linux-kernel - Re: [PATCH v16 8/8] x86/smpboot: Allow parallel bringup for SEV-ES

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Date:   Thu, 23 Mar 2023 10:23:02 -0400
From:   Brian Gerst <brgerst@...il.com>
To:     David Woodhouse <dwmw2@...radead.org>
Cc:     Borislav Petkov <bp@...en8.de>,
        Usama Arif <usama.arif@...edance.com>, tglx@...utronix.de,
        kim.phillips@....com, piotrgorski@...hyos.org,
        oleksandr@...alenko.name, arjan@...ux.intel.com, mingo@...hat.com,
        dave.hansen@...ux.intel.com, hpa@...or.com, x86@...nel.org,
        pbonzini@...hat.com, paulmck@...nel.org,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        rcu@...r.kernel.org, mimoja@...oja.de, hewenliang4@...wei.com,
        thomas.lendacky@....com, seanjc@...gle.com, pmenzel@...gen.mpg.de,
        fam.zheng@...edance.com, punit.agrawal@...edance.com,
        simon.evans@...edance.com, liangma@...ngbit.com,
        gpiccoli@...lia.com, Sabin Rapan <sabrapan@...zon.com>
Subject: Re: [PATCH v16 8/8] x86/smpboot: Allow parallel bringup for SEV-ES

On Thu, Mar 23, 2023 at 5:04 AM David Woodhouse <dwmw2@...radead.org> wrote:
>
> On Thu, 2023-03-23 at 09:51 +0100, Borislav Petkov wrote:
> > On Thu, Mar 23, 2023 at 08:32:49AM +0000, David Woodhouse wrote:
> > > and maybe find some other stuff to cargo-cult to make it safe to run
> > > C code that early...
> >
> > I'm trying to have less shit asm, not more if possible. We've been
> > aiming to convert stuff to C for years.
>
> Absolutely, I understand. There are a few hoops we have to jump through
> to be able to run C code this early, but it's worth it.
>
> > WTF are you calling cargo-cult?
>
> Off the top of my head, I don't actually *remember* all the hoops we
> have to jump through to run C code this early.

Making sure that the stack protector is either disabled or properly
set up, and disabling any instrumentation/profiling/debug crap that
isn't initialized yet.

--
Brian Gerst