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

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential
issue to consider:
- [Medium] gve: gve_verify_xdp_configuration() fails to reject
  GVE_GQI_RDA_FORMAT
--

commit effd5965643e22a2856ad20f55eafb8449ee0b34
Author: Amaan Cheval <amaan.cheval@gmail.com>

gve: block XDP on the DQO-QPL queue format

This commit rejects XDP program attachment on the GVE_DQO_QPL_FORMAT
queue format in gve_verify_xdp_configuration().

> diff --git a/drivers/net/ethernet/google/gve/gve_main.c b/drivers/net/ethernet/google/gve/gve_main.c
> index 2437cd8ba6331..4e9e692a0ed0a 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) {
> +		NL_SET_ERR_MSG_MOD(extack,
> +				   "XDP is not supported in DQO QPL queue format.");
> +		return -EOPNOTSUPP;
> +	}

[Severity: Medium]
Should gve_verify_xdp_configuration() also reject GVE_GQI_RDA_FORMAT (or
any queue format other than GVE_GQI_QPL_FORMAT and GVE_DQO_RDA_FORMAT)?

Before d8a8ca14c937 ("gve: add XDP_TX and XDP_REDIRECT support for DQ
RDA"), verify_xdp_configuration() rejected every queue format except
GVE_GQI_QPL_FORMAT, and gve_set_netdev_xdp_features() only advertises XDP
features on GVE_GQI_QPL_FORMAT and GVE_DQO_RDA_FORMAT.

With only GVE_DQO_QPL_FORMAT blocked here, attaching an XDP program on a
running GVE_GQI_RDA_FORMAT interface passes validation and enters
gve_set_xdp() -> gve_configure_rings_xdp() -> gve_adjust_config(). After
gve_close() tears down the existing queues, gve_queues_start() ->
gve_reg_xdp_info() takes the !gve_is_qpl(priv) branch:

drivers/net/ethernet/google/gve/gve_main.c:gve_reg_xdp_info() {
	...
		else if (gve_is_qpl(priv))
			err = xdp_rxq_info_reg_mem_model(&rx->xdp_rxq,
							 MEM_TYPE_PAGE_SHARED,
							 NULL);
		else
			err = xdp_rxq_info_reg_mem_model(&rx->xdp_rxq,
							 MEM_TYPE_PAGE_POOL,
							 rx->dqo.page_pool);
	...
}

Because GQI rings do not allocate rx->dqo.page_pool,
xdp_rxq_info_reg_mem_model() returns -EINVAL, causing gve_adjust_config()
to call gve_queues_mem_remove() and leave the interface with all queues
disabled and priv->tx_cfg.num_xdp_queues non-zero so subsequent
gve_open() calls also fail.

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261106114551.212675-1-amaan.cheval@gmail.com?part=1