[xdp-hints] Re: [PATCH bpf V7 4/7] mlx5: bpf_xdp_metadata_rx_hash add xdp rss hash type

[Simon Horman <simon.horman@corigine.com>]

On Wed, Apr 12, 2023 at 01:31:18PM +0200, Jesper Dangaard Brouer wrote:
> [You don't often get email from jbrouer@redhat.com. Learn why this is important at https://aka.ms/LearnAboutSenderIdentification ]
> 
> On 10/04/2023 17.11, Simon Horman wrote:
> > On Sat, Apr 08, 2023 at 09:24:56PM +0200, Jesper Dangaard Brouer wrote:
> > > Update API for bpf_xdp_metadata_rx_hash() with arg for xdp rss hash type
> > > via mapping table.
> > > 
> > > The mlx5 hardware can also identify and RSS hash IPSEC.  This indicate
> > > hash includes SPI (Security Parameters Index) as part of IPSEC hash.
> > > 
> > > Extend xdp core enum xdp_rss_hash_type with IPSEC hash type.
> > > 
> > > Fixes: bc8d405b1ba9 ("net/mlx5e: Support RX XDP metadata")
> > > Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
> > > Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
> > > Acked-by: Stanislav Fomichev <sdf@google.com>
> > > ---
> > >   drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c |   60 ++++++++++++++++++++++
> > >   include/linux/mlx5/device.h                      |   14 ++++-
> > >   include/net/xdp.h                                |    2 +
> > >   3 files changed, 73 insertions(+), 3 deletions(-)
> > > 
> > > diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c b/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c
> > > index efe609f8e3aa..97ef1df94d50 100644
> > > --- a/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c
> > > +++ b/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c
> > > @@ -34,6 +34,7 @@
> > >   #include <net/xdp_sock_drv.h>
> > >   #include "en/xdp.h"
> > >   #include "en/params.h"
> > > +#include <linux/bitfield.h>
> > > 
> > >   int mlx5e_xdp_max_mtu(struct mlx5e_params *params, struct mlx5e_xsk_param *xsk)
> > >   {
> > > @@ -169,15 +170,72 @@ static int mlx5e_xdp_rx_timestamp(const struct xdp_md *ctx, u64 *timestamp)
> > >      return 0;
> > >   }
> > > 
> > > +/* Mapping HW RSS Type bits CQE_RSS_HTYPE_IP + CQE_RSS_HTYPE_L4 into 4-bits*/
> > > +#define RSS_TYPE_MAX_TABLE  16 /* 4-bits max 16 entries */
> > > +#define RSS_L4              GENMASK(1, 0)
> > > +#define RSS_L3              GENMASK(3, 2) /* Same as CQE_RSS_HTYPE_IP */
> > > +
> > > +/* Valid combinations of CQE_RSS_HTYPE_IP + CQE_RSS_HTYPE_L4 sorted numerical */
> > > +enum mlx5_rss_hash_type {
> > > +    RSS_TYPE_NO_HASH        = (FIELD_PREP_CONST(RSS_L3, CQE_RSS_IP_NONE) |
> > > +                               FIELD_PREP_CONST(RSS_L4, CQE_RSS_L4_NONE)),
> > > +    RSS_TYPE_L3_IPV4        = (FIELD_PREP_CONST(RSS_L3, CQE_RSS_IPV4) |
> > > +                               FIELD_PREP_CONST(RSS_L4, CQE_RSS_L4_NONE)),
> > > +    RSS_TYPE_L4_IPV4_TCP    = (FIELD_PREP_CONST(RSS_L3, CQE_RSS_IPV4) |
> > > +                               FIELD_PREP_CONST(RSS_L4, CQE_RSS_L4_TCP)),
> > > +    RSS_TYPE_L4_IPV4_UDP    = (FIELD_PREP_CONST(RSS_L3, CQE_RSS_IPV4) |
> > > +                               FIELD_PREP_CONST(RSS_L4, CQE_RSS_L4_UDP)),
> > > +    RSS_TYPE_L4_IPV4_IPSEC  = (FIELD_PREP_CONST(RSS_L3, CQE_RSS_IPV4) |
> > > +                               FIELD_PREP_CONST(RSS_L4, CQE_RSS_L4_IPSEC)),
> > > +    RSS_TYPE_L3_IPV6        = (FIELD_PREP_CONST(RSS_L3, CQE_RSS_IPV6) |
> > > +                               FIELD_PREP_CONST(RSS_L4, CQE_RSS_L4_NONE)),
> > > +    RSS_TYPE_L4_IPV6_TCP    = (FIELD_PREP_CONST(RSS_L3, CQE_RSS_IPV6) |
> > > +                               FIELD_PREP_CONST(RSS_L4, CQE_RSS_L4_TCP)),
> > > +    RSS_TYPE_L4_IPV6_UDP    = (FIELD_PREP_CONST(RSS_L3, CQE_RSS_IPV6) |
> > > +                               FIELD_PREP_CONST(RSS_L4, CQE_RSS_L4_UDP)),
> > > +    RSS_TYPE_L4_IPV6_IPSEC  = (FIELD_PREP_CONST(RSS_L3, CQE_RSS_IPV6) |
> > > +                               FIELD_PREP_CONST(RSS_L4, CQE_RSS_L4_IPSEC)),
> > > +} mlx5_rss_hash_type;
> > 
> > Hi Jesper,
> > 
> > Sparse seems confused about 'mlx5_rss_hash_type' on the line above.
> > And I am too. Perhaps it can be removed?
> > 
> 
> Yes, it can be removed (in V8).
> 
> The reason/trick for doing this was to get compiler to create the enum
> symbol, which allowed me to inspect the type using pahole (see cmd
> below).  (This will also expose this to BTF, but it isn't actually
> useful to keep around for BTF, so I will remove it in V8.)

