kernel/linux.git/include/linux/dsa/8021q.h, branch v6.1.168

net: dsa: tag_8021q: rename dsa_8021q_bridge_tx_fwd_offload_vid

2022-02-27T11:06:14+00:00

The dsa_8021q_bridge_tx_fwd_offload_vid is no longer used just for bridge TX forwarding offload, it is the private VLAN reserved for VLAN-unaware bridging in a way that is compatible with FDB isolation. So just rename it dsa_tag_8021q_bridge_vid. Signed-off-by: Vladimir Oltean Signed-off-by: David S. Miller

net: dsa: tag_8021q: merge RX and TX VLANs

2022-02-27T11:06:14+00:00

In the old Shared VLAN Learning mode of operation that tag_8021q previously used for forwarding, we needed to have distinct concepts for an RX and a TX VLAN. An RX VLAN could be installed on all ports that were members of a given bridge, so that autonomous forwarding could still work, while a TX VLAN was dedicated for precise packet steering, so it just contained the CPU port and one egress port. Now that tag_8021q uses Independent VLAN Learning and imprecise RX/TX all over, those lines have been blurred and we no longer have the need to do precise TX towards a port that is in a bridge. As for standalone ports, it is fine to use the same VLAN ID for both RX and TX. This patch changes the tag_8021q format by shifting the VLAN range it reserves, and halving it. Previously, our DIR bits were encoding the VLAN direction (RX/TX) and were set to either 1 or 2. This meant that tag_8021q reserved 2K VLANs, or 50% of the available range. Change the DIR bits to a hardcoded value of 3 now, which makes tag_8021q reserve only 1K VLANs, and a different range now (the last 1K). This is done so that we leave the old format in place in case we need to return to it. In terms of code, the vid_is_dsa_8021q_rxvlan and vid_is_dsa_8021q_txvlan functions go away. Any vid_is_dsa_8021q is both a TX and an RX VLAN, and they are no longer distinct. For example, felix which did different things for different VLAN types, now needs to handle the RX and the TX logic for the same VLAN. Signed-off-by: Vladimir Oltean Signed-off-by: David S. Miller

net: dsa: tag_8021q: add support for imprecise RX based on the VBID

2022-02-27T11:06:13+00:00

The sja1105 switch can't populate the PORT field of the tag_8021q header when sending a frame to the CPU with a non-zero VBID. Similar to dsa_find_designated_bridge_port_by_vid() which performs imprecise RX for VLAN-aware bridges, let's introduce a helper in tag_8021q for performing imprecise RX based on the VLAN that it has allocated for a VLAN-unaware bridge. Signed-off-by: Vladimir Oltean Signed-off-by: David S. Miller

net: dsa: tag_8021q: replace the SVL bridging with VLAN-unaware IVL bridging

2022-02-27T11:06:13+00:00

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 Signed-off-by: David S. Miller

net: dsa: keep the bridge_dev and bridge_num as part of the same structure

2021-12-08T22:31:16+00:00

The main desire behind this is to provide coherent bridge information to the fast path without locking. For example, right now we set dp->bridge_dev and dp->bridge_num from separate code paths, it is theoretically possible for a packet transmission to read these two port properties consecutively and find a bridge number which does not correspond with the bridge device. Another desire is to start passing more complex bridge information to dsa_switch_ops functions. For example, with FDB isolation, it is expected that drivers will need to be passed the bridge which requested an FDB/MDB entry to be offloaded, and along with that bridge_dev, the associated bridge_num should be passed too, in case the driver might want to implement an isolation scheme based on that number. We already pass the {bridge_dev, bridge_num} pair to the TX forwarding offload switch API, however we'd like to remove that and squash it into the basic bridge join/leave API. So that means we need to pass this pair to the bridge join/leave API. During dsa_port_bridge_leave, first we unset dp->bridge_dev, then we call the driver's .port_bridge_leave with what used to be our dp->bridge_dev, but provided as an argument. When bridge_dev and bridge_num get folded into a single structure, we need to preserve this behavior in dsa_port_bridge_leave: we need a copy of what used to be in dp->bridge. Switch drivers check bridge membership by comparing dp->bridge_dev with the provided bridge_dev, but now, if we provide the struct dsa_bridge as a pointer, they cannot keep comparing dp->bridge to the provided pointer, since this only points to an on-stack copy. To make this obvious and prevent driver writers from forgetting and doing stupid things, in this new API, the struct dsa_bridge is provided as a full structure (not very large, contains an int and a pointer) instead of a pointer. An explicit comparison function needs to be used to determine bridge membership: dsa_port_offloads_bridge(). Signed-off-by: Vladimir Oltean Reviewed-by: Alvin Šipraga Signed-off-by: Jakub Kicinski

