KVM guests freeze under upstream kernel

[Paul Mackerras]

On Thu, Jul 20, 2017 at 12:02:23AM -0300, joserz at linux.vnet.ibm.com wrote:
> On Thu, Jul 20, 2017 at 09:42:50AM +1000, Benjamin Herrenschmidt wrote:
> > On Wed, 2017-07-19 at 16:46 -0300, joserz at linux.vnet.ibm.com wrote:
> > > Hello!
> > > 
> > > We're not able to boot any KVM guest using upstream kernel (cb8c65ccff7f77d0285f1b126c72d37b2572c865 - 4.13.0-rc1+).
> > > After reaching the SLOF initial counting, the guest simply freezes:
> > 
> > Can you send our .config ?
> 
> Sure,
> 
> Answering Michael as well:
> 
> It's a P9 with RHEL kernel 4.11.0-10.el7a.ppc64le installed. The problem
> was noticed with kernel > 4.13 (I'm currently running 4.13.0-rc1+).
> 
> QEMU is https://github.com/dgibson/qemu (ppc-for-2.10) but I gave the
> default packaged Qemu a try.
> 
> For the guest, I tried both a vanilla Ubuntu 17.04 and the host kernel.
> But they had never a chance to run since the freezing happened in SLOF.
> 
> Note that using the 4.11.0-10.el7a.ppc64le kernel it works fine
> (for any of these Qemu/Guest setup). With 4.13.0-rc1 I have it run after
> reverting that referred commit.

Is the host kernel running in radix mode?

Did you check the host kernel logs for any oops messages?

Paul.