Thanks Jesper,

I didn't know that trick :)

> $ pahole -C mlx5_rss_hash_type
> drivers/net/ethernet/mellanox/mlx5/core/en/xdp.o
> enum mlx5_rss_hash_type {
>        RSS_TYPE_NO_HASH       = 0,
>        RSS_TYPE_L3_IPV4       = 4,
>        RSS_TYPE_L4_IPV4_TCP   = 5,
>        RSS_TYPE_L4_IPV4_UDP   = 6,
>        RSS_TYPE_L4_IPV4_IPSEC = 7,
>        RSS_TYPE_L3_IPV6       = 8,
>        RSS_TYPE_L4_IPV6_TCP   = 9,
>        RSS_TYPE_L4_IPV6_UDP   = 10,
>        RSS_TYPE_L4_IPV6_IPSEC = 11,
> };
> 
> This is practical to for reviewers to see if below code is correct:
> 
> > +/* Invalid combinations will simply return zero, allows no boundary
> checks */
> > +static const enum xdp_rss_hash_type
> mlx5_xdp_rss_type[RSS_TYPE_MAX_TABLE] = {
> > +    [RSS_TYPE_NO_HASH]       = XDP_RSS_TYPE_NONE,
> > +    [1]                      = XDP_RSS_TYPE_NONE, /* Implicit zero */
> > +    [2]                      = XDP_RSS_TYPE_NONE, /* Implicit zero */
> > +    [3]                      = XDP_RSS_TYPE_NONE, /* Implicit zero */
> > +    [RSS_TYPE_L3_IPV4]       = XDP_RSS_TYPE_L3_IPV4,
> > +    [RSS_TYPE_L4_IPV4_TCP]   = XDP_RSS_TYPE_L4_IPV4_TCP,
> > +    [RSS_TYPE_L4_IPV4_UDP]   = XDP_RSS_TYPE_L4_IPV4_UDP,
> > +    [RSS_TYPE_L4_IPV4_IPSEC] = XDP_RSS_TYPE_L4_IPV4_IPSEC,
> > +    [RSS_TYPE_L3_IPV6]       = XDP_RSS_TYPE_L3_IPV6,
> > +    [RSS_TYPE_L4_IPV6_TCP]   = XDP_RSS_TYPE_L4_IPV6_TCP,
> > +    [RSS_TYPE_L4_IPV6_UDP]   = XDP_RSS_TYPE_L4_IPV6_UDP,
> > +    [RSS_TYPE_L4_IPV6_IPSEC] = XDP_RSS_TYPE_L4_IPV6_IPSEC,
> > +    [12]                     = XDP_RSS_TYPE_NONE, /* Implicit zero */
> > +    [13]                     = XDP_RSS_TYPE_NONE, /* Implicit zero */
> > +    [14]                     = XDP_RSS_TYPE_NONE, /* Implicit zero */
> > +    [15]                     = XDP_RSS_TYPE_NONE, /* Implicit zero */
> > +};
> 
> > drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c:198:3: warning: symbol 'mlx5_rss_hash_type' was not declared. Should it be static?
> > 
> > ...
> > 
>