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: <Y8m+pr3t84VQTQTM@a4bf019067fa.jf.intel.com>
Date:   Thu, 19 Jan 2023 14:05:26 -0800
From:   Ashok Raj <ashok.raj@...el.com>
To:     Thomas Gleixner <tglx@...utronix.de>
CC:     Borislav Petkov <bp@...en8.de>, 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>,
        Ashok Raj <ashok.raj@...el.com>
Subject: Re: [PATCH v1 Part2 1/5] x86/microcode: Move late load warning to
 the same function that taints kernel

On Thu, Jan 19, 2023 at 10:48:30PM +0100, Thomas Gleixner wrote:
> 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?
> 

Yes, that is accurate.. inspite of my awkward phrasing :-(

I should copy this commit verbatim before i resend :-)

Cheers,
Ashok