Linux kernel: powerpc: KVM guest can trigger host crash on Power8

[John Paul Adrian Glaubitz]

Hi Michael!

On 10/28/21 08:39, Michael Ellerman wrote:
>>> No, I will try that now.
> 
> That completed fine on my BE VM here.
> 
> I ran these in two tmux windows:
>   $ sbuild -d sid --arch=powerpc --no-arch-all gcc-11_11.2.0-10.dsc
>   $ sbuild -d sid --arch=ppc64 --no-arch-all gcc-11_11.2.0-10.dsc
> 
> 
> The VM has 32 CPUs, with 4 threads per core:
> 
>   $ ppc64_cpu --info
>   Core   0:    0*    1*    2*    3*
>   Core   1:    4*    5*    6*    7*
>   Core   2:    8*    9*   10*   11*
>   Core   3:   12*   13*   14*   15*
>   Core   4:   16*   17*   18*   19*
>   Core   5:   20*   21*   22*   23*
>   Core   6:   24*   25*   26*   27*
>   Core   7:   28*   29*   30*   31*

It seems I also can no longer reproduce the issue, even when building the most problematic
packages and I think we should consider it fixed for now. I will keep monitoring the server,
of course, and will let you know in case the problem shows again.

Thanks a lot again for fixing this issue!

Adrian

-- 
 .''`.  John Paul Adrian Glaubitz
: :' :  Debian Developer - glaubitz at debian.org
`. `'   Freie Universitaet Berlin - glaubitz at physik.fu-berlin.de
  `-    GPG: 62FF 8A75 84E0 2956 9546  0006 7426 3B37 F5B5 F913