On Thu, Feb 12, 2015 at 07:12:06AM +0100, Jan Kiszka wrote:
> On 2015-02-11 19:12, Kashyap Chamarthy wrote:
> > Hi,
> >
> > This was tested with kernel-3.19.0-1.fc22) and QEMU (qemu-2.2.0-5.fc22)
> > on L0 & L1.
> >
> >
> > Description
> > ---
> >
> > Inside L1, boot a nested KVM guest (L2) . Instead of a full blown
> > guest, let's use `qemu-sanity-check` with KVM:
> >
> > $ qemu-sanity-check --accel=kvm
> >
> > Wwich gives you this CLI (run from a different shell), that confirms
> > that the L2 guest is indeed running on KVM (and not TCG):
> >
> > $ ps -ef | grep -i qemu
> > root 763 762 35 11:49 ttyS000:00:00 qemu-system-x86_64
> > -nographic -nodefconfig -nodefaults -machine accel=kvm -no-reboot -serial
> > file:/tmp/tmp.rl3naPaCkZ.out -kernel /boot/vmlinuz-3.19.0-1.fc21.x86_64
> > -initrd /usr/lib64/qemu-sanity-check/initrd -append console=ttyS0
> > oops=panic panic=-1
> >
> >
> > Which results in:
> >
> > (a) L1 (guest hypervisor) completely hangs and is unresponsive. But
> > when I query libvirt, (`virsh list`) the guest is still reported
> > as 'running'
> >
> > (b) On L0, I notice a ton of these messages:
> >
> > skip_emulated_instruction: ip 0xffec next 0x8105e964
> >
> >
> > I can get `dmesg`, `dmidecode` , `x86info -a` on L0 and L1 if it helps
> > in narrowing down the issue.
> >
> >
> > Related bug and reproducer details
> > --
> >
> >
> > https://bugzilla.redhat.com/show_bug.cgi?id=1191665 -- Nested KVM with
> > AMD: L2 (nested guest) fails with "divide error: [#1] SMP"
> >
> >
>
> Is this a regression (of the kernel)? If so, can you bisect to the
> commit that introduced it?
[Sorry, I missed this reply and just noticed it.]
I can't certainly say that it's a regression of Kernel. I also heard
from Dan Berrange (CCed), that when an booting L2 guest it caused L1 to
panic and reboot on AMD. I don't have the AMD physical machine that I
tested this on, will try to find one this week and see if I can bisect.
Thanks.
--
/kashyap
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