** Description changed:

+ [Impact]
  
- [Impact] 
+  * When reading boot and boot-menu information from a block device (like a
+    passed through dasd) the bootloader can stumble over some data
+    structures due to mistakes in the code.
  
-  * When reading boot and boot-menu information from a block device (like a 
-    passed through dasd) the bootloader can stumble over some data 
-    structures due to mistakes in the code.
- 
-  * The fix is to improve the bootloader code to no more fail in those 
-    situations. The fixes are upstream for a while, small and well 
-    reviewable
+  * The fix is to improve the bootloader code to no more fail in those
+    situations. The fixes are upstream for a while, small and well
+    reviewable
  
  [Test Plan]
  
-  * The bad-case triggers when boot menu entries are in a given form. There 
-    is this fix applied here to be able to handle those, but there are also 
-    fixes to src:s390-tools to have zipl not write those hard-to-handle 
-    entries. Due to that only zipl versions 2.12/2.13 (in the KVM guest) 
-    should cause issues, and also then only in some combinations of 
-    zipl.conf entries.
-    The best known case to reliable trigger it can feel a bit cubersome for 
-    a Ubuntu user as it includes usage of a suse installation media
-    SLE-15-SP2-Full-s390x-GM-Media1.iso that happens to 
-    bring the combinatino triggering this.
-    Based on the guest code, focal guests would be affected as well, but we 
-    haven't found (nor searched) which zipl.conf we'd need to recreate it 
-    there.
-    IBM will do the tests as they have doen when finding this issues as 
-    they have the suse ISOs triggering this reliably.
+  * The bad-case triggers when boot menu entries are in a given form. There
+    is this fix applied here to be able to handle those, but there are also
+    fixes to src:s390-tools to have zipl not write those hard-to-handle
+    entries. Due to that only zipl versions 2.12/2.13 (in the KVM guest)
+    should cause issues, and also then only in some combinations of
+    zipl.conf entries - finally it also could depend on the build toolchain 
+    of the guest.
+    The best known case to reliable trigger it can feel a bit cubersome for
+    a Ubuntu user as it includes usage of a suse installation media
+    SLE-15-SP2-Full-s390x-GM-Media1.iso that happens to
+    bring the combinatino triggering this.
+    Based on the guest code, focal guests would be affected as well, but we
+    haven't found (nor searched) which zipl.conf we'd need to recreate it
+    there.
+    IBM will do the tests as they have doen when finding this issues as
+    they have the suse ISOs triggering this reliably.
  
  [Where problems could occur]
  
-  * Issues would be s390x only and bootup-only which already is a very 
-    narrow field one can easily look for in coming bug reports.
-    In that area the thing one can think of is e.g. special bootloader 
-    configs (many entries, long entries, ...) that might now fail to be 
-    handled correctly.
+  * Issues would be s390x only and bootup-only which already is a very
+    narrow field one can easily look for in coming bug reports.
+    In that area the thing one can think of is e.g. special bootloader
+    configs (many entries, long entries, ...) that might now fail to be
+    handled correctly.
  
  [Other Info]
-  
-  * Suse iso can be downloaded (behind license - free trial - wall) from
-    https://www.suse.com/download/sles/
  
+  * Suse iso can be downloaded (behind license - free trial - wall) from
+    https://www.suse.com/download/sles/
  
  ----
- 
  
  ---Problem Description---
  A KVM guest fails to find the zipl boot menu index if the "zIPL" magic value 
is listed at the end of a disk block.
  
  ---System Hang---
  System sits in disabled wait, last console display
  LOADPARM=[        ]
  Using virtio-blk.
  Using ECKD scheme (block size  4096), CDL
  VOLSER=[0X0067]
  
  ---Steps to Reproduce---
  1. Install Distro KVM guest from ISO on a DASD, e.g. using virt-install, my 
invocation was
  $ virt-install --name secguest2 --memory 2048 --disk 
path=/dev/disk/by-path/ccw-0.0.af6a --cdrom /var/lib/libvirt/images/xxxxxx.iso
  
  2. Select DHCP networking and ASCII console, and accept all defaults of
  the installer
  
  3. Let the installer reboot after the installation completes
  
  It is possible to recover by editing the domain XML with an explicit loadparm 
to select a boot menu entry. E.g. I changed the disk definition to
     <disk type='block' device='disk'>
        <driver name='qemu' type='raw' cache='none' io='native'/>
        <source dev='/dev/disk/by-path/ccw-0.0.af6a'/>
        <target dev='vda' bus='virtio'/>
        <boot order='1' loadparm='1'/>
        <address type='ccw' cssid='0xfe' ssid='0x0' devno='0xaf6a'/>
      </disk>
  
  The patches are now upstream:
  5f97ba0c74cc ("pc-bios/s390-ccw: fix off-by-one error")
  468184ec9024 ("pc-bios/s390-ccw: break loop if a null block number is 
reached")
  
  Current versions of qemu within Ubuntu
  
  focal (20.04LTS) 1:4.2-3ubuntu6 [ports]: arm64 armhf ppc64el s390x
  focal-updates (metapackages): 1:4.2-3ubuntu6.14: amd64 arm64 armhf ppc64el 
s390x
  
  groovy (20.10) (metapackages): 1:5.0-5ubuntu9 [ports]: arm64 armhf ppc64el 
s390x
  groovy-updates (metapackages): 1:5.0-5ubuntu9.6: amd64 arm64 armhf ppc64el 
s390x
  
  hirsute (metapackages): 1:5.2+dfsg-9ubuntu1: amd64 arm64 armhf ppc64el
  s390x
  
  git-commits will apply seamlessley for the requested levels if not
  already integrated

** Description changed:

  [Impact]
  
   * When reading boot and boot-menu information from a block device (like a
     passed through dasd) the bootloader can stumble over some data
     structures due to mistakes in the code.
  
