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

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Message-ID: <20230327193210.GCZCHvOmg0aT+CWorC@fat_crate.local>
Date:   Mon, 27 Mar 2023 21:32:10 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     David Woodhouse <dwmw2@...radead.org>
Cc:     Brian Gerst <brgerst@...il.com>,
        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 Mon, Mar 27, 2023 at 07:14:27PM +0100, David Woodhouse wrote:
> Shouldn't the rest of head64.c have the stack protector disabled, for
> similar reasons?

Not aware of any reason to that so far...

> Hm, doesn't most of that just go away (or at least become "Already
> Broken; Someone Else's Problem™") if you just concede to put your new C
> function into head64.c along with a whole bunch of other existing
> CONFIG_AMD_MEM_ENCRYPT support?

If it were only that, maybe, but we have to do the stack __va() thing as
Tom explained. So the jumping-through-hoops just to have a simple
function in C is not worth it... IMNSVHO, that is.

Thx.

-- 
Regards/Gruss,
    Boris.

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