user/sven/linux.git/include/net/dsa.h, branch v5.8

net: dsa: provide an option for drivers to always receive bridge VLANs

2020-05-12T20:08:07Z

DSA assumes that a bridge which has vlan filtering disabled is not vlan aware, and ignores all vlan configuration. However, the kernel software bridge code allows configuration in this state. This causes the kernel's idea of the bridge vlan state and the hardware state to disagree, so "bridge vlan show" indicates a correct configuration but the hardware lacks all configuration. Even worse, enabling vlan filtering on a DSA bridge immediately blocks all traffic which, given the output of "bridge vlan show", is very confusing. Provide an option that drivers can set to indicate they want to receive vlan configuration even when vlan filtering is disabled. At the very least, this is safe for Marvell DSA bridges, which do not look up ingress traffic in the VTU if the port is in 8021Q disabled state. It is also safe for the Ocelot switch family. Whether this change is suitable for all DSA bridges is not known. Signed-off-by: Russell King Signed-off-by: Vladimir Oltean Reviewed-by: Florian Fainelli Signed-off-by: David S. Miller

net: dsa: introduce a dsa_switch_find function

2020-05-11T02:52:33Z

Somewhat similar to dsa_tree_find, dsa_switch_find returns a dsa_switch structure pointer by searching for its tree index and switch index (the parameters from dsa,member). To be used, for example, by drivers who implement .crosschip_bridge_join and need a reference to the other switch indicated to by the tree_index and sw_index arguments. Signed-off-by: Vladimir Oltean Reviewed-by: Florian Fainelli Signed-off-by: Jakub Kicinski

net: dsa: permit cross-chip bridging between all trees in the system

2020-05-11T02:52:33Z

One way of utilizing DSA is by cascading switches which do not all have compatible taggers. Consider the following real-life topology: +---------------------------------------------------------------+ | LS1028A | | +------------------------------+ | | | DSA master for Felix | | | |(internal ENETC port 2: eno2))| | | +------------+------------------------------+-------------+ | | | Felix embedded L2 switch | | | | | | | | +--------------+ +--------------+ +--------------+ | | | | |DSA master for| |DSA master for| |DSA master for| | | | | | SJA1105 1 | | SJA1105 2 | | SJA1105 3 | | | | | |(Felix port 1)| |(Felix port 2)| |(Felix port 3)| | | +--+-+--------------+---+--------------+---+--------------+--+--+ +-----------------------+ +-----------------------+ +-----------------------+ | SJA1105 switch 1 | | SJA1105 switch 2 | | SJA1105 switch 3 | +-----+-----+-----+-----+ +-----+-----+-----+-----+ +-----+-----+-----+-----+ |sw1p0|sw1p1|sw1p2|sw1p3| |sw2p0|sw2p1|sw2p2|sw2p3| |sw3p0|sw3p1|sw3p2|sw3p3| +-----+-----+-----+-----+ +-----+-----+-----+-----+ +-----+-----+-----+-----+ The above can be described in the device tree as follows (obviously not complete): mscc_felix { dsa,member = <0 0>; ports { port@4 { ethernet = <&enetc_port2>; }; }; }; sja1105_switch1 { dsa,member = <1 1>; ports { port@4 { ethernet = <&mscc_felix_port1>; }; }; }; sja1105_switch2 { dsa,member = <2 2>; ports { port@4 { ethernet = <&mscc_felix_port2>; }; }; }; sja1105_switch3 { dsa,member = <3 3>; ports { port@4 { ethernet = <&mscc_felix_port3>; }; }; }; Basically we instantiate one DSA switch tree for every hardware switch in the system, but we still give them globally unique switch IDs (will come back to that later). Having 3 disjoint switch trees makes the tagger drivers "just work", because net devices are registered for the 3 Felix DSA master ports, and they are also DSA slave ports to the ENETC port. So packets received on the ENETC port are stripped of their stacked DSA tags one by one. Currently, hardware bridging between ports on the same sja1105 chip is possible, but switching between sja1105 ports on different chips is handled by the software bridge. This is fine, but we can do better. In fact, the dsa_8021q tag used by sja1105 is compatible with cascading. In other words, a sja1105 switch can correctly parse and route a packet containing a dsa_8021q tag. So if we could enable hardware bridging on the Felix DSA master ports, cross-chip bridging could be completely offloaded. Such as system would be used as follows: ip link add dev br0 type bridge && ip link set dev br0 up for port in sw0p0 sw0p1 sw0p2 sw0p3 \ sw1p0 sw1p1 sw1p2 sw1p3 \ sw2p0 sw2p1 sw2p2 sw2p3; do ip link set dev $port master br0 done The above makes switching between ports on the same row be performed in hardware, and between ports on different rows in software. Now assume the Felix switch ports are called swp0, swp1, swp2. By running the following extra commands: ip link add dev br1 type bridge && ip link set dev br1 up for port in swp0 swp1 swp2; do ip link set dev $port master br1 done the CPU no longer sees packets which traverse sja1105 switch boundaries and can be forwarded directly by Felix. The br1 bridge would not be used for any sort of traffic termination. For this to work, we need to give drivers an opportunity to listen for bridging events on DSA trees other than their own, and pass that other tree index as argument. I have made the assumption, for the moment, that the other existing DSA notifiers don't need to be broadcast to other trees. That assumption might turn out to be incorrect. But in the meantime, introduce a dsa_broadcast function, similar in purpose to dsa_port_notify, which is used only by the bridging notifiers. Signed-off-by: Vladimir Oltean Reviewed-by: Florian Fainelli Signed-off-by: Jakub Kicinski

