netdev - Re: [PATCH bpf-next v2 19/20] selftests/bpf: Check VLAN tag and proto in xdp

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Message-ID: <80792adb-ca6c-3870-8fdd-a7e814830d1f@redhat.com>
Date: Thu, 6 Jul 2023 12:10:01 +0200
From: Jesper Dangaard Brouer <jbrouer@...hat.com>
To: Larysa Zaremba <larysa.zaremba@...el.com>, bpf@...r.kernel.org
Cc: brouer@...hat.com, ast@...nel.org, daniel@...earbox.net,
 andrii@...nel.org, martin.lau@...ux.dev, song@...nel.org, yhs@...com,
 john.fastabend@...il.com, kpsingh@...nel.org, sdf@...gle.com,
 haoluo@...gle.com, jolsa@...nel.org, David Ahern <dsahern@...il.com>,
 Jakub Kicinski <kuba@...nel.org>, Willem de Bruijn <willemb@...gle.com>,
 Anatoly Burakov <anatoly.burakov@...el.com>,
 Alexander Lobakin <alexandr.lobakin@...el.com>,
 Magnus Karlsson <magnus.karlsson@...il.com>,
 Maryam Tahhan <mtahhan@...hat.com>, xdp-hints@...-project.net,
 netdev@...r.kernel.org
Subject: Re: [PATCH bpf-next v2 19/20] selftests/bpf: Check VLAN tag and proto
 in xdp_metadata


On 03/07/2023 20.12, Larysa Zaremba wrote:
> Verify, whether VLAN tag and proto are set correctly.
> 
> To simulate "stripped" VLAN tag on veth, send test packet from VLAN
> interface.
> 
> Signed-off-by: Larysa Zaremba <larysa.zaremba@...el.com>
> ---
>   .../selftests/bpf/prog_tests/xdp_metadata.c   | 21 +++++++++++++++++--
>   .../selftests/bpf/progs/xdp_metadata.c        |  4 ++++
>   2 files changed, 23 insertions(+), 2 deletions(-)
> 
> diff --git a/tools/testing/selftests/bpf/prog_tests/xdp_metadata.c b/tools/testing/selftests/bpf/prog_tests/xdp_metadata.c
> index 53b32a641e8e..50ac9f570bc5 100644
> --- a/tools/testing/selftests/bpf/prog_tests/xdp_metadata.c
> +++ b/tools/testing/selftests/bpf/prog_tests/xdp_metadata.c
> @@ -38,6 +38,13 @@
>   #define TX_MAC "00:00:00:00:00:01"
>   #define RX_MAC "00:00:00:00:00:02"
>   
> +#define VLAN_ID 59
> +#define VLAN_ID_STR "59"
> +#define VLAN_PROTO "802.1Q"
> +#define VLAN_PID htons(ETH_P_8021Q)
> +#define TX_NAME_VLAN TX_NAME "." VLAN_ID_STR
> +#define RX_NAME_VLAN RX_NAME "." VLAN_ID_STR
> +
>   #define XDP_RSS_TYPE_L4 BIT(3)
>   
>   struct xsk {
> @@ -215,6 +222,12 @@ static int verify_xsk_metadata(struct xsk *xsk)
>   	if (!ASSERT_NEQ(meta->rx_hash_type & XDP_RSS_TYPE_L4, 0, "rx_hash_type"))
>   		return -1;
>   
> +	if (!ASSERT_EQ(meta->rx_vlan_tag, VLAN_ID, "rx_vlan_tag"))
> +		return -1;

In other examples you are masking meta->rx_vlan_tag with VLAN_VID_MASK
(12 lower bits 0x0fff) to extract the VLAN_ID.  It would make the
selftest more correct, robust and pedagogical to also mask out the ID here.


> +
> +	if (!ASSERT_EQ(meta->rx_vlan_proto, VLAN_PID, "rx_vlan_proto"))
> +		return -1;
> +
>   	xsk_ring_cons__release(&xsk->rx, 1);
>   	refill_rx(xsk, comp_addr);
>   
> @@ -253,10 +266,14 @@ void test_xdp_metadata(void)
>   
>   	SYS(out, "ip link set dev " TX_NAME " address " TX_MAC);
>   	SYS(out, "ip link set dev " TX_NAME " up");
> -	SYS(out, "ip addr add " TX_ADDR "/" PREFIX_LEN " dev " TX_NAME);
> +
> +	SYS(out, "ip link add link " TX_NAME " " TX_NAME_VLAN
> +		 " type vlan proto " VLAN_PROTO " id " VLAN_ID_STR);
> +	SYS(out, "ip link set dev " TX_NAME_VLAN " up");
> +	SYS(out, "ip addr add " TX_ADDR "/" PREFIX_LEN " dev " TX_NAME_VLAN);
>   
>   	/* Avoid ARP calls */
> -	SYS(out, "ip -4 neigh add " RX_ADDR " lladdr " RX_MAC " dev " TX_NAME);
> +	SYS(out, "ip -4 neigh add " RX_ADDR " lladdr " RX_MAC " dev " TX_NAME_VLAN);
>   
>   	set_netns(rx_netns);
>   	SYS(out, "ip link set dev " RX_NAME " address " RX_MAC);
> diff --git a/tools/testing/selftests/bpf/progs/xdp_metadata.c b/tools/testing/selftests/bpf/progs/xdp_metadata.c
> index d151d406a123..382984a5d1c9 100644
> --- a/tools/testing/selftests/bpf/progs/xdp_metadata.c
> +++ b/tools/testing/selftests/bpf/progs/xdp_metadata.c
> @@ -23,6 +23,9 @@ extern int bpf_xdp_metadata_rx_timestamp(const struct xdp_md *ctx,
>   					 __u64 *timestamp) __ksym;
>   extern int bpf_xdp_metadata_rx_hash(const struct xdp_md *ctx, __u32 *hash,
>   				    enum xdp_rss_hash_type *rss_type) __ksym;
> +extern int bpf_xdp_metadata_rx_vlan_tag(const struct xdp_md *ctx,
> +					__u16 *vlan_tag,
> +					__be16 *vlan_proto) __ksym;
>   
>   SEC("xdp")
>   int rx(struct xdp_md *ctx)
> @@ -57,6 +60,7 @@ int rx(struct xdp_md *ctx)
>   		meta->rx_timestamp = 1;
>   
>   	bpf_xdp_metadata_rx_hash(ctx, &meta->rx_hash, &meta->rx_hash_type);
> +	bpf_xdp_metadata_rx_vlan_tag(ctx, &meta->rx_vlan_tag, &meta->rx_vlan_proto);
>   
>   	return bpf_redirect_map(&xsk, ctx->rx_queue_index, XDP_PASS);
>   }