Subject: Re: [PATCH bpf-next v3 16/21] selftests/bpf: Add flags and new hints to xdp_hw_metadata

From: Stanislav Fomichev <[email-masked]>
Date: Thu, 20 Jul 2023 15:00:48 -0700

On 07/19, Larysa Zaremba wrote:
> Add hints added in the previous patches (VLAN tag and checksum)
> to the xdp_hw_metadata program.
> 
> Also, to make metadata layout more straightforward, add flags field
> to pass information about validity of every separate hint separately.
> 
> Signed-off-by: Larysa Zaremba <[email-masked]>

Acked-by: Stanislav Fomichev <[email-masked]>

with a small nit below

> ---
>  .../selftests/bpf/progs/xdp_hw_metadata.c     | 37 +++++++--
>  tools/testing/selftests/bpf/xdp_hw_metadata.c | 79 +++++++++++++++++--
>  tools/testing/selftests/bpf/xdp_metadata.h    | 31 +++++++-
>  3 files changed, 135 insertions(+), 12 deletions(-)
> 
> diff --git a/tools/testing/selftests/bpf/progs/xdp_hw_metadata.c b/tools/testing/selftests/bpf/progs/xdp_hw_metadata.c
> index 63d7de6c6bbb..75a61317668d 100644
> --- a/tools/testing/selftests/bpf/progs/xdp_hw_metadata.c
> +++ b/tools/testing/selftests/bpf/progs/xdp_hw_metadata.c
> @@ -20,6 +20,12 @@ 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_tci,
> +					__be16 *vlan_proto) __ksym;
> +extern int bpf_xdp_metadata_rx_csum(const struct xdp_md *ctx,
> +				    enum xdp_csum_status *csum_status,
> +				    union xdp_csum_info *csum_info) __ksym;
>  
>  SEC("xdp")
>  int rx(struct xdp_md *ctx)
> @@ -84,15 +90,36 @@ int rx(struct xdp_md *ctx)
>  		return XDP_PASS;
>  	}
>  
> +	meta->hint_valid = 0;
> +
>  	err = bpf_xdp_metadata_rx_timestamp(ctx, &meta->rx_timestamp);
> -	if (!err)
> +	if (err) {
> +		meta->rx_timestamp_err = err;
> +	} else {
> +		meta->hint_valid |= XDP_META_FIELD_TS;
>  		meta->xdp_timestamp = bpf_ktime_get_tai_ns();
> +	}

Maybe we can call bpf_ktime_get_tai_ns unconditionally? Then it will
match the rest formatting-wise (no {}).

meta->xdp_timestamp = bpf_ktime_get_tai_ns();

err = bpf_xdp_metadata_rx_timestamp(ctx, &meta->rx_timestamp);
if (err)
	meta->rx_timestamp_err = err;
else
	meta->hint_valid |= XDP_META_FIELD_TS;

WDYT?