net: bridge: allow enslaving some DSA master network devices

2020-05-11T02:52:33Z

Commit 8db0a2ee2c63 ("net: bridge: reject DSA-enabled master netdevices as bridge members") added a special check in br_if.c in order to check for a DSA master network device with a tagging protocol configured. This was done because back then, such devices, once enslaved in a bridge would become inoperative and would not pass DSA tagged traffic anymore due to br_handle_frame returning RX_HANDLER_CONSUMED. But right now we have valid use cases which do require bridging of DSA masters. One such example is when the DSA master ports are DSA switch ports themselves (in a disjoint tree setup). This should be completely equivalent, functionally speaking, from having multiple DSA switches hanging off of the ports of a switchdev driver. So we should allow the enslaving of DSA tagged master network devices. Instead of the regular br_handle_frame(), install a new function br_handle_frame_dummy() on these DSA masters, which returns RX_HANDLER_PASS in order to call into the DSA specific tagging protocol handlers, and lift the restriction from br_add_if. Suggested-by: Nikolay Aleksandrov Suggested-by: Florian Fainelli Signed-off-by: Vladimir Oltean Acked-by: Nikolay Aleksandrov Reviewed-by: Florian Fainelli Tested-by: Florian Fainelli Signed-off-by: Jakub Kicinski

