Re: [Intel-wired-lan] [PATCH net v1] iavf: Fix max_rate limiting

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

On 6/6/2022 8:35 AM, Jun Zhang wrote:
> Fix max_rate option in tc, check for proper quanta boundaries.
> Check for minimum value provided and if it fits expected 50Mbps
> quanta.
> 
> Without this patch, iavf could send settings for max_rate limiting
> that would be accepted from by PF even the max_rate option is less
> than expected 50Mbps quanta. It results in no rate limiting
> on traffic as rate limiting will be floored to 0.
> 
> Example:
> tc qdisc add dev $vf root mqprio num_tc 3 map 0 2 1 queues \
> 2@0 2@2 2@4 hw 1 mode channel shaper bw_rlimit \
> max_rate 50Mbps 500Mbps 500Mbps
> 
> Should limit TC0 to circa 50 Mbps
> 
> tc qdisc add dev $vf root mqprio num_tc 3 map 0 2 1 queues \
> 2@0 2@2 2@4 hw 1 mode channel shaper bw_rlimit \
> max_rate 0Mbps 100Kbit 500Mbps
> 
> Should return error
> 
> Fixes: d5b33d024496 ("i40evf: add ndo_setup_tc callback to i40evf")
> Signed-off-by: Przemyslaw Patynowski <przemyslawx.patynowski@intel.com>
> Signed-off-by: Jun Zhang <xuejun.zhang@intel.com>

Who is the author for this? If it's Jun, your name needs to be first. If 
it's Przemyslaw, the author needs to be fixed on the patch.

> ---
>   drivers/net/ethernet/intel/iavf/iavf.h      |  1 +
>   drivers/net/ethernet/intel/iavf/iavf_main.c | 24 +++++++++++++++++++--
>   2 files changed, 23 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/ethernet/intel/iavf/iavf.h b/drivers/net/ethernet/intel/iavf/iavf.h
> index fda1198d2c00..0bd516ecebef 100644
> --- a/drivers/net/ethernet/intel/iavf/iavf.h
> +++ b/drivers/net/ethernet/intel/iavf/iavf.h
> @@ -93,6 +93,7 @@ struct iavf_vsi {
>   #define IAVF_HKEY_ARRAY_SIZE ((IAVF_VFQF_HKEY_MAX_INDEX + 1) * 4)
>   #define IAVF_HLUT_ARRAY_SIZE ((IAVF_VFQF_HLUT_MAX_INDEX + 1) * 4)
>   #define IAVF_MBPS_DIVISOR	125000 /* divisor to convert to Mbps */
> +#define IAVF_MBPS_QUANTA	50
>   
>   #define IAVF_VIRTCHNL_VF_RESOURCE_SIZE (sizeof(struct virtchnl_vf_resource) + \
>   					(IAVF_MAX_VF_VSI * \
> diff --git a/drivers/net/ethernet/intel/iavf/iavf_main.c b/drivers/net/ethernet/intel/iavf/iavf_main.c
> index 57c51a15bcbc..27a39d86268d 100644
> --- a/drivers/net/ethernet/intel/iavf/iavf_main.c
> +++ b/drivers/net/ethernet/intel/iavf/iavf_main.c
> @@ -3411,6 +3411,7 @@ static int iavf_validate_ch_config(struct iavf_adapter *adapter,
>   	u64 total_max_rate = 0;
>   	int i, num_qps = 0;
>   	u64 tx_rate = 0;
> +	u32 tx_rate_rem = 0;

nit: Please arrange as RCT.

>   	int ret = 0;
>   
>   	if (mqprio_qopt->qopt.num_tc > IAVF_MAX_TRAFFIC_CLASS ||
> @@ -3423,12 +3424,31 @@ static int iavf_validate_ch_config(struct iavf_adapter *adapter,
>   			return -EINVAL;
>   		if (mqprio_qopt->min_rate[i]) {
>   			dev_err(&adapter->pdev->dev,
> -				"Invalid min tx rate (greater than 0) specified\n");
> +				"Invalid min tx rate (greater than 0) specified for TC%d\n", i);
>   			return -EINVAL;
>   		}
> -		/*convert to Mbps */
> +
> +		/* convert to Mbps */
>   		tx_rate = div_u64(mqprio_qopt->max_rate[i],
>   				  IAVF_MBPS_DIVISOR);
> +
> +		if (mqprio_qopt->max_rate[i] &&
> +		    tx_rate < IAVF_MBPS_QUANTA) {
> +			dev_err(&adapter->pdev->dev,
> +				"Invalid max tx rate for TC%d, minimum %dMbps\n",
> +				i, IAVF_MBPS_QUANTA);
> +			return -EINVAL;
> +		}
> +
> +		(void)div_u64_rem(tx_rate, IAVF_MBPS_QUANTA, &tx_rate_rem); > +
> +		if (tx_rate_rem != 0) {

I believe the preference is
if(tx_rate_rem) {...

> +			dev_err(&adapter->pdev->dev,
> +				"Invalid max tx rate for TC%d, not divisible by %d\n",
> +				i, IAVF_MBPS_QUANTA);
> +			return -EINVAL;
> +		}
> +
>   		total_max_rate += tx_rate;
>   		num_qps += mqprio_qopt->qopt.count[i];
>   	}
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