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Message-ID: <CACLfguXp+bLbYTSvc7u+tKob92gBvarD6nBZ6h38MAKSwy-4Dw@mail.gmail.com>
Date: Mon, 19 Jan 2026 10:13:03 +0800
From: Cindy Lu <lulu@...hat.com>
To: Simon Horman <horms@...nel.org>
Cc: mst@...hat.com, jasowang@...hat.com, dtatulea@...dia.com,
virtualization@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
kvm@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: [PATCH v2 2/3] vdpa/mlx5: reuse common function for MAC address updates
On Wed, Jan 7, 2026 at 8:32 PM Simon Horman <horms@...nel.org> wrote:
>
> On Mon, Dec 29, 2025 at 03:16:13PM +0800, Cindy Lu 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>
> > ---
> > drivers/vdpa/mlx5/net/mlx5_vnet.c | 95 +++++++++++++++++--------------
> > 1 file changed, 53 insertions(+), 42 deletions(-)
> >
> > diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> > index 6e42bae7c9a1..c87e6395b060 100644
> > --- a/drivers/vdpa/mlx5/net/mlx5_vnet.c
> > +++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> > @@ -2125,62 +2125,48 @@ 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_new_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];
> > -
> > - 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 (!memcmp(ndev->config.mac, mac, 6)) {
> > - status = VIRTIO_NET_OK;
> > - break;
> > - }
> > + struct mlx5_vdpa_dev *mvdev = &ndev->mvdev;
> > + u8 old_mac[ETH_ALEN];
> >
> > - if (is_zero_ether_addr(mac))
> > - break;
> > + if (is_zero_ether_addr(new_mac))
> > + return -EINVAL;
> >
> > - 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;
> > - }
> > + 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 (mlx5_mpfs_add_mac(pfmdev, mac)) {
> > - mlx5_vdpa_warn(mvdev, "failed to insert new MAC %pM into MPFS table\n",
> > - 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;
> > + }
> >
> > /* backup the original mac address so that if failed to add the forward rules
> > * we could restore it
> > */
> > - memcpy(mac_back, ndev->config.mac, ETH_ALEN);
> > + memcpy(old_mac, ndev->config.mac, ETH_ALEN);
> >
> > - memcpy(ndev->config.mac, mac, ETH_ALEN);
> > + memcpy(ndev->config.mac, new_mac, ETH_ALEN);
>
> ...
>
> Hi Cindy,
>
> I realise that this makes the diffstat significantly more verbose.
> And hides material changes. So perhaps there is a nicer way to do this.
>
> But with the current arrangement of this patch, I think that
> the indentation from just above, until the end of this function
> needs to be updated.
>
> I.e. the following incremental patch on top of this one.
>
> This was flagged by Smatch.
>
> diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> index c87e6395b060..c796f502b604 100644
> --- a/drivers/vdpa/mlx5/net/mlx5_vnet.c
> +++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> @@ -2149,48 +2149,48 @@ static int mlx5_vdpa_change_new_mac(struct mlx5_vdpa_net *ndev,
> return -EIO;
> }
>
> - /* 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);
> + /* 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);
>
> - memcpy(ndev->config.mac, new_mac, ETH_ALEN);
> + memcpy(ndev->config.mac, new_mac, ETH_ALEN);
>
> - /* Need recreate the flow table entry, so that the packet could forward back
> - */
> - mac_vlan_del(ndev, old_mac, 0, false);
> + /* Need recreate the flow table entry, so that the packet could forward back
> + */
> + mac_vlan_del(ndev, old_mac, 0, false);
>
> - if (mac_vlan_add(ndev, ndev->config.mac, 0, false)) {
> - mlx5_vdpa_warn(mvdev, "failed to insert forward rules, try to restore\n");
> + if (mac_vlan_add(ndev, ndev->config.mac, 0, false)) {
> + mlx5_vdpa_warn(mvdev, "failed to insert forward rules, try to restore\n");
>
> - /* Although it hardly run here, we still need double check */
> - if (is_zero_ether_addr(old_mac)) {
> - mlx5_vdpa_warn(mvdev, "restore mac failed: Original MAC is zero\n");
> - return -EIO;
> - }
> + /* Although it hardly run here, we still need double check */
> + if (is_zero_ether_addr(old_mac)) {
> + mlx5_vdpa_warn(mvdev, "restore mac failed: Original MAC is zero\n");
> + return -EIO;
> + }
>
> - /* Try to restore original mac address to MFPS table, and try to restore
> - * the forward rule entry.
> - */
> - if (mlx5_mpfs_del_mac(pfmdev, ndev->config.mac)) {
> - mlx5_vdpa_warn(mvdev, "restore mac failed: delete MAC %pM from MPFS table failed\n",
> - ndev->config.mac);
> - }
> + /* Try to restore original mac address to MFPS table, and try to restore
> + * the forward rule entry.
> + */
> + if (mlx5_mpfs_del_mac(pfmdev, ndev->config.mac)) {
> + mlx5_vdpa_warn(mvdev, "restore mac failed: delete MAC %pM from MPFS table failed\n",
> + ndev->config.mac);
> + }
>
> - if (mlx5_mpfs_add_mac(pfmdev, old_mac)) {
> - mlx5_vdpa_warn(mvdev, "restore mac failed: insert old MAC %pM into MPFS table failed\n",
> - old_mac);
> - }
> + if (mlx5_mpfs_add_mac(pfmdev, old_mac)) {
> + mlx5_vdpa_warn(mvdev, "restore mac failed: insert old MAC %pM into MPFS table failed\n",
> + old_mac);
> + }
>
> - memcpy(ndev->config.mac, old_mac, ETH_ALEN);
> + memcpy(ndev->config.mac, old_mac, ETH_ALEN);
>
> - if (mac_vlan_add(ndev, ndev->config.mac, 0, false))
> - mlx5_vdpa_warn(mvdev, "restore forward rules failed: insert forward rules failed\n");
> + if (mac_vlan_add(ndev, ndev->config.mac, 0, false))
> + mlx5_vdpa_warn(mvdev, "restore forward rules failed: insert forward rules failed\n");
>
> - return -EIO;
> - }
> + return -EIO;
> + }
>
> - return 0;
> + return 0;
> }
>
> static virtio_net_ctrl_ack handle_ctrl_mac(struct mlx5_vdpa_dev *mvdev, u8 cmd)
>
Thanks Simon, will change this
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