igb: Add message when malformed packets detected by hw

This patch adds a check and prints the error cause register value when
the hardware detects a malformed packet.  This is a very unlikely
scenario but has been seen occasionally, so printing the message to
assist the user.
Signed-off-by: Carolyn Wyborny <carolyn.wyborny@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/igb/e1000_regs.h

@@ -355,6 +355,7 @@
 #define E1000_UTA       0x0A000 /* Unicast Table Array - RW */
 #define E1000_IOVTCL    0x05BBC /* IOV Control Register */
 #define E1000_TXSWC     0x05ACC /* Tx Switch Control */
+#define E1000_LVMMC	0x03548 /* Last VM Misbehavior cause */
 /* These act per VF so an array friendly macro is used */
 #define E1000_P2VMAILBOX(_n)   (0x00C00 + (4 * (_n)))
 #define E1000_VMBMEM(_n)       (0x00800 + (64 * (_n)))

drivers/net/ethernet/intel/igb/igb_main.c

@@ -4166,6 +4166,26 @@ static bool igb_thermal_sensor_event(struct e1000_hw *hw, u32 event)
 	return ret;
 }
 
+/**
+ *  igb_check_lvmmc - check for malformed packets received
+ *  and indicated in LVMMC register
+ *  @adapter: pointer to adapter
+ **/
+static void igb_check_lvmmc(struct igb_adapter *adapter)
+{
+	struct e1000_hw *hw = &adapter->hw;
+	u32 lvmmc;
+
+	lvmmc = rd32(E1000_LVMMC);
+	if (lvmmc) {
+		if (unlikely(net_ratelimit())) {
+			netdev_warn(adapter->netdev,
+				    "malformed Tx packet detected and dropped, LVMMC:0x%08x\n",
+				    lvmmc);
+		}
+	}
+}
+
 /**
  *  igb_watchdog - Timer Call-back
  *  @data: pointer to adapter cast into an unsigned long
@@ -4361,6 +4381,11 @@ static void igb_watchdog_task(struct work_struct *work)
 	igb_spoof_check(adapter);
 	igb_ptp_rx_hang(adapter);
 
+	/* Check LVMMC register on i350/i354 only */
+	if ((adapter->hw.mac.type == e1000_i350) ||
+	    (adapter->hw.mac.type == e1000_i354))
+		igb_check_lvmmc(adapter);
+
 	/* Reset the timer */
 	if (!test_bit(__IGB_DOWN, &adapter->state)) {
 		if (adapter->flags & IGB_FLAG_NEED_LINK_UPDATE)