pt., 7 maj 2021 o 18:47 Ferruh Yigit [off-list ref] napisał(a):

On 5/6/2021 3:25 PM, Michal Krawczyk wrote:

quoted

To make it possible to the app to determine if the hash was calculated
for the packet or not, the PKT_RX_RSS_HASH should be set in the mbuf's
ol_flags.

As the PMD wasn't setting that, the application couldn't check if there
is a hash in a proper way.

The hash is valid only if it's UDP or TCP and the IP packet wasn't
fragmented.

Fixes: e5df9f33db00 ("net/ena: fix passing RSS hash to mbuf")
Cc: stable@dpdk.org

Signed-off-by: Michal Krawczyk <redacted>
Reviewed-by: Igor Chauskin <redacted>
Reviewed-by: Amit Bernstein <redacted>
---
 drivers/net/ena/ena_ethdev.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ena/ena_ethdev.c b/drivers/net/ena/ena_ethdev.c
index 6092288239..5d107775f4 100644
--- a/drivers/net/ena/ena_ethdev.c
+++ b/drivers/net/ena/ena_ethdev.c

@@ -51,6 +51,8 @@

 #define ENA_MIN_RING_DESC    128

+#define ENA_PTYPE_HAS_HASH   (RTE_PTYPE_L4_TCP | RTE_PTYPE_L4_UDP)
+
 enum ethtool_stringset {
      ETH_SS_TEST             = 0,
      ETH_SS_STATS,

@@ -314,6 +316,11 @@ static inline void ena_rx_mbuf_prepare(struct rte_mbuf *mbuf,
              else
                      ol_flags |= PKT_RX_L4_CKSUM_GOOD;

+     if (likely((packet_type & ENA_PTYPE_HAS_HASH) && !ena_rx_ctx->frag)) {
+             ol_flags |= PKT_RX_RSS_HASH;
+             mbuf->hash.rss = ena_rx_ctx->hash;
+     }

The driver should announce the 'DEV_RX_OFFLOAD_RSS_HASH' offload capability
first, and should set 'PKT_RX_RSS_HASH' only if application requests the
'DEV_RX_OFFLOAD_RSS_HASH'.


Normally this is an optimization to not always update the 'mbuf->hash.rss' but
wait for explicit request from application for it.

But there is no practical performance gain for some PMDs and they enable it even
user does not ask for it [1] (of course if RSS is enabled), if this is same for
'ena' you can do the same.

Thanks for the reference - ENA should do the same, I will change that in v4.

[1]
https://git.dpdk.org/dpdk/tree/drivers/net/ixgbe/ixgbe_ethdev.c?h=v21.05-rc2#n2384

quoted

+
      mbuf->ol_flags = ol_flags;
      mbuf->packet_type = packet_type;
 }

@@ -2245,8 +2252,6 @@ static uint16_t eth_ena_recv_pkts(void *rx_queue, struct rte_mbuf **rx_pkts,
                      ++rx_ring->rx_stats.bad_csum;
              }

-             mbuf->hash.rss = ena_rx_ctx.hash;
-
              rx_pkts[completed] = mbuf;
              rx_ring->rx_stats.bytes += mbuf->pkt_len;
      }