xdp: add xdp_set_features_flag utility routine

Introduce xdp_set_features_flag utility routine in order to update
dynamically xdp_features according to the dynamic hw configuration via
ethtool (e.g. changing number of hw rx/tx queues).
Add xdp_clear_features_flag() in order to clear all xdp_feature flag.

Reviewed-by: Shay Agroskin <[e-mail]>
Signed-off-by: Lorenzo Bianconi <[e-mail]>
Signed-off-by: Jakub Kicinski <[e-mail]>

Documentation/netlink/specs/netdev.yaml

···
   -
     type: flags
     name: xdp-act
+    render-max: true
     entries:
       -
         name: basic

include/net/xdp.h

···
 #ifdef CONFIG_NET
 u32 bpf_xdp_metadata_kfunc_id(int id);
 bool bpf_dev_bound_kfunc_id(u32 btf_id);
+void xdp_set_features_flag(struct net_device *dev, xdp_features_t val);
 void xdp_features_set_redirect_target(struct net_device *dev, bool support_sg);
 void xdp_features_clear_redirect_target(struct net_device *dev);
 #else
 static inline u32 bpf_xdp_metadata_kfunc_id(int id) { return 0; }
 static inline bool bpf_dev_bound_kfunc_id(u32 btf_id) { return false; }
+
+static inline void
+xdp_set_features_flag(struct net_device *dev, xdp_features_t val)
+{
+}
 
 static inline void
 xdp_features_set_redirect_target(struct net_device *dev, bool support_sg)
···
 {
 }
 #endif
+
+static inline void xdp_clear_features_flag(struct net_device *dev)
+{
+	xdp_set_features_flag(dev, 0);
+}
 
 #endif /* __LINUX_NET_XDP_H__ */

include/uapi/linux/netdev.h

···
 	NETDEV_XDP_ACT_HW_OFFLOAD = 16,
 	NETDEV_XDP_ACT_RX_SG = 32,
 	NETDEV_XDP_ACT_NDO_XMIT_SG = 64,
+
+	NETDEV_XDP_ACT_MASK = 127,
 };
 
 enum {

net/core/xdp.c

···
 }
 late_initcall(xdp_metadata_init);
 
+void xdp_set_features_flag(struct net_device *dev, xdp_features_t val)
+{
+	val &= NETDEV_XDP_ACT_MASK;
+	if (dev->xdp_features == val)
+		return;
+
+	dev->xdp_features = val;
+	call_netdevice_notifiers(NETDEV_XDP_FEAT_CHANGE, dev);
+}
+EXPORT_SYMBOL_GPL(xdp_set_features_flag);
+
 void xdp_features_set_redirect_target(struct net_device *dev, bool support_sg)
 {
-	dev->xdp_features |= NETDEV_XDP_ACT_NDO_XMIT;
-	if (support_sg)
-		dev->xdp_features |= NETDEV_XDP_ACT_NDO_XMIT_SG;
+	xdp_features_t val = (dev->xdp_features | NETDEV_XDP_ACT_NDO_XMIT);
 
-	call_netdevice_notifiers(NETDEV_XDP_FEAT_CHANGE, dev);
+	if (support_sg)
+		val |= NETDEV_XDP_ACT_NDO_XMIT_SG;
+	xdp_set_features_flag(dev, val);
 }
 EXPORT_SYMBOL_GPL(xdp_features_set_redirect_target);
 
 void xdp_features_clear_redirect_target(struct net_device *dev)
 {
-	dev->xdp_features &= ~(NETDEV_XDP_ACT_NDO_XMIT |
-			       NETDEV_XDP_ACT_NDO_XMIT_SG);
-	call_netdevice_notifiers(NETDEV_XDP_FEAT_CHANGE, dev);
+	xdp_features_t val = dev->xdp_features;
+
+	val &= ~(NETDEV_XDP_ACT_NDO_XMIT | NETDEV_XDP_ACT_NDO_XMIT_SG);
+	xdp_set_features_flag(dev, val);
 }
 EXPORT_SYMBOL_GPL(xdp_features_clear_redirect_target);

tools/include/uapi/linux/netdev.h

···
 	NETDEV_XDP_ACT_HW_OFFLOAD = 16,
 	NETDEV_XDP_ACT_RX_SG = 32,
 	NETDEV_XDP_ACT_NDO_XMIT_SG = 64,
+
+	NETDEV_XDP_ACT_MASK = 127,
 };
 
 enum {