RE: [EXTERNAL] [PATCH v2 1/2] crypto/mlx5: optimize AES-GCM IPsec operation

[Suanming Mou <suanmingm@nvidia.com>]

> -----Original Message-----
> From: Akhil Goyal <gakhil@marvell.com>
> Sent: Monday, June 24, 2024 4:45 PM
> To: Suanming Mou <suanmingm@nvidia.com>; Matan Azrad
> <matan@nvidia.com>
> Cc: dev@dpdk.org
> Subject: RE: [EXTERNAL] [PATCH v2 1/2] crypto/mlx5: optimize AES-GCM
> IPsec operation
> 
> > > Subject: RE: [EXTERNAL] [PATCH v2 1/2] crypto/mlx5: optimize AES-GCM
> > > IPsec operation
> > >
> > > > Just to be more accurate, in fact our current PMD has supported
> > > > IPsec already via UMR's way. This series is an optimization, not
> > > > newly supporting IPsec, but to optimize the IPsec input case.
> > > > And like I replied above, it is not the patches invites the layout
> > > > and require user to have such buffers, but the truth is we want to
> > > > better serve the IPsec input come with that layout case in the
> > > > real world as API
> > > does not reject that IPsec input.
> > >
> > > Ok got it.
> > >
> > > But if we set the devarg for a mlx5 device, it will be a hint to the
> > > PMD for all the flows that it will process. Right?
> >
> > Yes, right. If the devarg is set, means user knows he only has that
> > IPsec inputs for all the flows.
> > If not, user will not set that devarg.
> >
> > >
> > > And there may be an application use case where it has 2 separate
> > > flows simultaneously - IPsec and non-IPsec.
> > >
> > > Then how would PMD handle that?
> > > Will it assume contiguous memory for non-IPsec case as well?
> > > How will PMD identify between IPsec and non-IPsec case?
> >
> > In that case, user will not set the devarg, PMD will always use UMR
> > WQE to build contiguous memory address space for HW. No matter it is
> IPsec or non-IPsec.
> >
> > Background: UMR WQE is a powerful WQE can generate new contiguous
> new
> > address space with several inputs. e.g.:
> > If we have 3 non-contiguous inputs addr_a, addr_b, addr_c, UMR WQE can
> > generate a new addr_d with these 3 memory address space combined.
> > The only disadvantage is that UMR WQE is a bit heavy for using in the
> > simple IPsec case. So we add that small optimization if user only use IPsec
> as inputs.
> >
> I do not see this limitation added in the documentation of the devarg/ PMD.
> 
> Please update documentation to remove this confusion.

Sure, will update.