[PATCH v2 0/2] Add OVS packet family YNL spec and unicast notification support

[PATCH v2 0/2] Add OVS packet family YNL spec and unicast notification support

[Minxi Hou]

This series adds a YAML netlink spec for the OVS_PACKET_FAMILY genetlink
family and a bind-only ntf_listen() helper for receiving unicast
notifications.

Changes in v2:
- patch 1: use YAML anchor (&event-attrs / *event-attrs) to avoid
  repeating the same attribute list for miss and action events
  (suggested by Donald Hunter)
- patch 1: fix enum-name from ovs-packet-attrs to ovs-packet-attr
  to match the kernel enum name ovs_packet_attr
- patch 2: add ntf_listen() to the YnlFamily docstring under the
  "Notification API" heading (suggested by Donald Hunter)

Minxi Hou (2):
  netlink: specs: add OVS packet family specification
  tools: ynl: add unicast notification receive support

 Documentation/netlink/specs/ovs_packet.yaml | 130 ++++++++++++++++++++
 tools/net/ynl/pyynl/lib/ynl.py              |   5 +
 2 files changed, 135 insertions(+)
 create mode 100644 Documentation/netlink/specs/ovs_packet.yaml

-- 
2.54.0

[PATCH v2 1/2] netlink: specs: add OVS packet family specification

[Minxi Hou]

Add YAML netlink spec for the OVS_PACKET_FAMILY (ovs_packet).
This completes the set of OVS genetlink family specs (ovs_datapath,
ovs_flow, ovs_vport already exist).

The spec defines three operations: MISS (event), ACTION (event),
and EXECUTE (do). MISS and ACTION are kernel-to-userspace upcalls
sent via genlmsg_unicast(); EXECUTE is the only registered genl
operation.

Key, actions, and egress-tun-key attributes are typed as binary
rather than nest because the nested attribute definitions belong
to the ovs_flow spec and cross-spec references are not supported
by the YNL framework.

Signed-off-by: Minxi Hou <houminxi@gmail.com>
---
 Documentation/netlink/specs/ovs_packet.yaml | 130 ++++++++++++++++++++
 1 file changed, 130 insertions(+)
 create mode 100644 Documentation/netlink/specs/ovs_packet.yaml

