Subject: Re: [PATCH rdma-next 0/8] User space steering

From: Leon Romanovsky <[email-masked]>
Date: Mon, 1 Apr 2019 09:28:16 +0300

On Sun, Mar 31, 2019 at 02:06:33PM -0700, Jakub Kicinski wrote:
> On Sun, 31 Mar 2019 19:44:42 +0300, Leon Romanovsky wrote:
> > From: Leon Romanovsky <[email-masked]>
> >
> > From Ariel,
> >
> > This series of patches adds user space managed steering infrastructure
> > to the mlx5_ib driver.
> >
> > User space managed steering requires the means to access a dedicated
> > memory space that is used by the device to store the packet steering
> > and header modification tables and rules in order to manage them directly
> > without the device's firmware involvement. This dedicated memory is part
> > of the ICM memory space.
> >
> > The changes are introducing the mlx5_ib API to allocate, deallocate and
> > register this dedicated SW ICM memory via the existing device memory API
> > using a private attribute which specifies the memory type.
> >
> > The allocated memory itself is not IO mapped and user can only access it
> > using remote RDMA operations.
> >
> > In addition, the series exposed the ICM address of the receive transport
> > interface (TIR) of Raw Packet and RSS QPs to user since they are required
> > to properly create and insert steering rules that direct flows to these QPs.
>
> Hi Leon!  Out of curiosity what protocols are you guys steering here?
> Is this some form of RoCE or IB?  Is there a good resource to read up on
> the DEVX stuff? (I presume this series is related?)

mlx5 devices steering operates on packets without relation to specific
protocol. The decision to steer is based on HW capabilities and user
configuration for matching specific fields. Such configuration is done
through kernel and through DEVX.

General description of DEVX can be found in manuals of libmlx5.
https://github.com/linux-rdma/rdma-core/blob/master/providers/mlx5/man/mlx5dv_devx_obj_create.3.md
https://github.com/linux-rdma/rdma-core/blob/master/providers/mlx5/man/

Thanks