llan: byte swap the receive queue entriesHEADmain

The receive queue of a PAPR logical LAN is filled in by the hypervisor, so
its fields are big endian, but llan_intr() read the offset and the length of
each frame natively.  On a little endian kernel the length of a 134 byte
frame reads as 0x86000000, and ether_input() discards the mbuf because m_len
is not even large enough for an ethernet header.  No frame is ever received.

Reproduced on a POWER9 pseries guest with a spapr-vlan interface.  Before:

  llan0: discard frame w/o leading ethernet header (len -2046820352
      pkt len -2046820352)
  llan0 1500 <Link#1> 52:54:00:12:34:56  123  118  0  5838733312  7  0

that is 118 input errors out of 123 packets, dhclient(8) never completes and
ping(8) loses every packet, although transmit works because the transmit
path passes the lengths in hcall registers rather than through memory.
Afterwards the interface gets a DHCP lease and ping reports no loss.

MFC after:	1 week
Differential Revision:	https://reviews.freebsd.org/D59926
Approved by:	jhibbits

0 files changed, 0 insertions, 0 deletions