[Bug 242890] vmxnet3 problem when RSS option is configured

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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=242890

            Bug ID: 242890
           Summary: vmxnet3 problem when RSS option is configured
           Product: Base System
           Version: CURRENT
          Hardware: Any
                OS: Any
            Status: New
          Severity: Affects Only Me
          Priority: ---
         Component: kern
          Assignee: bugs at FreeBSD.org
          Reporter: avg at FreeBSD.org

We are observing a strange problem on VMware when a kernel is compiled with RSS
option.
The problem appears as lib resolver not being able to resolve DNS names.
E.g., "host google.com" would resolve the name, but "ping google.com" would
fail with "Host name lookup failure".
A packet capture shows that both commands send exactly the same requests and
get the same replies, but in the case of ping the host replies a port
unreachable ICMP message.
For example:
10.180.106.180.29707 > 10.180.106.5.53: 50740+ A? s3.us-east-2.amazonaws.com.
(55)
10.180.106.5.53 > 10.180.106.180.29707: 50740 1/0/0 A 52.219.80.194 (71)
10.180.106.180 > 10.180.106.5: ICMP 10.180.106.180 udp port 29707 unreachable,
length 107

One difference between host(1)'s code and libc resolver's code might be that
the latter performs connect(2) on the datagram / UDP socket used for DNS
queries.

On the kernel side, I see that in_pcblookup_mbuf() fails to find the PCB
matching the reply packet.
Potentially interesting fields from the mbuf are:
                uint32_t flowid = 0xc48d76be
                uint8_t rsstype = 0x81 // M_HASHTYPE_RSS_IPV4

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