amd64/186061: FreeBSD 10 crashes as KVM guest on GNU/Linux on AMD family 10h CPUs

[Simon Matter]

> On Thursday, February 06, 2014 6:00:01 am Simon Matter wrote:
>> The following reply was made to PR amd64/186061; it has been noted by
>> GNATS.
>>
>> From: "Simon Matter" <simon.matter at invoca.ch>
>> To: bug-followup at FreeBSD.org
>> Cc: simon.matter at invoca.ch
>> Subject: Re: amd64/186061: FreeBSD 10 crashes as KVM guest on GNU/Linux
>> on
>>  AMD family 10h CPUs
>> Date: Thu, 6 Feb 2014 11:46:41 +0100
>>
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>>
>>  Hi,
>>
>>  After thinking about it again it seems the proposed solution may not be
>>  enough. At least KVM allows to migrate guests from an Intel to an AMD
>>  processor. That means in case of running as a vm guest, it's required
>> to
>>  always enable "AMD Erratum 383" workaround. Otherwise, after migration
>> to
>>  an affected AMD Family 10h processor, the guest could triggered AMD
>>  Erratum 383.
>>
>>  I've tried to implement this and attached patch fixes the problem for
>> me.
>>  Would me nice if someone with more experience than me could have a look
>> at
>>  it.
>
> I suspect you do not need the mca.c change as I doubt any hypervisors are
> going to pass machine check handling on to guests.  Presumably they will
> handle that in the host OS instead.

Hi John,

you are right, my test box is also working without the mca.c change.

BTW, setting vm.pmap.pg_ps_enabled="0" in loader.conf also helps to make
the vm survive but I guess that's not the same and should be avoided?
Isn't the suggested patch the better solution?

Thanks,
Simon