MIME-Version: 1.0
Date:   Tue, 21 Feb 2023 13:14:07 +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
In-Reply-To: <10CA27BB-ADC6-4421-86D2-A83BD7FA12E0@infradead.org>
References: <20230215145425.420125-1-usama.arif@bytedance.com>
 <2668869.mvXUDI8C0e@natalenko.name>
 <2a67f6cf18dd2c1879fad9fd8a28242918d3e5d2.camel@infradead.org>
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 <67dbc69f-b712-8971-f1c9-5d07f506a19c@amd.com>
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On 21.02.2023 12:49, David Woodhouse wrote:
> On 21 February 2023 11:46:04 GMT, Oleksandr Natalenko 
> <oleksandr@natalenko.name> wrote:
>> On 21.02.2023 11:27, David Woodhouse wrote:
>>> On 21 February 2023 09:49:51 GMT, Oleksandr Natalenko 
>>> <oleksandr@natalenko.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.

With this in place:

```
	early_gdt_descr.address = (unsigned long)get_cpu_gdt_rw(0);
	initial_gs = per_cpu_offset(0);
	smpboot_control = 0;
```

the resume does not work.

-- 
   Oleksandr Natalenko (post-factum)