net: dsa: make dp->bridge_num one-based

2021-12-08T22:31:14+00:00

I have seen too many bugs already due to the fact that we must encode an invalid dp->bridge_num as a negative value, because the natural tendency is to check that invalid value using (!dp->bridge_num). Latest example can be seen in commit 1bec0f05062c ("net: dsa: fix bridge_num not getting cleared after ports leaving the bridge"). Convert the existing users to assume that dp->bridge_num == 0 is the encoding for invalid, and valid bridge numbers start from 1. Signed-off-by: Vladimir Oltean Reviewed-by: Alvin Šipraga Signed-off-by: Jakub Kicinski

net: dsa: tag_8021q: make dsa_8021q_{rx,tx}_vid take dp as argument

2021-10-21T11:44:07+00:00

Pass a single argument to dsa_8021q_rx_vid and dsa_8021q_tx_vid that contains the necessary information from the two arguments that are currently provided: the switch and the port number. Also rename those functions so that they have a dsa_port_* prefix, since they operate on a struct dsa_port *. Signed-off-by: Vladimir Oltean Signed-off-by: David S. Miller

net: dsa: sja1105: add bridge TX data plane offload based on tag_8021q

2021-07-26T21:35:22+00:00

The main desire for having this feature in sja1105 is to support network stack termination for traffic coming from a VLAN-aware bridge. For sja1105, offloading the bridge data plane means sending packets as-is, with the proper VLAN tag, to the chip. The chip will look up its FDB and forward them to the correct destination port. But we support bridge data plane offload even for VLAN-unaware bridges, and the implementation there is different. In fact, VLAN-unaware bridging is governed by tag_8021q, so it makes sense to have the .bridge_fwd_offload_add() implementation fully within tag_8021q. The key difference is that we only support 1 VLAN-aware bridge, but we support multiple VLAN-unaware bridges. So we need to make sure that the forwarding domain is not crossed by packets injected from the stack. For this, we introduce the concept of a tag_8021q TX VLAN for bridge forwarding offload. As opposed to the regular TX VLANs which contain only 2 ports (the user port and the CPU port), a bridge data plane TX VLAN is "multicast" (or "imprecise"): it contains all the ports that are part of a certain bridge, and the hardware will select where the packet goes within this "imprecise" forwarding domain. Each VLAN-unaware bridge has its own "imprecise" TX VLAN, so we make use of the unique "bridge_num" provided by DSA for the data plane offload. We use the same 3 bits from the tag_8021q VLAN ID format to encode this bridge number. Note that these 3 bit positions have been used before for sub-VLANs in best-effort VLAN filtering mode. The difference is that for best-effort, the sub-VLANs were only valid on RX (and it was documented that the sub-VLAN field needed to be transmitted as zero). Whereas for the bridge data plane offload, these 3 bits are only valid on TX. Signed-off-by: Vladimir Oltean Signed-off-by: David S. Miller