> +
> +	err = bpf_xdp_metadata_rx_hash(ctx, &meta->rx_hash,
> +				       &meta->rx_hash_type);
> +	if (err)
> +		meta->rx_hash_err = err;
>  	else
> -		meta->rx_timestamp = 0; /* Used by AF_XDP as not avail signal */
> +		meta->hint_valid |= XDP_META_FIELD_RSS;
>  
> -	err = bpf_xdp_metadata_rx_hash(ctx, &meta->rx_hash, &meta->rx_hash_type);
> -	if (err < 0)
> -		meta->rx_hash_err = err; /* Used by AF_XDP as no hash signal */
> +	err = bpf_xdp_metadata_rx_vlan_tag(ctx, &meta->rx_vlan_tci,
> +					   &meta->rx_vlan_proto);
> +	if (err)
> +		meta->rx_vlan_tag_err = err;
> +	else
> +		meta->hint_valid |= XDP_META_FIELD_VLAN_TAG;
> +
> +	err = bpf_xdp_metadata_rx_csum(ctx, &meta->rx_csum_status,
> +				       (void *)&meta->rx_csum_info);
> +	if (err)
> +		meta->rx_csum_err = err;
> +	else
> +		meta->hint_valid |= XDP_META_FIELD_CSUM;
>  
>  	__sync_add_and_fetch(&pkts_redir, 1);
>  	return bpf_redirect_map(&xsk, ctx->rx_queue_index, XDP_PASS);
> diff --git a/tools/testing/selftests/bpf/xdp_hw_metadata.c b/tools/testing/selftests/bpf/xdp_hw_metadata.c
> index 613321eb84c1..a045de7dc910 100644
> --- a/tools/testing/selftests/bpf/xdp_hw_metadata.c
> +++ b/tools/testing/selftests/bpf/xdp_hw_metadata.c
> @@ -19,6 +19,9 @@
>  #include "xsk.h"
>  
>  #include <error.h>
> +#include <linux/kernel.h>
> +#include <linux/bits.h>
> +#include <linux/bitfield.h>
>  #include <linux/errqueue.h>
>  #include <linux/if_link.h>
>  #include <linux/net_tstamp.h>
> @@ -150,21 +153,70 @@ static __u64 gettime(clockid_t clock_id)
>  	return (__u64) t.tv_sec * NANOSEC_PER_SEC + t.tv_nsec;
>  }
>  
> +#define VLAN_PRIO_MASK		GENMASK(15, 13) /* Priority Code Point */
> +#define VLAN_DEI_MASK		GENMASK(12, 12) /* Drop Eligible Indicator */
> +#define VLAN_VID_MASK		GENMASK(11, 0)	/* VLAN Identifier */
> +static void print_vlan_tci(__u16 tag)
> +{
> +	__u16 vlan_id = FIELD_GET(VLAN_VID_MASK, tag);
> +	__u8 pcp = FIELD_GET(VLAN_PRIO_MASK, tag);
> +	bool dei = FIELD_GET(VLAN_DEI_MASK, tag);
> +
> +	printf("PCP=%u, DEI=%d, VID=0x%X\n", pcp, dei, vlan_id);
> +}
> +
> +#define XDP_CHECKSUM_VALID_NUM_MASK	GENMASK(2, 0)
> +#define XDP_CHECKSUM_PARTIAL		BIT(3)
> +#define XDP_CHECKSUM_COMPLETE		BIT(4)
> +
> +struct partial_csum_info {
> +	__u16 csum_start;
> +	__u16 csum_offset;
> +};
> +
> +static void print_csum_state(__u32 status, __u32 info)
> +{
> +	u8 csum_num = status & XDP_CHECKSUM_VALID_NUM_MASK;
> +
> +	printf("Checksum status: ");
> +	if (status != XDP_CHECKSUM_PARTIAL &&
> +	    status & ~(XDP_CHECKSUM_COMPLETE | XDP_CHECKSUM_VALID_NUM_MASK))
> +		printf("cannot be interpreted, status=0x%X\n", status);
> +
> +	if (status == XDP_CHECKSUM_PARTIAL) {
> +		struct partial_csum_info *partial_info = (void *)&info;
> +
> +		printf("partial, csum_start=%u, csum_offset=%u\n",
> +		       partial_info->csum_start, partial_info->csum_offset);
> +		return;
> +	}
> +
> +	if (status & XDP_CHECKSUM_COMPLETE)
> +		printf("complete, checksum=0x%X%s", info,
> +		       csum_num ? ", " : "\n");
> +
> +	if (csum_num > 1)
