Re: [PATCH net v4 1/2] gve: block XDP on the DQO-QPL queue format

[Joshua Washington]

On Fri, Nov 6, 2026 at 3:46 AM Amaan Cheval <amaan.cheval@xxxxxxxxx> wrote:
>
> Commit d8a8ca14c937 ("gve: add XDP_TX and XDP_REDIRECT support for DQ
> RDA") enabled XDP on DQO-RDA by dropping the queue_format check from
> verify_xdp_configuration(), which until then refused every format but
> GQI-QPL. Nothing replaced it for DQO-QPL: gve_set_netdev_xdp_features()
> advertises no XDP features there and gve_xdp_xmit() rejects it, but the
> core only checks that ndo_bpf exists, so a native XDP program, and an
> AF_XDP socket on top of it, can still be attached on DQO-QPL.
>
> The DQO-QPL RX path was never written for that. Its page accounting
> assumes the driver keeps a reference of its own across every handoff:
> gve_xdp_done_dqo() passes the buffer to xdp_do_redirect() and then
> recycles it with gve_reuse_buffer(), so a redirect target that releases
> the buffer synchronously, such as an AF_XDP socket in copy mode, can
> drop the page's last reference when pagecnt_bias runs out. The page is
> then freed while it is still DMA-mapped and registered in the QPL, and
> the driver posts it back to the device.
>
> Refuse XDP program setup on DQO-QPL in gve_verify_xdp_configuration(),
> matching the features the driver advertises. A zero-copy XSK pool bind
> is already refused by the core for the same reason, and a copy-mode
> bind never reaches the driver and is harmless without a program.
>
> Fixes: d8a8ca14c937 ("gve: add XDP_TX and XDP_REDIRECT support for DQ RDA")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Amaan Cheval <amaan.cheval@xxxxxxxxx>
> ---
>  drivers/net/ethernet/google/gve/gve_main.c | 6 ++++++
>  1 file changed, 6 insertions(+)
>
> diff --git a/drivers/net/ethernet/google/gve/gve_main.c b/drivers/net/ethernet/google/gve/gve_main.c
> index 2437cd8ba633..4e9e692a0ed0 100644
> --- a/drivers/net/ethernet/google/gve/gve_main.c
> +++ b/drivers/net/ethernet/google/gve/gve_main.c
> @@ -1723,6 +1723,12 @@ static int gve_verify_xdp_configuration(struct net_device *dev,
>         struct gve_priv *priv = netdev_priv(dev);
>         u16 max_xdp_mtu;
>
> +       if (priv->queue_format == GVE_DQO_QPL_FORMAT) {

Thanks for implementing this!

Minor suggestion: Can we check based on dev->xdp_features
(NETDEV_XDP_ACT_BASIC) instead?

> +               NL_SET_ERR_MSG_MOD(extack,
> +                                  "XDP is not supported in DQO QPL queue format.");
> +               return -EOPNOTSUPP;
> +       }
> +
>         if (dev->features & NETIF_F_GRO_HW) {
>                 NL_SET_ERR_MSG_MOD(extack,
>                                    "XDP is not supported when HW-GRO is on.");
> --
> 2.47.3
>