net: dsa: tag_8021q: add proper cross-chip notifier support

2021-07-20T13:36:42+00:00

The big problem which mandates cross-chip notifiers for tag_8021q is this: | sw0p0 sw0p1 sw0p2 sw0p3 sw0p4 [ user ] [ user ] [ user ] [ dsa ] [ cpu ] | +---------+ | sw1p0 sw1p1 sw1p2 sw1p3 sw1p4 [ user ] [ user ] [ user ] [ dsa ] [ dsa ] | +---------+ | sw2p0 sw2p1 sw2p2 sw2p3 sw2p4 [ user ] [ user ] [ user ] [ dsa ] [ dsa ] When the user runs: ip link add br0 type bridge ip link set sw0p0 master br0 ip link set sw2p0 master br0 It doesn't work. This is because dsa_8021q_crosschip_bridge_join() assumes that "ds" and "other_ds" are at most 1 hop away from each other, so it is sufficient to add the RX VLAN of {ds, port} into {other_ds, other_port} and vice versa and presto, the cross-chip link works. When there is another switch in the middle, such as in this case switch 1 with its DSA links sw1p3 and sw1p4, somebody needs to tell it about these VLANs too. Which is exactly why the problem is quadratic: when a port joins a bridge, for each port in the tree that's already in that same bridge we notify a tag_8021q VLAN addition of that port's RX VLAN to the entire tree. It is a very complicated web of VLANs. It must be mentioned that currently we install tag_8021q VLANs on too many ports (DSA links - to be precise, on all of them). For example, when sw2p0 joins br0, and assuming sw1p0 was part of br0 too, we add the RX VLAN of sw2p0 on the DSA links of switch 0 too, even though there isn't any port of switch 0 that is a member of br0 (at least yet). In theory we could notify only the switches which sit in between the port joining the bridge and the port reacting to that bridge_join event. But in practice that is impossible, because of the way 'link' properties are described in the device tree. The DSA bindings require DT writers to list out not only the real/physical DSA links, but in fact the entire routing table, like for example switch 0 above will have: sw0p3: port@3 { link = <&sw1p4 &sw2p4>; }; This was done because: /* TODO: ideally DSA ports would have a single dp->link_dp member, * and no dst->rtable nor this struct dsa_link would be needed, * but this would require some more complex tree walking, * so keep it stupid at the moment and list them all. */ but it is a perfect example of a situation where too much information is actively detrimential, because we are now in the position where we cannot distinguish a real DSA link from one that is put there to avoid the 'complex tree walking'. And because DT is ABI, there is not much we can change. And because we do not know which DSA links are real and which ones aren't, we can't really know if DSA switch A is in the data path between switches B and C, in the general case. So this is why tag_8021q RX VLANs are added on all DSA links, and probably why it will never change. On the other hand, at least the number of additions/deletions is well balanced, and this means that once we implement reference counting at the cross-chip notifier level a la fdb/mdb, there is absolutely zero need for a struct dsa_8021q_crosschip_link, it's all self-managing. In fact, with the tag_8021q notifiers emitted from the bridge join notifiers, it becomes so generic that sja1105 does not need to do anything anymore, we can just delete its implementation of the .crosschip_bridge_{join,leave} methods. Among other things we can simply delete is the home-grown implementation of sja1105_notify_crosschip_switches(). The reason why that is wrong is because it is not quadratic - it only covers remote switches to which we have a cross-chip bridging link and that does not cover in-between switches. This deletion is part of the same patch because sja1105 used to poke deep inside the guts of the tag_8021q context in order to do that. Because the cross-chip links went away, so needs the sja1105 code. Last but not least, dsa_8021q_setup_port() is simplified (and also renamed). Because our TAG_8021Q_VLAN_ADD notifier is designed to react on the CPU port too, the four dsa_8021q_vid_apply() calls: - 1 for RX VLAN on user port - 1 for the user port's RX VLAN on the CPU port - 1 for TX VLAN on user port - 1 for the user port's TX VLAN on the CPU port now get squashed into only 2 notifier calls via dsa_port_tag_8021q_vlan_add. And because the notifiers to add and to delete a tag_8021q VLAN are distinct, now we finally break up the port setup and teardown into separate functions instead of relying on a "bool enabled" flag which tells us what to do. Arguably it should have been this way from the get go. Signed-off-by: Vladimir Oltean Signed-off-by: David S. Miller

net: dsa: tag_8021q: absorb dsa_8021q_setup into dsa_tag_8021q_{,un}register

2021-07-20T13:36:42+00:00

Right now, setting up tag_8021q is a 2-step operation for a driver, first the context structure needs to be created, then the VLANs need to be installed on the ports. A similar thing is true for teardown. Merge the 2 steps into the register/unregister methods, to be as transparent as possible for the driver as to what tag_8021q does behind the scenes. This also gets rid of the funny "bool setup == true means setup, == false means teardown" API that tag_8021q used to expose. Note that dsa_tag_8021q_register() must be called at least in the .setup() driver method and never earlier (like in the driver probe function). This is because the DSA switch tree is not initialized at probe time, and the cross-chip notifiers will not work. For symmetry with .setup(), the unregister method should be put in .teardown(). Signed-off-by: Vladimir Oltean Signed-off-by: David S. Miller