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

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Message-ID: <10CA27BB-ADC6-4421-86D2-A83BD7FA12E0@infradead.org>
Date:   Tue, 21 Feb 2023 11:49:26 +0000
From:   David Woodhouse <dwmw2@...radead.org>
To:     Oleksandr Natalenko <oleksandr@...alenko.name>
CC:     Kim Phillips <kim.phillips@....com>, tglx@...utronix.de,
        Usama Arif <usama.arif@...edance.com>, 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: [PATCH v9 0/8] Parallel CPU bringup for x86_64



On 21 February 2023 11:46:04 GMT, Oleksandr Natalenko <oleksandr@...alenko.name> wrote:
>On 21.02.2023 11:27, 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?
>> 
>> Hm, yes please. There's another one to make zero on the next line up, I think?
>
>So,
>
>```
>early_gdt_descr.address = (unsigned long)get_cpu_gdt_rw(0);
>initial_gs = per_cpu_offset(0);
>```
>
>?
>
>Should I leave `smpboot_control = 0;` commented out, or I should uncomment it back?

Put it back, else those things don't matter. Thanks.