netdev - Re: [PATCH net-next 1/3] net: Add support to configure SR-IOV VF minimum and maximum queues.

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <6dd76ffc-4097-0e5e-6f66-78fd178f89c2@intel.com>
Date:   Wed, 30 May 2018 14:23:06 -0700
From:   "Samudrala, Sridhar" <sridhar.samudrala@...el.com>
To:     Jakub Kicinski <jakub.kicinski@...ronome.com>,
        Michael Chan <michael.chan@...adcom.com>
Cc:     David Miller <davem@...emloft.net>,
        Netdev <netdev@...r.kernel.org>,
        Or Gerlitz <gerlitz.or@...il.com>
Subject: Re: [PATCH net-next 1/3] net: Add support to configure SR-IOV VF
 minimum and maximum queues.

On 5/29/2018 11:33 PM, Jakub Kicinski wrote:
> On Tue, 29 May 2018 23:08:11 -0700, Michael Chan wrote:
>> On Tue, May 29, 2018 at 10:56 PM, Jakub Kicinski wrote:
>>> On Tue, 29 May 2018 20:19:54 -0700, Michael Chan wrote:
>>>> On Tue, May 29, 2018 at 1:46 PM, Samudrala, Sridhar wrote:
>>>>> Isn't ndo_set_vf_xxx() considered a legacy interface and not planned to be
>>>>> extended?
>>> +1 it's painful to see this feature being added to the legacy
>>> API :(  Another duplicated configuration knob.
>>>
>>>> I didn't know about that.
>>>>
>>>>> Shouldn't we enable this via ethtool on the port representor netdev?
>>>> We discussed about this.  ethtool on the VF representor will only work
>>>> in switchdev mode and also will not support min/max values.
>>> Ethtool channel API may be overdue a rewrite in devlink anyway, but I
>>> feel like implementing switchdev mode and rewriting features in devlink
>>> may be too much to ask.
>> Totally agreed.  And switchdev mode doesn't seem to be that widely
>> used at the moment.  Do you have other suggestions besides NDO?
> At some points you (Broadcom) were working whole bunch of devlink
> configuration options for the PCIe side of the ASIC.  The number of
> queues relates to things like number of allocated MSI-X vectors, which
> if memory serves me was in your devlink patch set.  In an ideal world
> we would try to keep all those in one place :)
>
> For PCIe config there is always the question of what can be configured
> at runtime, and what requires a HW reset.  Therefore that devlink API
> which could configure current as well as persistent device settings was
> quite nice.  I'm not sure if reallocating queues would ever require
> PCIe block reset but maybe...  Certainly it seems the notion of min
> queues would make more sense in PCIe configuration devlink API than
> ethtool channel API to me as well.
>
> Queues are in the grey area between netdev and non-netdev constructs.
> They make sense both from PCIe resource allocation perspective (i.e.
> devlink PCIe settings) and netdev perspective (ethtool) because they
> feed into things like qdisc offloads, maybe per-queue stats etc.
>
> So yes...  IMHO it would be nice to add this to a devlink SR-IOV config
> API and/or switchdev representors.  But neither of those are really an
> option for you today so IDK :)

One reason why 'switchdev' mode is not yet widely used or enabled by default
could be due to the requirement to program the flow rules only via slow path.

Would it make sense to relax this requirement and support a mode where port
representors are created and let the PF driver implement a default policy that
adds flow rules for all the VFs to enable connectivity and let the user
add/modify the rules via port representors?