diff --git a/Documentation/netlink/specs/ovs_packet.yaml b/Documentation/netlink/specs/ovs_packet.yaml
new file mode 100644
index 000000000000..4c1f06630e4e
--- /dev/null
+++ b/Documentation/netlink/specs/ovs_packet.yaml
@@ -0,0 +1,130 @@
+# SPDX-License-Identifier: ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause)
+
+name: ovs_packet
+version: 1
+protocol: genetlink-legacy
+uapi-header: linux/openvswitch.h
+
+doc: |
+  OVS packet execution over generic netlink.
+
+  Only OVS_PACKET_CMD_EXECUTE is exposed as a genl operation.
+  OVS_PACKET_CMD_MISS and OVS_PACKET_CMD_ACTION are kernel-to-userspace
+  upcalls sent via genlmsg_unicast() to the vport's upcall_pid and have
+  no associated genl_ops or multicast group.
+
+  Several attributes in the attribute set (userdata, egress-tun-key, len)
+  exist for the upcall path and are not used by the EXECUTE operation.
+  For EXECUTE, packet, key, and actions are mandatory (kernel returns
+  -EINVAL without them).
+
+definitions:
+  -
+    name: ovs-header
+    type: struct
+    members:
+      -
+        name: dp-ifindex
+        type: u32
+
+attribute-sets:
+  -
+    name: packet
+    name-prefix: ovs-packet-attr-
+    enum-name: ovs-packet-attr
+    attributes:
+      -
+        name: packet
+        type: binary
+        doc: Packet data, from the start of the Ethernet header.
+        checks:
+          min-len: 14
+      -
+        name: key
+        type: binary
+        doc: |
+          Nested OVS_KEY_ATTR_* attributes, extracted flow key.
+          Defined as binary because the key attribute-set belongs to the
+          ovs_flow family spec; cross-spec references are not supported.
+      -
+        name: actions
+        type: binary
+        doc: |
+          Nested OVS_ACTION_ATTR_* attributes.
+          Defined as binary for the same reason as key.
+      -
+        name: userdata
+        type: binary
+        doc: Opaque userspace cookie from OVS_USERSPACE_ATTR_USERDATA.
+      -
+        name: egress-tun-key
+        type: binary
+        doc: Nested OVS_TUNNEL_KEY_ATTR_* for output tunnel metadata.
+      -
+        name: unused1
+        type: unused
+      -
+        name: unused2
+        type: unused
+      -
+        name: probe
+        type: flag
+        doc: Packet operation is a feature probe, error logging suppressed.
+      -
+        name: mru
+        type: u16
+        doc: Maximum received IP fragment size.
+      -
+        name: len
+        type: u32
+        doc: Packet size before truncation.
+      -
+        name: hash
+        type: u64
+        doc: Packet hash, low 32 bits are skb hash, upper bits are flags.
+      -
+        name: upcall-pid
+        type: u32
+        doc: Netlink PID to use for upcalls during EXECUTE processing.
+
+operations:
+  fixed-header: ovs-header
+  name-prefix: ovs-packet-cmd-
+  list:
+    -
+      name: miss
+      doc: Notify userspace of a flow table miss for a received packet.
+      value: 1
+      attribute-set: packet
+      event:
+        attributes: &event-attrs
+          - packet
+          - key
+          - userdata
+          - actions
+          - egress-tun-key
+          - mru
+          - len
+          - hash
+    -
+      name: action
+      doc: Notify userspace as requested by an OVS_ACTION_ATTR_USERSPACE action.
+      value: 2
+      attribute-set: packet
+      event:
+        attributes: *event-attrs
+    -
+      name: execute
+      doc: Apply actions to a packet.
+      value: 3
+      attribute-set: packet
+      do:
+        request:
+          attributes:
+            - packet
+            - key
+            - actions
+            - probe
+            - mru
+            - hash
+            - upcall-pid
-- 
2.54.0

[PATCH v2 2/2] tools: ynl: add unicast notification receive support

[Minxi Hou]

Add ntf_listen() method to YnlFamily for binding the netlink
socket without joining a multicast group. This enables receiving
unicast notifications through the existing poll_ntf/check_ntf
path.

The OVS packet family sends MISS and ACTION upcalls via
genlmsg_unicast() to a per-vport PID rather than through a
multicast group. The existing ntf_subscribe() couples bind()
with setsockopt(ADD_MEMBERSHIP), which does not fit the unicast
case. ntf_listen() provides the bind-only alternative.

Signed-off-by: Minxi Hou <houminxi@gmail.com>
---
 tools/net/ynl/pyynl/lib/ynl.py | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/tools/net/ynl/pyynl/lib/ynl.py b/tools/net/ynl/pyynl/lib/ynl.py
index f63c6f828735..04743a79a7a3 100644
--- a/tools/net/ynl/pyynl/lib/ynl.py
+++ b/tools/net/ynl/pyynl/lib/ynl.py
@@ -680,6 +680,7 @@ class YnlFamily(SpecFamily):
     Notification API:
 
       ynl.ntf_subscribe(mcast_name)      -- join a multicast group
+      ynl.ntf_listen()                   -- bind socket for unicast notifications
       ynl.check_ntf()                    -- drain pending notifications
       ynl.poll_ntf(duration=None)        -- yield notifications
 
@@ -748,6 +749,10 @@ class YnlFamily(SpecFamily):
         self.sock.setsockopt(Netlink.SOL_NETLINK, Netlink.NETLINK_ADD_MEMBERSHIP,
                              mcast_id)
 
+    def ntf_listen(self):
+        """Bind socket for receiving unicast notifications."""
+        self.sock.bind((0, 0))
+
     def set_recv_dbg(self, enabled):
         self._recv_dbg = enabled
 
