e1000e: Driver workaround for IPv6 Header Extension Erratum.

Previously, IPv6 extension header parsing was disabled for all devices
supported by e1000e when using packet split mode. However, as per a
silicon errata, only certain devices need this restriction and will need
to disable IPv6 extension header parsing for all modes.

Signed-off-by: Matthew Vick <matthew.vick@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
diff --git a/drivers/net/ethernet/intel/e1000e/82571.c b/drivers/net/ethernet/intel/e1000e/82571.c
index 7b02e87..98632f4 100644
--- a/drivers/net/ethernet/intel/e1000e/82571.c
+++ b/drivers/net/ethernet/intel/e1000e/82571.c
@@ -1279,6 +1279,16 @@
 		ew32(CTRL_EXT, reg);
 	}
 
+	/*
+	 * Disable IPv6 extension header parsing because some malformed
+	 * IPv6 headers can hang the Rx.
+	 */
+	if (hw->mac.type <= e1000_82573) {
+		reg = er32(RFCTL);
+		reg |= (E1000_RFCTL_IPV6_EX_DIS | E1000_RFCTL_NEW_IPV6_EXT_DIS);
+		ew32(RFCTL, reg);
+	}
+
 	/* PCI-Ex Control Registers */
 	switch (hw->mac.type) {
 	case e1000_82574: