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Subject: Re: qemu-x86: kernel panic when host is loaded
To:     Thomas Gleixner <tglx@linutronix.de>,
        Corentin Labbe <clabbe.montjoie@gmail.com>,
        qemu-discuss@nongnu.org, mingo@redhat.com, bp@alien8.de,
        hpa@zytor.com, x86@kernel.org
Cc:     linux-kernel@vger.kernel.org
References: <20200402093132.GA15839@Red>
 <87eet6nra7.fsf@nanos.tec.linutronix.de>
From:   Dongli Zhang <dongli.zhang@oracle.com>
Message-ID: <18354be1-8dba-84f1-bdf5-6821a5013d78@oracle.com>
Date:   Thu, 2 Apr 2020 07:04:57 -0700
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On 4/2/20 2:57 AM, Thomas Gleixner wrote:
> Corentin,
> 
> Corentin Labbe <clabbe.montjoie@gmail.com> writes:
>> On our kernelci lab, each qemu worker pass an healtcheck job each day and after each job failure, so it is heavily used.
>> The healtcheck job is a Linux boot with a stable release.
>>
>> Since we upgraded our worker to buster, the qemu x86_64 healthcheck randomly panic with:
>> <0>[    0.009000] Kernel panic - not syncing: IO-APIC + timer doesn't work!  Boot with apic=debug and send a report.  Then try booting with the 'noapic' option.
>>
>> After some test I found the source of this kernel panic, the host is
>> loaded and qemu run "slower".  Simply renicing all qemu removed this
>> behavour.
>>
>> So now what can I do ?
>> Appart renicing qemu process, does something could be done ?
> 
> As the qemu timer/ioapic routing is actually sane, you might try to add
> "no_timer_check" to the kernel command line.
> 

The no_timer_check is already permanently disabled in below commit?

commit a90ede7b17d1 ("KVM: x86: paravirt skip pit-through-ioapic boot check")

In addition, hyperv and vmware also disabled that:

commit ca3ba2a2f4a4 ("x86, hyperv: Bypass the timer_irq_works() check").

commit 854dd54245f7 ("x86/vmware: Skip timer_irq_works() check on VMware")

Dongli Zhang