Subject: Re: [PATCH mlx5-next] RDMA/mlx5: Enable multiplane mode only when it is supported

From: Leon Romanovsky <[email-masked]>
Date: Thu, 19 Dec 2024 16:01:40 +0200

On Thu, Dec 19, 2024 at 02:23:04PM +0100, Michal Swiatkowski wrote:
> On Thu, Dec 19, 2024 at 02:23:36PM +0200, Leon Romanovsky wrote:
> > From: Mark Zhang <[email-masked]>
> > 
> > Driver queries vport_cxt.num_plane and enables multiplane when it is
> > greater then 0, but some old FWs (versions from x.40.1000 till x.42.1000),
> > report vport_cxt.num_plane = 1 unexpectedly.
> > 
> > Fix it by querying num_plane only when HCA_CAP2.multiplane bit is set.
> > 
> > Fixes: 2a5db20fa532 ("RDMA/mlx5: Add support to multi-plane device and port")
> > Cc: [email-masked]
> > Reported-by: Francesco Poli <[email-masked]>
> > Closes: https://lore.kernel.org/all/nvs4i2v7o6vn6zhmtq4sgazy2hu5kiulukxcntdelggmznnl7h@so3oul6uwgbl/
> > Signed-off-by: Mark Zhang <[email-masked]>
> > Signed-off-by: Leon Romanovsky <[email-masked]>
> > ---
> >  drivers/infiniband/hw/mlx5/main.c | 2 +-
> >  include/linux/mlx5/mlx5_ifc.h     | 4 +++-
> >  2 files changed, 4 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/infiniband/hw/mlx5/main.c b/drivers/infiniband/hw/mlx5/main.c
> > index c2314797afc9..f5b59d02f4d3 100644
> > --- a/drivers/infiniband/hw/mlx5/main.c
> > +++ b/drivers/infiniband/hw/mlx5/main.c
> > @@ -2839,7 +2839,7 @@ static int mlx5_ib_get_plane_num(struct mlx5_core_dev *mdev, u8 *num_plane)
> >  	int err;
> >  
> >  	*num_plane = 0;
> > -	if (!MLX5_CAP_GEN(mdev, ib_virt))
> > +	if (!MLX5_CAP_GEN(mdev, ib_virt) || !MLX5_CAP_GEN_2(mdev, multiplane))
> >  		return 0;
> >  
> >  	err = mlx5_query_hca_vport_context(mdev, 0, 1, 0, &vport_ctx);
> > diff --git a/include/linux/mlx5/mlx5_ifc.h b/include/linux/mlx5/mlx5_ifc.h
> > index 4fbbcf35498b..48d47181c7cd 100644
> > --- a/include/linux/mlx5/mlx5_ifc.h
> > +++ b/include/linux/mlx5/mlx5_ifc.h
> > @@ -2119,7 +2119,9 @@ struct mlx5_ifc_cmd_hca_cap_2_bits {
> >  	u8	   migration_in_chunks[0x1];
> >  	u8	   reserved_at_d1[0x1];
> >  	u8	   sf_eq_usage[0x1];
> > -	u8	   reserved_at_d3[0xd];
> > +	u8	   reserved_at_d3[0x5];
> > +	u8	   multiplane[0x1];
> > +	u8	   reserved_at_d9[0x7];
> >  
> >  	u8	   cross_vhca_object_to_object_supported[0x20];
> 
> Reviewed-by: Michal Swiatkowski <[email-masked]>
> 
> Just out of curiosity, don't you have mlx5-net or sth like that for
> fixes?

No, we don't have such as it is so rare situation that we have fix for
shared branch. I wrote here mlx5-next target because this patch changes
the shared mlx5_ifc.h file and for the visibility, but it doesn't affect
mlx5 eth devices.

Most likely, we will end taking this patch directly to rdma-rc and sending
as part of usual PR to Linus.

Thanks

> > -- 
> > 2.47.0