kernel/include/linux/dsa, branch linux-5.14.y

net: dsa: felix: fix broken VLAN-tagged PTP under VLAN-aware bridge

2021-11-17T10:04:38Z

[ Upstream commit 92f62485b3715882cd397b0cbd80a96d179b86d6 ] Normally it is expected that the dsa_device_ops :: rcv() method finishes parsing the DSA tag and consumes it, then never looks at it again. But commit c0bcf537667c ("net: dsa: ocelot: add hardware timestamping support for Felix") added support for RX timestamping in a very unconventional way. On this switch, a partial timestamp is available in the DSA header, but the driver got away with not parsing that timestamp right away, but instead delayed that parsing for a little longer: dsa_switch_rcv(): nskb = cpu_dp->rcv(skb, dev); <------------- not here -> ocelot_rcv() ... skb = nskb; skb_push(skb, ETH_HLEN); skb->pkt_type = PACKET_HOST; skb->protocol = eth_type_trans(skb, skb->dev); ... if (dsa_skb_defer_rx_timestamp(p, skb)) <--- but here -> felix_rxtstamp() return 0; When in felix_rxtstamp(), this driver accounted for the fact that eth_type_trans() happened in the meanwhile, so it got a hold of the extraction header again by subtracting (ETH_HLEN + OCELOT_TAG_LEN) bytes from the current skb->data. This worked for quite some time but was quite fragile from the very beginning. Not to mention that having DSA tag parsing split in two different files, under different folders (net/dsa/tag_ocelot.c vs drivers/net/dsa/ocelot/felix.c) made it quite non-obvious for patches to come that they might break this. Finally, the blamed commit does the following: at the end of ocelot_rcv(), it checks whether the skb payload contains a VLAN header. If it does, and this port is under a VLAN-aware bridge, that VLAN ID might not be correct in the sense that the packet might have suffered VLAN rewriting due to TCAM rules (VCAP IS1). So we consume the VLAN ID from the skb payload using __skb_vlan_pop(), and take the classified VLAN ID from the DSA tag, and construct a hwaccel VLAN tag with the classified VLAN, and the skb payload is VLAN-untagged. The big problem is that __skb_vlan_pop() does: memmove(skb->data + VLAN_HLEN, skb->data, 2 * ETH_ALEN); __skb_pull(skb, VLAN_HLEN); aka it moves the Ethernet header 4 bytes to the right, and pulls 4 bytes from the skb headroom (effectively also moving skb->data, by definition). So for felix_rxtstamp()'s fragile logic, all bets are off now. Instead of having the "extraction" pointer point to the DSA header, it actually points to 4 bytes _inside_ the extraction header. Corollary, the last 4 bytes of the "extraction" header are in fact 4 stale bytes of the destination MAC address from the Ethernet header, from prior to the __skb_vlan_pop() movement. So of course, RX timestamps are completely bogus when the system is configured in this way. The fix is actually very simple: just don't structure the code like that. For better or worse, the DSA PTP timestamping API does not offer a straightforward way for drivers to present their RX timestamps, but other drivers (sja1105) have established a simple mechanism to carry their RX timestamp from dsa_device_ops :: rcv() all the way to dsa_switch_ops :: port_rxtstamp() and even later. That mechanism is to simply save the partial timestamp to the skb->cb, and complete it later. Question: why don't we simply populate the skb's struct skb_shared_hwtstamps from ocelot_rcv(), and bother with this complication of propagating the timestamp to felix_rxtstamp()? Answer: dsa_switch_ops :: port_rxtstamp() answers the question whether PTP packets need sleepable context to retrieve the full RX timestamp. Currently felix_rxtstamp() answers "no, thanks" to that question, and calls ocelot_ptp_gettime64() from softirq atomic context. This is understandable, since Felix VSC9959 is a PCIe memory-mapped switch, so hardware access does not require sleeping. But the felix driver is preparing for the introduction of other switches where hardware access is over a slow bus like SPI or MDIO: https://lore.kernel.org/lkml/20210814025003.2449143-1-colin.foster@in-advantage.com/ So I would like to keep this code structure, so the rework needed when that driver will need PTP support will be minimal (answer "yes, I need deferred context for this skb's RX timestamp", then the partial timestamp will still be found in the skb->cb. Fixes: ea440cd2d9b2 ("net: dsa: tag_ocelot: use VLAN information from tagging header when available") Reported-by: Po Liu Cc: Yangbo Lu Signed-off-by: Vladimir Oltean Signed-off-by: David S. Miller Signed-off-by: Sasha Levin

