[Intel-wired-lan] [PATCH v2] i40e: avoid redundant VF link state updates

[Romanowski, Rafal]

> -----Original Message-----
> From: Intel-wired-lan <intel-wired-lan-bounces at osuosl.org> On Behalf Of
> Robert Malz
> Sent: Wednesday, October 22, 2025 6:12 PM
> To: intel-wired-lan at lists.osuosl.org; netdev at vger.kernel.org
> Cc: Jamie Bainbridge <jamie.bainbridge at gmail.com>; Michal Swiatkowski
> <michal.swiatkowski at linux.intel.com>; Dennis Chen <dechen at redhat.com>;
> Robert Malz <robert.malz at canonical.com>; Kitszel, Przemyslaw
> <przemyslaw.kitszel at intel.com>; Czapnik, Lukasz
> <lukasz.czapnik at intel.com>; Loktionov, Aleksandr
> <aleksandr.loktionov at intel.com>; Andrew Lunn <andrew+netdev at lunn.ch>;
> Eric Dumazet <edumazet at google.com>; Nguyen, Anthony L
> <anthony.l.nguyen at intel.com>; Simon Horman <horms at kernel.org>; Keller,
> Jacob E <jacob.e.keller at intel.com>; Jakub Kicinski <kuba at kernel.org>; Paolo
> Abeni <pabeni at redhat.com>; David S . Miller <davem at davemloft.net>
> Subject: [Intel-wired-lan] [PATCH v2] i40e: avoid redundant VF link state
> updates
> 
> From: Jay Vosburgh <jay.vosburgh at canonical.com>
> 
> 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 <robert.malz at canonical.com>
> Signed-off-by: Robert Malz <robert.malz at canonical.com>
> Signed-off-by: Jay Vosburgh <jay.vosburgh at canonical.com>
> 
> ---
> 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(+)
> 

Tested-by: Rafal Romanowski <rafal.romanowski at intel.com>