linux-kernel - Re: [PATCH 2/2] vdpa: Add support to update speed/duplex in vDPA/mlx5

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Message-ID: <CACGkMEtsNeL+o6Rgb=ehj8OJpfkoojasPK1ZMp4S5bMKBjwcng@mail.gmail.com>
Date: Mon, 2 Sep 2024 12:27:50 +0800
From: Jason Wang <jasowang@...hat.com>
To: Carlos Bilbao <cbilbao@...italocean.com>
Cc: Dragos Tatulea <dtatulea@...dia.com>, Carlos Bilbao <carlos.bilbao.osdev@...il.com>, mst@...hat.com, 
	bilbao@...edu, xuanzhuo@...ux.alibaba.com, eperezma@...hat.com, 
	cratiu@...dia.com, lingshan.zhu@...el.com, virtualization@...ts.linux.dev, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] vdpa: Add support to update speed/duplex in vDPA/mlx5_vnet

On Fri, Aug 30, 2024 at 9:15 PM Carlos Bilbao <cbilbao@...italocean.com> wrote:
>
> Hello,
>
> On 8/29/24 9:31 PM, Jason Wang wrote:
> > On Fri, Aug 30, 2024 at 5:08 AM Dragos Tatulea <dtatulea@...dia.com> wrote:
> >> (resending as I accidentally replied only to Carlos)
> >>
> >> On 29.08.24 18:16, Carlos Bilbao wrote:
> >>> From: Carlos Bilbao <cbilbao@...italocean.com>
> >>>
> >>> Include support to update the vDPA configuration fields of speed and
> >>> duplex (as needed by VHOST_VDPA_SET_CONFIG). This includes function
> >>> mlx5_vdpa_set_config() as well as changes in vdpa.c to fill the initial
> >>> values to UNKNOWN. Also add a warning message for when
> >>> mlx5_vdpa_get_config() receives offset and length out of bounds.
> >>>
> >>> Signed-off-by: Carlos Bilbao <cbilbao@...italocean.com>
> >>> ---
> >>>  drivers/vdpa/mlx5/net/mlx5_vnet.c | 34 ++++++++++++++++++++++++++++++-
> >>>  drivers/vdpa/vdpa.c               | 27 ++++++++++++++++++++++++
> >>>  include/uapi/linux/vdpa.h         |  2 ++
> >>>  3 files changed, 62 insertions(+), 1 deletion(-)
> >>>
> >>> diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> >>> index c47009a8b472..a44bb2072eec 100644
> >>> --- a/drivers/vdpa/mlx5/net/mlx5_vnet.c
> >>> +++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> >>> @@ -3221,12 +3221,44 @@ static void mlx5_vdpa_get_config(struct vdpa_device *vdev, unsigned int offset,
> >>>
> >>>       if (offset + len <= sizeof(struct virtio_net_config))
> >>>               memcpy(buf, (u8 *)&ndev->config + offset, len);
> >>> +     else
> >>> +             mlx5_vdpa_warn(mvdev, "Offset and length out of bounds\n");
> >>>  }
> >>>
> >>>  static void mlx5_vdpa_set_config(struct vdpa_device *vdev, unsigned int offset, const void *buf,
> >>>                                unsigned int len)
> >>>  {
> >>> -     /* not supported */
> >>> +     struct mlx5_vdpa_dev *mvdev = to_mvdev(vdev);
> >>> +     struct mlx5_vdpa_net *ndev = to_mlx5_vdpa_ndev(mvdev);
> >>> +
> >>> +     if (offset + len > sizeof(struct virtio_net_config)) {
> >>> +             mlx5_vdpa_warn(mvdev, "Offset and length out of bounds\n");
> >>> +             return;
> >>> +     }
> >>> +
> >>> +     /*
> >>> +      * Note that this will update the speed/duplex configuration fields
> >>> +      * but the hardware support to actually perform this change does
> >>> +      * not exist yet.
> >>> +      */
> >>> +     switch (offset) {
> >>> +     case offsetof(struct virtio_net_config, speed):
> >>> +             if (len == sizeof(((struct virtio_net_config *) 0)->speed))
> >>> +                     memcpy(&ndev->config.speed, buf, len);
> >>> +             else
> >>> +                     mlx5_vdpa_warn(mvdev, "Invalid length for speed.\n");
> >>> +             break;
> >>> +
> >>> +     case offsetof(struct virtio_net_config, duplex):
> >>> +             if (len == sizeof(((struct virtio_net_config *)0)->duplex))
> >>> +                     memcpy(&ndev->config.duplex, buf, len);
> >>> +             else
> >>> +                     mlx5_vdpa_warn(mvdev, "Invalid length for duplex.\n");
> >>> +             break;
> >>> +
> >>> +     default:
> >>> +             mlx5_vdpa_warn(mvdev, "Configuration field not supported.\n");
> >> This will trigger noise in dmesg because there is a MAC configuration here.
> >>> +     }
> >> I would prefer that the .set_config remains a stub TBH. Setting the fields here is
> >> misleading: the user might deduce that the configuration worked when they read the
> >> values and see that they were updated.
> > Yes, and actually, those fields are read-only according to the spec:
> >
> > """
> > The network device has the following device configuration layout. All
> > of the device configuration fields are read-only for the driver.
> > """
> >
> > Thanks
>
>
> Should I go ahead and remove the ioctl then?

If you meant mlx5_vdpa_set_config, I think yes.

Thanks