linux-kernel - Re: [PATCH v3 2/3] vdpa/mlx5: reuse common function for MAC address updates

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Message-ID: <aW3JstEHDXjj80OL@test-OptiPlex-Tower-Plus-7010>
Date: Mon, 19 Jan 2026 11:35:38 +0530
From: Hariprasad Kelam <hkelam@...vell.com>
To: Cindy Lu <lulu@...hat.com>
CC: <dtatulea@...dia.com>, <mst@...hat.com>, <jasowang@...hat.com>,
        <netdev@...r.kernel.org>, <virtualization@...ts.linux-foundation.org>,
        <linux-kernel@...r.kernel.org>, <kvm@...r.kernel.org>
Subject: Re: [PATCH v3 2/3] vdpa/mlx5: reuse common function for MAC address
 updates

On 2026-01-19 at 11:23:52, Cindy Lu (lulu@...hat.com) wrote:
> Factor out MAC address update logic and reuse it from handle_ctrl_mac().
> 
> This ensures that old MAC entries are removed from the MPFS table
> before adding a new one and that the forwarding rules are updated
> accordingly. If updating the flow table fails, the original MAC and
> rules are restored as much as possible to keep the software and
> hardware state consistent.
> 
> Signed-off-by: Cindy Lu <lulu@...hat.com>
> 
> Reviewed-by: Dragos Tatulea <dtatulea@...dia.com>
> ---
>  drivers/vdpa/mlx5/net/mlx5_vnet.c | 131 ++++++++++++++++--------------
>  1 file changed, 71 insertions(+), 60 deletions(-)
> 
> diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> index 6e42bae7c9a1..7a39843de243 100644
> --- a/drivers/vdpa/mlx5/net/mlx5_vnet.c
> +++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> @@ -2125,86 +2125,97 @@ static void teardown_steering(struct mlx5_vdpa_net *ndev)
>  	mlx5_destroy_flow_table(ndev->rxft);
>  }
>  
> -static virtio_net_ctrl_ack handle_ctrl_mac(struct mlx5_vdpa_dev *mvdev, u8 cmd)
> +static int mlx5_vdpa_change_mac(struct mlx5_vdpa_net *ndev,
> +				struct mlx5_core_dev *pfmdev,
> +				const u8 *new_mac)
>  {
> -	struct mlx5_vdpa_net *ndev = to_mlx5_vdpa_ndev(mvdev);
> -	struct mlx5_control_vq *cvq = &mvdev->cvq;
> -	virtio_net_ctrl_ack status = VIRTIO_NET_ERR;
> -	struct mlx5_core_dev *pfmdev;
> -	size_t read;
> -	u8 mac[ETH_ALEN], mac_back[ETH_ALEN];
> +	struct mlx5_vdpa_dev *mvdev = &ndev->mvdev;
> +	u8 old_mac[ETH_ALEN];
>  
> -	pfmdev = pci_get_drvdata(pci_physfn(mvdev->mdev->pdev));
> -	switch (cmd) {
> -	case VIRTIO_NET_CTRL_MAC_ADDR_SET:
> -		read = vringh_iov_pull_iotlb(&cvq->vring, &cvq->riov, (void *)mac, ETH_ALEN);
> -		if (read != ETH_ALEN)
> -			break;
> +	if (is_zero_ether_addr(new_mac))
> +		return -EINVAL;
>  
> -		if (!memcmp(ndev->config.mac, mac, 6)) {
> -			status = VIRTIO_NET_OK;
> -			break;
> +	if (!is_zero_ether_addr(ndev->config.mac)) {
> +		if (mlx5_mpfs_del_mac(pfmdev, ndev->config.mac)) {
> +			mlx5_vdpa_warn(mvdev, "failed to delete old MAC %pM from MPFS table\n",
> +				       ndev->config.mac);
> +			return -EIO;
>  		}
> +	}
>  
> -		if (is_zero_ether_addr(mac))
> -			break;
> +	if (mlx5_mpfs_add_mac(pfmdev, (u8 *)new_mac)) {
> +		mlx5_vdpa_warn(mvdev, "failed to insert new MAC %pM into MPFS table\n",
> +			       new_mac);
> +		return -EIO;
> +	}
>  
> -		if (!is_zero_ether_addr(ndev->config.mac)) {
> -			if (mlx5_mpfs_del_mac(pfmdev, ndev->config.mac)) {
> -				mlx5_vdpa_warn(mvdev, "failed to delete old MAC %pM from MPFS table\n",
> -					       ndev->config.mac);
> -				break;
> -			}
> -		}
> +	/* backup the original mac address so that if failed to add the forward rules
> +	 * we could restore it
> +	 */
> +	memcpy(old_mac, ndev->config.mac, ETH_ALEN);
        can we use "ether_addr_copy" instead of memcpy?
Thanks,
Hariprasad k