Xenserver 7.0 SMP HVM Guest 4.10.1 hang on boot

We are observing an issue booting Linux 4.10.1 kernel HVM SMP guests on our
XenServer cluster (effects all 3 Skylake nodes) across multiple guest distros
(Ubuntu and CoreOS) with the guests hanging on boot.

The guests will hang with the last boot message being:

"[ 0.132038] x86: Booting SMP configuration"

Bisecting the revision from 4.9 to 4.10.1 I tracked it down to

1. first bad commit: [3be134e5152f08e8bd3c2afdaac723f64d93c2bb] Merge tag
   'libnvdimm-for-4.10' of
   git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm

Changing the Guests to 1 CPU permits it to continue booting (it later hangs
on:

[ 1.633261] xvda: xvda1 xvda2 xvda3 xvda4 xvda6 xvda7 xvda9

Which I will bisect and discuss separately.). I have more detail on
https://github.com/coreos/bugs/issues/1849 , since it effect ubuntu as well I
believe its better handled here.