> -----Original Message-----
> From: Robert Malz <[email protected]>
> Sent: Wednesday, October 22, 2025 6:12 PM
> To: [email protected]; [email protected]
> Cc: Nguyen, Anthony L <[email protected]>; Kitszel,
> Przemyslaw <[email protected]>; Andrew Lunn
> <[email protected]>; David S . Miller <[email protected]>; Eric
> Dumazet <[email protected]>; Jakub Kicinski <[email protected]>; Paolo
> Abeni <[email protected]>; Simon Horman <[email protected]>; Loktionov,
> Aleksandr <[email protected]>; Czapnik, Lukasz
> <[email protected]>; Robert Malz <[email protected]>;
> Jamie Bainbridge <[email protected]>; Jay Vosburgh
> <[email protected]>; Dennis Chen <[email protected]>; Keller,
> Jacob E <[email protected]>; Michal Swiatkowski
> <[email protected]>
> Subject: [PATCH v2] i40e: avoid redundant VF link state updates
>
> From: Jay Vosburgh <[email protected]>
>
> Multiple sources can request VF link state changes with identical
> parameters. For example, OpenStack Neutron may request to set the VF
> link state to IFLA_VF_LINK_STATE_AUTO during every initialization or
> user can
> issue: `ip link set <ifname> vf 0 state auto` multiple times.
> Currently, the i40e driver processes each of these requests, even if
> the requested state is the same as the current one. This leads to
> unnecessary VF resets and can cause performance degradation or
> instability in the VF driver, particularly in environment using Data
> Plane Development Kit (DPDK).
>
> With this patch i40e will skip VF link state change requests when the
> desired link state matches the current configuration. This prevents
> unnecessary VF resets and reduces PF-VF communication overhead.
>
> To reproduce the problem run following command multiple times on the
> same interface: 'ip link set <ifname> vf 0 state auto'
> Every time command is executed, PF driver will trigger VF reset.
>
> Co-developed-by: Robert Malz <[email protected]>
> Signed-off-by: Robert Malz <[email protected]>
> Signed-off-by: Jay Vosburgh <[email protected]>
>
> ---
> V1 -> V2: updated commit message, added information how to reproduce
>
> drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c | 12 ++++++++++++
> 1 file changed, 12 insertions(+)
>
> diff --git a/drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c
> b/drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c
> index 081a4526a2f0..0fe0d52c796b 100644
> --- a/drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c
> +++ b/drivers/net/ethernet/intel/i40e/i40e_virtchnl_pf.c
> @@ -4788,6 +4788,7 @@ int i40e_ndo_set_vf_link_state(struct net_device
> *netdev, int vf_id, int link)
> unsigned long q_map;
> struct i40e_vf *vf;
> int abs_vf_id;
> + int old_link;
> int ret = 0;
> int tmp;
>
> @@ -4806,6 +4807,17 @@ int i40e_ndo_set_vf_link_state(struct
> net_device *netdev, int vf_id, int link)
> vf = &pf->vf[vf_id];
> abs_vf_id = vf->vf_id + hw->func_caps.vf_base_id;
>
> + /* skip VF link state change if requested state is already set
> */
> + if (!vf->link_forced)
> + old_link = IFLA_VF_LINK_STATE_AUTO;
> + else if (vf->link_up)
> + old_link = IFLA_VF_LINK_STATE_ENABLE;
> + else
> + old_link = IFLA_VF_LINK_STATE_DISABLE;
> +
> + if (link == old_link)
> + goto error_out;
> +
> pfe.event = VIRTCHNL_EVENT_LINK_CHANGE;
> pfe.severity = PF_EVENT_SEVERITY_INFO;
>
> --
> 2.34.1
Reviewed-by: Aleksandr Loktionov <[email protected]>
