Re: [PATCH 1/6] x86/microcode: Introduce staging option to reduce late-loading latency
From: Borislav Petkov
Date: Tue Feb 18 2025 - 06:37:06 EST
On Mon, Feb 17, 2025 at 11:51:28PM -0800, Chang S. Bae wrote:
> On 2/17/2025 5:33 AM, Borislav Petkov wrote:
> >
> > Why are you even touching this function instead of doing the staging in the
> > beginning of load_late_stop_cpus()?
>
> I thought staging is logically distinguishable.
What does that even mean?
> While load_late_stop_cpus() currently performs loading when CPUs are
> _stopped_,
Not entirely - it does preparatory work and then stops the CPUs. Staging could
be part of that prep work.
> staging occurs on a non-critical path and remains interruptible.
So if you really wanna do that and be really "free", then you should do it
outside of load_late_locked() because that runs with the hotplug lock taken.
But then the only thing that matters is, when *exactly* you should stage. If
->request_microcode_fw() fails, staging would be unnecessary work.
So instead of trying to too hard, just stick the staging at the beginning of
load_late_stop_cpus() and be done with it.
Also, if you want to send a patch, don't send it from a mail client which will
mangle it so that it is inapplicable and no one can play with it.
Thx.
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette