[nested] virt-install falls to SLOF

[nested] virt-install falls to SLOF: after starting installer (ISO/CDROM), it crashes w/ a kernel panic due to an HTM (Hardware Transactional Memory) exception.

Scenario:
Host=Ubuntu 16.04 Xenial (Ubuntu KVM ppc64el POWER8E 8247-22L)
Guest=Ubuntu 16.04 Xenial (Ubuntu Xenial Cloud Image QCOW2)
Nested=Ubuntu 16.04 Xenial (Ubuntu Xenial Server ISO *or* NetInstall mini.iso)

Inside Guest (1st level), run virt-install as shown below to reproduce the bug.

Facts:
 * ISO images (from both Server or netinstall mini.iso) fail to boot on xenial/yakkety
 * Cloud image (xenial/yakkety/zesty) on nested virt boots fine, the login prompt is seen.
 * Reproducible with Xenial and Yakkety
 * NOT reproducible with Zesty (Installer menu starts just normally)
 * virtio-scsi, virtio-net and virtio-blk modules are seen in zesty. Only virtio-scsi is seen on xenial/yakkety (-net and -blk are built-in modules?)
 * kvm-pr is loaded for all tested scenarios
 * This patch[1] rings a bell, however, it doesn't explain how cloud images boot just fine and don't hit the bug, since the kernel used in the cloud images also enable HTM[2].

[1] https://lists.ozlabs.org/pipermail/linuxppc-dev/2016-April/141292.html

[2] grep TRANSA /boot/config-4.8.0-26-generic
CONFIG_PPC_TRANSACTIONAL_MEM=y

# cat virt-inst.sh
virt-install --virt-type=kvm --cpu=host --name=nested-xenial --controller type=scsi,model=virtio-scsi --graphics none --console pty,target_type=serial --disk path=/home/nested-xenial.qcow2,size=20 --vcpus=4 --ram=4096 --os-type=linux --os-variant ubuntu16.04 --network bridge=virbr0,model=virtio --cdrom=$1

# ./virt-inst.sh ubuntu-16.04-server-ppc64el.iso
WARNING CDROM media does not print to the text console by default, so you likely will not see text install output. You might want to use --location. See the man page for examples of using --location with CDROM media

Starting install...
Creating domain... | 0 B 00:00:00
Connected to domain nested-xenial
Escape character is ^]
Populating /vdevice methods
Populating /vdevice/vty@30000000
Populating /vdevice/nvram@71000000
Populating /pci@800000020000000
                     00 2800 (D) : 1af4 1002 unknown-legacy-device*
                     00 2000 (D) : 1af4 1001 virtio [ block ]
                     00 1800 (D) : 106b 003f serial bus [ usb-ohci ]
                     00 1000 (D) : 1af4 1004 virtio [ scsi ]
Populating /pci@800000020000000/scsi@2
       SCSI: Looking for devices
          100000000000000 CD-ROM : "QEMU QEMU CD-ROM 2.5+"
                     00 0800 (D) : 10ec 8139 network [ ethernet ]
No NVRAM common partition, re-initializing...
Scanning USB
  OHCI: initializing
Using default console: /vdevice/vty@30000000

  Welcome to Open Firmware

  Copyright (c) 2004, 2011 IBM Corporation All rights reserved.
  This program and the accompanying materials are made available
  under the terms of the BSD License available at
  http://www.opensource.org/licenses/bsd-license.php

Trying to load: from: /pci@800000020000000/scsi@2/disk@100000000000000 ... Successfully loaded

                     GNU GRUB version 2.02~beta2-36ubuntu3

 +----------------------------------------------------------------------------+
 |*Install |
 | Rescue mode |
 | |
 | |
 | |
 | |
 | |
 | |
 | |
 | |
 | |
 | |
 +----------------------------------------------------------------------------+

      Use the ^ and v keys to select which entry is highlighted.
      Press enter to boot the selected OS, `e' to edit the commands
      before booting or `c' for a command-line.

