Comment 2 for bug 1540532

Hi,

commit 3f11933efc9ef55ecb2ac7e6d626e8d05a99a4b1 - KVM: x86: expose MSR_TSC_AUX to userspace
breaks KVM/QEMU live migration of host with a graphical user interface.

== Software Versions: ==
Kenel: this one, namely: Ubuntu-4.2.0-30.35
kvm-qemu: 2.5.0

== Reproduction ==
Install kernel with 3f11933efc9ef55ecb2ac7e6d626e8d05a99a4b1 included (Ubuntu-4.2.0-30.35)
Start VM with GUI
Start migration (no post copy, same migration as you'd in qemu 2.4)
When migration has finished snf you switch the vnc over to the migration target the VM running but frozen showing the last frame buffer, its also not ping-able

== VMs tested ==
Linux Mint Live ISO
elementaryOS Live ISO
Windows 7

VMs tested with minimal configuration. No disks on live cds, no network (but also with both enabled tested, same result)

== Hardware Used ==
Two Nested VMs on an Intel(R) Core(TM) i7-4790K CPU @ 4.00GHz
Two physical supermicro servers with Intel(R) Xeon(R) CPU E5-2620 v3 @ 2.40GHz
NFS for storage (for the live ISOs and diskes)

==
If I revert 3f11933efc9ef55ecb2ac7e6d626e8d05a99a4b1 and install the kernel on _both_ hosts the freeze does not happen anymore.
But this commit is also included in the ubuntu-xenial kernel (master and master-next tested) and there I have no such problem, thus its a side effect from some other (missing?) commit.

I'm currently trying to break the problem further down and try find the real culprit (or get closer to it).

Backtrace of the hung Linux Mint ISO follows in next comment.