Re: [PATCH net-next 6/6] net/mlx5e: Properly match IPsec subnet addresses

[Leon Romanovsky]

On Tue, Mar 04, 2025 at 08:50:46AM +0100, Michal Swiatkowski wrote:
> On Wed, Feb 26, 2025 at 01:47:52PM +0200, Tariq Toukan wrote:
> > From: Leon Romanovsky <leonro@xxxxxxxxxx>
> > 
> > Existing match criteria didn't allow to match whole subnet and
> > only by specific addresses only. This caused to tunnel mode do not
> > forward such traffic through relevant SA.
> > 
> > In tunnel mode, policies look like this:
> > src 192.169.0.0/16 dst 192.169.0.0/16
> >         dir out priority 383615 ptype main
> >         tmpl src 192.169.101.2 dst 192.169.101.1
> >                 proto esp spi 0xc5141c18 reqid 1 mode tunnel
> >         crypto offload parameters: dev eth2 mode packet
> > 
> > In this case, the XFRM core code handled all subnet calculations and
> > forwarded network address to the drivers e.g. 192.169.0.0.
> > 
> > For mlx5 devices, there is a need to set relevant prefix e.g. 0xFFFF00
> > to perform flow steering match operation.
> > 
> > Signed-off-by: Leon Romanovsky <leonro@xxxxxxxxxx>
> > Signed-off-by: Tariq Toukan <tariqt@xxxxxxxxxx>
> > ---
> >  .../mellanox/mlx5/core/en_accel/ipsec.c       | 49 +++++++++++++++++++
> >  .../mellanox/mlx5/core/en_accel/ipsec.h       |  9 +++-
> >  .../mellanox/mlx5/core/en_accel/ipsec_fs.c    | 20 +++++---
> >  3 files changed, 69 insertions(+), 9 deletions(-)
> > 
> 
> [...]
> 
> >  
> > +static __be32 word_to_mask(int prefix)
> > +{
> > +	if (prefix < 0)
> > +		return 0;
> > +
> > +	if (!prefix || prefix > 31)
> > +		return cpu_to_be32(0xFFFFFFFF);
> > +
> > +	return cpu_to_be32(((1U << prefix) - 1) << (32 - prefix));
> 
> Isn't it GENMASK(31, 32 - prefix)? I don't know if it is preferable to
> use this macro in such place.

GENMASK(a, b) expects "b" to be const type, see
#define GENMASK_INPUT_CHECK(h, l) BUILD_BUG_ON_ZERO(const_true((l) > (h)))

Thanks