> +		printf("%u consecutive checksums are verified\n", csum_num);
> +	else if (csum_num)
> +		printf("outermost checksum is verified\n");
> +}
> +
>  static void verify_xdp_metadata(void *data, clockid_t clock_id)
>  {
>  	struct xdp_meta *meta;
>  
>  	meta = data - sizeof(*meta);
>  
> -	if (meta->rx_hash_err < 0)
> -		printf("No rx_hash err=%d\n", meta->rx_hash_err);
> -	else
> +	if (meta->hint_valid & XDP_META_FIELD_RSS)
>  		printf("rx_hash: 0x%X with RSS type:0x%X\n",
>  		       meta->rx_hash, meta->rx_hash_type);
> +	else
> +		printf("No rx_hash, err=%d\n", meta->rx_hash_err);
> +
> +	if (meta->hint_valid & XDP_META_FIELD_TS) {
> +		printf("rx_timestamp:  %llu (sec:%0.4f)\n", meta->rx_timestamp,
> +		       (double)meta->rx_timestamp / NANOSEC_PER_SEC);
>  
> -	printf("rx_timestamp:  %llu (sec:%0.4f)\n", meta->rx_timestamp,
> -	       (double)meta->rx_timestamp / NANOSEC_PER_SEC);
> -	if (meta->rx_timestamp) {
>  		__u64 usr_clock = gettime(clock_id);
>  		__u64 xdp_clock = meta->xdp_timestamp;
>  		__s64 delta_X = xdp_clock - meta->rx_timestamp;
> @@ -179,8 +231,23 @@ static void verify_xdp_metadata(void *data, clockid_t clock_id)
>  		       usr_clock, (double)usr_clock / NANOSEC_PER_SEC,
>  		       (double)delta_X2U / NANOSEC_PER_SEC,
>  		       (double)delta_X2U / 1000);
> +	} else {
> +		printf("No rx_timestamp, err=%d\n", meta->rx_timestamp_err);
>  	}
>  
> +	if (meta->hint_valid & XDP_META_FIELD_VLAN_TAG) {
> +		printf("rx_vlan_proto: 0x%X\n", ntohs(meta->rx_vlan_proto));
> +		printf("rx_vlan_tci: ");
> +		print_vlan_tci(meta->rx_vlan_tci);
> +	} else {
> +		printf("No rx_vlan_tci or rx_vlan_proto, err=%d\n",
> +		       meta->rx_vlan_tag_err);
> +	}
> +
> +	if (meta->hint_valid & XDP_META_FIELD_CSUM)
> +		print_csum_state(meta->rx_csum_status, meta->rx_csum_info);
> +	else
> +		printf("Checksum was not checked, err=%d\n", meta->rx_csum_err);
>  }
>  
>  static void verify_skb_metadata(int fd)
> diff --git a/tools/testing/selftests/bpf/xdp_metadata.h b/tools/testing/selftests/bpf/xdp_metadata.h
> index 6664893c2c77..95e7b53d6bfb 100644
> --- a/tools/testing/selftests/bpf/xdp_metadata.h
> +++ b/tools/testing/selftests/bpf/xdp_metadata.h
> @@ -17,12 +17,41 @@
>  #define ETH_P_8021AD 0x88A8
>  #endif
>  
> +#ifndef BIT
> +#define BIT(nr)			(1 << (nr))
> +#endif
> +
> +enum xdp_meta_field {
> +	XDP_META_FIELD_TS	= BIT(0),
> +	XDP_META_FIELD_RSS	= BIT(1),
> +	XDP_META_FIELD_VLAN_TAG	= BIT(2),
> +	XDP_META_FIELD_CSUM	= BIT(3),
> +};
> +
>  struct xdp_meta {
> -	__u64 rx_timestamp;
> +	union {
> +		__u64 rx_timestamp;
> +		__s32 rx_timestamp_err;
> +	};
>  	__u64 xdp_timestamp;
>  	__u32 rx_hash;
>  	union {
>  		__u32 rx_hash_type;
>  		__s32 rx_hash_err;
>  	};
> +	union {
> +		struct {
> +			__u16 rx_vlan_tci;
> +			__be16 rx_vlan_proto;
> +		};
> +		__s32 rx_vlan_tag_err;
> +	};
> +	union {
> +		struct {
> +			__u32 rx_csum_status;
> +			__u32 rx_csum_info;
> +		};
> +		__s32 rx_csum_err;
> +	};
> +	enum xdp_meta_field hint_valid;
>  };
> -- 
> 2.41.0
>