Due to an invalid conflict resolution on my side while working on 2
different series (LAG FDBs and FDB isolation), dsa_switch_do_lag_fdb_add()
does not store the database associated with a dsa_mac_addr structure.

So after adding an FDB entry associated with a LAG, dsa_mac_addr_find()
fails to find it while deleting it, because &a->db is zeroized memory
for all stored FDB entries of lag->fdbs, and dsa_switch_do_lag_fdb_del()
returns -ENOENT rather than deleting the entry.

Fixes: c26933639b54 ("net: dsa: request drivers to perform FDB isolation")
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Link: https://lore.kernel.org/r/20220723012411.1125066-1-vladimir.oltean@nxp.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

DSA has not supported (and probably will not support in the future
either) independent tagging protocols per CPU port.

Different switch drivers have different requirements, some may need to
replicate some settings for each CPU port, some may need to apply some
settings on a single CPU port, while some may have to configure some
global settings and then some per-CPU-port settings.

In any case, the current model where DSA calls ->change_tag_protocol for
each CPU port turns out to be impractical for drivers where there are
global things to be done. For example, felix calls dsa_tag_8021q_register(),
which makes no sense per CPU port, so it suppresses the second call.

Let drivers deal with replication towards all CPU ports, and remove the
CPU port argument from the function prototype.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Acked-by: Luiz Angelo Daros de Luca <luizluca@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

A cross-chip notifier with "targeted_match=true" is one that matches
only the local port of the switch that emitted it. In other words,
passing through the cross-chip notifier layer serves no purpose.

Eliminate this concept by calling directly ds->ops->port_change_mtu
instead of emitting a targeted cross-chip notifier. This leaves the
DSA_NOTIFIER_MTU event being emitted only for MTU updates on the CPU
port, which need to be reflected also across all DSA links.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

To determine whether a given port should react to the port targeted by
the notifier, dsa_port_host_vlan_match() and dsa_port_host_address_match()
look at the positioning of the switch port currently executing the
notifier relative to the switch port for which the notifier was emitted.

To maintain stylistic compatibility with the other match functions from
switch.c, the host address and host VLAN match functions take the
notifier information about targeted port, switch and tree indices as
argument. However, these functions only use that information to retrieve
the struct dsa_port *targeted_dp, which is an invariant for the outer
loop that calls them. So it makes more sense to calculate the targeted
dp only once, and pass it to them as argument.

But furthermore, the targeted dp is actually known at the time the call
to dsa_port_notify() is made. It is just that we decide to only save the
indices of the port, switch and tree in the notifier structure, just to
retrace our steps and find the dp again using dsa_switch_find() and
dsa_to_port().

But both the above functions are relatively expensive, since they need
to iterate through lists. It appears more straightforward to make all
notifiers just pass the targeted dp inside their info structure, and
have the code that needs the indices to look at info->dp->index instead
of info->port, or info->dp->ds->index instead of info->sw_index, or
info->dp->ds->dst->index instead of info->tree_index.

For the sake of consistency, all cross-chip notifiers are converted to
pass the "dp" directly.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

In dsa_port_switchdev_unsync_attrs() there is a comment that resetting
the VLAN filtering isn't done where it is expected. And since commit
108dc8741c20 ("net: dsa: Avoid cross-chip syncing of VLAN filtering"),
there is no reason to handle this in switch.c either.

Therefore, move the logic to port.c, and adapt it slightly to the data
structures and naming conventions from there.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

The Felix driver declares FDB isolation but puts all standalone ports in
VID 0. This is mostly problem-free as discussed with Alvin here:
https://patchwork.kernel.org/project/netdevbpf/cover/20220302191417.1288145-1-vladimir.oltean@nxp.com/#24763870

however there is one catch. DSA still thinks that FDB entries are
installed on the CPU port as many times as there are user ports, and
this is problematic when multiple user ports share the same MAC address.

Consider the default case where all user ports inherit their MAC address
from the DSA master, and then the user runs:

ip link set swp0 address 00:01:02:03:04:05

The above will make dsa_slave_set_mac_address() call
dsa_port_standalone_host_fdb_add() for 00:01:02:03:04:05 in port 0's
standalone database, and dsa_port_standalone_host_fdb_del() for the old
address of swp0, again in swp0's standalone database.

Both the ->port_fdb_add() and ->port_fdb_del() will be propagated down
to the felix driver, which will end up deleting the old MAC address from
the CPU port. But this is still in use by other user ports, so we end up
breaking unicast termination for them.

There isn't a problem in the fact that DSA keeps track of host
standalone addresses in the individual database of each user port: some
drivers like sja1105 need this. There also isn't a problem in the fact
that some drivers choose the same VID/FID for all standalone ports.
It is just that the deletion of these host addresses must be delayed
until they are known to not be in use any longer, and only the driver
has this knowledge. Since DSA keeps these addresses in &cpu_dp->fdbs and
&cpu_db->mdbs, it is just a matter of walking over those lists and see
whether the same MAC address is present on the CPU port in the port db
of another user port.

