Messages in this thread | | | Date | Tue, 17 Nov 2020 10:18:37 +0100 | From | Borislav Petkov <> | Subject | Re: [PATCH][v2] x86/microcode/intel: check cpu stepping and processor flag before saving microcode |
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On Tue, Nov 17, 2020 at 10:25:18AM +0800, Chen Yu wrote: > If I understand correctly, the only place that invokes > save_mc_for_early() is in generic_load_microcode(). While in > generic_load_microcode() only microcode has a newer version will be > saved by checking has_newer_microcode(), and this function leverages > find_matching_signature() to check if the candidate is of the same > signature. So when it comes to save_microcode_patch(), the signature > already matches. In case save_mc_for_early() will be invoked by other > function in the future, it is okay to add this check too.
The important aspect is that you need to save in intel_ucode_patch the *exact* patch for the CPU you're running on. The code above that in save_microcode_patch() adds patches of the same family/model but *not* same stepping to the microcode cache in case we want to support mixed-stepping revisions. And those you don't need to check for exact match.
What I'd like, however, is to get rid of that mixed-stepping support - which is total nonsense anyway, if you ask me - and that would simplify the code a *lot* more.
Thx for testing.
-- Regards/Gruss, Boris.
https://people.kernel.org/tglx/notes-about-netiquette
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