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Subject: [PATCH bpf RFC-V2 3/5] veth: bpf_xdp_metadata_rx_hash return xdp rss
 hash type
From:   Jesper Dangaard Brouer <brouer@redhat.com>
To:     bpf@vger.kernel.org, Stanislav Fomichev <sdf@google.com>
Cc:     Jesper Dangaard Brouer <brouer@redhat.com>, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org, martin.lau@kernel.org,
        ast@kernel.org, daniel@iogearbox.net, alexandr.lobakin@intel.com,
        larysa.zaremba@intel.com, xdp-hints@xdp-project.net,
        anthony.l.nguyen@intel.com, yoong.siang.song@intel.com,
        boon.leong.ong@intel.com, intel-wired-lan@lists.osuosl.org,
        pabeni@redhat.com, jesse.brandeburg@intel.com, kuba@kernel.org,
        edumazet@google.com, john.fastabend@gmail.com, hawk@kernel.org,
        davem@davemloft.net
Date:   Wed, 29 Mar 2023 18:29:13 +0200
Message-ID: <168010735338.3039990.5752685085641326312.stgit@firesoul>
In-Reply-To: <168010726310.3039990.2753040700813178259.stgit@firesoul>
References: <168010726310.3039990.2753040700813178259.stgit@firesoul>
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Update API for bpf_xdp_metadata_rx_hash() by returning xdp rss hash type.

The veth driver currently only support XDP-hints based on SKB code path.
The SKB have lost information about the RSS hash type, by compressing
the information down to a single bitfield skb->l4_hash, that only knows
if this was a L4 hash value.

In preparation for veth, the xdp_rss_hash_type have an L4 indication
bit that allow us to return a meaningful L4 indication when working
with SKB based packets.

Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
---
 drivers/net/veth.c |    7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/net/veth.c b/drivers/net/veth.c
index 046461ee42ea..770eee664b4c 100644
--- a/drivers/net/veth.c
+++ b/drivers/net/veth.c
@@ -1619,12 +1619,13 @@ static int veth_xdp_rx_timestamp(const struct xdp_md *ctx, u64 *timestamp)
 static int veth_xdp_rx_hash(const struct xdp_md *ctx, u32 *hash)
 {
 	struct veth_xdp_buff *_ctx = (void *)ctx;
+	struct sk_buff *skb = _ctx->skb;
 
-	if (!_ctx->skb)
+	if (!skb)
 		return -ENODATA;
 
-	*hash = skb_get_hash(_ctx->skb);
-	return 0;
+	*hash = skb_get_hash(skb);
+	return skb->l4_hash ? XDP_RSS_TYPE_L4_ANY : XDP_RSS_TYPE_NONE;
 }
 
 static const struct net_device_ops veth_netdev_ops = {