net: dsa: tag_ocelot: break circular dependency with ocelot switch lib driver

2021-11-17T10:04:38Z

[ Upstream commit deab6b1cd9789bb9bd466d5e76aecb8b336259b4 ] As explained here: https://lore.kernel.org/netdev/20210908220834.d7gmtnwrorhharna@skbuf/ DSA tagging protocol drivers cannot depend on symbols exported by switch drivers, because this creates a circular dependency that breaks module autoloading. The tag_ocelot.c file depends on the ocelot_ptp_rew_op() function exported by the common ocelot switch lib. This function looks at OCELOT_SKB_CB(skb) and computes how to populate the REW_OP field of the DSA tag, for PTP timestamping (the command: one-step/two-step, and the TX timestamp identifier). None of that requires deep insight into the driver, it is quite stateless, as it only depends upon the skb->cb. So let's make it a static inline function and put it in include/linux/dsa/ocelot.h, a file that despite its name is used by the ocelot switch driver for populating the injection header too - since commit 40d3f295b5fe ("net: mscc: ocelot: use common tag parsing code with DSA"). With that function declared as static inline, its body is expanded inside each call site, so the dependency is broken and the DSA tagger can be built without the switch library, upon which the felix driver depends. Fixes: 39e5308b3250 ("net: mscc: ocelot: support PTP Sync one-step timestamping") Signed-off-by: Vladimir Oltean Reviewed-by: Florian Fainelli Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin

net: dsa: sja1105: implement TX timestamping for SJA1110

2021-06-11T19:45:38Z

The TX timestamping procedure for SJA1105 is a bit unconventional because the transmit procedure itself is unconventional. Control packets (and therefore PTP as well) are transmitted to a specific port in SJA1105 using "management routes" which must be written over SPI to the switch. These are one-shot rules that match by destination MAC address on traffic coming from the CPU port, and select the precise destination port for that packet. So to transmit a packet from NET_TX softirq context, we actually need to defer to a process context so that we can perform that SPI write before we send the packet. The DSA master dev_queue_xmit() runs in process context, and we poll until the switch confirms it took the TX timestamp, then we annotate the skb clone with that TX timestamp. This is why the sja1105 driver does not need an skb queue for TX timestamping. But the SJA1110 is a bit (not much!) more conventional, and you can request 2-step TX timestamping through the DSA header, as well as give the switch a cookie (timestamp ID) which it will give back to you when it has the timestamp. So now we do need a queue for keeping the skb clones until their TX timestamps become available. The interesting part is that the metadata frames from SJA1105 haven't disappeared completely. On SJA1105 they were used as follow-ups which contained RX timestamps, but on SJA1110 they are actually TX completion packets, which contain a variable (up to 32) array of timestamps. Why an array? Because: - not only is the TX timestamp on the egress port being communicated, but also the RX timestamp on the CPU port. Nice, but we don't care about that, so we ignore it. - because a packet could be multicast to multiple egress ports, each port takes its own timestamp, and the TX completion packet contains the individual timestamps on each port. This is unconventional because switches typically have a timestamping FIFO and raise an interrupt, but this one doesn't. So the tagger needs to detect and parse meta frames, and call into the main switch driver, which pairs the timestamps with the skbs in the TX timestamping queue which are waiting for one. Signed-off-by: Vladimir Oltean Signed-off-by: David S. Miller