-- 
2.54.0

Re: [PATCH v2 1/2] netlink: specs: add OVS packet family specification

[Donald Hunter]

Minxi Hou <houminxi@gmail.com> writes:

> Add YAML netlink spec for the OVS_PACKET_FAMILY (ovs_packet).
> This completes the set of OVS genetlink family specs (ovs_datapath,
> ovs_flow, ovs_vport already exist).
>
> The spec defines three operations: MISS (event), ACTION (event),
> and EXECUTE (do). MISS and ACTION are kernel-to-userspace upcalls
> sent via genlmsg_unicast(); EXECUTE is the only registered genl
> operation.
>
> Key, actions, and egress-tun-key attributes are typed as binary
> rather than nest because the nested attribute definitions belong
> to the ovs_flow spec and cross-spec references are not supported
> by the YNL framework.
>
> Signed-off-by: Minxi Hou <houminxi@gmail.com>

Reviewed-by: Donald Hunter <donald.hunter@gmail.com>

Re: [PATCH v2 2/2] tools: ynl: add unicast notification receive support

[Donald Hunter]

Minxi Hou <houminxi@gmail.com> writes:

> Add ntf_listen() method to YnlFamily for binding the netlink
> socket without joining a multicast group. This enables receiving
> unicast notifications through the existing poll_ntf/check_ntf
> path.
>
> The OVS packet family sends MISS and ACTION upcalls via
> genlmsg_unicast() to a per-vport PID rather than through a
> multicast group. The existing ntf_subscribe() couples bind()
> with setsockopt(ADD_MEMBERSHIP), which does not fit the unicast
> case. ntf_listen() provides the bind-only alternative.
>
> Signed-off-by: Minxi Hou <houminxi@gmail.com>

Reviewed-by: Donald Hunter <donald.hunter@gmail.com>

Re: [PATCH v2 2/2] tools: ynl: add unicast notification receive support

[侯敏熙]

Hello Donald

Should I re-spain a new version to fix the yaml check issue?

 ====== Checking the tree with the patch ======
New warnings added
--- /tmp/tmp.2uYmXlzyoK 2026-05-18 12:59:32.034644770 -0400
+++ /tmp/tmp.UAwK6To8IX 2026-05-18 12:59:32.187643683 -0400
@@ -0,0 +1,3 @@
+ovs_packet.yaml
+  3:1       warning  missing document start "---"  (document-start)

+
B.R
Minxi

Donald Hunter <donald.hunter@gmail.com> 于2026年5月19日周二 17:45写道：
>
> Minxi Hou <houminxi@gmail.com> writes:
>
> > Add ntf_listen() method to YnlFamily for binding the netlink
> > socket without joining a multicast group. This enables receiving
> > unicast notifications through the existing poll_ntf/check_ntf
> > path.
> >
> > The OVS packet family sends MISS and ACTION upcalls via
> > genlmsg_unicast() to a per-vport PID rather than through a
> > multicast group. The existing ntf_subscribe() couples bind()
> > with setsockopt(ADD_MEMBERSHIP), which does not fit the unicast
> > case. ntf_listen() provides the bind-only alternative.
> >
> > Signed-off-by: Minxi Hou <houminxi@gmail.com>
>
> Reviewed-by: Donald Hunter <donald.hunter@gmail.com>

Re: [PATCH v2 2/2] tools: ynl: add unicast notification receive support

[Donald Hunter]

On Tue, 19 May 2026 at 10:51, 侯敏熙 <houminxi@gmail.com> wrote:
>
> Hello Donald
>
> Should I re-spain a new version to fix the yaml check issue?
>
>  ====== Checking the tree with the patch ======
> New warnings added
> --- /tmp/tmp.2uYmXlzyoK 2026-05-18 12:59:32.034644770 -0400
> +++ /tmp/tmp.UAwK6To8IX 2026-05-18 12:59:32.187643683 -0400
> @@ -0,0 +1,3 @@
> +ovs_packet.yaml
> +  3:1       warning  missing document start "---"  (document-start)

Good catch, yes please.