From: David Woodhouse <dwmw2@infradead.org>
To: Paul Menzel <pmenzel@molgen.mpg.de>,
Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
x86@kernel.org, "H . Peter Anvin" <hpa@zytor.com>,
Paolo Bonzini <pbonzini@redhat.com>,
"Paul E . McKenney" <paulmck@kernel.org>,
linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
rcu@vger.kernel.org, mimoja@mimoja.de, hewenliang4@huawei.com,
hushiyuan@huawei.com, luolongjun@huawei.com,
hejingxian@huawei.com
Subject: Re: [PATCH v3 0/9] Parallel CPU bringup for x86_64
Date: Wed, 29 Dec 2021 13:54:54 +0000 [thread overview]
Message-ID: <efbe0d3d92e6c279e3a6d7a4191ca7470bc4beec.camel@infradead.org> (raw)
In-Reply-To: <ea433e41-0038-554d-3348-70aa98aff9e1@molgen.mpg.de>
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On Wed, 2021-12-29 at 14:18 +0100, Paul Menzel wrote:
> > Or the one in
> > https://lore.kernel.org/lkml/d4cde50b4aab24612823714dfcbe69bc4bb63b60.camel@infradead.org
> >
> > which makes it do nothing except prepare all the CPUs before bringing
> > them up one at a time?
>
> I applied it on top the other one, and it made no difference either.
It's possible I missed something else in the prepare stage that doesn't
cope with all CPUs being prepared first.
My next attempt might be to change the loop in bringup_nonboot_cpus()
to bring all the CPUs not to the CPUHP_BP_PARALLEL_DYN state(s) but
instead just bring them to somewhere like CPUHP_RCUTREE_PREP, which is
somewhere in the middle between CPUHP_OFFLINE and CPUHP_BRINGUP_CPU.
Then a binary chop search — if that one boots, try maybe
CPUHP_TOPOLOGY_PREPARE. And if not, try CPUHP_PROFILE_PREPARE. Etc.
> > My current theory (not that I've spent that much time thinking about it
> > in the last week) is that there's something about the existing CPU
> > bringup, possibly a CPU bug or something special about the AMD CPUs,
> > which is triggered by just making it a little bit *faster*, which is
> > why bringing them up from kexec (especially in qemu) can cause it too?
>
> Would having the serial console enabled make a difference?
>
Yes. I couldn't make this fail in my EC2 m6a instance (for clean boots;
I have never managed to kexec it) until I turned off the serial console
to make things go faster.
> > Tom seemed to find that it was in load_TR_desc(), so if you could try
> > this hack on a machine that doesn't magically wink out of existence on
> > a triplefault before even flushing its serial output, that would be
> > much appreciated...
> Unfortunately, no more messages were printed on the serial console.
I suppose we need to litter those outputs somewhere earlier in the
trampoline then, perhaps it *isn't* getting to load_TR_desc() in your
case?
Will be back online properly next week and can actually provide some of
the above suggestions in patch form if you're willing to keep testing.
Thanks!
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next prev parent reply other threads:[~2021-12-29 13:55 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-15 14:56 [PATCH v3 0/9] Parallel CPU bringup for x86_64 David Woodhouse
2021-12-15 14:56 ` [PATCH v3 1/9] x86/apic/x2apic: Fix parallel handling of cluster_mask David Woodhouse
2021-12-15 14:56 ` [PATCH v3 2/9] cpu/hotplug: Move idle_thread_get() to <linux/smpboot.h> David Woodhouse
2021-12-15 14:56 ` [PATCH v3 3/9] cpu/hotplug: Add dynamic parallel bringup states before CPUHP_BRINGUP_CPU David Woodhouse
2021-12-15 14:56 ` [PATCH v3 4/9] x86/smpboot: Reference count on smpboot_setup_warm_reset_vector() David Woodhouse
2021-12-15 14:56 ` [PATCH v3 5/9] x86/smpboot: Split up native_cpu_up into separate phases and document them David Woodhouse
2021-12-15 14:56 ` [PATCH v3 6/9] x86/smpboot: Support parallel startup of secondary CPUs David Woodhouse
2021-12-16 14:24 ` Tom Lendacky
2021-12-16 18:24 ` David Woodhouse
2021-12-16 19:00 ` Tom Lendacky
2021-12-16 19:20 ` David Woodhouse
2022-01-29 12:04 ` David Woodhouse
2022-01-31 13:59 ` Borislav Petkov
2022-02-01 10:25 ` David Woodhouse
2022-02-01 10:56 ` Borislav Petkov
2022-02-01 12:39 ` David Woodhouse
2022-02-01 12:56 ` Borislav Petkov
2022-02-01 13:02 ` David Woodhouse
2021-12-15 14:56 ` [PATCH v3 7/9] x86/smpboot: Send INIT/SIPI/SIPI to secondary CPUs in parallel David Woodhouse
2021-12-15 14:56 ` [PATCH v3 8/9] x86/mtrr: Avoid repeated save of MTRRs on boot-time CPU bringup David Woodhouse
2021-12-15 14:56 ` [PATCH v3 9/9] x86/smpboot: Serialize topology updates for secondary bringup David Woodhouse
2021-12-16 16:27 ` [PATCH v3 0/9] Parallel CPU bringup for x86_64 Tom Lendacky
2021-12-16 19:24 ` David Woodhouse
2021-12-16 22:52 ` Tom Lendacky
2021-12-17 0:13 ` David Woodhouse
2021-12-17 10:09 ` Igor Mammedov
2021-12-17 15:40 ` David Woodhouse
2021-12-20 17:10 ` David Woodhouse
2021-12-20 18:54 ` Tom Lendacky
2021-12-20 21:29 ` David Woodhouse
2021-12-20 21:47 ` Tom Lendacky
2021-12-21 22:25 ` Tom Lendacky
2021-12-21 22:33 ` David Woodhouse
2021-12-17 17:48 ` Tom Lendacky
2021-12-17 19:11 ` David Woodhouse
2021-12-17 19:26 ` David Woodhouse
2021-12-17 20:15 ` Tom Lendacky
2021-12-17 19:46 ` Tom Lendacky
2021-12-17 20:13 ` David Woodhouse
2021-12-17 20:55 ` Tom Lendacky
2021-12-17 22:48 ` David Woodhouse
2022-01-28 9:54 ` David Woodhouse
2022-01-28 21:40 ` Sean Christopherson
2022-01-28 21:48 ` David Woodhouse
2022-01-29 9:22 ` David Woodhouse
2021-12-16 19:52 ` David Woodhouse
2021-12-16 19:55 ` Tom Lendacky
2021-12-16 19:59 ` David Woodhouse
2021-12-27 16:57 ` Paul Menzel
2021-12-28 11:34 ` Paul Menzel
2021-12-28 14:18 ` David Woodhouse
2021-12-29 13:18 ` Paul Menzel
2021-12-29 13:54 ` David Woodhouse [this message]
2022-02-14 13:45 ` Paul Menzel
2022-04-21 10:00 ` Mimoja
2022-04-22 21:19 ` Tom Lendacky
2022-06-01 8:30 ` David Woodhouse
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