ixgbe: Add support for Double VLAN mode

There is no practical limit on number of stacked vlans in Linux which
means multiple VLAN headers could be present in Ethernet frames.

However it is less common to have stacking depth more than two which
is known as 802.1ad or QinQ protocols.

By default driver provides hardware offloading only for one VLAN header:
it supports filtering by vlan id (vid), strip on receive, insert on
transmit; as well as skipping header to provide offload for next
protocol.

In case of stacked vlans next protocol is also VLAN which is in turn
isn't known to hardware without additional configuration. That means
hardware does not provide any additional offload like receive hash
calculation, direction to specific receive queue etc. Last one means
that RSS does not work for packets with multiple VLAN headers.

Hardware supports double vlans when configured in specific mode called
Global Double VLAN in "Intel(R) 82599 10 GbE Controller Datasheet".

With this change we implement support for this mode in ixgbe driver.

Signed-off-by: Serhey Popovych <[email protected]>

ixgbe.7

@@ -209,6 +209,20 @@ This parameter is only relevant for devices operating in SR-IOV mode.
 When this parameter is set, the driver detects malicious VF driver and
 disables its Tx/Rx queues until a VF driver reset occurs.
 .LP
+.B DV (Double VLAN)
+.IP
+.B Valid Range: 0-1
+.IP
+0 = Disabled
+.IP
+1 = Enabled
+.IP
+Control Double VLAN mode on device. If enabled hardware assumes that at least
+single vlan header present in packet buffer and second header is skipped to
+enable rest of L2/L3 offloading processing (e.g. RSS). It is disabled by default
+since VID filtering, if enabled, is done in software by driver and not compatible
+with VMDq.
+.LP
 .B Jumbo Frames
 .IP
 Jumbo Frames support is enabled by changing the Maximum Transmission Unit (MTU) to a value larger than the default value of 1500.

src/ixgbe.h

@@ -906,7 +906,9 @@ struct ixgbe_adapter {
 #define IXGBE_FLAG2_PHY_INTERRUPT		(u32)(1 << 17)
 #define IXGBE_FLAG2_VLAN_PROMISC		(u32)(1 << 18)
 #define IXGBE_FLAG2_RX_LEGACY			(u32)(1 << 19)
-#define IXGBE_FLAG2_AUTO_DISABLE_VF		BIT(20)
+#define IXGBE_FLAG2_AUTO_DISABLE_VF		(u32)(1 << 20)
+#define IXGBE_FLAG2_VLAN_STAG_RX		(u32)(1 << 21)
+#define IXGBE_FLAG2_VLAN_STAG_FILTER		(u32)(1 << 22)
 
 	/* Tx fast path data */
 	int num_tx_queues;
@@ -1275,6 +1277,13 @@ void ixgbe_disable_tx_queue(struct ixgbe_adapter *adapter);
 #ifdef ETHTOOL_OPS_COMPAT
 int ethtool_ioctl(struct ifreq *ifr);
 #endif
+#ifdef HAVE_RHEL6_NET_DEVICE_OPS_EXT
+u32 ixgbe_vlan_double_fix_features(struct net_device *netdev, u32 features);
+#else
+netdev_features_t ixgbe_vlan_double_fix_features(struct net_device *netdev,
+						 netdev_features_t features);
+#endif
+
 
 #if IS_ENABLED(CONFIG_FCOE)
 void ixgbe_configure_fcoe(struct ixgbe_adapter *adapter);

src/ixgbe_ethtool.c

@@ -187,6 +187,10 @@ static const char ixgbe_priv_flags_strings[][ETH_GSTRING_LEN] = {
 #endif
 #define IXGBE_PRIV_FLAGS_AUTO_DISABLE_VF		BIT(2)
 	"mdd-disable-vf",
+#define IXGBE_PRIV_FLAGS_VLAN_STAG_RX			BIT(3)
+	"vlan-stag-rx",
+#define IXGBE_PRIV_FLAGS_VLAN_STAG_FILTER		BIT(4)
+	"vlan-stag-filter",
 };
 
 #define IXGBE_PRIV_FLAGS_STR_LEN ARRAY_SIZE(ixgbe_priv_flags_strings)
@@ -3390,7 +3394,7 @@ static int ixgbe_set_tso(struct net_device *netdev, u32 data)
 static int ixgbe_set_flags(struct net_device *netdev, u32 data)
 {
 	struct ixgbe_adapter *adapter = netdev_priv(netdev);
-	u32 supported_flags = ETH_FLAG_RXVLAN | ETH_FLAG_TXVLAN;
+	u32 supported_flags = ETH_FLAG_RXVLAN;
 	u32 changed = netdev->features ^ data;
 	bool need_reset = false;
 	int rc;
@@ -3402,6 +3406,8 @@ static int ixgbe_set_flags(struct net_device *netdev, u32 data)
 #endif
 	if (adapter->flags2 & IXGBE_FLAG2_RSC_CAPABLE)
 		supported_flags |= ETH_FLAG_LRO;
+	if (!(adapter->flags & IXGBE_FLAG2_VLAN_STAG_RX))
+		supported_flags |= ETH_FLAG_TXVLAN;
 
