bonding: allow xfrm offload setup post-module-load

At the moment, bonding xfrm crypto offload can only be set up if the bonding
module is loaded with active-backup mode already set. We need to be able to
make this work with bonds set to AB after the bonding driver has already
been loaded.

So what's done here is:

1) move #define BOND_XFRM_FEATURES to net/bonding.h so it can be used
by both bond_main.c and bond_options.c
2) set BOND_XFRM_FEATURES in bond_dev->hw_features universally, rather than
only when loading in AB mode
3) wire up xfrmdev_ops universally too
4) disable BOND_XFRM_FEATURES in bond_dev->features if not AB
5) exit early (non-AB case) from bond_ipsec_offload_ok, to prevent a
performance hit from traversing into the underlying drivers
5) toggle BOND_XFRM_FEATURES in bond_dev->wanted_features and call
netdev_change_features() from bond_option_mode_set()

In my local testing, I can change bonding modes back and forth on the fly,
have hardware offload work when I'm in AB, and see no performance penalty
to non-AB software encryption, despite having xfrm bits all wired up for
all modes now.

Fixes: 18cb261 ("bonding: support hardware encryption offload to slaves")
Reported-by: Huy Nguyen <huyn@mellanox.com>
CC: Saeed Mahameed <saeedm@mellanox.com>
CC: Jay Vosburgh <j.vosburgh@gmail.com>
CC: Veaceslav Falico <vfalico@gmail.com>
CC: Andy Gospodarek <andy@greyhouse.net>
CC: "David S. Miller" <davem@davemloft.net>
CC: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
CC: Jakub Kicinski <kuba@kernel.org>
CC: Steffen Klassert <steffen.klassert@secunet.com>
CC: Herbert Xu <herbert@gondor.apana.org.au>
CC: netdev@vger.kernel.org
CC: intel-wired-lan@lists.osuosl.org
Signed-off-by: Jarod Wilson <jarod@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/bonding/bond_main.c

@@ -434,6 +434,9 @@ static bool bond_ipsec_offload_ok(struct sk_buff *skb, struct xfrm_state *xs)
 	struct slave *curr_active = rtnl_dereference(bond->curr_active_slave);
 	struct net_device *slave_dev = curr_active->dev;
 
+	if (BOND_MODE(bond) != BOND_MODE_ACTIVEBACKUP)
+		return true;
+
 	if (!(slave_dev->xfrmdev_ops
 	      && slave_dev->xfrmdev_ops->xdo_dev_offload_ok)) {
 		slave_warn(bond_dev, slave_dev, "%s: no slave xdo_dev_offload_ok\n", __func__);
@@ -1218,11 +1221,6 @@ static netdev_features_t bond_fix_features(struct net_device *dev,
 #define BOND_ENC_FEATURES	(NETIF_F_HW_CSUM | NETIF_F_SG | \
 				 NETIF_F_RXCSUM | NETIF_F_ALL_TSO)
 
-#ifdef CONFIG_XFRM_OFFLOAD
-#define BOND_XFRM_FEATURES	(NETIF_F_HW_ESP | NETIF_F_HW_ESP_TX_CSUM | \
-				 NETIF_F_GSO_ESP)
-#endif /* CONFIG_XFRM_OFFLOAD */
-
 #define BOND_MPLS_FEATURES	(NETIF_F_HW_CSUM | NETIF_F_SG | \
 				 NETIF_F_ALL_TSO)
 
@@ -4654,8 +4652,7 @@ void bond_setup(struct net_device *bond_dev)
 
 #ifdef CONFIG_XFRM_OFFLOAD
 	/* set up xfrm device ops (only supported in active-backup right now) */
-	if (BOND_MODE(bond) == BOND_MODE_ACTIVEBACKUP)
-		bond_dev->xfrmdev_ops = &bond_xfrmdev_ops;
+	bond_dev->xfrmdev_ops = &bond_xfrmdev_ops;
 	bond->xs = NULL;
 #endif /* CONFIG_XFRM_OFFLOAD */
 
@@ -4678,11 +4675,15 @@ void bond_setup(struct net_device *bond_dev)
 
 	bond_dev->hw_features |= NETIF_F_GSO_ENCAP_ALL | NETIF_F_GSO_UDP_L4;
 #ifdef CONFIG_XFRM_OFFLOAD
-	if (BOND_MODE(bond) == BOND_MODE_ACTIVEBACKUP)
-		bond_dev->hw_features |= BOND_XFRM_FEATURES;
+	bond_dev->hw_features |= BOND_XFRM_FEATURES;
 #endif /* CONFIG_XFRM_OFFLOAD */
 	bond_dev->features |= bond_dev->hw_features;
 	bond_dev->features |= NETIF_F_HW_VLAN_CTAG_TX | NETIF_F_HW_VLAN_STAG_TX;
+#ifdef CONFIG_XFRM_OFFLOAD
+	/* Disable XFRM features if this isn't an active-backup config */
+	if (BOND_MODE(bond) != BOND_MODE_ACTIVEBACKUP)
+		bond_dev->features &= ~BOND_XFRM_FEATURES;
+#endif /* CONFIG_XFRM_OFFLOAD */
 }
 
 /* Destroy a bonding device.

drivers/net/bonding/bond_options.c

@@ -767,6 +767,14 @@ static int bond_option_mode_set(struct bonding *bond,
 	if (newval->value == BOND_MODE_ALB)
 		bond->params.tlb_dynamic_lb = 1;
 
+#ifdef CONFIG_XFRM_OFFLOAD
+	if (newval->value == BOND_MODE_ACTIVEBACKUP)
+		bond->dev->wanted_features |= BOND_XFRM_FEATURES;
+	else
+		bond->dev->wanted_features &= ~BOND_XFRM_FEATURES;
+	netdev_change_features(bond->dev);
+#endif /* CONFIG_XFRM_OFFLOAD */
+
 	/* don't cache arp_validate between modes */
 	bond->params.arp_validate = BOND_ARP_VALIDATE_NONE;
 	bond->params.mode = newval->value;

include/net/bonding.h

@@ -86,6 +86,11 @@
 #define bond_for_each_slave_rcu(bond, pos, iter) \
 	netdev_for_each_lower_private_rcu((bond)->dev, pos, iter)
 
+#ifdef CONFIG_XFRM_OFFLOAD
+#define BOND_XFRM_FEATURES (NETIF_F_HW_ESP | NETIF_F_HW_ESP_TX_CSUM | \
+			    NETIF_F_GSO_ESP)
+#endif /* CONFIG_XFRM_OFFLOAD */
+
 #ifdef CONFIG_NET_POLL_CONTROLLER
 extern atomic_t netpoll_block_tx;