Please remember to enable tha AMD-V support in the bios, every time you upgrade bios they normally reset to "disabled".
You can find this issue when in logs appears something like:
Apr 20 11:45:11 ovirt-node3 journal[2011]: Unable to open /dev/kvm: No such file or directory
to resolve remember to launch the command:
virt-host-validate
it checks the host environment to verify qemu support
I would add that if AMD-SVM is disabled, you should see "KVM is disabled in the BIOS" message in the kernel log. (This is what I saw before the reset).