linux-kernel - Re: [PATCH] x86/microcode: Add an option to reload microcode even if revision is unchanged

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Message-ID: <alpine.DEB.2.21.1909051244250.1902@nanos.tec.linutronix.de>
Date:   Thu, 5 Sep 2019 12:51:18 +0200 (CEST)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Borislav Petkov <bp@...en8.de>
cc:     "Raj, Ashok" <ashok.raj@...el.com>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Mihai Carabas <mihai.carabas@...cle.com>,
        "H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...hat.com>,
        Jon Grimm <Jon.Grimm@....com>, kanth.ghatraju@...cle.com,
        konrad.wilk@...cle.com, patrick.colp@...cle.com,
        Tom Lendacky <thomas.lendacky@....com>,
        x86-ml <x86@...nel.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86/microcode: Add an option to reload microcode even
 if revision is unchanged

On Thu, 5 Sep 2019, Borislav Petkov wrote:
> On Wed, Sep 04, 2019 at 05:21:32PM -0700, Raj, Ashok wrote:
> > But echo 2 > reload would allow reading a microcode file from 
> > /lib/firmware/intel-ucode/ even if the revision hasn't changed right?
> > 
> > #echo 1 > reload wouldn't load if the revision on disk is same as what's loaded,
> > and we want to permit that with the echo 2 option.
> 
> Then before we continue with this, please specify what the exact
> requirements are. Talk to your microcoders or whoever is going to use
> this and give the exact use cases which should be supported and describe
> them in detail.

Plus I have to ask whether this facility makes any sense outside of
microcode development. If so, then please explain the use case and give
a proper justification why this needs to be in the mainline kernel.

Thanks,

	tglx