linux-kernel - Re: [External] Re: [PATCH v9 0/8] Parallel CPU bringup for x86

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Message-ID: <6e7d75d98266ab68b57bf6db644ecc75@natalenko.name>
Date:   Tue, 21 Feb 2023 12:42:36 +0100
From:   Oleksandr Natalenko <oleksandr@...alenko.name>
To:     Usama Arif <usama.arif@...edance.com>
Cc:     David Woodhouse <dwmw2@...radead.org>,
        Kim Phillips <kim.phillips@....com>, tglx@...utronix.de,
        arjan@...ux.intel.com, mingo@...hat.com, bp@...en8.de,
        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,
        "Limonciello, Mario" <Mario.Limonciello@....com>,
        Piotr Gorski <piotrgorski@...hyos.org>
Subject: Re: [External] Re: [PATCH v9 0/8] Parallel CPU bringup for x86_64

On 21.02.2023 11:47, Usama Arif wrote:
> On 21/02/2023 10:27, David Woodhouse wrote:
>> 
>> On 21 February 2023 09:49:51 GMT, Oleksandr Natalenko 
>> <oleksandr@...alenko.name> wrote:
>>> On 21.02.2023 10:06, David Woodhouse wrote:
>>>> Why does arch/x86/kernel/acpi/sleep.c::x86_acpi_suspend_lowlevel() 
>>>> set
>>>> 
>>>>      initial_gs = per_cpu_offset(smp_processor_id()) ?
>>>> 
>>>> Would it not be CPU#0 that comes back up, and should it not get
>>>> per_cpu_offset(0) ?
>>> 
>>> Wanna me try `initial_gs = per_cpu_offset(0);` too?
>> 
> 
> I think it might be smp_processor_id() and not 0 incase CPU0 was 
> offline at the point the system was suspended?

Is it even possible for CPU 0 to be offline, at least on x86?

-- 
   Oleksandr Natalenko (post-factum)