Description of problem:
Trying to run more than 1 VM with /dev/hwrng source failed with vdsm.log ERROR: 
- libvirtError: Requested operation is not valid: PCI device 0000:02:00.0 is in use by driver QEMU, domain 1_VFIO_f23_Intel

And qemu log ERRORL
ERROR:backends/rng-random.c:47:entropy_available: assertion failed: (len != -1)

Version-Release number of selected component (if applicable):
ovirt-engine-4.1.1-0.1.el7
libvirt-client-2.0.0-10.el7_3.4.x86_64
qemu-kvm-rhev-2.6.0-28.el7_3.5.x86_64
vdsm-4.19.5-1.el7ev.x86_64
sanlock-3.4.0-1.el7.x86_64

How reproducible:
100%

Steps to Reproduce:
1. Browse webadmin -> cluster tab -> edit cluster: Verify compatibility version is 4.1. check /dev/hwrng source checkbox.
2. Run VM with /dev/hwrng source enabled.
3. Try to run another VM with /dev/hwrng source enabled.

Actual results:
The second Vm is not going up.

Expected results:
More than one VM should be able to run with /dev/hwrng source.

Additional info:
qemu log attached (2017-02-09 15:54:35.886+0000)
and vdsm.log attached (2017-02-12 15:54:54,232)