From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
To: Baoquan He <bhe@redhat.com>, pbonzini@redhat.com, mlevitsk@redhat.com
Cc: Peter Zijlstra <peterz@infradead.org>,
linux-kernel@vger.kernel.org,
Thomas Gleixner <tglx@linutronix.de>,
x86@kernel.org, kexec@lists.infradead.org
Subject: Re: [PATCH] Revert "x86/apic/x2apic: Implement IPI shorthands support"
Date: Wed, 4 Jan 2023 15:18:27 +0000 [thread overview]
Message-ID: <Y7WYw0YH27hdsD11@work-vm> (raw)
In-Reply-To: <Y6Gsz4mqnZCtC9rn@MiWiFi-R3L-srv>
* Baoquan He (bhe@redhat.com) wrote:
> On 12/20/22 at 12:38pm, Peter Zijlstra wrote:
> > On Tue, Dec 20, 2022 at 01:34:58PM +0800, Baoquan He wrote:
> > > This reverts commit 43931d350f30c6cd8c2f498d54ef7d65750abc92.
> > >
> > > On kvm guest with 4 cpus deployed, when adding 'nr_cpus=2' to normal
> > > kernel's cmdline, and triggering crash to jump to kdump kernel, kdump
> > > kernel will stably hang. Reverting commit 43931d350f30 ("x86/apic/x2apic:
> > > Implement IPI shorthands support") can fix it.
> > >
> > > The problem will disappear if removing 'nr_cpus=2' from normal kerne's
> > > cmdline.
> >
> > And the root cause for this is... ? Does the kvm x2apic emulation
> > somehow get upset when we shorthand CPUs that haven't been initialized?
>
> Thanks for checking.
>
> I haven't figure out the root cause. I haven't read the apic code for
> long time, and not familiar with the kvm code. So raise the issue to
> upstream.
>
> I can do testing if any suggestion.
>
> Add our virt dev Dr. David Alan Gilbert to CC.
Hmm I don't know that code well enough; cc'ing Paolo and Maxim.
Dave
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
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WARNING: multiple messages have this Message-ID (diff)
From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
To: Baoquan He <bhe@redhat.com>, pbonzini@redhat.com, mlevitsk@redhat.com
Cc: Peter Zijlstra <peterz@infradead.org>,
linux-kernel@vger.kernel.org,
Thomas Gleixner <tglx@linutronix.de>,
x86@kernel.org, kexec@lists.infradead.org
Subject: Re: [PATCH] Revert "x86/apic/x2apic: Implement IPI shorthands support"
Date: Wed, 4 Jan 2023 15:18:27 +0000 [thread overview]
Message-ID: <Y7WYw0YH27hdsD11@work-vm> (raw)
In-Reply-To: <Y6Gsz4mqnZCtC9rn@MiWiFi-R3L-srv>
* Baoquan He (bhe@redhat.com) wrote:
> On 12/20/22 at 12:38pm, Peter Zijlstra wrote:
> > On Tue, Dec 20, 2022 at 01:34:58PM +0800, Baoquan He wrote:
> > > This reverts commit 43931d350f30c6cd8c2f498d54ef7d65750abc92.
> > >
> > > On kvm guest with 4 cpus deployed, when adding 'nr_cpus=2' to normal
> > > kernel's cmdline, and triggering crash to jump to kdump kernel, kdump
> > > kernel will stably hang. Reverting commit 43931d350f30 ("x86/apic/x2apic:
> > > Implement IPI shorthands support") can fix it.
> > >
> > > The problem will disappear if removing 'nr_cpus=2' from normal kerne's
> > > cmdline.
> >
> > And the root cause for this is... ? Does the kvm x2apic emulation
> > somehow get upset when we shorthand CPUs that haven't been initialized?
>
> Thanks for checking.
>
> I haven't figure out the root cause. I haven't read the apic code for
> long time, and not familiar with the kvm code. So raise the issue to
> upstream.
>
> I can do testing if any suggestion.
>
> Add our virt dev Dr. David Alan Gilbert to CC.
Hmm I don't know that code well enough; cc'ing Paolo and Maxim.
Dave
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
next prev parent reply other threads:[~2023-01-04 16:52 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-12-20 5:34 [PATCH] Revert "x86/apic/x2apic: Implement IPI shorthands support" Baoquan He
2022-12-20 5:34 ` Baoquan He
2022-12-20 5:41 ` kdump kernel randomly hang with tick_periodic call trace on bare metal system Baoquan He
2022-12-20 5:41 ` Baoquan He
2022-12-20 5:51 ` Baoquan He
2022-12-20 5:51 ` Baoquan He
2022-12-21 15:46 ` Guilherme G. Piccoli
2022-12-21 15:46 ` Guilherme G. Piccoli
2022-12-22 4:09 ` Baoquan He
2022-12-22 4:09 ` Baoquan He
2023-01-09 21:57 ` Thomas Gleixner
2023-01-09 21:57 ` Thomas Gleixner
2023-01-14 2:08 ` Baoquan He
2023-01-14 2:08 ` Baoquan He
2023-01-16 9:08 ` Baoquan He
2023-01-16 9:08 ` Baoquan He
2023-01-16 16:27 ` [tip: x86/urgent] x86/i8259: Mark legacy PIC interrupts with IRQ_LEVEL tip-bot2 for Thomas Gleixner
2022-12-20 11:38 ` [PATCH] Revert "x86/apic/x2apic: Implement IPI shorthands support" Peter Zijlstra
2022-12-20 11:38 ` Peter Zijlstra
2022-12-20 12:38 ` Baoquan He
2022-12-20 12:38 ` Baoquan He
2023-01-04 15:18 ` Dr. David Alan Gilbert [this message]
2023-01-04 15:18 ` Dr. David Alan Gilbert
2023-01-09 21:59 ` Thomas Gleixner
2023-01-09 21:59 ` Thomas Gleixner
2023-01-10 2:24 ` Baoquan He
2023-01-10 2:24 ` Baoquan He
2023-01-17 8:27 ` Baoquan He
2023-01-17 8:27 ` Baoquan He
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