I have considered reusing the generic dsa_port_walk_fdbs() and
dsa_port_walk_mdbs() schemes for this, but locking makes it difficult.
In the ->port_fdb_add() method and co, &dp->addr_lists_lock is held, but
dsa_port_walk_fdbs() also acquires that lock. Also, even assuming that
we introduce an unlocked variant of the address iterator, we'd still
need some relatively complex data structures, and a void *ctx in the
dsa_fdb_walk_cb_t which we don't currently pass, such that drivers are
able to figure out, after iterating, whether the same MAC address is or
isn't present in the port db of another port.

All the above, plus the fact that I expect other drivers to follow the
same model as felix where all standalone ports use the same FID, made me
conclude that a generic method provided by DSA is necessary:
dsa_fdb_present_in_other_db() and the mdb equivalent. Felix calls this
from the ->port_fdb_del() handler for the CPU port, when the database
was classified to either a port db, or a LAG db.

For symmetry, we also call this from ->port_fdb_add(), because if the
address was installed once, then installing it a second time serves no
purpose: it's already in hardware in VID 0 and it affects all standalone
ports.

This change moves dsa_db_equal() from switch.c to dsa.c, since it now
has one more caller.

Fixes: 54c319846086 ("net: mscc: ocelot: enforce FDB isolation when VLAN-unaware")
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

As FDB isolation cannot be enforced between VLAN-aware bridges in lack
of hardware assistance like extra FID bits, it seems plausible that many
DSA switches cannot do it. Therefore, they need to reject configurations
with multiple VLAN-aware bridges from the two code paths that can
transition towards that state:

- joining a VLAN-aware bridge
- toggling VLAN awareness on an existing bridge

The .port_vlan_filtering method already propagates the netlink extack to
the driver, let's propagate it from .port_bridge_join too, to make sure
that the driver can use the same function for both.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

For DSA, to encourage drivers to perform FDB isolation simply means to
track which bridge does each FDB and MDB entry belong to. It then
becomes the driver responsibility to use something that makes the FDB
entry from one bridge not match the FDB lookup of ports from other
bridges.

The top-level functions where the bridge is determined are:
- dsa_port_fdb_{add,del}
- dsa_port_host_fdb_{add,del}
- dsa_port_mdb_{add,del}
- dsa_port_host_mdb_{add,del}

aka the pre-crosschip-notifier functions.

Changing the API to pass a reference to a bridge is not superfluous, and
looking at the passed bridge argument is not the same as having the
driver look at dsa_to_port(ds, port)->bridge from the ->port_fdb_add()
method.

DSA installs FDB and MDB entries on shared (CPU and DSA) ports as well,
and those do not have any dp->bridge information to retrieve, because
they are not in any bridge - they are merely the pipes that serve the
user ports that are in one or multiple bridges.

The struct dsa_bridge associated with each FDB/MDB entry is encapsulated
in a larger "struct dsa_db" database. Although only databases associated
to bridges are notified for now, this API will be the starting point for
implementing IFF_UNICAST_FLT in DSA. There, the idea is to install FDB
entries on the CPU port which belong to the corresponding user port's
port database. These are supposed to match only when the port is
standalone.

It is better to introduce the API in its expected final form than to
introduce it for bridges first, then to have to change drivers which may
have made one or more assumptions.

Drivers can use the provided bridge.num, but they can also use a
different numbering scheme that is more convenient.

DSA must perform refcounting on the CPU and DSA ports by also taking
into account the bridge number. So if two bridges request the same local
address, DSA must notify the driver twice, once for each bridge.

In fact, if the driver supports FDB isolation, DSA must perform
refcounting per bridge, but if the driver doesn't, DSA must refcount
host addresses across all bridges, otherwise it would be telling the
driver to delete an FDB entry for a bridge and the driver would delete
it for all bridges. So introduce a bool fdb_isolation in drivers which
would make all bridge databases passed to the cross-chip notifier have
the same number (0). This makes dsa_mac_addr_find() -> dsa_db_equal()
say that all bridge databases are the same database - which is
essentially the legacy behavior.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

For VLAN-unaware bridging, tag_8021q uses something perhaps a bit too
tied with the sja1105 switch: each port uses the same pvid which is also
used for standalone operation (a unique one from which the source port
and device ID can be retrieved when packets from that port are forwarded
to the CPU). Since each port has a unique pvid when performing
autonomous forwarding, the switch must be configured for Shared VLAN
Learning (SVL) such that the VLAN ID itself is ignored when performing
FDB lookups. Without SVL, packets would always be flooded, since FDB
lookup in the source port's VLAN would never find any entry.

