On July 5, 2022 3:00:04 PM PDT, Borislav Petkov [off-list ref] wrote:

On Tue, Jul 05, 2022 at 02:50:34PM -0700, H. Peter Anvin wrote:

quoted

It's just math. The only variable is your confidence level, i.e. at
what level do you decide that the likelihood of pure chance is way
smaller than the likelihood of hardware failure.

That might be but the likelyhood of certain BIOSes dropping the ball
after resume is 100%:

7879fc4bdc75 ("x86/rdrand: Sanity-check RDRAND output")

What I'm wondering is if we shouldn't be simply instrument *every* invocation, and set the trust to zero if we ever trip it.