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From: Vladimir Oltean <vladimir.oltean@nxp.com>
To: Joergen Andreasen <joergen.andreasen@microchip.com>
Cc: Xiaoliang Yang <xiaoliang.yang_1@nxp.com>,
	"davem@davemloft.net" <davem@davemloft.net>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	"allan.nielsen@microchip.com" <allan.nielsen@microchip.com>,
	"UNGLinuxDriver@microchip.com" <UNGLinuxDriver@microchip.com>,
	"vinicius.gomes@intel.com" <vinicius.gomes@intel.com>,
	"michael.chan@broadcom.com" <michael.chan@broadcom.com>,
	"saeedm@mellanox.com" <saeedm@mellanox.com>,
	"jiri@mellanox.com" <jiri@mellanox.com>,
	"idosch@mellanox.com" <idosch@mellanox.com>,
	"alexandre.belloni@bootlin.com" <alexandre.belloni@bootlin.com>,
	"kuba@kernel.org" <kuba@kernel.org>, Po Liu <po.liu@nxp.com>,
	Leo Li <leoyang.li@nxp.com>
Subject: Re: [PATCH v3 net-next 5/8] net: dsa: felix: support psfp filter on vsc9959
Date: Thu, 9 Sep 2021 12:01:21 +0000	[thread overview]
Message-ID: <20210909120120.zrizaaheaanyl7dq@skbuf> (raw)
In-Reply-To: <9619848400baaa0d0d12cc6a2d799934323e2657.camel@microchip.com>

On Thu, Sep 09, 2021 at 01:33:57PM +0200, Joergen Andreasen wrote:
> > > Yes, Using redirect action can give PSFP filter a forward port to
> > > add
> > > MAC table entry. But it also has the issue that when using "bridge
> > > fdb
> > > del" to delete the MAC entry will cause the tc-filter rule not
> > > working.
> >
> > We need to define the expected behavior.
> >
> > As far as the 802.1Q-2018 spec is concerned, there is no logical
> > dependency between the FDB lookup and the PSFP streams. But there
> > seems
> > to be no explicit text that forbids it either, though.
> >
> > If you install a tc-redirect rule and offload it as a bridge FDB
> > entry,
> > it needs to behave like a tc-redirect rule and not a bridge FDB
> > entry.
> > So it only needs to match on the intended source port. I don't
> > believe
> > that is possible. If it is, let's do that.
> >
> > To me, putting PSFP inside the bridge driver is completely outside of
> > the question. There is no evidence that it belongs there, and there
> > are
> > switch implementations from other vendors where the FDB lookup
> > process
> > is completely independent from the Qci stream identification process.
> > Anyway, this strategy of combining the two could only work for the
> > NULL
> > stream identifiers in the first place (MAC DA + VLAN ID), not for the
> > others (IP Stream identification etc etc).
> >
> > So what remains, if nothing else is possible, is to require the user
> > to
> > manage the bridge FDB entries, and make sure that the kernel side is
> > sane, and does not remain with broken data structures. That is going
> > to
> > be a PITA both for the user and for the kernel side, because we are
> > going to make the tc-flower filters effectively depend upon the
> > bridge
> > state.
> >
> > Let's wait for some feedback from Microchip engineers, how they
> > envisioned this to be integrated with operating systems.
>
> We at Microchip agrees that it is a difficult task to map the PSFP
> implementation in Felix to the “tc flower” filter command, but please
> remember that Ocelot and its derivatives were designed long before
> the 802.1Qci standard was ratified and also before anyone has
> considered how to control it in Linux.
>
> We think that the best approach is to require the user to manage
> bridge FDB entries manually as suggested by Xiaoliang.
>
> Our newer PSFP designs uses the TCAM instead of the MAC table
> which maps a lot better to the “tc flower” filter command.

Well, that's even more unfortunate, because as explained by Ido here:
https://lore.kernel.org/netdev/YSHzLKpixhCrrgJ0@shredder/

the return code from SWITCHDEV_FDB_{ADD,DEL}_TO_DEVICE event handlers is
not propagated to br_switchdev_fdb_notify. So in effect, the device driver
cannot stop the bridge from removing an FDB entry which would lead it to
having a broken tc filter.

Now, the ocelot switchdev driver uses the bridge bypass .ndo_fdb_add and
.ndo_fdb_del, while DSA actually listens for switchdev events on the
atomic call chain. So any solution needs to work with switchdev, not
just with the bridge bypass ops.

  reply	other threads:[~2021-09-09 12:07 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-31  3:45 [PATCH v3 net-next 0/8] net: dsa: felix: psfp support " Xiaoliang Yang
2021-08-31  3:45 ` [PATCH v3 net-next 1/8] net: mscc: ocelot: export struct ocelot_mact_entry Xiaoliang Yang
2021-08-31  3:45 ` [PATCH v3 net-next 2/8] net: mscc: ocelot: add MAC table write and lookup operations Xiaoliang Yang
2021-08-31  3:45 ` [PATCH v3 net-next 3/8] net: mscc: ocelot: set vcap IS2 chain to goto PSFP chain Xiaoliang Yang
2021-08-31  3:45 ` [PATCH v3 net-next 4/8] net: mscc: ocelot: add gate and police action offload to PSFP Xiaoliang Yang
2021-08-31  3:45 ` [PATCH v3 net-next 5/8] net: dsa: felix: support psfp filter on vsc9959 Xiaoliang Yang
2021-08-31  7:54   ` Vladimir Oltean
2021-08-31  8:41     ` Xiaoliang Yang
2021-08-31  8:46       ` Vladimir Oltean
2021-08-31  8:55         ` Vladimir Oltean
2021-08-31  8:59         ` Xiaoliang Yang
2021-08-31  9:07           ` Vladimir Oltean
2021-08-31  9:18             ` Vladimir Oltean
2021-08-31  9:59               ` Xiaoliang Yang
2021-08-31 10:49                 ` Vladimir Oltean
2021-09-02  3:14                   ` Xiaoliang Yang
2021-09-09 11:33                   ` Joergen Andreasen
2021-09-09 12:01                     ` Vladimir Oltean [this message]
2021-08-31  3:45 ` [PATCH v3 net-next 6/8] net: dsa: felix: add stream gate settings for psfp Xiaoliang Yang
2021-08-31  3:45 ` [PATCH v3 net-next 7/8] net: mscc: ocelot: use index to set vcap policer Xiaoliang Yang
2021-08-31  3:45 ` [PATCH v3 net-next 8/8] net: dsa: felix: use vcap policer to set flow meter for psfp Xiaoliang Yang

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