OF stdout device is: /vdevice/vty@30000000
Preparing to boot Linux version 4.4.0-21-generic (buildd@bos01-ppc64el-017) (gcc version 5.3.1 20160413 (Ubuntu/IBM 5.3.1-14ubuntu2) ) #37-Ubuntu SMP Mon Apr 18 18:30:22 UTC 2016 (Ubuntu 4.4.0-21.37-generic 4.4.6)
Detected machine type: 0000000000000101
Max number of cores passed to firmware: 2048 (NR_CPUS = 2048)
Calling ibm,client-architecture-support... done
command line: BOOT_IMAGE=/install/vmlinux tasks=standard pkgsel/language-pack-patterns= pkgsel/install-language-support=false --- quiet
memory layout at init:
  memory_limit : 0000000000000000 (16 MB aligned)
  alloc_bottom : 0000000004640000
  alloc_top : 0000000030000000
  alloc_top_hi : 0000000100000000
  rmo_top : 0000000030000000
  ram_top : 0000000100000000
instantiating rtas at 0x000000002fff0000... done
prom_hold_cpus: skipped
copying OF device tree...
Building dt strings...
Building dt structure...
Device tree strings 0x0000000004650000 -> 0x0000000004650a5b
Device tree struct 0x0000000004660000 -> 0x0000000004670000
Quiescing Open Firmware ...
Booting Linux via __start() ...
 -> smp_release_cpus()
spinning_secondaries = 3
 <- smp_release_cpus()
 <- setup_system()
Linux ppc64le
#37-Ubuntu SMP M[ 2.155665] Facility 'TM' unavailable, exception at 0x3fff9f3d8644, MSR=b00000014280f033
[ 2.161582] Facility 'TM' unavailable, exception at 0x3fff8a488644, MSR=b00000014280f033
[ 2.168973] Facility 'TM' unavailable, exception at 0x3fffb2df8644, MSR=b00000014280f033
[ 2.174818] Facility 'TM' unavailable, exception at 0x3fff902f8644, MSR=b00000014280f033
[ 2.180887] Facility 'TM' unavailable, exception at 0x3fff84728644, MSR=b00000014280f033
[ 2.186023] Facility 'TM' unavailable, exception at 0x3fff8f1f8644, MSR=b00000014280f033
[ 2.193073] Facility 'TM' unavailable, exception at 0x3fffa8ecfe30, MSR=b00000014280f033
[ 2.193697] Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000004
[ 2.193697]
[ 2.193751] CPU: 3 PID: 1 Comm: init Not tainted 4.4.0-21-generic #37-Ubuntu
[ 2.193788] Call Trace:
[ 2.193826] [c0000000fea83a50] [c000000000aedc1c] dump_stack+0xb0/0xf0 (unreliable)
[ 2.193868] [c0000000fea83a90] [c000000000ae9e50] panic+0x100/0x2c0
[ 2.193914] [c0000000fea83b20] [c0000000000bd474] do_exit+0xc24/0xc30
[ 2.193945] [c0000000fea83be0] [c0000000000bd564] do_group_exit+0x64/0x100
[ 2.193979] [c0000000fea83c20] [c0000000000ce9cc] get_signal+0x55c/0x7b0
[ 2.194012] [c0000000fea83d10] [c000000000017424] do_signal+0x54/0x2b0
[ 2.194043] [c0000000fea83e00] [c00000000001787c] do_notify_resume+0xbc/0xd0
[ 2.194072] [c0000000fea83e30] [c000000000009838] ret_from_except_lite+0x64/0x68

Domain creation completed.
Restarting guest.
Connected to domain nested-xenial
Escape character is ^]
Populating /vdevice methods
Populating /vdevice/vty@30000000
Populating /vdevice/nvram@71000000
Populating /pci@800000020000000
                     00 2800 (D) : 1af4 1002 unknown-legacy-device*
                     00 2000 (D) : 1af4 1001 virtio [ block ]
                     00 1800 (D) : 106b 003f serial bus [ usb-ohci ]
                     00 1000 (D) : 1af4 1004 virtio [ scsi ]
Populating /pci@800000020000000/scsi@2
       SCSI: Looking for devices
          100000000000000 CD-ROM : "QEMU QEMU CD-ROM 2.5+"
                     00 0800 (D) : 10ec 8139 network [ ethernet ]
No NVRAM common partition, re-initializing...
Scanning USB
  OHCI: initializing
Using default console: /vdevice/vty@30000000

  Welcome to Open Firmware

  Copyright (c) 2004, 2011 IBM Corporation All rights reserved.
  This program and the accompanying materials are made available
  under the terms of the BSD License available at
  http://www.opensource.org/licenses/bsd-license.php

Trying to load: from: /pci@800000020000000/scsi@4 ...
E3404: Not a bootable device!
Trying to load: from: HALT ...
E3405: No such device

E3407: Load failed

        ..`. .. ....... .. ...... .......
    ..`...`''.`'. .''``````..''. .`''```''`. `''``````
       .`` .:' ': `''..... .''. ''` .''..''.......
         ``.':.';. ``````''`.''. .''. ''``''`````'`
         ``.':':` .....`''.`'`...... `'`.....`''.`'`
        .`.`'`` .'`'`````. ``'''''' ``''`'''`. `'`
  Type 'boot' and press return to continue booting the system.
  Type 'reset-all' and press return to reboot the system.

Ready!
0 >