 #ifdef ETHTOOL_GRXRINGS
 	switch (adapter->hw.mac.type) {
@@ -4678,6 +4684,12 @@ static u32 ixgbe_get_priv_flags(struct net_device *netdev)
 	if (adapter->flags2 & IXGBE_FLAG2_AUTO_DISABLE_VF)
 		priv_flags |= IXGBE_PRIV_FLAGS_AUTO_DISABLE_VF;
 
+	if (adapter->flags2 & IXGBE_FLAG2_VLAN_STAG_RX)
+		priv_flags |= IXGBE_PRIV_FLAGS_VLAN_STAG_RX;
+
+	if (adapter->flags2 & IXGBE_FLAG2_VLAN_STAG_FILTER)
+		priv_flags |= IXGBE_PRIV_FLAGS_VLAN_STAG_FILTER;
+
 	return priv_flags;
 }
 
@@ -4694,6 +4706,8 @@ static int ixgbe_set_priv_flags(struct net_device *netdev, u32 priv_flags)
 		IXGBE_SPF_NONE		= 0,
 		IXGBE_SPF_REINIT_LOCKED	= (1 << 0),
 		IXGBE_SPF_RESET		= (1 << 1),
+		IXGBE_SPF_SET_RX_MODE	= (1 << 2),
+		IXGBE_SPF_SET_FEATURES	= (1 << 3),
 	} do_reset = IXGBE_SPF_NONE;
 
 	if (!changed)
@@ -4749,14 +4763,84 @@ static int ixgbe_set_priv_flags(struct net_device *netdev, u32 priv_flags)
 		do_reset |= IXGBE_SPF_REINIT_LOCKED;
 	}
 
+	/* Global Double VLAN features handling */
+	if (changed & IXGBE_PRIV_FLAGS_VLAN_STAG_RX) {
+		struct ixgbe_hw *hw = &adapter->hw;
+
+		switch (hw->mac.type) {
+		case ixgbe_mac_82599EB:
+		case ixgbe_mac_X540:
+		case ixgbe_mac_X550:
+		case ixgbe_mac_X550EM_x:
+		case ixgbe_mac_X550EM_a:
+			/* VMDq requires vlan filtering to be enbled */
+			if (!(adapter->flags & IXGBE_FLAG_VMDQ_ENABLED) &&
+			    (priv_flags & IXGBE_PRIV_FLAGS_VLAN_STAG_RX)) {
+				/* Turn on STAG filter by default: user might
+				 * turn it off later if required.
+				 */
+				if (!(adapter->flags2 & IXGBE_FLAG2_VLAN_STAG_RX)) {
+#ifndef HAVE_VLAN_RX_REGISTER
+					adapter->flags2 |=
+						(IXGBE_FLAG2_VLAN_STAG_RX|
+						 IXGBE_FLAG2_VLAN_STAG_FILTER);
+#else
+					/* No filtering by driver by default: there
+					 * are setups with old kernels where filtering
+					 * might be broken (e.g. vlan on top of macvlan)
+					 */
+					adapter->flags2 |=
+						(IXGBE_FLAG2_VLAN_STAG_RX);
+#endif
+				}
+				break;
+			}
+			/* fall thru */
+		default:
+			/* No filtering by outer tag without outer VLAN
+			 * header acceleration on receive.
+			 */
+			adapter->flags2 &= ~(IXGBE_FLAG2_VLAN_STAG_RX |
+					     IXGBE_FLAG2_VLAN_STAG_FILTER);
+		}
+
+		changed &= ~IXGBE_PRIV_FLAGS_VLAN_STAG_FILTER;
+		do_reset |= IXGBE_SPF_SET_FEATURES;
+	}
+
+	if (changed & IXGBE_PRIV_FLAGS_VLAN_STAG_FILTER) {
+		if (adapter->flags2 & IXGBE_FLAG2_VLAN_STAG_RX) {
+			adapter->flags2 ^= IXGBE_FLAG2_VLAN_STAG_FILTER;
+			do_reset |= IXGBE_SPF_SET_FEATURES;
+		}
+	}
+
+	if (do_reset & IXGBE_SPF_SET_FEATURES) {
+		typeof(netdev->features) features = netdev->features;
+
+		features = ixgbe_vlan_double_fix_features(netdev, features);
+		if (features != netdev->features) {
+			netdev->features = features;
+			netdev_features_change(netdev);
+		}
+
+		do_reset |= IXGBE_SPF_SET_RX_MODE;
+	}
+
 	if (do_reset & IXGBE_SPF_RESET) {
 		ixgbe_do_reset(netdev);
+		do_reset &= ~IXGBE_SPF_SET_RX_MODE;
 	} else if (do_reset & IXGBE_SPF_REINIT_LOCKED) {
 		/* reset interface to repopulate queues */
-		if (netif_running(netdev))
+		if (netif_running(netdev)) {
 			ixgbe_reinit_locked(adapter);
+			do_reset &= ~IXGBE_SPF_SET_RX_MODE;
+		}
 	}
 
+	if (do_reset & IXGBE_SPF_SET_RX_MODE)
+		ixgbe_set_rx_mode(netdev);
+
 	return 0;
 }