FreeBSD bhyve VM Exiting

[Shawn Webb]

On Friday, December 26, 2014 12:07:44 PM Neel Natu wrote:
> Hi Shawn,
> 
> On Fri, Dec 26, 2014 at 6:26 AM, Shawn Webb <lattera at gmail.com> wrote:
> > Hey All,
> > 
> > I'm running a FreeBSD/amd64 11-current (r276204) guest VM in bhyve. It
> > seems that running Poudriere in it causes the VM to exit.
> > 
> > This is what bhyve outputs when the VM dies:
> >         reason          VMX
> >         rip             0xffffffff80d68564
> >         inst_length     5
> >         status          0
> >         exit_reason     2
> >         qualification   0x0000000000000000
> >         inst_type               0
> >         inst_error              0
> > 
> > I have no idea what "reason VMX" means or what "exit_reason 2" means. Is
> > there a way to decode that?
> 
> Exit reason '2' is a triple fault.
> 
> > What kinds of info/data do you guys need to debug this?
> 
> You'll need a FreeBSD host with svn revision >= 276098 and a custom
> kernel config to enable KTR.
> https://svnweb.freebsd.org/base?view=revision&revision=276098
> 
> Then you can set the following tunable "hw.vmm.trace_guest_exceptions"
> to "1" before loading vmm.ko. This will cause bhyve to trace all guest
> exceptions via KTR. You can verify that the tunable took effect using
> 'sysctl hw.vmm.trace_guest_exceptions'.
> 
> When the bhyve process exits you can then dump the KTR entries using
> something like this: 'sudo ktrdump -cto /tmp/ktrdump.out'. You'll
> probably want to do this in a script so the ktrdump(8) happens
> immediately after bhyve(8) exits.
> 
> I use the following options in my kernel config to enable KTR:
> options KTR
> options KTR_MASK=(KTR_GEN)
> options KTR_ENTRIES=(4*1024*1024)
> 
> Hope this helps.
> 
> best
> Neel

Hey Neel,

Thanks for the helpful suggestions! The good thing is that my host is already 
on a revision >= 276098 and my kernel is already built with KTR. With 31c3 
going on, the soonest I can do that will be Tuesday or Wednesday of next week. 
I'll update you then.

Thanks,

Shawn
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