First of all, to make tag_8021q more palatable to switches which might
not support Shared VLAN Learning, let's just use a common VLAN for all
ports that are under the same bridge.

Secondly, using Shared VLAN Learning means that FDB isolation can never
be enforced. But if all ports under the same VLAN-unaware bridge share
the same VLAN ID, it can.

The disadvantage is that the CPU port can no longer perform precise
source port identification for these packets. But at least we have a
mechanism which has proven to be adequate for that situation: imprecise
RX (dsa_find_designated_bridge_port_by_vid), which is what we use for
termination on VLAN-aware bridges.

The VLAN ID that VLAN-unaware bridges will use with tag_8021q is the
same one as we were previously using for imprecise TX (bridge TX
forwarding offload). It is already allocated, it is just a matter of
using it.

Note that because now all ports under the same bridge share the same
VLAN, the complexity of performing a tag_8021q bridge join decreases
dramatically. We no longer have to install the RX VLAN of a newly
joining port into the port membership of the existing bridge ports.
The newly joining port just becomes a member of the VLAN corresponding
to that bridge, and the other ports are already members of it from when
they joined the bridge themselves. So forwarding works properly.

This means that we can unhook dsa_tag_8021q_bridge_{join,leave} from the
cross-chip notifier level dsa_switch_bridge_{join,leave}. We can put
these calls directly into the sja1105 driver.

With this new mode of operation, a port controlled by tag_8021q can have
two pvids whereas before it could only have one. The pvid for standalone
operation is different from the pvid used for VLAN-unaware bridging.
This is done, again, so that FDB isolation can be enforced.
Let tag_8021q manage this by deleting the standalone pvid when a port
joins a bridge, and restoring it when it leaves it.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

This change introduces support for installing static FDB entries towards
a bridge port that is a LAG of multiple DSA switch ports, as well as
support for filtering towards the CPU local FDB entries emitted for LAG
interfaces that are bridge ports.

Conceptually, host addresses on LAG ports are identical to what we do
for plain bridge ports. Whereas FDB entries _towards_ a LAG can't simply
be replicated towards all member ports like we do for multicast, or VLAN.
Instead we need new driver API. Hardware usually considers a LAG to be a
"logical port", and sets the entire LAG as the forwarding destination.
The physical egress port selection within the LAG is made by hashing
policy, as usual.

To represent the logical port corresponding to the LAG, we pass by value
a copy of the dsa_lag structure to all switches in the tree that have at
least one port in that LAG.

To illustrate why a refcounted list of FDB entries is needed in struct
dsa_lag, it is enough to say that:
- a LAG may be a bridge port and may therefore receive FDB events even
  while it isn't yet offloaded by any DSA interface
- DSA interfaces may be removed from a LAG while that is a bridge port;
  we don't want FDB entries lingering around, but we don't want to
  remove entries that are still in use, either

For all the cases below to work, the idea is to always keep an FDB entry
on a LAG with a reference count equal to the DSA member ports. So:
- if a port joins a LAG, it requests the bridge to replay the FDB, and
  the FDB entries get created, or their refcount gets bumped by one
- if a port leaves a LAG, the FDB replay deletes or decrements refcount
  by one
- if an FDB is installed towards a LAG with ports already present, that
  entry is created (if it doesn't exist) and its refcount is bumped by
  the amount of ports already present in the LAG

echo "Adding FDB entry to bond with existing ports"
ip link del bond0
ip link add bond0 type bond mode 802.3ad
ip link set swp1 down && ip link set swp1 master bond0 && ip link set swp1 up
ip link set swp2 down && ip link set swp2 master bond0 && ip link set swp2 up
ip link del br0
ip link add br0 type bridge
ip link set bond0 master br0
bridge fdb add dev bond0 00:01:02:03:04:05 master static

ip link del br0
ip link del bond0

echo "Adding FDB entry to empty bond"
ip link del bond0
ip link add bond0 type bond mode 802.3ad
ip link del br0
ip link add br0 type bridge
ip link set bond0 master br0
bridge fdb add dev bond0 00:01:02:03:04:05 master static
ip link set swp1 down && ip link set swp1 master bond0 && ip link set swp1 up
ip link set swp2 down && ip link set swp2 master bond0 && ip link set swp2 up

ip link del br0
ip link del bond0

echo "Adding FDB entry to empty bond, then removing ports one by one"
ip link del bond0
ip link add bond0 type bond mode 802.3ad
ip link del br0
ip link add br0 type bridge
ip link set bond0 master br0
bridge fdb add dev bond0 00:01:02:03:04:05 master static
ip link set swp1 down && ip link set swp1 master bond0 && ip link set swp1 up
ip link set swp2 down && ip link set swp2 master bond0 && ip link set swp2 up

ip link set swp1 nomaster
ip link set swp2 nomaster
ip link del br0
ip link del bond0

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>