Re: Hang on reboot in FreeBSD guest on Linux KVM host

[Bandan Das <bsd@redhat.com>]

John Nielsen <lists@jnielsen.net> writes:

> On Jun 17, 2014, at 10:48 AM, John Nielsen <lists@jnielsen.net> wrote:
>
>> On Jun 17, 2014, at 12:05 AM, Gleb Natapov <gleb@kernel.org> wrote:
>> 
>>> On Tue, Jun 17, 2014 at 06:21:23AM +0200, Paolo Bonzini wrote:
>>>> Il 16/06/2014 18:47, John Nielsen ha scritto:
>>>>> On Jun 16, 2014, at 10:39 AM, Paolo Bonzini <pbonzini@redhat.com>
>>>>> wrote:
>>>>> 
>>>>>> Il 16/06/2014 18:09, John Nielsen ha scritto:
>>>>>>>>> The only substantial difference on the hardware side is the
>>>>>>>>> CPU.  The hosts where the problem occurs use "Intel(R)
>>>>>>>>> Xeon(R) CPU E5-2650 v2 @ 2.60GHz", while the hosts that don't
>>>>>>>>> show the problem use the prior revision, "Intel(R) Xeon(R)
>>>>>>>>> CPU E5-2650 0 @ 2.00GHz".
>>>>>>  Can you do "grep . /sys/module/kvm_intel/parameters/*" on both
>>>>>> hosts please?
>>>>>  No differences that I can see. Output below.
>>>>  Not really:
>>>> 
>>>>> Working host: Intel(R) Xeon(R) CPU E5-2650 0 @ 2.00GHz # grep
>>>>> . /sys/module/kvm_intel/parameters/*
>>>>> /sys/module/kvm_intel/parameters/enable_apicv:N
>>>>> 
>>>>> Problem host: Intel(R) Xeon(R) CPU E5-2650 v2 @ 2.60GHz # grep
>>>>> . /sys/module/kvm_intel/parameters/*
>>>>> /sys/module/kvm_intel/parameters/enable_apicv:Y
>>>>  So we have a clue.  Let me study the code more, I'll try to get
>>>> back with a suggestion.
>>  Wow, can't believe I missed that. Good catch!
>> 
>>> Does disabling apicv on E5-2650 v2 make reboot problem go away?
>>  Yes it does!
>> 
>> # modprobe kvm_intel /sys/module/kvm_intel/parameters/enable_apicv:Y
>> # /usr/bin/qemu-system-x86_64 -machine accel=kvm -name bsdtest -m
>> 512 -smp 2,sockets=1,cores=1,threads=2 -drive
>> file=./20140613_FreeBSD_9.2-RELEASE_ufs.qcow2,if=none,id=drive0,format=qcow2
>> -device virtio-blk-pci,scsi=off,drive=drive0 -vnc 0.0.0.0:0 -net
>> none
>> 
>> [problem occurs]
>> 
>> # rmmod kvm_intel # modprobe kvm_intel enable_apicv=N
>> /sys/module/kvm_intel/parameters/enable_apicv:N #
>> /usr/bin/qemu-system-x86_64 -machine accel=kvm -name bsdtest -m 512
>> -smp 2,sockets=1,cores=1,threads=2 -drive
>> file=./20140613_FreeBSD_9.2-RELEASE_ufs.qcow2,if=none,id=drive0,format=qcow2
>> -device virtio-blk-pci,scsi=off,drive=drive0 -vnc 0.0.0.0:0 -net
>> none
>> 
>> [problem does not occur]
>> 
>> Thank you. This both narrows the problem considerably and provides
>> an acceptable workaround. It would still be nice to see it fixed, of
>> course. Keep me CC'ed as I'm not on the KVM list.
>
> I’m resurrecting an old thread since I haven’t heard anything in a
> while. Has anyone looked in to the KVM+apicv bug documented above as
> well as here:
>
> https://bugs.launchpad.net/qemu/+bug/1329956 ?
>
> If appropriate, where should I go to file a KVM bug (since this isn’t
> really Qemu’s problem)?

Hi John, does this happen with the latest upstream kernel version ?

Bandan

> Thanks,
>
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