linux-kernel - Re: [PATCH 2/2] x86/microcode: Add a "microcode=" command line option

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Message-ID: <20230609122828.GBZIMa7OtCIpSkYGxV@fat_crate.local>
Date:   Fri, 9 Jun 2023 14:28:28 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Ashok Raj <ashok.raj@...el.com>
Cc:     X86 ML <x86@...nel.org>, LKML <linux-kernel@...r.kernel.org>,
        Dave Hansen <dave.hansen@...el.com>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH 2/2] x86/microcode: Add a "microcode=" command line option

On Wed, Jun 07, 2023 at 06:55:39PM -0700, Ashok Raj wrote:
> When end user changes the behavior, isn't it against the design
> specification? And if so, should that result in kernel being tainted
> after a reload?

That's a chicken bit and should not be used usually. I'm adding it just
in case.

> Is this reload on all threads required by all models, or only certain
> models? I was wondering if the forced reload could be limited to only
> affected CPUs instead of doing it on all unconditionally.

Unconditionally.

> Shouldn't the "control" be under LATE_LOADING? Since this only controls
> late-loading behavior?

No, that's a bitfield and is going to be used for other flags, if
needed and which are not necessarily late-loading related.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette