IB/hfi1: Verify port data VLs credits on transition to Armed

There is a window where the FM can read the buffer control table
and decide not to program buffers. When a port goes down, the code
clears the table and if it is not programmed, posted SDMA descriptors
will never complete due to no buffer credits.
Reviewed-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: Alex Estrin <alex.estrin@intel.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/hw/hfi1/chip.c

@@ -10489,6 +10489,14 @@ void set_link_down_reason(struct hfi1_pportdata *ppd, u8 lcl_reason,
 	}
 }
 
+/*
+ * Verify if BCT for data VLs is non-zero.
+ */
+static inline bool data_vls_operational(struct hfi1_pportdata *ppd)
+{
+	return !!ppd->actual_vls_operational;
+}
+
 /*
  * Change the physical and/or logical link state.
  *
@@ -10587,6 +10595,13 @@ int set_link_state(struct hfi1_pportdata *ppd, u32 state)
 		if (ppd->host_link_state != HLS_UP_INIT)
 			goto unexpected;
 
+		if (!data_vls_operational(ppd)) {
+			dd_dev_err(dd,
+				   "%s: data VLs not operational\n", __func__);
+			ret = -EINVAL;
+			break;
+		}
+
 		ppd->host_link_state = HLS_UP_ARMED;
 		set_logical_state(dd, LSTATE_ARMED);
 		ret = wait_logical_linkstate(ppd, IB_PORT_ARMED, 1000);
@@ -14832,7 +14847,6 @@ struct hfi1_devdata *hfi1_init_dd(struct pci_dev *pdev,
 		}
 		ppd->vls_supported = num_vls;
 		ppd->vls_operational = ppd->vls_supported;
-		ppd->actual_vls_operational = ppd->vls_supported;
 		/* Set the default MTU. */
 		for (vl = 0; vl < num_vls; vl++)
 			dd->vld[vl].mtu = hfi1_max_mtu;

drivers/infiniband/hw/hfi1/intr.c

@@ -164,6 +164,7 @@ void handle_linkup_change(struct hfi1_devdata *dd, u32 linkup)
 		ppd->linkup = 0;
 
 		/* clear HW details of the previous connection */
+		ppd->actual_vls_operational = 0;
 		reset_link_credits(dd);
 
 		/* freeze after a link down to guarantee a clean egress */