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Date:   Tue, 30 May 2023 16:13:52 -0500
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Subject: Re: [patch] x86/smpboot: Disable parallel bootup if cc_vendor != NONE
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To:     Thomas Gleixner <tglx@linutronix.de>,
        Sean Christopherson <seanjc@google.com>
Cc:     "Kirill A. Shutemov" <kirill@shutemov.name>,
        LKML <linux-kernel@vger.kernel.org>, x86@kernel.org,
        David Woodhouse <dwmw2@infradead.org>,
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        Brian Gerst <brgerst@gmail.com>,
        Arjan van de Veen <arjan@linux.intel.com>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Paul McKenney <paulmck@kernel.org>,
        Oleksandr Natalenko <oleksandr@natalenko.name>,
        Paul Menzel <pmenzel@molgen.mpg.de>,
        "Guilherme G. Piccoli" <gpiccoli@igalia.com>,
        Piotr Gorski <lucjan.lucjanov@gmail.com>,
        Usama Arif <usama.arif@bytedance.com>,
        Juergen Gross <jgross@suse.com>,
        Boris Ostrovsky <boris.ostrovsky@oracle.com>,
        xen-devel@lists.xenproject.org,
        Russell King <linux@armlinux.org.uk>,
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        Will Deacon <will@kernel.org>, Guo Ren <guoren@kernel.org>,
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        "James E.J. Bottomley" <James.Bottomley@hansenpartnership.com>,
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        Mark Rutland <mark.rutland@arm.com>,
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From:   Tom Lendacky <thomas.lendacky@amd.com>
In-Reply-To: <871qiximen.ffs@tglx>
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On 5/30/23 15:39, Thomas Gleixner wrote:
> On Tue, May 30 2023 at 15:03, Tom Lendacky wrote:
>> On 5/30/23 14:51, Thomas Gleixner wrote:
>>> That aside. From a semantical POV making this decision about parallel
>>> bootup based on some magic CC encryption attribute is questionable.
>>>
>>> I'm tending to just do the below and make this CC agnostic (except that
>>> I couldn't find the right spot for SEV-ES to clear that flag.)
>>
>> Maybe in sme_sev_setup_real_mode() in arch/x86/realmode/init.c? You could
>> clear the flag within the CC_ATTR_GUEST_STATE_ENCRYPT check.
> 
> Eeew.
> 
> Can we please have a AMD SEV-ES init specific place and not hijack some
> random code which has to check CC_ATTR_GUEST_STATE_ENCRYPT?

As long as it's not too early, you could try sme_early_init() in 
arch/x86/mm/mem_encrypt_amd.c. Add a check for sev_status & 
MSR_AMD64_SEV_ES_ENABLED and clear the flag.

Thanks,
Tom

> 
> Thanks,
> 
>          tglx