Re: [PATCH v1] net/mlx5: Add support for configuring max device MTU

From: "Michael S. Tsirkin" <mst@redhat.com>
To: Eli Cohen <elic@nvidia.com>
Cc: lvivier@redhat.com, virtualization@lists.linux-foundation.org,
	eperezma@redhat.com, Si-Wei Liu <si-wei.liu@oracle.com>
Subject: Re: [PATCH v1] net/mlx5: Add support for configuring max device MTU
Date: Mon, 28 Mar 2022 16:57:22 -0400	[thread overview]
Message-ID: <20220328165657-mutt-send-email-mst@kernel.org> (raw)
In-Reply-To: <20220221121927.194728-1-elic@nvidia.com>

On Mon, Feb 21, 2022 at 02:19:27PM +0200, Eli Cohen wrote:
> Allow an admin creating a vdpa device to specify the max MTU for the
> net device.
> 
> For example, to create a device with max MTU of 1000, the following
> command can be used:
> 
> $ vdpa dev add name vdpa-a mgmtdev auxiliary/mlx5_core.sf.1 mtu 1000
> 
> This configuration mechanism assumes that vdpa is the sole real user of
> the function. mlx5_core could theoretically change the mtu of the
> function using the ip command on the mlx5_core net device but this
> should not be done.
> 
> Reviewed-by: Si-Wei Liu<si-wei.liu@oracle.com>

missing space before <

> Signed-off-by: Eli Cohen <elic@nvidia.com>
> ---
> v0 -> v1:
> Update changelog

can you rebase pls? does not seem to apply

>  drivers/vdpa/mlx5/net/mlx5_vnet.c | 32 ++++++++++++++++++++++++++++++-
>  1 file changed, 31 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> index 6156cf6e9377..be095dc1134e 100644
> --- a/drivers/vdpa/mlx5/net/mlx5_vnet.c
> +++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> @@ -2689,6 +2689,28 @@ static int event_handler(struct notifier_block *nb, unsigned long event, void *p
>  	return ret;
>  }
>  
> +static int config_func_mtu(struct mlx5_core_dev *mdev, u16 mtu)
> +{
> +	int inlen = MLX5_ST_SZ_BYTES(modify_nic_vport_context_in);
> +	void *in;
> +	int err;
> +
> +	in = kvzalloc(inlen, GFP_KERNEL);
> +	if (!in)
> +		return -ENOMEM;
> +
> +	MLX5_SET(modify_nic_vport_context_in, in, field_select.mtu, 1);
> +	MLX5_SET(modify_nic_vport_context_in, in, nic_vport_context.mtu,
> +		 mtu + MLX5V_ETH_HARD_MTU);
> +	MLX5_SET(modify_nic_vport_context_in, in, opcode,
> +		 MLX5_CMD_OP_MODIFY_NIC_VPORT_CONTEXT);
> +
> +	err = mlx5_cmd_exec_in(mdev, modify_nic_vport_context, in);
> +
> +	kvfree(in);
> +	return err;
> +}
> +
>  static int mlx5_vdpa_dev_add(struct vdpa_mgmt_dev *v_mdev, const char *name,
>  			     const struct vdpa_dev_set_config *add_config)
>  {
> @@ -2749,6 +2771,13 @@ static int mlx5_vdpa_dev_add(struct vdpa_mgmt_dev *v_mdev, const char *name,
>  	mutex_init(&ndev->reslock);
>  	mutex_init(&ndev->numq_lock);
>  	config = &ndev->config;
> +
> +	if (add_config->mask & BIT_ULL(VDPA_ATTR_DEV_NET_CFG_MTU)) {
> +		err = config_func_mtu(mdev, add_config->net.mtu);
> +		if (err)
> +			goto err_mtu;
> +	}
> +
>  	err = query_mtu(mdev, &mtu);
>  	if (err)
>  		goto err_mtu;
> @@ -2867,7 +2896,8 @@ static int mlx5v_probe(struct auxiliary_device *adev,
>  	mgtdev->mgtdev.device = mdev->device;
>  	mgtdev->mgtdev.id_table = id_table;
>  	mgtdev->mgtdev.config_attr_mask = BIT_ULL(VDPA_ATTR_DEV_NET_CFG_MACADDR) |
> -					  BIT_ULL(VDPA_ATTR_DEV_NET_CFG_MAX_VQP);
> +					  BIT_ULL(VDPA_ATTR_DEV_NET_CFG_MAX_VQP) |
> +					  BIT_ULL(VDPA_ATTR_DEV_NET_CFG_MTU);
>  	mgtdev->mgtdev.max_supported_vqs =
>  		MLX5_CAP_DEV_VDPA_EMULATION(mdev, max_num_virtio_queues) + 1;
>  	mgtdev->mgtdev.supported_features = get_supported_features(mdev);
> -- 
> 2.35.1

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