RDMA/vmw_pvrdma: Report CQ missed events

There is a chance of a race between arming the CQ and receiving
completions. By reporting CQ missed events any ULPs should poll
again to get the completions.

Fixes: 29c8d9eb ("IB: Add vmw_pvrdma driver")
Acked-by: Aditya Sarwade <asarwade@vmware.com>
Signed-off-by: Bryan Tan <bryantan@vmware.com>
Signed-off-by: Adit Ranadive <aditr@vmware.com>
Reviewed-by: Yuval Shaia <yuval.shaia@oracle.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/hw/vmw_pvrdma/pvrdma_cq.c

@@ -65,13 +65,28 @@ int pvrdma_req_notify_cq(struct ib_cq *ibcq,
 	struct pvrdma_dev *dev = to_vdev(ibcq->device);
 	struct pvrdma_cq *cq = to_vcq(ibcq);
 	u32 val = cq->cq_handle;
+	unsigned long flags;
+	int has_data = 0;
 
 	val |= (notify_flags & IB_CQ_SOLICITED_MASK) == IB_CQ_SOLICITED ?
 		PVRDMA_UAR_CQ_ARM_SOL : PVRDMA_UAR_CQ_ARM;
 
+	spin_lock_irqsave(&cq->cq_lock, flags);
+
 	pvrdma_write_uar_cq(dev, val);
 
-	return 0;
+	if (notify_flags & IB_CQ_REPORT_MISSED_EVENTS) {
+		unsigned int head;
+
+		has_data = pvrdma_idx_ring_has_data(&cq->ring_state->rx,
+						    cq->ibcq.cqe, &head);
+		if (unlikely(has_data == PVRDMA_INVALID_IDX))
+			dev_err(&dev->pdev->dev, "CQ ring state invalid\n");
+	}
+
+	spin_unlock_irqrestore(&cq->cq_lock, flags);
+
+	return has_data;
 }
 
 /**