linux-kernel - Re: Boot regression with bacf6b499e11 ("x86/mm: Use a struct to reduce parameters for SME PGD mapping") on top of -rc8

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Date:   Fri, 19 Jan 2018 22:13:56 -0600
From:   Tom Lendacky <thomas.lendacky@....com>
To:     Linus Torvalds <torvalds@...ux-foundation.org>,
        Laura Abbott <labbott@...hat.com>
Cc:     Borislav Petkov <bp@...e.de>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...nel.org>,
        Brijesh Singh <brijesh.singh@....com>, X86 ML <x86@...nel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: Boot regression with bacf6b499e11 ("x86/mm: Use a struct to
 reduce parameters for SME PGD mapping") on top of -rc8

On 1/19/2018 8:38 PM, Linus Torvalds wrote:
> On Fri, Jan 19, 2018 at 5:23 PM, Laura Abbott <labbott@...hat.com> wrote:
>>
>> Fedora got multiple reports of an early bootup crash post -rc8.
>> Bisection showed bacf6b499e11 ("x86/mm: Use a struct to reduce
>> parameters for SME PGD mapping") . It doesn't revert cleanly
>> but if I revert the few other changes in arch/x86/mm/mem_encrypt.c
>> as well it boots up fine.
> 
> Odd. I've tried to read through that patch three times to find
> anything it actually changes, and I can't find anything.
> 
> It looks like that patch should have absolutely no actual behavioral impact.
> 
> But clearly I'm missing something. Can anybody see what the mistake in
> the conversion is?

I'll take a closer look at this, but it really shouldn't have any effect,
especially on a non-AMD box (which I'm assuming this is?) and with memory
encryption off by default.

Thanks,
Tom

> 
>              Linus
>