Re: [dpdk-dev] [PATCH] vdpa/mlx5: fix the compatibility with MISC4

[Bing Zhao <bingz@mellanox.com>]

Thanks a lot.

BR. Bing

> -----Original Message-----
> From: Maxime Coquelin <maxime.coquelin@redhat.com>
> Sent: Tuesday, July 28, 2020 3:15 PM
> To: Bing Zhao <bingz@mellanox.com>; Slava Ovsiienko
> <viacheslavo@mellanox.com>; Matan Azrad <matan@mellanox.com>
> Cc: dev@dpdk.org
> Subject: Re: [dpdk-dev] [PATCH] vdpa/mlx5: fix the compatibility with
> MISC4
> 
> 
> 
> On 7/21/20 10:13 AM, Bing Zhao wrote:
> > When dynamic flex parser feature is introduced, the support for misc
> > parameters 4 of flow table entry (FTE) match set is needed. The
> > structure of "mlx5_ifc_fte_match_param_bits" is extended with
> > "mlx5_ifc_fte_match_set_misc4_bits" at the end of it. The total size
> > of the FTE match set will be changed into 384 bytes from 320 bytes.
> > Low level user space driver (rdma-core) will have the validation of
> > the length of FTE match set. In the old release that no MISC4
> > supported in the rdma-core, and this will break the backward
> > compatibility, even if the MISC4 is not used in most cases, like in
> > vDPA driver.
> > In order not to break the compatibility old rdma-core, the length
> > adjustment needs to be done. In mlx5 vDPA driver, the lengths of
> the
> > matcher and value are both set to 320 without MISC4. There is no
> need
> > to change the structure definition, all bytes of the MISC4 will be
> > discarded if it is not needed. Since the MISC4 parameter is aligned
> > with a 64B boundary and so does the whole FTE match set parameter,
> > there is no need to take any padding and alignment into
> consideration
> > when calculating the size.
> >
> > Fixes: 32132fb8517c ("net/mlx5: add flow translation of eCPRI
> header")
> >
> > Signed-off-by: Bing Zhao <bingz@mellanox.com>
> > Acked-by: Matan Azrad <matan@mellanox.com>
> > ---
> >  drivers/vdpa/mlx5/mlx5_vdpa_steer.c | 6 ++++--
> >  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>
> 
> Thanks,
> Maxime