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

[Larysa Zaremba <larysa.zaremba@intel.com>]

On Thu, Jul 06, 2023 at 12:10:01PM +0200, Jesper Dangaard Brouer wrote:
> 
> 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@intel.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.
>

True, will do.
 
> 
> > +
> > +	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);
> >   }
>