net: dsa: add support for the SJA1110 native tagging protocol

2021-06-11T19:45:38Z

The SJA1110 has improved a few things compared to SJA1105: - To send a control packet from the host port with SJA1105, one needed to program a one-shot "management route" over SPI. This is no longer true with SJA1110, you can actually send "in-band control extensions" in the packets sent by DSA, these are in fact DSA tags which contain the destination port and switch ID. - When receiving a control packet from the switch with SJA1105, the source port and switch ID were written in bytes 3 and 4 of the destination MAC address of the frame (which was a very poor shot at a DSA header). If the control packet also had an RX timestamp, that timestamp was sent in an actual follow-up packet, so there were reordering concerns on multi-core/multi-queue DSA masters, where the metadata frame with the RX timestamp might get processed before the actual packet to which that timestamp belonged (there is no way to pair a packet to its timestamp other than the order in which they were received). On SJA1110, this is no longer true, control packets have the source port, switch ID and timestamp all in the DSA tags. - Timestamps from the switch were partial: to get a 64-bit timestamp as required by PTP stacks, one would need to take the partial 24-bit or 32-bit timestamp from the packet, then read the current PTP time very quickly, and then patch in the high bits of the current PTP time into the captured partial timestamp, to reconstruct what the full 64-bit timestamp must have been. That is awful because packet processing is done in NAPI context, but reading the current PTP time is done over SPI and therefore needs sleepable context. But it also aggravated a few things: - Not only is there a DSA header in SJA1110, but there is a DSA trailer in fact, too. So DSA needs to be extended to support taggers which have both a header and a trailer. Very unconventional - my understanding is that the trailer exists because the timestamps couldn't be prepared in time for putting them in the header area. - Like SJA1105, not all packets sent to the CPU have the DSA tag added to them, only control packets do: * the ones which match the destination MAC filters/traps in MAC_FLTRES1 and MAC_FLTRES0 * the ones which match FDB entries which have TRAP or TAKETS bits set So we could in theory hack something up to request the switch to take timestamps for all packets that reach the CPU, and those would be DSA-tagged and contain the source port / switch ID by virtue of the fact that there needs to be a timestamp trailer provided. BUT: - The SJA1110 does not parse its own DSA tags in a way that is useful for routing in cross-chip topologies, a la Marvell. And the sja1105 driver already supports cross-chip bridging from the SJA1105 days. It does that by automatically setting up the DSA links as VLAN trunks which contain all the necessary tag_8021q RX VLANs that must be communicated between the switches that span the same bridge. So when using tag_8021q on sja1105, it is possible to have 2 switches with ports sw0p0, sw0p1, sw1p0, sw1p1, and 2 VLAN-unaware bridges br0 and br1, and br0 can take sw0p0 and sw1p0, and br1 can take sw0p1 and sw1p1, and forwarding will happen according to the expected rules of the Linux bridge. We like that, and we don't want that to go away, so as a matter of fact, the SJA1110 tagger still needs to support tag_8021q. So the sja1110 tagger is a hybrid between tag_8021q for data packets, and the native hardware support for control packets. On RX, packets have a 13-byte trailer if they contain an RX timestamp. That trailer is padded in such a way that its byte 8 (the start of the "residence time" field - not parsed by Linux because we don't care) is aligned on a 16 byte boundary. So the padding has a variable length between 0 and 15 bytes. The DSA header contains the offset of the beginning of the padding relative to the beginning of the frame (and the end of the padding is obviously the end of the packet minus 13 bytes, the length of the trailer). So we discard it. Packets which don't have a trailer contain the source port and switch ID information in the header (they are "trap-to-host" packets). Packets which have a trailer contain the source port and switch ID in the trailer. On TX, the destination port mask and switch ID is always in the trailer, so we always need to say in the header that a trailer is present. The header needs a custom EtherType and this was chosen as 0xdadc, after 0xdada which is for Marvell and 0xdadb which is for VLANs in VLAN-unaware mode on SJA1105 (and SJA1110 in fact too). Because we use tag_8021q in concert with the native tagging protocol, control packets will have 2 DSA tags. Signed-off-by: Vladimir Oltean Signed-off-by: David S. Miller

