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

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Message-ID: <42dc683e2846ae8fc1e09715aaf7884660e1a386.camel@infradead.org>
Date:   Mon, 20 Feb 2023 23:30:17 +0000
From:   David Woodhouse <dwmw2@...radead.org>
To:     Kim Phillips <kim.phillips@....com>,
        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 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:
> > > Hello.
> > > 
> > > 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?

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)
...


> > Perhaps we turn it off for any AMD CPU that doesn't have X2APIC and CPUID 0xB?
> 
> Perhaps.
> 
> > > > Does your box have a proper serial port?
> > > 
> > > No, sorry. I know it'd help with getting logs, and I do have a serial-to-USB cable that I use for another machine, but in this one the port is not routed to outside. I think I can put a header there as the motherboard does have pins, but I'd have to buy one first. In theory, I can do that, but that won't happen within the next few weeks.
> > > 
> > > P.S. Piotr Gorski (in Cc) also reported this: "My friend from CachyOS can confirm bugs with smpboot patches. AMD FX 6300 only shows 1 core when using smp boot patchset". Probably, he can reply to this thread and provide more details.
> > > 
> 
> I ran mem/disk versions of 'sudo rtcwake --mode mem -s 60'
> on my Rome server, and multiple suspend/resumes succeeded, and
> with all CPUs, but then the NETDEV WATCHDOG fired - not sure
> if it's related:

I suspect not.


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