kernel/linux.git/include/uapi/linux/openvswitch.h, branch v6.18.21

net: openvswitch: allow providing upcall pid for the 'execute' command

2025-07-07T21:30:39+00:00

When a packet enters OVS datapath and there is no flow to handle it, packet goes to userspace through a MISS upcall. With per-CPU upcall dispatch mechanism, we're using the current CPU id to select the Netlink PID on which to send this packet. This allows us to send packets from the same traffic flow through the same handler. The handler will process the packet, install required flow into the kernel and re-inject the original packet via OVS_PACKET_CMD_EXECUTE. While handling OVS_PACKET_CMD_EXECUTE, however, we may hit a recirculation action that will pass the (likely modified) packet through the flow lookup again. And if the flow is not found, the packet will be sent to userspace again through another MISS upcall. However, the handler thread in userspace is likely running on a different CPU core, and the OVS_PACKET_CMD_EXECUTE request is handled in the syscall context of that thread. So, when the time comes to send the packet through another upcall, the per-CPU dispatch will choose a different Netlink PID, and this packet will end up processed by a different handler thread on a different CPU. The process continues as long as there are new recirculations, each time the packet goes to a different handler thread before it is sent out of the OVS datapath to the destination port. In real setups the number of recirculations can go up to 4 or 5, sometimes more. There is always a chance to re-order packets while processing upcalls, because userspace will first install the flow and then re-inject the original packet. So, there is a race window when the flow is already installed and the second packet can match it and be forwarded to the destination before the first packet is re-injected. But the fact that packets are going through multiple upcalls handled by different userspace threads makes the reordering noticeably more likely, because we not only have a race between the kernel and a userspace handler (which is hard to avoid), but also between multiple userspace handlers. For example, let's assume that 10 packets got enqueued through a MISS upcall for handler-1, it will start processing them, will install the flow into the kernel and start re-injecting packets back, from where they will go through another MISS to handler-2. Handler-2 will install the flow into the kernel and start re-injecting the packets, while handler-1 continues to re-inject the last of the 10 packets, they will hit the flow installed by handler-2 and be forwarded without going to the handler-2, while handler-2 still re-injects the first of these 10 packets. Given multiple recirculations and misses, these 10 packets may end up completely mixed up on the output from the datapath. Let's allow userspace to specify on which Netlink PID the packets should be upcalled while processing OVS_PACKET_CMD_EXECUTE. This makes it possible to ensure that all the packets are processed by the same handler thread in the userspace even with them being upcalled multiple times in the process. Packets will remain in order since they will be enqueued to the same socket and re-injected in the same order. This doesn't eliminate re-ordering as stated above, since we still have a race between kernel and the userspace thread, but it allows to eliminate races between multiple userspace threads. Userspace knows the PID of the socket on which the original upcall is received, so there is no need to send it up from the kernel. Solution requires storing the value somewhere for the duration of the packet processing. There are two potential places for this: our skb extension or the per-CPU storage. It's not clear which is better, so just following currently used scheme of storing this kind of things along the skb. We still have a decent amount of space in the cb. Signed-off-by: Ilya Maximets Acked-by: Flavio Leitner Acked-by: Eelco Chaudron Acked-by: Aaron Conole Link: https://patch.msgid.link/20250702155043.2331772-1-i.maximets@ovn.org Signed-off-by: Jakub Kicinski

net: openvswitch: store sampling probability in cb.

2024-07-06T00:45:47+00:00

When a packet sample is observed, the sampling rate that was used is important to estimate the real frequency of such event. Store the probability of the parent sample action in the skb's cb area and use it in psample action to pass it down to psample module. Reviewed-by: Aaron Conole Acked-by: Eelco Chaudron Reviewed-by: Ilya Maximets Signed-off-by: Adrian Moreno Link: https://patch.msgid.link/20240704085710.353845-7-amorenoz@redhat.com Signed-off-by: Jakub Kicinski

net: openvswitch: add psample action

2024-07-06T00:45:47+00:00

Add support for a new action: psample. This action accepts a u32 group id and a variable-length cookie and uses the psample multicast group to make the packet available for observability. The maximum length of the user-defined cookie is set to 16, same as tc_cookie, to discourage using cookies that will not be offloadable. Reviewed-by: Michal Kubiak Reviewed-by: Aaron Conole Reviewed-by: Ilya Maximets Acked-by: Eelco Chaudron Signed-off-by: Adrian Moreno Link: https://patch.msgid.link/20240704085710.353845-6-amorenoz@redhat.com Signed-off-by: Jakub Kicinski

net: openvswitch: add explicit drop action

2023-08-14T07:01:06+00:00

From: Eric Garver This adds an explicit drop action. This is used by OVS to drop packets for which it cannot determine what to do. An explicit action in the kernel allows passing the reason _why_ the packet is being dropped or zero to indicate no particular error happened (i.e: OVS intentionally dropped the packet). Since the error codes coming from userspace mean nothing for the kernel, we squash all of them into only two drop reasons: - OVS_DROP_EXPLICIT_WITH_ERROR to indicate a non-zero value was passed - OVS_DROP_EXPLICIT to indicate a zero value was passed (no error) e.g. trace all OVS dropped skbs # perf trace -e skb:kfree_skb --filter="reason >= 0x30000" [..] 106.023 ping/2465 skb:kfree_skb(skbaddr: 0xffffa0e8765f2000, \ location:0xffffffffc0d9b462, protocol: 2048, reason: 196611) reason: 196611 --> 0x30003 (OVS_DROP_EXPLICIT) Also, this patch allows ovs-dpctl.py to add explicit drop actions as: "drop" -> implicit empty-action drop "drop(0)" -> explicit non-error action drop "drop(42)" -> explicit error action drop Signed-off-by: Eric Garver Co-developed-by: Adrian Moreno Signed-off-by: Adrian Moreno Signed-off-by: David S. Miller

