Bisecting kernel gave bad results, recording here so that I can get another pair of eyes on things.  Started with reverse bisect between v3.5 and v3.8 mainline source limited to changes on the ixgbevf source.  Bisection indicated that the "fix" was a cleanup patch.  Given that this was not the issue, I used the last tested boundaries from that as the input to a full kernel tree bisection which lead me to another 'fix' which only changes the formatting of debug printk in the tun driver.
 
Notes from debug:
- using ubuntu/images-testing/hvm/ubuntu-precise-daily-amd64-server-20140210 because it boots without sriov 'simple' attribute
- performing kernel bisect on mainline from v3.5..v3.8 limited to driver source ('git bisect start v3.8 v3.5 -- drivers/net/ethernet/intel/ixgbevf/')

$ git bisect log
# bad: [19f949f52599ba7c3f67a5897ac6be14bfcb1200] Linux 3.8
# good: [28a33cbc24e4256c143dce96c7d93bf423229f92] Linux 3.5
git bisect start 'v3.8' 'v3.5' '--' 'drivers/net/ethernet/intel/ixgbevf/'
# good: [5c60f81a2553213856b3bb80f18003e56a6a110d] ixgbevf: Add fix to VF to handle multi-descriptor buffers
git bisect good 5c60f81a2553213856b3bb80f18003e56a6a110d
# good: [810b6d7638a288216f99bd190470d67061c8bd88] Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/jkirsher/net-next
git bisect good 810b6d7638a288216f99bd190470d67061c8bd88
# bad: [6259a01fb2d458b4157918b2da0d0f42242a9d72] ixgbevf: Fix unnecessary dereference where local var is available.
git bisect bad 6259a01fb2d458b4157918b2da0d0f42242a9d72
# bad: [a5f9337bdc45bb8c13037bdb70d16fd9017bb83a] ixgbevf: fix possible use of uninitialized variable
git bisect bad a5f9337bdc45bb8c13037bdb70d16fd9017bb83a
# bad: [46acc460c07b5c74287560a00b6cbc6111136ab6] eth: Make is_link_local() consistent with other address tests
git bisect bad 46acc460c07b5c74287560a00b6cbc6111136ab6
# first bad commit: [46acc460c07b5c74287560a00b6cbc6111136ab6] eth: Make is_link_local() consistent with other address tests
==============================================================================
46acc460c07b5c74287560a00b6cbc6111136ab6 is the first bad commit
commit 46acc460c07b5c74287560a00b6cbc6111136ab6
Author: Ben Hutchings <email address hidden>
Date:   Thu Nov 1 09:11:11 2012 +0000

    eth: Make is_link_local() consistent with other address tests

    Function name should include '_ether_addr'.
    Return type should be bool.
    Parameter name should be 'addr' not 'dest' (also matching kernel-doc).

    Signed-off-by: Ben Hutchings <email address hidden>
    Acked-by: John Fastabend <email address hidden>
    Signed-off-by: David S. Miller <email address hidden>

- Used last good/bad from prior search as input to a bisect operation on the full tree source ('git bisect start 46acc46 810b6d7')
$ git bisect log
# bad: [46acc460c07b5c74287560a00b6cbc6111136ab6] eth: Make is_link_local() consistent with other address tests
# good: [810b6d7638a288216f99bd190470d67061c8bd88] Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/jkirsher/net-next
git bisect start '46acc46' '810b6d7'
# bad: [9750a3ade7b635a18f04371b4fddad0de0b4e6d8] cpsw: support both silicon versions
git bisect bad 9750a3ade7b635a18f04371b4fddad0de0b4e6d8
# bad: [dd87b22f9096863adfd5daf281beb0a83379bd8f] bfin_mac: offer a PTP Hardware Clock.
git bisect bad dd87b22f9096863adfd5daf281beb0a83379bd8f
# bad: [96442e42429e5f268ab97a3586c7694a3acc55a7] tuntap: choose the txq based on rxq
git bisect bad 96442e42429e5f268ab97a3586c7694a3acc55a7
# bad: [6e914fc70793f540015bd99744cd456b8d7fdfbd] tuntap: RCUify dereferencing between tun_struct and tun_file
git bisect bad 6e914fc70793f540015bd99744cd456b8d7fdfbd
# bad: [54f968d6efdbf7dec36faa44fc11f01b0e4d1990] tuntap: move socket to tun_file
git bisect bad 54f968d6efdbf7dec36faa44fc11f01b0e4d1990
# bad: [1e5883382c3287a61aeebc33a301fd50f3a1005b] tuntap: log the unsigned informaiton with %u
git bisect bad 1e5883382c3287a61aeebc33a301fd50f3a1005b
# first bad commit: [1e5883382c3287a61aeebc33a301fd50f3a1005b] tuntap: log the unsigned informaiton with %u

$ git bisect bad
\1e5883382c3287a61aeebc33a301fd50f3a1005b is the first bad commit
commit 1e5883382c3287a61aeebc33a301fd50f3a1005b
Author: Jason Wang <email address hidden>
Date:   Wed Oct 31 19:45:56 2012 +0000

    tuntap: log the unsigned informaiton with %u

    Signed-off-by: Jason Wang <email address hidden>
    Signed-off-by: David S. Miller <email address hidden>