Re: [PATCH iwl-net 10/10] ice: allow setting min_tx_rate to 0 to resolve VF bandwidth oversubscription

[Tony Nguyen <anthony.l.nguyen@intel.com>]

On 4/2/2026 10:40 PM, Aleksandr Loktionov wrote:
> ice_set_vf_bw() refuses to accept any min_tx_rate value when the
> total guaranteed bandwidth is already oversubscribed, even when the
> requested value is 0. This makes it impossible to recover from an
> oversubscribed state via "ip link set <pf> vf <id> min_tx_rate 0".
> 
> Allow a zero min_tx_rate to bypass the oversubscription check so
> users can always clear the guaranteed rate. Additionally print an
> informational message when the oversubscription guard fires to help
> diagnose why a non-zero request was rejected.
> 
> Fixes: 4ecc8633056b ("ice: Add support for VF rate limiting")
> Cc: stable@vger.kernel.org
> Signed-off-by: Sudheer Mogilappagari <sudheer.mogilappagari@intel.com>
> Signed-off-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>
> ---
>   drivers/net/ethernet/intel/ice/ice_sriov.c | 8 +++++++-
>   1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/intel/ice/ice_sriov.c b/drivers/net/ethernet/intel/ice/ice_sriov.c
> index 7e00e09..6e3bec7 100644
> --- a/drivers/net/ethernet/intel/ice/ice_sriov.c
> +++ b/drivers/net/ethernet/intel/ice/ice_sriov.c
> @@ -1507,6 +1507,12 @@ ice_min_tx_rate_oversubscribed(struct ice_vf *vf, int min_tx_rate)
>   	all_vfs_min_tx_rate -= vf->min_tx_rate;
>   
>   	if (all_vfs_min_tx_rate + min_tx_rate > link_speed_mbps) {
> +		if (ice_calc_all_vfs_min_tx_rate(vf->pf) > link_speed_mbps) {

ice_calc_all_vfs_min_tx_rate() is already called above (out of this 
patch context), can we save that to an interim var and save this second 
call?

> +			dev_info(ice_pf_to_dev(vf->pf),
> +				 "The sum of min_tx_rate for all VFs is greater than the link speed\n");
> +			dev_info(ice_pf_to_dev(vf->pf),
> +				 "Set min_tx_rate to 0 on VFs to resolve oversubscription\n");

Why not 1 string/call?

Thanks,
Tony

> +		}
>   		dev_err(ice_pf_to_dev(vf->pf), "min_tx_rate of %d Mbps on VF %u would cause oversubscription of %d Mbps based on the current link speed %d Mbps\n",
>   			min_tx_rate, vf->vf_id,
>   			all_vfs_min_tx_rate + min_tx_rate - link_speed_mbps,
> @@ -1556,7 +1562,7 @@ ice_set_vf_bw(struct net_device *netdev, int vf_id, int min_tx_rate,
>   		goto out_put_vf;
>   	}
>   
> -	if (ice_min_tx_rate_oversubscribed(vf, min_tx_rate)) {
> +	if (min_tx_rate && ice_min_tx_rate_oversubscribed(vf, min_tx_rate)) {
>   		ret = -EINVAL;
>   		goto out_put_vf;
>   	}