[Intel-wired-lan] [next-queue RFC 1/4] ethtool: Add support for configuring frame preemption

[Murali Karicheri]

Hi Vinicius,

On 5/15/20 9:29 PM, Vinicius Costa Gomes wrote:
> Frame preemption (described in IEEE 802.3br-2016) defines the concept
> of preemptible and express queues. It allows traffic from express
> queues to "interrupt" traffic from preemptible queues, which are
> "resumed" after the express traffic has finished transmitting.
> 
> Frame preemption can only be used when both the local device and the
> link partner support it.
> 
> A new ethtool command was added to support the configuration
> parameters.
> 
> Signed-off-by: Vinicius Costa Gomes <vinicius.gomes at intel.com>
> ---
>   include/linux/ethtool.h      |  6 ++++++
>   include/uapi/linux/ethtool.h | 25 +++++++++++++++++++++++++
>   net/ethtool/ioctl.c          | 36 ++++++++++++++++++++++++++++++++++++
>   3 files changed, 67 insertions(+)
> 
> diff --git a/include/linux/ethtool.h b/include/linux/ethtool.h
> index a23b26e..e4a6710 100644
> --- a/include/linux/ethtool.h
> +++ b/include/linux/ethtool.h
> @@ -360,6 +360,8 @@ bool ethtool_convert_link_mode_to_legacy_u32(u32 *legacy_u32,
>    * @get_ethtool_phy_stats: Return extended statistics about the PHY device.
>    *	This is only useful if the device maintains PHY statistics and
>    *	cannot use the standard PHY library helpers.
> + * @get_preempt: Get the network device Frame Preemption parameters.
> + * @set_preempt: Set the network device Frame Preemption parameters.
>    *
>    * All operations are optional (i.e. the function pointer may be set
>    * to %NULL) and callers must take this into account.  Callers must
> @@ -454,6 +456,10 @@ struct ethtool_ops {
>   				      struct ethtool_fecparam *);
>   	int	(*set_fecparam)(struct net_device *,
>   				      struct ethtool_fecparam *);
> +	int	(*get_preempt)(struct net_device *,
> +			       struct ethtool_fp *);
> +	int	(*set_preempt)(struct net_device *,
> +			       struct ethtool_fp *);
>   	void	(*get_ethtool_phy_stats)(struct net_device *,
>   					 struct ethtool_stats *, u64 *);

I understand this series for IET Preemption. But want to see if we can
also add EST parameter, queueMaxSDU, that is also configurable.

This is defined as up to 8 entries of queueMaxSDU (unsigned int) defined
in 12.29.1.1,12.29.1.1.1 of 802.1Q 2018 edition. May be
set_queue_max_sdu() with per traffic class queue value as an array
of __u16 values?


>   };
> diff --git a/include/uapi/linux/ethtool.h b/include/uapi/linux/ethtool.h
> index f4662b3..d63f9f8 100644
> --- a/include/uapi/linux/ethtool.h
> +++ b/include/uapi/linux/ethtool.h
> @@ -369,6 +369,28 @@ struct ethtool_eee {
>   	__u32	reserved[2];
>   };
>   
> +/**
> + * struct ethtool_fp - Frame Preemption information
> + * @cmd: ETHTOOL_{G,S}FP
> + * @fp_supported: If frame preemption is supported.
> + * @fp_enabled: If frame preemption should be advertised to the link partner
> + *	as enabled.
> + * @supported_queues_mask: Bitmask indicating which queues support being
> + *	configured as preemptible (bit 0 -> queue 0, bit N -> queue N).
> + * @preemptible_queues_mask: Bitmask indicating which queues are
> + *	configured as preemptible (bit 0 -> queue 0, bit N -> queue N).
> + * @min_frag_size: Minimum size for all non-final fragment size.
> + */
> +struct ethtool_fp {
> +	__u32	cmd;
> +	__u8	fp_supported;
> +	__u8	fp_enabled;

Could we add verify_supported and verify_enabled?

> +	__u32	supported_queues_mask;
> +	__u32	preemptible_queues_mask;
> +	__u32	min_frag_size;
> +	__u32	reserved[2];
> +};
> +
>   /**
>    * struct ethtool_modinfo - plugin module eeprom information
>    * @cmd: %ETHTOOL_GMODULEINFO
> @@ -1441,6 +1463,9 @@ enum ethtool_fec_config_bits {
>   #define ETHTOOL_GFECPARAM	0x00000050 /* Get FEC settings */
>   #define ETHTOOL_SFECPARAM	0x00000051 /* Set FEC settings */
>   
> +#define ETHTOOL_GFP		0x00000052 /* Get Frame Preemption settings */
> +#define ETHTOOL_SFP		0x00000053 /* Set Frame Preemption settings */
> +
>   /* compatibility with older code */
>   #define SPARC_ETH_GSET		ETHTOOL_GSET
>   #define SPARC_ETH_SSET		ETHTOOL_SSET
> diff --git a/net/ethtool/ioctl.c b/net/ethtool/ioctl.c
> index 52102ab..e15ad5c 100644
> --- a/net/ethtool/ioctl.c
> +++ b/net/ethtool/ioctl.c
> @@ -2531,6 +2531,36 @@ static int ethtool_set_fecparam(struct net_device *dev, void __user *useraddr)
>   	return dev->ethtool_ops->set_fecparam(dev, &fecparam);
>   }
>   
> +static int ethtool_get_preempt(struct net_device *dev, void __user *useraddr)
> +{
> +	struct ethtool_fp fpparam = { .cmd = ETHTOOL_GFP };
> +	int rc;
> +
> +	if (!dev->ethtool_ops->get_preempt)
> +		return -EOPNOTSUPP;
> +
> +	rc = dev->ethtool_ops->get_preempt(dev, &fpparam);
> +	if (rc)
> +		return rc;
> +
> +	if (copy_to_user(useraddr, &fpparam, sizeof(fpparam)))
> +		return -EFAULT;
> +	return 0;
> +}
> +
> +static int ethtool_set_preempt(struct net_device *dev, void __user *useraddr)
> +{
> +	struct ethtool_fp fpparam;
> +
> +	if (!dev->ethtool_ops->set_preempt)
> +		return -EOPNOTSUPP;
> +
> +	if (copy_from_user(&fpparam, useraddr, sizeof(fpparam)))
> +		return -EFAULT;
> +
> +	return dev->ethtool_ops->set_preempt(dev, &fpparam);
> +}
> +
>   /* The main entry point in this file.  Called from net/core/dev_ioctl.c */
>   
>   int dev_ethtool(struct net *net, struct ifreq *ifr)
> @@ -2810,6 +2840,12 @@ int dev_ethtool(struct net *net, struct ifreq *ifr)
>   	case ETHTOOL_SFECPARAM:
>   		rc = ethtool_set_fecparam(dev, useraddr);
>   		break;
> +	case ETHTOOL_GFP:
> +		rc = ethtool_get_preempt(dev, useraddr);
> +		break;
> +	case ETHTOOL_SFP:
> +		rc = ethtool_set_preempt(dev, useraddr);
> +		break;
>   	default:
>   		rc = -EOPNOTSUPP;
>   	}
> 

-- 
Murali Karicheri
Texas Instruments