Re: [PATCHv10 bpf-next 2/5] xdp: add a new helper for dev map multicast support

diff --git a/include/net/xdp.h b/include/net/xdp.h
index 3814fb631d52..8453d477bb22 100644
--- a/include/net/xdp.h
+++ b/include/net/xdp.h

@@ -132,6 +132,7 @@ void xdp_warn(const char *msg, const char *func, const int line);
  #define XDP_WARN(msg) xdp_warn(msg, __func__, __LINE__)
  
  struct xdp_frame *xdp_convert_zc_to_xdp_frame(struct xdp_buff *xdp);
+struct xdp_frame *xdpf_clone(struct xdp_frame *xdpf);
  
  static inline
  void xdp_convert_frame_to_buff(struct xdp_frame *frame, struct xdp_buff *xdp)

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 8dda13880957..e897c4a04061 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h

@@ -3576,6 +3576,27 @@ union bpf_attr {
   * 		the data in *dst*. This is a wrapper of copy_from_user().
   * 	Return
   * 		0 on success, or a negative error in case of failure.
+ *
+ * long bpf_redirect_map_multi(struct bpf_map *map, struct bpf_map *ex_map, u64 flags)
+ * 	Description
+ * 		This is a multicast implementation for XDP redirect. It will
+ * 		redirect the packet to ALL the interfaces in *map*, but
+ * 		exclude the interfaces in *ex_map*.
+ *
+ * 		The frowarding *map* could be either BPF_MAP_TYPE_DEVMAP or

+ * 		BPF_MAP_TYPE_DEVMAP_HASH. But the *ex_map* must be
+ * 		BPF_MAP_TYPE_DEVMAP_HASH to get better performance.
+ *
+ * 		Currently the *flags* only supports *BPF_F_EXCLUDE_INGRESS*,
+ * 		which additionally excludes the current ingress device.
+ *
+ * 		See also bpf_redirect_map() as a unicast implementation,
+ * 		which supports redirecting packet to a specific ifindex
+ * 		in the map. As both helpers use struct bpf_redirect_info
+ * 		to store the redirect info, we will use a a NULL tgt_value
+ * 		to distinguish multicast and unicast redirecting.
+ * 	Return
+ * 		**XDP_REDIRECT** on success, or **XDP_ABORTED** on error.
   */
  #define __BPF_FUNC_MAPPER(FN)		\
  	FN(unspec),			\

@@ -3727,6 +3748,7 @@ union bpf_attr {
  	FN(inode_storage_delete),	\
  	FN(d_path),			\
  	FN(copy_from_user),		\
+	FN(redirect_map_multi),		\
  	/* */
  
  /* integer value in 'imm' field of BPF_CALL instruction selects which helper

@@ -3898,6 +3920,11 @@ enum bpf_lwt_encap_mode {
  	BPF_LWT_ENCAP_IP,
  };
  
+/* BPF_FUNC_redirect_map_multi flags. */
+enum {
+	BPF_F_EXCLUDE_INGRESS		= (1ULL << 0),
+};
+
  #define __bpf_md_ptr(type, name)	\
  union {					\
  	type name;			\

diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c
index 2b5ca93c17de..04950e96282c 100644
--- a/kernel/bpf/devmap.c
+++ b/kernel/bpf/devmap.c

@@ -511,6 +511,130 @@ int dev_map_enqueue(struct bpf_dtab_netdev *dst, struct xdp_buff *xdp,
  	return __xdp_enqueue(dev, xdp, dev_rx);
  }
  
+/* Use direct call in fast path instead of map->ops->map_get_next_key() */
+static int devmap_get_next_key(struct bpf_map *map, void *key, void *next_key)
+{
+
+	switch (map->map_type) {
+	case BPF_MAP_TYPE_DEVMAP:
+		return dev_map_get_next_key(map, key, next_key);
+	case BPF_MAP_TYPE_DEVMAP_HASH:
+		return dev_map_hash_get_next_key(map, key, next_key);
+	default:
+		break;
+	}
+
+	return -ENOENT;
+}
+
+bool dev_in_exclude_map(struct bpf_dtab_netdev *obj, struct bpf_map *map,
+			int exclude_ifindex)
+{
+	if (obj->dev->ifindex == exclude_ifindex)
+		return true;
+
+	if (!map)
+		return false;
+
+	return __dev_map_hash_lookup_elem(map, obj->dev->ifindex) != NULL;
+}
+
+static struct bpf_dtab_netdev *devmap_get_next_obj(struct xdp_buff *xdp, struct bpf_map *map,
+						   struct bpf_map *ex_map, u32 *key,
+						   u32 *next_key, int ex_ifindex)
+{
+	struct bpf_dtab_netdev *obj;
+	struct net_device *dev;
+	u32 *tmp_key = key;
+	int err;
+
+	err = devmap_get_next_key(map, tmp_key, next_key);
+	if (err)
+		return NULL;
+
+	for (;;) {
+		switch (map->map_type) {
+		case BPF_MAP_TYPE_DEVMAP:
+			obj = __dev_map_lookup_elem(map, *next_key);
+			break;
+		case BPF_MAP_TYPE_DEVMAP_HASH:
+			obj = __dev_map_hash_lookup_elem(map, *next_key);
+			break;
+		default:
+			break;
+		}
+
+		if (!obj || dev_in_exclude_map(obj, ex_map, ex_ifindex))
+			goto find_next;
+
+		dev = obj->dev;
+
+		if (!dev->netdev_ops->ndo_xdp_xmit)
+			goto find_next;
+
+		err = xdp_ok_fwd_dev(dev, xdp->data_end - xdp->data);
+		if (unlikely(err))
+			goto find_next;
+
+		return obj;
+
+find_next:
+		tmp_key = next_key;
+		err = devmap_get_next_key(map, tmp_key, next_key);