By introducing packet type-aware pipeline, match on ethertype was
removed when packet type is not Ethernet. As pointed out by Eric Garver,
this could have a side effect on the kernel datapath:
https://patchwork.ozlabs.org/patch/782991/

This patch does approach the problem from a different perspective.
Instead of re-introducing the unconditional match on Ethernet type in all
megaflow entries, as suggested by Eric, mapping of packet_type != PT_ETH to
dl_type could be handled in the put_exclude_packet_type() in dpif-netlink.c.

Put_exclude_packet_type() filters the packet_type netlink attribute out,
before all attributes are sent from userspace to kernel. This commit modifies
the put_exclude_packet_type() function to do a proper conversation and add the
missing OVS_KEY_ATTR_ETHERTYPE attribute if it's needed.

Signed-off-by: Zoltán Balogh <[email protected]>
Reported-by: Eric Garver <[email protected]>
---
 lib/dpif-netlink.c | 34 ++++++++++++++++++++++++++++------
 1 file changed, 28 insertions(+), 6 deletions(-)

diff --git a/lib/dpif-netlink.c b/lib/dpif-netlink.c
index 562f6134c..d8051a09e 100644
--- a/lib/dpif-netlink.c
+++ b/lib/dpif-netlink.c
@@ -3434,11 +3434,11 @@ dpif_netlink_flow_from_ofpbuf(struct dpif_netlink_flow 
*flow,
 
 
 /*
- * If PACKET_TYPE attribute is present in 'data', it filters PACKET_TYPE out,
- * then puts 'data' to 'buf'.
+ * If PACKET_TYPE attribute is present in 'data', converts it to ETHERNET and
+ * ETHERTYPE attributes, then puts 'data' to 'buf'.
  */
 static void
-put_exclude_packet_type(struct ofpbuf *buf, uint16_t type,
+put_convert_packet_type(struct ofpbuf *buf, uint16_t type,
                         const struct nlattr *data, uint16_t data_len)
 {
     const struct nlattr *packet_type;
@@ -3446,8 +3446,9 @@ put_exclude_packet_type(struct ofpbuf *buf, uint16_t type,
     packet_type = nl_attr_find__(data, data_len, OVS_KEY_ATTR_PACKET_TYPE);
 
     if (packet_type) {
-        /* exclude PACKET_TYPE Netlink attribute. */
+        /* Convert PACKET_TYPE Netlink attribute. */
         ovs_assert(NLA_ALIGN(packet_type->nla_len) == NL_A_U32_SIZE);
+        ovs_be32 value = nl_attr_get_be32(packet_type);
         size_t packet_type_len = NL_A_U32_SIZE;
         size_t first_chunk_size = (uint8_t *)packet_type - (uint8_t *)data;
         size_t second_chunk_size = data_len - first_chunk_size
@@ -3455,10 +3456,31 @@ put_exclude_packet_type(struct ofpbuf *buf, uint16_t 
type,
         uint8_t *first_attr = NULL;
         struct nlattr *next_attr = nl_attr_next(packet_type);
 
+        bool ethernet_present = nl_attr_find__(data, data_len,
+                                               OVS_KEY_ATTR_ETHERNET);
+
         first_attr = nl_msg_put_unspec_uninit(buf, type,
                                               data_len - packet_type_len);
         memcpy(first_attr, data, first_chunk_size);
         memcpy(first_attr + first_chunk_size, next_attr, second_chunk_size);
+
+        /* Put OVS_KEY_ATTR_ETHERTYPE if needed. */
+        if (ntohl(value) == PT_ETH) {
+            ovs_assert(ethernet_present);
+        } else {
+            const struct nlattr *eth_type;
+            ovs_be16 ns_type = pt_ns_type_be(value);
+
+            ovs_assert(ethernet_present == false);
+
+            eth_type = nl_attr_find__(data, data_len, OVS_KEY_ATTR_ETHERTYPE);
+            if (eth_type) {
+                ovs_assert(nl_attr_get_be16(eth_type) == ns_type);
+            } else {
+                nl_msg_put_be16(buf, OVS_KEY_ATTR_ETHERTYPE, ns_type);
+            }
+        }
+
     } else {
         nl_msg_put_unspec(buf, type, data, data_len);
     }
@@ -3489,11 +3511,11 @@ dpif_netlink_flow_to_ofpbuf(const struct 
dpif_netlink_flow *flow,
     }
     if (!flow->ufid_terse || !flow->ufid_present) {
         if (flow->key_len) {
-            put_exclude_packet_type(buf, OVS_FLOW_ATTR_KEY, flow->key,
+            put_convert_packet_type(buf, OVS_FLOW_ATTR_KEY, flow->key,
                                            flow->key_len);
         }
         if (flow->mask_len) {
-            put_exclude_packet_type(buf, OVS_FLOW_ATTR_MASK, flow->mask,
+            put_convert_packet_type(buf, OVS_FLOW_ATTR_MASK, flow->mask,
                                            flow->mask_len);
         }
         if (flow->actions || flow->actions_len) {
-- 
2.11.0

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