net: dsa: sja1105: make SJA1105_SKB_CB fit a full timestamp

2021-06-11T19:45:38Z

In SJA1105, RX timestamps for packets sent to the CPU are transmitted in separate follow-up packets (metadata frames). These contain partial timestamps (24 or 32 bits) which are kept in SJA1105_SKB_CB(skb)->meta_tstamp. Thankfully, SJA1110 improved that, and the RX timestamps are now transmitted in-band with the actual packet, in the timestamp trailer. The RX timestamps are now full-width 64 bits. Because we process the RX DSA tags in the rcv() method in the tagger, but we would like to preserve the DSA code structure in that we populate the skb timestamp in the port_rxtstamp() call which only happens later, the implication is that we must somehow pass the 64-bit timestamp from the rcv() method all the way to port_rxtstamp(). We can use the skb->cb for that. Rename the meta_tstamp from struct sja1105_skb_cb from "meta_tstamp" to "tstamp", and increase its size to 64 bits. Signed-off-by: Vladimir Oltean Signed-off-by: David S. Miller

net: dsa: tag_8021q: refactor RX VLAN parsing into a dedicated function

2021-06-11T19:45:38Z

The added value of this function is that it can deal with both the case where the VLAN header is in the skb head, as well as in the offload field. This is something I was not able to do using other functions in the network stack. Since both ocelot-8021q and sja1105 need to do the same stuff, let's make it a common service provided by tag_8021q. This is done as refactoring for the new SJA1110 tagger, which partly uses tag_8021q as well (just like SJA1105), and will be the third caller. Signed-off-by: Vladimir Oltean Signed-off-by: David S. Miller

net: dsa: tag_8021q: remove shim declarations

2021-06-11T19:45:38Z

All users of tag_8021q select it in Kconfig, so shim functions are not needed because it is not possible for it to be disabled and its callers enabled. Signed-off-by: Vladimir Oltean Signed-off-by: David S. Miller

net: dsa: free skb->cb usage in core driver

2021-04-27T21:10:15Z

Free skb->cb usage in core driver and let device drivers decide to use or not. The reason having a DSA_SKB_CB(skb)->clone was because dsa_skb_tx_timestamp() which may set the clone pointer was called before p->xmit() which would use the clone if any, and the device driver has no way to initialize the clone pointer. This patch just put memset(skb->cb, 0, sizeof(skb->cb)) at beginning of dsa_slave_xmit(). Some new features in the future, like one-step timestamp may need more bytes of skb->cb to use in dsa_skb_tx_timestamp(), and p->xmit(). Signed-off-by: Yangbo Lu Acked-by: Richard Cochran Signed-off-by: David S. Miller

net: ocelot: Remove ocelot_xfh_get_cpuq

2021-03-16T22:49:52Z

Now when extracting frames from CPU the cpuq is not used anymore so remove it. Signed-off-by: Horatiu Vultur Signed-off-by: David S. Miller

net: mscc: ocelot: Add support for MRP

2021-02-16T22:47:46Z

Add basic support for MRP. The HW will just trap all MRP frames on the ring ports to CPU and allow the SW to process them. In this way it is possible to for this node to behave both as MRM and MRC. Current limitations are: - it doesn't support Interconnect roles. - it supports only a single ring. - the HW should be able to do forwarding of MRP Test frames so the SW will not need to do this. So it would be able to have the role MRC without SW support. Signed-off-by: Horatiu Vultur Signed-off-by: David S. Miller