[RFC net-next 14/18] virtio_net: add XDP prog offload infrastructure

[Prashant Bhole <prashantbhole.linux@gmail.com>]

From: Jason Wang <jasowang@redhat.com>

This patch prepares virtio_net of XDP offloading. It adds data
structures, blank callback implementations for bpf_prog_offload_ops.
It also implements ndo_init, ndo_uninit operations for setting up
offload related data structures.

Signed-off-by: Jason Wang <jasowang@redhat.com>
Co-developed-by: Prashant Bhole <prashantbhole.linux@gmail.com>
Signed-off-by: Prashant Bhole <prashantbhole.linux@gmail.com>
---
 drivers/net/virtio_net.c | 103 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 103 insertions(+)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index cee5c2b15c62..a1088d0114f2 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -229,8 +229,14 @@ struct virtnet_info {
 	struct failover *failover;
 
 	struct bpf_prog __rcu *xdp_prog;
+	struct bpf_prog __rcu *offload_xdp_prog;
 
 	struct xdp_attachment_info xdp;
+	struct xdp_attachment_info xdp_hw;
+
+	struct bpf_offload_dev *bpf_dev;
+
+	struct list_head bpf_bound_progs;
 };
 
 struct padded_vnet_hdr {
@@ -258,6 +264,14 @@ static struct xdp_frame *ptr_to_xdp(void *ptr)
 	return (struct xdp_frame *)((unsigned long)ptr & ~VIRTIO_XDP_FLAG);
 }
 
+struct virtnet_bpf_bound_prog {
+	struct virtnet_info *vi;
+	struct bpf_prog *prog;
+	struct list_head list;
+	u32 len;
+	struct bpf_insn insnsi[0];
+};
+
 /* Converting between virtqueue no. and kernel tx/rx queue no.
  * 0:rx0 1:tx0 2:rx1 3:tx1 ... 2N:rxN 2N+1:txN 2N+2:cvq
  */
@@ -2506,13 +2520,63 @@ static int virtnet_xdp_set(struct net_device *dev, struct netdev_bpf *bpf)
 	return err;
 }
 
+static int virtnet_bpf_verify_insn(struct bpf_verifier_env *env, int insn_idx,
+				   int prev_insn)
+{
+	return 0;
+}
+
+static void virtnet_bpf_destroy_prog(struct bpf_prog *prog)
+{
+}
+
+static int virtnet_xdp_set_offload(struct virtnet_info *vi,
+				   struct netdev_bpf *bpf)
+{
+	return -EBUSY;
+}
+
+static int virtnet_bpf_verifier_setup(struct bpf_prog *prog)
+{
+	return -ENOMEM;
+}
+
+static int virtnet_bpf_verifier_prep(struct bpf_prog *prog)
+{
+	return 0;
+}
+
+static int virtnet_bpf_translate(struct bpf_prog *prog)
+{
+	return 0;
+}
+
+static int virtnet_bpf_finalize(struct bpf_verifier_env *env)
+{
+	return 0;
+}
+
+static const struct bpf_prog_offload_ops virtnet_bpf_dev_ops = {
+	.setup		= virtnet_bpf_verifier_setup,
+	.prepare	= virtnet_bpf_verifier_prep,
+	.insn_hook	= virtnet_bpf_verify_insn,
+	.finalize	= virtnet_bpf_finalize,
+	.translate	= virtnet_bpf_translate,
+	.destroy	= virtnet_bpf_destroy_prog,
+};
+
 static int virtnet_xdp(struct net_device *dev, struct netdev_bpf *xdp)
 {
+	struct virtnet_info *vi = netdev_priv(dev);
 	switch (xdp->command) {
 	case XDP_SETUP_PROG:
 		return virtnet_xdp_set(dev, xdp);
 	case XDP_QUERY_PROG:
 		return xdp_attachment_query(&vi->xdp, xdp);
+	case XDP_SETUP_PROG_HW:
+		return virtnet_xdp_set_offload(vi, xdp);
+	case XDP_QUERY_PROG_HW:
+		return xdp_attachment_query(&vi->xdp_hw, xdp);
 	default:
 		return -EINVAL;
 	}
@@ -2559,7 +2623,46 @@ static int virtnet_set_features(struct net_device *dev,
 	return 0;
 }
 
+static int virtnet_bpf_init(struct virtnet_info *vi)
+{
+	int err;
+
+	vi->bpf_dev = bpf_offload_dev_create(&virtnet_bpf_dev_ops, NULL);
+	err = PTR_ERR_OR_ZERO(vi->bpf_dev);
+	if (err)
+		return err;
+
+	err = bpf_offload_dev_netdev_register(vi->bpf_dev, vi->dev);
+	if (err)
+		goto err_netdev_register;
+
+	INIT_LIST_HEAD(&vi->bpf_bound_progs);
+
+	return 0;
+
+err_netdev_register:
+	bpf_offload_dev_destroy(vi->bpf_dev);
+	return err;
+}
+
+static int virtnet_init(struct net_device *dev)
+{
+	struct virtnet_info *vi = netdev_priv(dev);
+
+	return virtnet_bpf_init(vi);
+}
+
+static void virtnet_uninit(struct net_device *dev)
+{
+	struct virtnet_info *vi = netdev_priv(dev);
+
+	bpf_offload_dev_netdev_unregister(vi->bpf_dev, vi->dev);
+	bpf_offload_dev_destroy(vi->bpf_dev);
+}
+
 static const struct net_device_ops virtnet_netdev = {
+	.ndo_init            = virtnet_init,
+	.ndo_uninit          = virtnet_uninit,
 	.ndo_open            = virtnet_open,
 	.ndo_stop   	     = virtnet_close,
 	.ndo_start_xmit      = start_xmit,
-- 
2.20.1