Bug#931644: Buster kernel entropy pool too low on VM boot

["Michael J. Redd" <micredd@gmail.com>]

Apologies for the late reply. I can certainly test on some of my VMs if
you're willing to provide packages.

Reading over Linus' explanation of deriving jitter from the CPU's cycle
counter, while I'm no cryptographer, I might have some concerns about
the quality of the entropy that will be generated by this patch on
hypervisors that virtualize the time stamp counter. In my environment,
I know I can instruct Xen to never virtualize the TSC (
https://xenbits.xen.org/docs/unstable/man/xen-tscmode.7.html), which
would probably benefit the patch, but AWS and other public cloud users
may not have that option.

-Michael