bpf, xdp: Maintain info on attached XDP BPF programs in net_device

Instead of delegating to drivers, maintain information about which BPF
programs are attached in which XDP modes (generic/skb, driver, or hardware)
locally in net_device. This effectively obsoletes XDP_QUERY_PROG command.

Such re-organization simplifies existing code already. But it also allows to
further add bpf_link-based XDP attachments without drivers having to know
about any of this at all, which seems like a good setup.
XDP_SETUP_PROG/XDP_SETUP_PROG_HW are just low-level commands to driver to
install/uninstall active BPF program. All the higher-level concerns about
prog/link interaction will be contained within generic driver-agnostic logic.

All the XDP_QUERY_PROG calls to driver in dev_xdp_uninstall() were removed.
It's not clear for me why dev_xdp_uninstall() were passing previous prog_flags
when resetting installed programs. That seems unnecessary, plus most drivers
don't populate prog_flags anyways. Having XDP_SETUP_PROG vs XDP_SETUP_PROG_HW
should be enough of an indicator of what is required of driver to correctly
reset active BPF program. dev_xdp_uninstall() is also generalized as an
iteration over all three supported mode.

Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200722064603.3350758-3-andriin@fb.com

1 files changed, 15 insertions, 2 deletions

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index ac2cd3f49aba..cad44b40c776 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -889,6 +889,17 @@ struct netlink_ext_ack;
 struct xdp_umem;
 struct xdp_dev_bulk_queue;
 
+enum bpf_xdp_mode {
+	XDP_MODE_SKB = 0,
+	XDP_MODE_DRV = 1,
+	XDP_MODE_HW = 2,
+	__MAX_XDP_MODE
+};
+
+struct bpf_xdp_entity {
+	struct bpf_prog *prog;
+};
+
 struct netdev_bpf {
 	enum bpf_netdev_command command;
 	union {
@@ -2142,6 +2153,9 @@ struct net_device {
 #endif
 	const struct udp_tunnel_nic_info	*udp_tunnel_nic_info;
 	struct udp_tunnel_nic	*udp_tunnel_nic;
+
+	/* protected by rtnl_lock */
+	struct bpf_xdp_entity	xdp_state[__MAX_XDP_MODE];
 };
 #define to_net_dev(d) container_of(d, struct net_device, dev)
 
@@ -3817,8 +3831,7 @@ struct sk_buff *dev_hard_start_xmit(struct sk_buff *skb, struct net_device *dev,
 typedef int (*bpf_op_t)(struct net_device *dev, struct netdev_bpf *bpf);
 int dev_change_xdp_fd(struct net_device *dev, struct netlink_ext_ack *extack,
 		      int fd, int expected_fd, u32 flags);
-u32 __dev_xdp_query(struct net_device *dev, bpf_op_t xdp_op,
-		    enum bpf_netdev_command cmd);
+u32 dev_xdp_prog_id(struct net_device *dev, enum bpf_xdp_mode mode);
 int xdp_umem_query(struct net_device *dev, u16 queue_id);
 
 int __dev_forward_skb(struct net_device *dev, struct sk_buff *skb);