RE: [PATCH iwl-net v2 1/2] ice: detach the VF representor when ice_start_vfs() fails

["Loktionov, Aleksandr" <aleksandr.loktionov@intel.com>]

> -----Original Message-----
> From: Linkui Xiao <xiaolinkui@126.com>
> Sent: Monday, September 28, 2026 8:53 AM
> To: Nguyen, Anthony L <anthony.l.nguyen@intel.com>; Kitszel,
> Przemyslaw <przemyslaw.kitszel@intel.com>; andrew+netdev@lunn.ch;
> davem@davemloft.net; edumazet@google.com; kuba@kernel.org;
> pabeni@redhat.com
> Cc: intel-wired-lan@lists.osuosl.org; netdev@vger.kernel.org; linux-
> kernel@vger.kernel.org; Linkui Xiao <xiaolinkui@kylinos.cn>;
> stable@vger.kernel.org
> Subject: [PATCH iwl-net v2 1/2] ice: detach the VF representor when
> ice_start_vfs() fails
> 
> From: Linkui Xiao <xiaolinkui@kylinos.cn>
> 
> ice_start_vfs() attaches every VF it brings up to the eswitch with
> ice_eswitch_attach_vf(), but the teardown path only undoes the queue
> mappings and the VF VSI. Nothing calls ice_eswitch_detach_vf() for the
> VFs that were attached before the failure, and the caller,
> ice_ena_vfs(), goes straight to ice_free_vf_entries(), which drops its
> reference to every VF.
> 
> The port representors created for those VFs therefore outlive the
> failed VF creation:
> 
>   - the representor netdev stays registered and its devlink port stays
>     registered too. That port is embedded in struct ice_vf, so it ends
>     up pointing into the memory that ice_sriov_free_vf() releases;
> 
>   - repr->vf keeps pointing at the freed struct ice_vf, and repr-
> >src_vsi
>     at the VF VSI that ice_vf_vsi_release() tore down. The leftover
>     netdev is still visible to the user, so even a plain
>     "ip -s link show" of it reaches ice_repr_get_stats64(), which
> calls
>     repr->ops.ready() -> ice_check_vf_ready_for_cfg(repr->vf) and then
>     reads repr->src_vsi through ice_update_eth_stats();
> 
>   - the virtchnl ops of that VF, which ice_repr_add_vf() replaced with
>     ice_virtchnl_set_repr_ops(), are never handed back to
>     ice_virtchnl_set_dflt_ops();
> 
>   - pf->eswitch.reprs never becomes empty, so ice_eswitch_detach()
> never
>     calls ice_eswitch_disable_switchdev(). pf->eswitch.is_running
> stays
>     true, with the bridge offloads and the devlink rate topology still
>     up, and ice_eswitch_release_env() is skipped, so the uplink VSI is
>     left in the switchdev configuration that ice_eswitch_setup_env()
>     gave it.
> 
> Detach the representor in the teardown loop the way ice_free_vfs()
> does, ahead of ice_vf_vsi_release(), because ice_repr_rem_vf() and
> ice_eswitch_release_repr() both need repr->src_vsi to still be valid.
> Every VF the teardown loop walks completed ice_eswitch_attach_vf()
> successfully, and ice_eswitch_detach_vf() already returns early for a
> VF without a representor, so no extra condition is needed.
> 
> Hold vf->cfg_lock across the teardown of each VF as well, like
> ice_free_vfs() does. The VFs unwound here are the ones that already
> reached set_bit(ICE_VF_STATE_INIT), which is exactly what
> ice_check_vf_ready_for_cfg() checks, so a host administrator can still
> run "ip link set dev <pf> vf N ..." and a VF can still send a mailbox
> message while the loop walks them. Both paths take cfg_lock and then
> run ice_reset_vf(), which gets to ice_eswitch_update_repr() and writes
> through the representor that is being freed, or reach
> ice_vc_process_vf_msg() reading vf->virtchnl_ops while
> ice_virtchnl_set_dflt_ops() hands them back.
> 
> Fixes: fff292b47ac1 ("ice: add VF representors one by one")
> Cc: stable@vger.kernel.org
> Signed-off-by: Linkui Xiao <xiaolinkui@kylinos.cn>
> ---
> v1:
> - Link: https://lore.kernel.org/netdev/20260921031616.3390259-1-
> xiaolinkui@126.com/
> 
> Changes in v2:
> - Hold vf->cfg_lock across the teardown of each VF, the way
> ice_free_vfs()
>   does, so that a concurrent VF reconfiguration cannot walk through
> the
>   representor and the virtchnl ops that are being torn down.
>   (Sashiko AI review)
> - Patch 2/2 is new and returns the VF MSI-X window that the same
> failure path
>   reserves. That is a separate, pre-existing bug, so it is not folded
> in here.
>   (Sashiko AI review)
> - Not carrying over the Reviewed-by from Aleksandr Loktionov, as the
> code
>   changed after his review.
> 
>  drivers/net/ethernet/intel/ice/ice_sriov.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/net/ethernet/intel/ice/ice_sriov.c
> b/drivers/net/ethernet/intel/ice/ice_sriov.c
> index e04de0215596..95abc6704820 100644
> --- a/drivers/net/ethernet/intel/ice/ice_sriov.c
> +++ b/drivers/net/ethernet/intel/ice/ice_sriov.c
> @@ -508,8 +508,13 @@ static int ice_start_vfs(struct ice_pf *pf)
>  		if (it_cnt == 0)
>  			break;
> 
> +		mutex_lock(&vf->cfg_lock);
> +
> +		ice_eswitch_detach_vf(pf, vf);
>  		ice_dis_vf_mappings(vf);
>  		ice_vf_vsi_release(vf);
> +		mutex_unlock(&vf->cfg_lock);
> +
>  		it_cnt--;
>  	}
> 
> --
> 2.25.1

Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>