linux-kernel - Re: [PATCH v1 Part2 1/5] x86/microcode: Move late load warning to the same function that taints kernel

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Message-ID: <875yd2i4b5.ffs@tglx>
Date:   Thu, 19 Jan 2023 22:48:30 +0100
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Ashok Raj <ashok.raj@...el.com>, Borislav Petkov <bp@...en8.de>
Cc:     Ashok Raj <ashok.raj@...el.com>, Tony Luck <tony.luck@...el.com>,
        LKML <linux-kernel@...r.kernel.org>, x86 <x86@...nel.org>,
        Ingo Molnar <mingo@...nel.org>,
        Dave Hansen <dave.hansen@...el.com>,
        Alison Schofield <alison.schofield@...el.com>,
        Reinette Chatre <reinette.chatre@...el.com>,
        Tom Lendacky <thomas.lendacky@....com>,
        Stefan Talpalaru <stefantalpalaru@...oo.com>,
        David Woodhouse <dwmw2@...radead.org>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Jonathan Corbet <corbet@....net>,
        "Rafael J . Wysocki" <rafael@...nel.org>,
        Peter Zilstra <peterz@...radead.org>,
        Andy Lutomirski <luto@...nel.org>,
        Andrew Cooper <Andrew.Cooper3@...rix.com>
Subject: Re: [PATCH v1 Part2 1/5] x86/microcode: Move late load warning to
 the same function that taints kernel

On Fri, Jan 13 2023 at 09:29, Ashok Raj wrote:
> Currently the warning about late loading and tainting are issued from two
> different functions.
>
> Later patches will re-enable microcode late-loading.
>
> Having both messages in the same function helps issuing warnings only
> when required.
>
> Move the warning from microcode_reload_late() -> reload_store() where the
> kernel tainting also happens.
>
> No functional change.

I had to read this more than once to make sense of it. Let me try a
translation:

  Late microcode loading issues a warning and taints the
  kernel. Tainting the kernel and emitting the warning happens in two
  different functions.

  The upcoming support for safe late loading under certain conditions
  needs to prevent both the warning and the tainting when the safe
  conditions are met. That would require to hand the result of the safe
  condition check into the function which emits the warning.

  To avoid this awkward construct, move the warning into reload_store()
  next to the taint() invocation as that is also the function which will
  later contain the safe condition check.

  No functional change.

Did my decoder get that right?

Thanks,

        tglx