net: dsa: introduce a dsa_port_from_netdev public helper

2020-05-08T00:31:57Z

As its implementation shows, this is synonimous with calling dsa_slave_dev_check followed by dsa_slave_to_port, so it is quite simple already and provides functionality which is already there. However there is now a need for these functions outside dsa_priv.h, for example in drivers that perform mirroring and redirection through tc-flower offloads (they are given raw access to the flow_cls_offload structure), where they need to call this function on act->dev. But simply exporting dsa_slave_to_port would make it non-inline and would result in an extra function call in the hotpath, as can be seen for example in sja1105: Before: 000006dc : { 6dc: e92d4ff0 push {r4, r5, r6, r7, r8, r9, sl, fp, lr} 6e0: e1a04000 mov r4, r0 6e4: e591958c ldr r9, [r1, #1420] ; 0x58c <- Inline dsa_slave_to_port 6e8: e1a05001 mov r5, r1 6ec: e24dd004 sub sp, sp, #4 u16 tx_vid = dsa_8021q_tx_vid(dp->ds, dp->index); 6f0: e1c901d8 ldrd r0, [r9, #24] 6f4: ebfffffe bl 0 6f4: R_ARM_CALL dsa_8021q_tx_vid u8 pcp = netdev_txq_to_tc(netdev, queue_mapping); 6f8: e1d416b0 ldrh r1, [r4, #96] ; 0x60 u16 tx_vid = dsa_8021q_tx_vid(dp->ds, dp->index); 6fc: e1a08000 mov r8, r0 After: 000006e4 : { 6e4: e92d4ff0 push {r4, r5, r6, r7, r8, r9, sl, fp, lr} 6e8: e1a04000 mov r4, r0 6ec: e24dd004 sub sp, sp, #4 struct dsa_port *dp = dsa_slave_to_port(netdev); 6f0: e1a00001 mov r0, r1 { 6f4: e1a05001 mov r5, r1 struct dsa_port *dp = dsa_slave_to_port(netdev); 6f8: ebfffffe bl 0 6f8: R_ARM_CALL dsa_slave_to_port 6fc: e1a09000 mov r9, r0 u16 tx_vid = dsa_8021q_tx_vid(dp->ds, dp->index); 700: e1c001d8 ldrd r0, [r0, #24] 704: ebfffffe bl 0 704: R_ARM_CALL dsa_8021q_tx_vid Because we want to avoid possible performance regressions, introduce this new function which is designed to be public. Suggested-by: Vivien Didelot Signed-off-by: Vladimir Oltean Reviewed-by: Vivien Didelot Signed-off-by: David S. Miller

net: dsa: add port policers

2020-03-30T18:44:00Z

The approach taken to pass the port policer methods on to drivers is pragmatic. It is similar to the port mirroring implementation (in that the DSA core does all of the filter block interaction and only passes simple operations for the driver to implement) and dissimilar to how flow-based policers are going to be implemented (where the driver has full control over the flow_cls_offload data structure). Signed-off-by: Vladimir Oltean Signed-off-by: David S. Miller

net: dsa: implement auto-normalization of MTU for bridge hardware datapath

2020-03-27T23:07:25Z

Many switches don't have an explicit knob for configuring the MTU (maximum transmission unit per interface). Instead, they do the length-based packet admission checks on the ingress interface, for reasons that are easy to understand (why would you accept a packet in the queuing subsystem if you know you're going to drop it anyway). So it is actually the MRU that these switches permit configuring. In Linux there only exists the IFLA_MTU netlink attribute and the associated dev_set_mtu function. The comments like to play blind and say that it's changing the "maximum transfer unit", which is to say that there isn't any directionality in the meaning of the MTU word. So that is the interpretation that this patch is giving to things: MTU == MRU. When 2 interfaces having different MTUs are bridged, the bridge driver MTU auto-adjustment logic kicks in: what br_mtu_auto_adjust() does is it adjusts the MTU of the bridge net device itself (and not that of the slave net devices) to the minimum value of all slave interfaces, in order for forwarded packets to not exceed the MTU regardless of the interface they are received and send on. The idea behind this behavior, and why the slave MTUs are not adjusted, is that normal termination from Linux over the L2 forwarding domain should happen over the bridge net device, which _is_ properly limited by the minimum MTU. And termination over individual slave devices is possible even if those are bridged. But that is not "forwarding", so there's no reason to do normalization there, since only a single interface sees that packet. The problem with those switches that can only control the MRU is with the offloaded data path, where a packet received on an interface with MRU 9000 would still be forwarded to an interface with MRU 1500. And the br_mtu_auto_adjust() function does not really help, since the MTU configured on the bridge net device is ignored. In order to enforce the de-facto MTU == MRU rule for these switches, we need to do MTU normalization, which means: in order for no packet larger than the MTU configured on this port to be sent, then we need to limit the MRU on all ports that this packet could possibly come from. AKA since we are configuring the MRU via MTU, it means that all ports within a bridge forwarding domain should have the same MTU. And that is exactly what this patch is trying to do. >From an implementation perspective, we try to follow the intent of the user, otherwise there is a risk that we might livelock them (they try to change the MTU on an already-bridged interface, but we just keep changing it back in an attempt to keep the MTU normalized). So the MTU that the bridge is normalized to is either: - The most recently changed one: ip link set dev swp0 master br0 ip link set dev swp1 master br0 ip link set dev swp0 mtu 1400 This sequence will make swp1 inherit MTU 1400 from swp0. - The one of the most recently added interface to the bridge: ip link set dev swp0 master br0 ip link set dev swp1 mtu 1400 ip link set dev swp1 master br0 The above sequence will make swp0 inherit MTU 1400 as well. Suggested-by: Florian Fainelli Signed-off-by: Vladimir Oltean Signed-off-by: David S. Miller

