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

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Date:   Mon, 20 Feb 2023 22:20:41 -0600
From:   Kim Phillips <kim.phillips@....com>
To:     David Woodhouse <dwmw2@...radead.org>,
        Oleksandr Natalenko <oleksandr@...alenko.name>
Cc:     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,
        Piotr Gorski <lucjan.lucjanov@...il.com>,
        "Limonciello, Mario" <Mario.Limonciello@....com>
Subject: Re: [PATCH v9 0/8] Parallel CPU bringup for x86_64

On 2/20/23 5:30 PM, David Woodhouse wrote:
> On Mon, 2023-02-20 at 17:23 -0600, Kim Phillips wrote:
>> On 2/20/23 3:39 PM, David Woodhouse wrote:
>>> On 20 February 2023 21:23:38 GMT, Oleksandr Natalenko <oleksandr@...alenko.name> wrote:
>>>> On 20.02.2023 21:31, David Woodhouse wrote:
>>>>> On Mon, 2023-02-20 at 17:40 +0100, Oleksandr Natalenko wrote:
>>>>>> On pondělí 20. února 2023 17:20:13 CET David Woodhouse wrote:
>>>>>>> On Mon, 2023-02-20 at 17:08 +0100, Oleksandr Natalenko wrote:
>>>>>>>>
>>>>>>>> I've applied this to the v6.2 kernel, and suspend/resume broke on
>>>>>>>> my
>>>>>>>> Ryzen 5950X desktop. The machine suspends just fine, but on
>>>>>>>> resume
>>>>>>>> the screen stays blank, and there's no visible disk I/O.
>>>>>>>>
>>>>>>>> Reverting the series brings suspend/resume back to working state.
>>>>>>>
>>>>>>> Hm, thanks. What if you add 'no_parallel_bringup' on the command
>>>>>>> line?
>>>>>>
>>>>>> If the `no_parallel_bringup` param is added, the suspend/resume
>>>>>> works.
>>>>>
>>>>> Thanks for the testing. Can I ask you to do one further test: apply the
>>>>> series only as far as patch 6/8 'x86/smpboot: Support parallel startup
>>>>> of secondary CPUs'.
>>>>>
>>>>> That will do the new startup asm sequence where each CPU finds its own
>>>>> per-cpu data so it *could* work in parallel, but doesn't actually do
>>>>> the bringup in parallel yet.
>>>>
>>>> With patches 1 to 6 (including) applied and no extra cmdline
>>>> params added the resume doesn't work.
>>>
>>> Hm. Kim, is there some weirdness with the way AMD CPUs get their
>>> APIC ID in CPUID 0x1? Especially after resume?
>>
>> Not to my knowledge.  Mario?

I tested v9-up-to-6/8 on a Ryzen 3000 that passed your between-v6 & v7
tree commits (ce7e2d1e046a for the parallel-6.2-rc6-part1 tag
and 17bbd12ee03 for parallel-6.2-rc6), and it, too, fails to resume
v9-up-to-6/8 after suspend.

> Oleksandr, please could you show the output of 'cpuid' after a
> successful resume?  I'm particularly looking for this part...
> 
> 
> $ sudo cpuid | grep -A1 1/ebx
>     miscellaneous (1/ebx):
>        process local APIC physical ID = 0x0 (0)
> --
>     miscellaneous (1/ebx):
>        process local APIC physical ID = 0x2 (2)
> ...

The Ryzens have a different pattern it seems:

$ sudo cpuid | grep -A1 \(1/ebx
    miscellaneous (1/ebx):
       process local APIC physical ID = 0x0 (0)
--
    miscellaneous (1/ebx):
       process local APIC physical ID = 0x1 (1)
--
    miscellaneous (1/ebx):
       process local APIC physical ID = 0x2 (2)
--
    miscellaneous (1/ebx):
       process local APIC physical ID = 0x3 (3)
--
    miscellaneous (1/ebx):
       process local APIC physical ID = 0x4 (4)
--
    miscellaneous (1/ebx):
       process local APIC physical ID = 0x5 (5)
--
    miscellaneous (1/ebx):
       process local APIC physical ID = 0x6 (6)
--
    miscellaneous (1/ebx):
       process local APIC physical ID = 0x7 (7)


I tested the v7 series on Ryzen, it also fails, so
Ryzen users were last known good with those two
aforementioned commits on your tree:

git://git.infradead.org/users/dwmw2/linux.git

Thanks,

Kim