Re: [RFC] Randomness on confidential computing platforms

[Dave Hansen]

On 1/29/24 13:33, Kirill A. Shutemov wrote:
>> Let's assume buggy userspace exists.  Is that userspace *uniquely*
>> exposed to a naughty VMM or is that VMM just added to the list of things
>> that can attack buggy userspace?
> This is good question.
> 
> VMM has control over when a VCPU gets scheduled and on what CPU which
> gives it tighter control over the target workload. It can make a
> difference if there's small window for an attack before RDRAND is
> functional again.

This is all a bit too theoretical for my taste.  I'm fine with doing
some generic mitigation (WARN_ON_ONCE(hardware_is_exhausted)), but we're
talking about a theoretical attack with theoretical buggy software when
in a theoretically unreachable hardware state.

Until it's clearly much more practical, we have much bigger problems to
worry about.