net: dsa: configure the MTU for switch ports

2020-03-27T23:07:24Z

It is useful be able to configure port policers on a switch to accept frames of various sizes: - Increase the MTU for better throughput from the default of 1500 if it is known that there is no 10/100 Mbps device in the network. - Decrease the MTU to limit the latency of high-priority frames under congestion, or work around various network segments that add extra headers to packets which can't be fragmented. For DSA slave ports, this is mostly a pass-through callback, called through the regular ndo ops and at probe time (to ensure consistency across all supported switches). The CPU port is called with an MTU equal to the largest configured MTU of the slave ports. The assumption is that the user might want to sustain a bidirectional conversation with a partner over any switch port. The DSA master is configured the same as the CPU port, plus the tagger overhead. Since the MTU is by definition L2 payload (sans Ethernet header), it is up to each individual driver to figure out if it needs to do anything special for its frame tags on the CPU port (it shouldn't except in special cases). So the MTU does not contain the tagger overhead on the CPU port. However the MTU of the DSA master, minus the tagger overhead, is used as a proxy for the MTU of the CPU port, which does not have a net device. This is to avoid uselessly calling the .change_mtu function on the CPU port when nothing should change. So it is safe to assume that the DSA master and the CPU port MTUs are apart by exactly the tagger's overhead in bytes. Some changes were made around dsa_master_set_mtu(), function which was now removed, for 2 reasons: - dev_set_mtu() already calls dev_validate_mtu(), so it's redundant to do the same thing in DSA - __dev_set_mtu() returns 0 if ops->ndo_change_mtu is an absent method That is to say, there's no need for this function in DSA, we can safely call dev_set_mtu() directly, take the rtnl lock when necessary, and just propagate whatever errors get reported (since the user probably wants to be informed). Some inspiration (mainly in the MTU DSA notifier) was taken from a vaguely similar patch from Murali and Florian, who are credited as co-developers down below. Co-developed-by: Murali Krishna Policharla Signed-off-by: Murali Krishna Policharla Co-developed-by: Florian Fainelli Signed-off-by: Florian Fainelli Signed-off-by: Vladimir Oltean Signed-off-by: David S. Miller

net: dsa: Add bypass operations for the flower classifier-action filter

2020-03-04T02:57:49Z

Due to the immense variety of classification keys and actions available for tc-flower, as well as due to potentially very different DSA switch capabilities, it doesn't make a lot of sense for the DSA mid layer to even attempt to interpret these. So just pass them on to the underlying switch driver. DSA implements just the standard boilerplate for binding and unbinding flow blocks to ports, since nobody wants to deal with that. Signed-off-by: Vladimir Oltean Reviewed-by: Florian Fainelli Signed-off-by: David S. Miller

net: dsa: propagate resolved link config via mac_link_up()

2020-02-27T20:02:14Z

Propagate the resolved link configuration down via DSA's phylink_mac_link_up() operation to allow split PCS/MAC to work. Tested-by: Vladimir Oltean Signed-off-by: Russell King Signed-off-by: David S. Miller