net: openvswitch: add support for l4 symmetric hashing

2023-06-12T08:46:30+00:00

Since its introduction, the ovs module execute_hash action allowed hash algorithms other than the skb->l4_hash to be used. However, additional hash algorithms were not implemented. This means flows requiring different hash distributions weren't able to use the kernel datapath. Now, introduce support for symmetric hashing algorithm as an alternative hash supported by the ovs module using the flow dissector. Output of flow using l4_sym hash: recirc_id(0),in_port(3),eth(),eth_type(0x0800), ipv4(dst=64.0.0.0/192.0.0.0,proto=6,frag=no), packets:30473425, bytes:45902883702, used:0.000s, flags:SP., actions:hash(sym_l4(0)),recirc(0xd) Some performance testing with no GRO/GSO, two veths, single flow: hash(l4(0)): 4.35 GBits/s hash(l4_sym(0)): 4.24 GBits/s Signed-off-by: Aaron Conole Signed-off-by: David S. Miller

net: openvswitch: Add support to count upcall packets

2022-12-09T10:43:46+00:00

Add support to count upall packets, when kmod of openvswitch upcall to count the number of packets for upcall succeed and failed, which is a better way to see how many packets upcalled on every interfaces. Signed-off-by: wangchuanlei Acked-by: Eelco Chaudron Signed-off-by: David S. Miller

openvswitch: allow specifying ifindex of new interfaces

2022-08-27T02:31:20+00:00

CRIU is preserving ifindexes of net devices after restoration. However, current Open vSwitch API does not allow to target ifindex, so we cannot correctly restore OVS configuration. Add new OVS_DP_ATTR_IFINDEX for OVS_DP_CMD_NEW and use it as desired ifindex. Use OVS_VPORT_ATTR_IFINDEX during OVS_VPORT_CMD_NEW to specify new netdev ifindex. Signed-off-by: Andrey Zhadchenko Acked-by: Christian Brauner (Microsoft) Signed-off-by: Jakub Kicinski

net: openvswitch: fix uAPI incompatibility with existing user space

2022-03-11T04:14:52+00:00

Few years ago OVS user space made a strange choice in the commit [1] to define types only valid for the user space inside the copy of a kernel uAPI header. '#ifndef __KERNEL__' and another attribute was added later. This leads to the inevitable clash between user space and kernel types when the kernel uAPI is extended. The issue was unveiled with the addition of a new type for IPv6 extension header in kernel uAPI. When kernel provides the OVS_KEY_ATTR_IPV6_EXTHDRS attribute to the older user space application, application tries to parse it as OVS_KEY_ATTR_PACKET_TYPE and discards the whole netlink message as malformed. Since OVS_KEY_ATTR_IPV6_EXTHDRS is supplied along with every IPv6 packet that goes to the user space, IPv6 support is fully broken. Fixing that by bringing these user space attributes to the kernel uAPI to avoid the clash. Strictly speaking this is not the problem of the kernel uAPI, but changing it is the only way to avoid breakage of the older user space applications at this point. These 2 types are explicitly rejected now since they should not be passed to the kernel. Additionally, OVS_KEY_ATTR_TUNNEL_INFO moved out from the '#ifdef __KERNEL__' as there is no good reason to hide it from the userspace. And it's also explicitly rejected now, because it's for in-kernel use only. Comments with warnings were added to avoid the problem coming back. (1 << type) converted to (1ULL << type) to avoid integer overflow on OVS_KEY_ATTR_IPV6_EXTHDRS, since it equals 32 now. [1] beb75a40fdc2 ("userspace: Switching of L3 packets in L2 pipeline") Fixes: 28a3f0601727 ("net: openvswitch: IPv6: Add IPv6 extension header support") Link: https://lore.kernel.org/netdev/3adf00c7-fe65-3ef4-b6d7-6d8a0cad8a5f@nvidia.com Link: https://github.com/openvswitch/ovs/commit/beb75a40fdc295bfd6521b0068b4cd12f6de507c Reported-by: Roi Dayan Signed-off-by: Ilya Maximets Acked-by: Nicolas Dichtel Acked-by: Aaron Conole Link: https://lore.kernel.org/r/20220309222033.3018976-1-i.maximets@ovn.org Signed-off-by: Jakub Kicinski

net: openvswitch: IPv6: Add IPv6 extension header support

2022-02-25T10:32:55+00:00

This change adds a new OpenFlow field OFPXMT_OFB_IPV6_EXTHDR and packets can be filtered using ipv6_ext flag. Signed-off-by: Toms Atteka Acked-by: Pravin B Shelar Signed-off-by: David S. Miller

openvswitch: fix alignment issues

2021-07-27T10:48:42+00:00

Signed-off-by: Mark Gray Signed-off-by: David S. Miller