Re: [dpdk-dev] [PATCH 2/2] net/mlx5: fix missing RSS expansion of IPv6 frag

[Jack Min <jackmin@nvidia.com>]

On Mon, 21-07-12, 08:05, Raslan Darawsheh wrote:

Hey,
> Hi,
> 
> > -----Original Message-----
> > From: dev <dev-bounces@dpdk.org> On Behalf Of Xiaoyu Min
> > Sent: Wednesday, July 7, 2021 5:33 AM
> > To: Matan Azrad <matan@nvidia.com>; Shahaf Shuler
> > <shahafs@nvidia.com>; Slava Ovsiienko <viacheslavo@nvidia.com>; Dekel
> > Peled <dekelp@nvidia.com>; Ori Kam <orika@nvidia.com>
> > Cc: dev@dpdk.org; stable@dpdk.org
> > Subject: [dpdk-dev] [PATCH 2/2] net/mlx5: fix missing RSS expansion of IPv6
> > frag
> > 
> > IPV6_FRAG_EXT item is missed for RSS expansion which causes flows like
> > [1] are wrongly expanded.
> > 
> > Different from other items, IPV6_FRAG_EXT hasn't next field because HW
> > only support to do hash of UDP/TCP for non-fragment.
> > 
> > This MLX5_EXPANSION_IPV6_FRAG_EXT node in RSS expansion graph only
> > helps
> > RSS expansion function to locate right node in graph from which start
> > to expand.
> > 
> > Fixes: 0e5a0d8f7556 ("net/mlx5: support match on IPv6 fragment
> > extension")
> > Cc: stable@dpdk.org
> > 
> > [1]:
> > flow create 0 ingress pattern eth / ipv6 / udp dst is 250 / vxlan-gpe /
> > ipv6 / ipv6_frag_ext / end actions rss level 2 types ip end / end
> > 
> > Signed-off-by: Xiaoyu Min <jackmin@nvidia.com>
> > ---
> >  drivers/net/mlx5/mlx5_flow.c | 8 +++++++-
> >  1 file changed, 7 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/net/mlx5/mlx5_flow.c b/drivers/net/mlx5/mlx5_flow.c
> > index 1b682ac8ed..90b8cf6692 100644
> > --- a/drivers/net/mlx5/mlx5_flow.c
> > +++ b/drivers/net/mlx5/mlx5_flow.c
> > @@ -134,6 +134,7 @@ mlx5_flow_is_rss_expandable_item(const struct
> > rte_flow_item *item)
> >  	case RTE_FLOW_ITEM_TYPE_MPLS:
> >  	case RTE_FLOW_ITEM_TYPE_VXLAN_GPE:
> >  	case RTE_FLOW_ITEM_TYPE_GRE_KEY:
> > +	case RTE_FLOW_ITEM_TYPE_IPV6_FRAG_EXT:
> 
> Adding IPV6_FRAG_EXT to the list of expandable is not accurate,
> Assuming HW support matching on L4 info after frag - which I think it doesn't.
> It will lead that the first frag will get different hash than other frags since it the only one which contain info of L4 header
> This will lead to different RSS spreading and that's not correct.

No, it will not expand to any items because the .next field is empty of entry
MLX5_EXPANSION_IPV6_FRAG_EXT in mlx5_support_expansion[].

-Jack
> 
> Kindest regards,
> Raslan Darawsheh