On 30/03/2023 21.02, Stanislav Fomichev wrote:

On Thu, Mar 30, 2023 at 11:56 AM Jesper Dangaard Brouer

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On 30/03/2023 20.35, Stanislav Fomichev wrote:

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On 03/30, Jesper Dangaard Brouer wrote:

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diff --git a/net/core/xdp.c b/net/core/xdp.c
index 528d4b37983d..38d2dee16b47 100644
--- a/net/core/xdp.c
+++ b/net/core/xdp.c

@@ -734,14 +734,22 @@ __bpf_kfunc int

bpf_xdp_metadata_rx_timestamp(const struct xdp_md *ctx, u64 *tim
    * bpf_xdp_metadata_rx_hash - Read XDP frame RX hash.
    * @ctx: XDP context pointer.
    * @hash: Return value pointer.
+ * @rss_type: Return value pointer for RSS type.
+ *
+ * The RSS hash type (@rss_type) specifies what portion of packet headers NIC
+ * hardware were used when calculating RSS hash value.  The type combinations
+ * are defined via &enum xdp_rss_hash_type and individual bits can be decoded
+ * via &enum xdp_rss_type_bits.
    *
    * Return:
    * * Returns 0 on success or ``-errno`` on error.
    * * ``-EOPNOTSUPP`` : means device driver doesn't implement kfunc
    * * ``-ENODATA``    : means no RX-hash available for this frame
    */
-__bpf_kfunc int bpf_xdp_metadata_rx_hash(const struct xdp_md *ctx,
u32 *hash)
+__bpf_kfunc int bpf_xdp_metadata_rx_hash(const struct xdp_md *ctx,
u32 *hash,
+                     enum xdp_rss_hash_type *rss_type)
   {

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+    BTF_TYPE_EMIT(enum xdp_rss_type_bits);

nit: Do we still need this with an extra argument?

Yes, unfortunately (compiler optimizes out enum xdp_rss_type_bits).
Do notice the difference xdp_rss_type_bits vs xdp_rss_hash_type.
We don't need it for "xdp_rss_hash_type" but need it for
"xdp_rss_type_bits".

 >

Ah, I missed that. Then why not expose xdp_rss_type_bits?
Keep xdp_rss_hash_type for internal drivers' tables, and export the
enum with the bits?

Great suggestion, xdp_rss_hash_type will be internal for drivers.
I will do that in V4.

--Jesper