netdev - Re: [PATCH net-next v3 7/7] net/smc: manage system EID in SMC stack instead of ISM driver

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Date: Fri, 1 Dec 2023 12:18:42 +0100
From: Alexandra Winter <wintera@...ux.ibm.com>
To: Wen Gu <guwen@...ux.alibaba.com>, wenjia@...ux.ibm.com, hca@...ux.ibm.com,
        gor@...ux.ibm.com, agordeev@...ux.ibm.com, davem@...emloft.net,
        edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com,
        kgraul@...ux.ibm.com, jaka@...ux.ibm.com
Cc: borntraeger@...ux.ibm.com, svens@...ux.ibm.com, alibuda@...ux.alibaba.com,
        tonylu@...ux.alibaba.com, raspl@...ux.ibm.com, schnelle@...ux.ibm.com,
        linux-s390@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next v3 7/7] net/smc: manage system EID in SMC stack
 instead of ISM driver



On 30.11.23 12:28, Wen Gu wrote:
> The System EID (SEID) is an internal EID that is used by the SMCv2
> software stack that has a predefined and constant value representing
> the s390 physical machine that the OS is executing on. So it should
> be managed by SMC stack instead of ISM driver and be consistent for
> all ISMv2 device (including virtual ISM devices) on s390 architecture.
> 
> Suggested-by: Alexandra Winter <wintera@...ux.ibm.com>
> Signed-off-by: Wen Gu <guwen@...ux.alibaba.com>
> ---

Reviewed-by: Alexandra Winter <wintera@...ux.ibm.com>


[...]
> diff --git a/net/smc/smc_ism.c b/net/smc/smc_ism.c
> index a33f861..ac88de2 100644
> --- a/net/smc/smc_ism.c
> +++ b/net/smc/smc_ism.c
[...]
> @@ -431,14 +452,8 @@ static void smcd_register_dev(struct ism_dev *ism)
>  
>  	mutex_lock(&smcd_dev_list.mutex);
>  	if (list_empty(&smcd_dev_list.list)) {
> -		u8 *system_eid = NULL;
> -
> -		system_eid = smcd->ops->get_system_eid();
> -		if (smcd->ops->supports_v2()) {
> +		if (smcd->ops->supports_v2())
>  			smc_ism_v2_capable = true;
> -			memcpy(smc_ism_v2_system_eid, system_eid,
> -			       SMC_MAX_EID_LEN);
> -		}
>  	}

Just a comment:
Here we only check the first smcd device to determine whether we support v2.
Which is ok, for today's platform firmware ISM devices, as they are always the same version.

When you add virtual ISM devices (loopback-ism, virtio-ism) then this needs to be changed.
IMO the logic then needs to be "if all smcd devices support v2,
then smc_ism_v2_capable = true;
else smc_ism_v2_capable = false;"

I don't know if you would like to change that now in this patch, or later when
you add when you add the support for loopback.