netdev - [PATCH net 1/5] Revert "net: macsec: report real_dev features when HW offloading is enabled"

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Message-Id: <dc221ba5aefd21ff2a0b89d3f58ff714899613aa.1665416630.git.sd@queasysnail.net>
Date:   Thu, 13 Oct 2022 16:15:39 +0200
From:   Sabrina Dubroca <sd@...asysnail.net>
To:     netdev@...r.kernel.org
Cc:     Antoine Tenart <atenart@...nel.org>,
        Sabrina Dubroca <sd@...asysnail.net>,
        Mark Starovoytov <mstarovoitov@...vell.com>,
        Igor Russkikh <irusskikh@...vell.com>
Subject: [PATCH net 1/5] Revert "net: macsec: report real_dev features when HW offloading is enabled"

This reverts commit c850240b6c4132574a00f2da439277ab94265b66.

Copying the features of the real device doesn't work when it also
supports IPsec offload, because then we'll have a device with
NETIF_F_HW_ESP but no netdev->xfrmdev_ops.

Example perf trace when running
  ip link add link eni1np1 type macsec port 4 offload mac

    ip   737 [003]   795.477676: probe:xfrm_dev_event__REGISTER      name="macsec0" features=0x1c000080014869
              xfrm_dev_event+0x3a
              notifier_call_chain+0x47
              register_netdevice+0x846
              macsec_newlink+0x25a

    ip   737 [003]   795.477687:   probe:xfrm_dev_event__return      ret=0x8002 (NOTIFY_BAD)
             notifier_call_chain+0x47
             register_netdevice+0x846
             macsec_newlink+0x25a

dev->features includes NETIF_F_HW_ESP (0x04000000000000), so
xfrm_api_check returns NOTIFY_BAD because we don't have
dev->xfrmdev_ops on the macsec device.

We could probably propagate GSO and a few other features from the
lower device, similar to macvlan. This will be done in a future patch.

Signed-off-by: Sabrina Dubroca <sd@...asysnail.net>
---
 drivers/net/macsec.c | 27 ++++-----------------------
 1 file changed, 4 insertions(+), 23 deletions(-)

diff --git a/drivers/net/macsec.c b/drivers/net/macsec.c
index c891b60937a7..b3f76e8071f2 100644
--- a/drivers/net/macsec.c
+++ b/drivers/net/macsec.c
@@ -2654,11 +2654,6 @@ static int macsec_upd_offload(struct sk_buff *skb, struct genl_info *info)
 	if (ret)
 		goto rollback;
 
-	/* Force features update, since they are different for SW MACSec and
-	 * HW offloading cases.
-	 */
-	netdev_update_features(dev);
-
 	rtnl_unlock();
 	return 0;
 
@@ -3432,16 +3427,9 @@ static netdev_tx_t macsec_start_xmit(struct sk_buff *skb,
 	return ret;
 }
 
-#define SW_MACSEC_FEATURES \
+#define MACSEC_FEATURES \
 	(NETIF_F_SG | NETIF_F_HIGHDMA | NETIF_F_FRAGLIST)
 
-/* If h/w offloading is enabled, use real device features save for
- *   VLAN_FEATURES - they require additional ops
- *   HW_MACSEC - no reason to report it
- */
-#define REAL_DEV_FEATURES(dev) \
-	((dev)->features & ~(NETIF_F_VLAN_FEATURES | NETIF_F_HW_MACSEC))
-
 static int macsec_dev_init(struct net_device *dev)
 {
 	struct macsec_dev *macsec = macsec_priv(dev);
@@ -3458,12 +3446,8 @@ static int macsec_dev_init(struct net_device *dev)
 		return err;
 	}
 
-	if (macsec_is_offloaded(macsec)) {
-		dev->features = REAL_DEV_FEATURES(real_dev);
-	} else {
-		dev->features = real_dev->features & SW_MACSEC_FEATURES;
-		dev->features |= NETIF_F_LLTX | NETIF_F_GSO_SOFTWARE;
-	}
+	dev->features = real_dev->features & MACSEC_FEATURES;
+	dev->features |= NETIF_F_LLTX | NETIF_F_GSO_SOFTWARE;
 
 	dev->needed_headroom = real_dev->needed_headroom +
 			       MACSEC_NEEDED_HEADROOM;
@@ -3495,10 +3479,7 @@ static netdev_features_t macsec_fix_features(struct net_device *dev,
 	struct macsec_dev *macsec = macsec_priv(dev);
 	struct net_device *real_dev = macsec->real_dev;
 
-	if (macsec_is_offloaded(macsec))
-		return REAL_DEV_FEATURES(real_dev);
-
-	features &= (real_dev->features & SW_MACSEC_FEATURES) |
+	features &= (real_dev->features & MACSEC_FEATURES) |
 		    NETIF_F_GSO_SOFTWARE | NETIF_F_SOFT_FEATURES;
 	features |= NETIF_F_LLTX;
 
-- 
2.38.0