Re: [PATCH for-9.2 00/10] s390: Convert virtio-ccw, cpu to three-phase reset, and followup cleanup

[Nico Boehr]

Quoting Peter Maydell (2024-08-28 17:46:42)
[...]
> Well, the series is *supposed* to be just a refactoring, not a change of
> behaviour, so I'm not sure. I don't suppose you have a reproduce case
> that I can run? (I do have access to an s390 machine if that helps.)

Well, it's on an internal testing framework which we do not release
publicly. :-(

Luckily, it's not that difficult to reproduce.  It seems like this only
happens when a reboot is initiated over SSH connection via vsock. Here are
some instructions on how to reproduce (with mkosi and Fedora):

1. Craft an mkosi.conf like this:
   [Distribution]
   Distribution=fedora
   Architecture=s390x
   
   [Output]
   Format=cpio
   CompressOutput=xz
   
   [Content]
   Packages=openssh-server
   Packages=kernel-modules-core-6.8.5-301.fc40.s390x
   Bootloader=none
   MakeInitrd=no
   Ssh=yes
   Autologin=yes
   RootPassword=hunter
   Timezone=Etc/UTC
   Locale=C.UTF-8
2. Generate SSH host key:
   mkdir -p mkosi.extra/etc/ssh && ssh-keygen -t ed25519 -f 
mkosi.extra/etc/ssh/ssh_host_ed25519_key
3. Build image:
   mkosi
4. Boot with QEMU:
   qemu-system-s390x -machine s390-ccw-virtio,accel=kvm -nodefaults -nographic 
-chardev stdio,id=con0 -device sclpconsole,chardev=con0 -m 2048 -kernel 
image.vmlinuz -initrd image.cpio.xz -device vhost-vsock-ccw,guest-cid=3
5. In a different terminal, run a reboot loop:
   i=0; while true; do ssh -o ProxyCommand='socat VSOCK-CONNECT:3:22 -' 
localhost -l root reboot; echo $i; let i=i+1; done

After a while (10 minutes, sometimes longer) you should see the quest crash
either with "Attempted to kill init" or "Unable to mount rootfs" and a message
about corrupted initramfs:
[    1.599082] Initramfs unpacking failed: XZ-compressed data is corrupt

I had this run without your series for 45 minutes, while with your series
this crashed within ~5-10 minutes.

Thanks!