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

[John Baldwin]

On Friday, February 07, 2014 8:07:07 am Simon Matter wrote:
> > 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
> >>
> >>  ------=_20140206114641_95473
> >>  Content-Type: text/plain; charset="iso-8859-1"
> >>  Content-Transfer-Encoding: 8bit
> >>
> >>  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?

Yes, I think it is, just talking to alc@ about it.

-- 
John Baldwin