Re: [Qemu-devel] strange situation, guest cpu thread spinning at ~100%, but display not yet initialized

[Chris Friesen]

On 11/2/2018 1:51 AM, Alex Bennée wrote:
> Chris Friesen <address@hidden> writes:
>
> > Hi all,
> >
> > I have an odd situation which occurs very infrequently and I'm hoping
> > to get some advice on how to debug.  Apologies for the length of this
> > message, I tried to include as much potentially useful information as
> > possible.
> >
> > In the context of an OpenStack compute node I have a qemu guest (with
> > kvm acceleration) that has started up.  The virtual console shows
> > "Guest has not initialized the display (yet)."   I'm trying to figure
> > out what's going on and how we got into this state.  I assume it's
> > some sort of deadlock/livelock, but I can't figure out what's causing
> > it.

> > At this point gdb appears to be stuck, though the task is still
> > chewing 99.9% of host cpu 43.
>
> That's because the vcpu_ioctl you just trace through is into the
> VCPU_RUN, basically when you enter the guest code (assuming the in
> kernel KVM code isn't spinning).

That's what I figured, thanks for the confirmation.

> If you want to get an idea why your guest is spinning you probably want
> to enable the gdb stub and look at what your guest kernel is doing.

Given the "not initialized" message on the console, I wasn't sure 
whether the kernel had even started yet.

Chris