bnxt_en: Fix the PCI-AER routines

We do not support two simultaneous recoveries so check for reset
flag, BNXT_STATE_IN_FW_RESET, and do not proceed with AER further.
When the pci channel state is pci_channel_io_frozen, the PCIe link
can not be trusted so we disable the traffic immediately and stop
BAR access by calling bnxt_fw_fatal_close().  BAR access after
AER fatal error can cause an NMI.

Fixes: f75d9a0a ("bnxt_en: Re-write PCI BARs after PCI fatal error.")
Signed-off-by: Vikas Gupta <vikas.gupta@broadcom.com>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/broadcom/bnxt/bnxt.c

@@ -15378,6 +15378,7 @@ static pci_ers_result_t bnxt_io_error_detected(struct pci_dev *pdev,
 {
 	struct net_device *netdev = pci_get_drvdata(pdev);
 	struct bnxt *bp = netdev_priv(netdev);
+	bool abort = false;
 
 	netdev_info(netdev, "PCI I/O error detected\n");
 
@@ -15386,16 +15387,27 @@ static pci_ers_result_t bnxt_io_error_detected(struct pci_dev *pdev,
 
 	bnxt_ulp_stop(bp);
 
-	if (state == pci_channel_io_perm_failure) {
+	if (test_and_set_bit(BNXT_STATE_IN_FW_RESET, &bp->state)) {
+		netdev_err(bp->dev, "Firmware reset already in progress\n");
+		abort = true;
+	}
+
+	if (abort || state == pci_channel_io_perm_failure) {
 		rtnl_unlock();
 		return PCI_ERS_RESULT_DISCONNECT;
 	}
 
-	if (state == pci_channel_io_frozen)
+	/* Link is not reliable anymore if state is pci_channel_io_frozen
+	 * so we disable bus master to prevent any potential bad DMAs before
+	 * freeing kernel memory.
+	 */
+	if (state == pci_channel_io_frozen) {
 		set_bit(BNXT_STATE_PCI_CHANNEL_IO_FROZEN, &bp->state);
+		bnxt_fw_fatal_close(bp);
+	}
 
 	if (netif_running(netdev))
-		bnxt_close(netdev);
+		__bnxt_close_nic(bp, true, true);
 
 	if (pci_is_enabled(pdev))
 		pci_disable_device(pdev);
@@ -15479,6 +15491,7 @@ static pci_ers_result_t bnxt_io_slot_reset(struct pci_dev *pdev)
 	}
 
 reset_exit:
+	clear_bit(BNXT_STATE_IN_FW_RESET, &bp->state);
 	bnxt_clear_reservations(bp, true);
 	rtnl_unlock();