Re: [Patch v3 Part2 3/9] x86/microcode/intel: Fix collect_cpu_info() to reflect current microcode

[Borislav Petkov]

On Tue, Jan 31, 2023 at 05:34:14PM +0000, Luck, Tony wrote:
> But those get out of step when applying ucode on one logical CPU does
> an update to other(s) (in this case the HT sibling for the same core).

They shouldn't.

I presume you're talking about late update. If so and if it finds a
patch in the cache, it'll do this:

apply_microcode_intel:

        /*
         * Save us the MSR write below - which is a particular expensive
         * operation - when the other hyperthread has updated the microcode
         * already.
         */
        rev = intel_get_microcode_revision();
        if (rev >= mc->hdr.rev) {
                ret = UCODE_OK;
                goto out;
        }

and at the out: label it'll update the revision.

-- 
Regards/Gruss,
    Boris.

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