[xdp-hints] Re: [PATCH bpf-next v8 17/17] selftests/bpf: Simple program to dump XDP RX metadata

[Jesper Dangaard Brouer <jbrouer@redhat.com>]

Testing this on mlx5 and I'm not getting the RX-timestamp.
See command details below.

On 19/01/2023 23.15, Stanislav Fomichev wrote:
> To be used for verification of driver implementations. Note that
> the skb path is gone from the series, but I'm still keeping the
> implementation for any possible future work.
> 
> $ xdp_hw_metadata <ifname>

sudo ./xdp_hw_metadata mlx5p1

Output:
[...cut ...]
open bpf program...
load bpf program...
prepare skb endpoint...
XXX timestamping_enable(): setsockopt(SO_TIMESTAMPING) ret:0
prepare xsk map...
map[0] = 3
map[1] = 4
map[2] = 5
map[3] = 6
map[4] = 7
map[5] = 8
attach bpf program...
poll: 0 (0)
poll: 0 (0)
poll: 0 (0)
poll: 1 (0)
xsk_ring_cons__peek: 1
0x1821788: rx_desc[0]->addr=100000000008000 addr=8100 comp_addr=8000
rx_timestamp: 0
rx_hash: 2773355807
0x1821788: complete idx=8 addr=8000
poll: 0 (0)

The trace_pipe:

$ sudo cat /sys/kernel/debug/tracing/trace_pipe
           <idle>-0       [005] ..s2.  2722.884762: bpf_trace_printk: 
forwarding UDP:9091 to AF_XDP
           <idle>-0       [005] ..s2.  2722.884771: bpf_trace_printk: 
populated rx_hash with 2773355807


> On the other machine:
> 
> $ echo -n xdp | nc -u -q1 <target> 9091 # for AF_XDP

Fixing the source-port to see if RX-hash remains the same.

  $ echo xdp | nc --source-port=2000 --udp 198.18.1.1 9091

> $ echo -n skb | nc -u -q1 <target> 9092 # for skb
> 
> Sample output:
> 
>    # xdp
>    xsk_ring_cons__peek: 1
>    0x19f9090: rx_desc[0]->addr=100000000008000 addr=8100 comp_addr=8000
>    rx_timestamp_supported: 1
>    rx_timestamp: 1667850075063948829
>    0x19f9090: complete idx=8 addr=8000

xsk_ring_cons__peek: 1
0x1821788: rx_desc[0]->addr=100000000008000 addr=8100 comp_addr=8000
rx_timestamp: 0
rx_hash: 2773355807
0x1821788: complete idx=8 addr=8000

It doesn't look like hardware RX-timestamps are getting enabled.

[... cut to relevant code ...]

> diff --git a/tools/testing/selftests/bpf/xdp_hw_metadata.c b/tools/testing/selftests/bpf/xdp_hw_metadata.c
> new file mode 100644
> index 000000000000..0008f0f239e8
> --- /dev/null
> +++ b/tools/testing/selftests/bpf/xdp_hw_metadata.c
> @@ -0,0 +1,403 @@
[...]

> +static void timestamping_enable(int fd, int val)
> +{
> +	int ret;
> +
> +	ret = setsockopt(fd, SOL_SOCKET, SO_TIMESTAMPING, &val, sizeof(val));
> +	if (ret < 0)
> +		error(-1, errno, "setsockopt(SO_TIMESTAMPING)");
> +}
> +
> +int main(int argc, char *argv[])
> +{
[...]

> +	printf("prepare skb endpoint...\n");
> +	server_fd = start_server(AF_INET6, SOCK_DGRAM, NULL, 9092, 1000);
> +	if (server_fd < 0)
> +		error(-1, errno, "start_server");
> +	timestamping_enable(server_fd,
> +			    SOF_TIMESTAMPING_SOFTWARE |
> +			    SOF_TIMESTAMPING_RAW_HARDWARE);
> +

I don't think this timestamping_enable() with these flags are enough to
enable hardware timestamping.

--Jesper