RDMA/bnxt_re: Report MISSED_EVENTS in req_notify_cq

While invoking the req_notify_cq hook, ULPs can request
whether the CQs have any CQEs pending. If CQEs are pending,
drivers can indicate  it by returning 1 for req_notify_cq.
The stack will poll CQ again till CQ is empty.

This patch peeks the CQ for any valid entries and return accordingly.
Signed-off-by: Selvin Xavier <selvin.xavier@broadcom.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/hw/bnxt_re/ib_verbs.c

@@ -3027,6 +3027,11 @@ int bnxt_re_req_notify_cq(struct ib_cq *ib_cq,
 	else if (ib_cqn_flags & IB_CQ_SOLICITED)
 		type = DBR_DBR_TYPE_CQ_ARMSE;
 
+	/* Poll to see if there are missed events */
+	if ((ib_cqn_flags & IB_CQ_REPORT_MISSED_EVENTS) &&
+	    !(bnxt_qplib_is_cq_empty(&cq->qplib_cq)))
+		return 1;
+
 	bnxt_qplib_req_notify_cq(&cq->qplib_cq, type);
 
 	return 0;

drivers/infiniband/hw/bnxt_re/qplib_fp.c

@@ -1895,6 +1895,25 @@ static int bnxt_qplib_cq_process_res_ud(struct bnxt_qplib_cq *cq,
 	return rc;
 }
 
+bool bnxt_qplib_is_cq_empty(struct bnxt_qplib_cq *cq)
+{
+	struct cq_base *hw_cqe, **hw_cqe_ptr;
+	unsigned long flags;
+	u32 sw_cons, raw_cons;
+	bool rc = true;
+
+	spin_lock_irqsave(&cq->hwq.lock, flags);
+	raw_cons = cq->hwq.cons;
+	sw_cons = HWQ_CMP(raw_cons, &cq->hwq);
+	hw_cqe_ptr = (struct cq_base **)cq->hwq.pbl_ptr;
+	hw_cqe = &hw_cqe_ptr[CQE_PG(sw_cons)][CQE_IDX(sw_cons)];
+
+	 /* Check for Valid bit. If the CQE is valid, return false */
+	rc = !CQE_CMP_VALID(hw_cqe, raw_cons, cq->hwq.max_elements);
+	spin_unlock_irqrestore(&cq->hwq.lock, flags);
+	return rc;
+}
+
 static int bnxt_qplib_cq_process_res_raweth_qp1(struct bnxt_qplib_cq *cq,
 						struct cq_res_raweth_qp1 *hwcqe,
 						struct bnxt_qplib_cqe **pcqe,

drivers/infiniband/hw/bnxt_re/qplib_fp.h

@@ -449,6 +449,7 @@ int bnxt_qplib_create_cq(struct bnxt_qplib_res *res, struct bnxt_qplib_cq *cq);
 int bnxt_qplib_destroy_cq(struct bnxt_qplib_res *res, struct bnxt_qplib_cq *cq);
 int bnxt_qplib_poll_cq(struct bnxt_qplib_cq *cq, struct bnxt_qplib_cqe *cqe,
 		       int num, struct bnxt_qplib_qp **qp);
+bool bnxt_qplib_is_cq_empty(struct bnxt_qplib_cq *cq);
 void bnxt_qplib_req_notify_cq(struct bnxt_qplib_cq *cq, u32 arm_type);
 void bnxt_qplib_free_nq(struct bnxt_qplib_nq *nq);
 int bnxt_qplib_alloc_nq(struct pci_dev *pdev, struct bnxt_qplib_nq *nq);