 
-	return -EOPNOTSUPP;
+	/* Check that state is OK to post receive. */
+	if (!(ib_rvt_state_ops[qp->state] & RVT_POST_RECV_OK) || !wq) {
+		*bad_wr = wr;
+		return -EINVAL;
+	}
+
+	for (; wr; wr = wr->next) {
+		struct rvt_rwqe *wqe;
+		u32 next;
+		int i;
+
+		if ((unsigned)wr->num_sge > qp->r_rq.max_sge) {
+			*bad_wr = wr;
+			return -EINVAL;
+		}
+
+		spin_lock_irqsave(&qp->r_rq.lock, flags);
+		next = wq->head + 1;
+		if (next >= qp->r_rq.size)
+			next = 0;
+		if (next == wq->tail) {
+			spin_unlock_irqrestore(&qp->r_rq.lock, flags);
+			*bad_wr = wr;
+			return -ENOMEM;
+		}
+
+		wqe = rvt_get_rwqe_ptr(&qp->r_rq, wq->head);
+		wqe->wr_id = wr->wr_id;
+		wqe->num_sge = wr->num_sge;
+		for (i = 0; i < wr->num_sge; i++)
+			wqe->sg_list[i] = wr->sg_list[i];
+		/* Make sure queue entry is written before the head index. */
+		smp_wmb();
+		wq->head = next;
+		spin_unlock_irqrestore(&qp->r_rq.lock, flags);
+	}
+	return 0;
 }
 
 /**