   * The fix is to improve the bootloader code to no more fail in those
     situations. The fixes are upstream for a while, small and well
     reviewable
  
  [Test Plan]
  
   * The bad-case triggers when boot menu entries are in a given form. There
     is this fix applied here to be able to handle those, but there are also
     fixes to src:s390-tools to have zipl not write those hard-to-handle
     entries. Due to that only zipl versions 2.12/2.13 (in the KVM guest)
     should cause issues, and also then only in some combinations of
-    zipl.conf entries - finally it also could depend on the build toolchain 
-    of the guest.
+    zipl.conf entries - finally it also could depend on the build toolchain
+    of the guest.
     The best known case to reliable trigger it can feel a bit cubersome for
     a Ubuntu user as it includes usage of a suse installation media
     SLE-15-SP2-Full-s390x-GM-Media1.iso that happens to
     bring the combinatino triggering this.
     Based on the guest code, focal guests would be affected as well, but we
     haven't found (nor searched) which zipl.conf we'd need to recreate it
     there.
     IBM will do the tests as they have doen when finding this issues as
     they have the suse ISOs triggering this reliably.
+    See below for a ste by step test from the initial report.
  
  [Where problems could occur]
  
   * Issues would be s390x only and bootup-only which already is a very
     narrow field one can easily look for in coming bug reports.
     In that area the thing one can think of is e.g. special bootloader
     configs (many entries, long entries, ...) that might now fail to be
     handled correctly.
  
  [Other Info]
  
   * Suse iso can be downloaded (behind license - free trial - wall) from
     https://www.suse.com/download/sles/
  
  ----
  
  ---Problem Description---
  A KVM guest fails to find the zipl boot menu index if the "zIPL" magic value 
is listed at the end of a disk block.
  
  ---System Hang---
  System sits in disabled wait, last console display
  LOADPARM=[        ]
  Using virtio-blk.
  Using ECKD scheme (block size  4096), CDL
  VOLSER=[0X0067]
  
  ---Steps to Reproduce---
  1. Install Distro KVM guest from ISO on a DASD, e.g. using virt-install, my 
invocation was
- $ virt-install --name secguest2 --memory 2048 --disk 
path=/dev/disk/by-path/ccw-0.0.af6a --cdrom /var/lib/libvirt/images/xxxxxx.iso
+ $ virt-install --name secguest2 --memory 2048 --disk 
path=/dev/disk/by-path/ccw-0.0.af6a --cdrom 
/var/lib/libvirt/images/SLE-15-SP2-Full-s390x-GM-Media1.iso
  
  2. Select DHCP networking and ASCII console, and accept all defaults of
  the installer
  
  3. Let the installer reboot after the installation completes
  
  It is possible to recover by editing the domain XML with an explicit loadparm 
to select a boot menu entry. E.g. I changed the disk definition to
     <disk type='block' device='disk'>
        <driver name='qemu' type='raw' cache='none' io='native'/>
        <source dev='/dev/disk/by-path/ccw-0.0.af6a'/>
        <target dev='vda' bus='virtio'/>
        <boot order='1' loadparm='1'/>
        <address type='ccw' cssid='0xfe' ssid='0x0' devno='0xaf6a'/>
      </disk>
  
  The patches are now upstream:
  5f97ba0c74cc ("pc-bios/s390-ccw: fix off-by-one error")
  468184ec9024 ("pc-bios/s390-ccw: break loop if a null block number is 
reached")
  
  Current versions of qemu within Ubuntu
  
  focal (20.04LTS) 1:4.2-3ubuntu6 [ports]: arm64 armhf ppc64el s390x
  focal-updates (metapackages): 1:4.2-3ubuntu6.14: amd64 arm64 armhf ppc64el 
s390x
  
  groovy (20.10) (metapackages): 1:5.0-5ubuntu9 [ports]: arm64 armhf ppc64el 
s390x
  groovy-updates (metapackages): 1:5.0-5ubuntu9.6: amd64 arm64 armhf ppc64el 
s390x
  
  hirsute (metapackages): 1:5.2+dfsg-9ubuntu1: amd64 arm64 armhf ppc64el
  s390x
  
  git-commits will apply seamlessley for the requested levels if not
  already integrated

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https://bugs.launchpad.net/bugs/1921468

Title:
  [UBUNTU 20.04] KVM guest fails to find zipl boot menu index

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