MIME-Version: 1.0
Date:   Tue, 21 Feb 2023 10:49:51 +0100
From:   Oleksandr Natalenko <oleksandr@natalenko.name>
To:     David Woodhouse <dwmw2@infradead.org>
Cc:     Kim Phillips <kim.phillips@amd.com>, tglx@linutronix.de,
        Usama Arif <usama.arif@bytedance.com>, arjan@linux.intel.com,
        mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com,
        hpa@zytor.com, x86@kernel.org, pbonzini@redhat.com,
        paulmck@kernel.org, linux-kernel@vger.kernel.org,
        kvm@vger.kernel.org, rcu@vger.kernel.org, mimoja@mimoja.de,
        hewenliang4@huawei.com, thomas.lendacky@amd.com, seanjc@google.com,
        pmenzel@molgen.mpg.de, fam.zheng@bytedance.com,
        punit.agrawal@bytedance.com, simon.evans@bytedance.com,
        liangma@liangbit.com,
        "Limonciello, Mario" <Mario.Limonciello@amd.com>,
        Piotr Gorski <piotrgorski@cachyos.org>
Subject: Re: [PATCH v9 0/8] Parallel CPU bringup for x86_64
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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?

> Or maybe we should just set up smpboot_control for the CPU to find its
> own stuff, *even* on waking. Since the structures are already set up,
> it isn't like a clean boot.
> 
> If you let it boot in parallel mode, what if you just *remove* the line
> that sets smpboot_control=0 ?

If the `smpboot_control = 0;` line in 
arch/x86/kernel/acpi/sleep.c::x86_acpi_suspend_lowlevel() is commented 
out, and the system is booted in parallel mode, then suspend/resume 
works.

-- 
   Oleksandr Natalenko (post-factum)