Messages in this thread | | | From | "Reshetova, Elena" <> | Subject | RE: [PATCH v2 2/2] x86/coco: Require seeding RNG with RDRAND on CoCo systems | Date | Wed, 21 Feb 2024 07:52:30 +0000 |
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> Hi Elena, > > On Fri, Feb 16, 2024 at 8:57 AM Reshetova, Elena > <elena.reshetova@intel.com> wrote: > > So, yes, coco_random_init() happens first, which actually now has a nice > > side-effect that on coco platforms we drop HW CPU output even earlier > > in the entropy pool (Yay!). > > Which at this point would be almost perfect, *if* we could also > > count this entropy drop and allow ChaCha seeding to benefit straight from > > this early drop of entropy. > > I addressed this already in my last reply. I wouldn't get too hung up > on the entropy counting stuff. The RNG is going to get initialized > just fine anyway no matter what, and whether or not it's counted, > it'll still be used and available basically immediately anyway. > > > How about changing this to use add_hwgenerator_randomness()? > > That function is only for the hwrng API. It handles sleep semantics > and that's specific to that interface boundary. It is not for random > drivers and platforms to call directory. > > > And adjust cc_random_init() to try rdseed first and only fallback to rdrand > > if it fails? > > I guess that's possible, but what even is the point? I don't think > that really more directly accomplishes the objective here anyway. The > whole idea is we want to ensure that RDRAND is at least working for 32 > bytes and if not panic. That's *all* we care about. Later on the RNG > will eat rdseed opportunistically as it can; let it handle that as it > does, and leave this patch here to be simple and direct and accomplish > the one single solitary goal of panicking if it can't avoid the worst > case scenario.
Okay, I guess I won’t start fighting for a cleanliness of an overall construction (and rest of people stay pretty quiet in this discussion thread). Functionally-wise we will get what we need in practice and I learned that "disagree and commit" is a very useful principle to exercise for moving things forward, so I am ok with this approach.
Would you submit the patch or how do we proceed on this?
Best Regards, Elena.
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