By default dracut set 600 mode. While it isn't a problem for starting a
VM (which is done as root), it is a problem for creating standalone VM,
which has it's own copy of kernel directory.
(cherry picked from commit 2f1c8ea459)
This is preparation for pvgrub support, where all VM kernel files will
be installed inside of VM instead of dom0.
But also the same could be used to prepare VM kernel image from any dom0
kernel.
