Public bug reported:

== Comment: #0 - Chanh H. Nguyen <chngu...@us.ibm.com> - 2018-01-23 14:55:05 ==
root@boslcp4g5:~# cat /etc/os-release
NAME="Ubuntu"
VERSION="18.04 LTS (Bionic Beaver)"
ID=ubuntu
ID_LIKE=debian
PRETTY_NAME="Ubuntu Bionic Beaver (development branch)"
VERSION_ID="18.04"
HOME_URL="https://www.ubuntu.com/";
SUPPORT_URL="https://help.ubuntu.com/";
BUG_REPORT_URL="https://bugs.launchpad.net/ubuntu/";
PRIVACY_POLICY_URL="https://www.ubuntu.com/legal/terms-and-policies/privacy-policy";
VERSION_CODENAME=bionic
UBUNTU_CODENAME=bionic
root@boslcp4g5:~# uname -r
4.13.0-25-generic
root@boslcp4g5:~# kdump-config show
DUMP_MODE:        kdump
USE_KDUMP:        1
KDUMP_SYSCTL:     kernel.panic_on_oops=1
KDUMP_COREDIR:    /var/crash
crashkernel addr:
   /var/lib/kdump/vmlinuz: symbolic link to /boot/vmlinux-4.13.0-25-generic
kdump initrd:
   /var/lib/kdump/initrd.img: symbolic link to 
/var/lib/kdump/initrd.img-4.13.0-25-generic
current state:    ready to kdump

kexec command:
  /sbin/kexec -p --command-line="BOOT_IMAGE=/boot/vmlinux-4.13.0-25-generic 
root=UUID=8a776bc5-d9e0-4a1d-9218-135f9c702e11 ro splash quiet nr_cpus=1 
systemd.unit=kdump-tools.service irqpoll noirqdistrib nousb" 
--initrd=/var/lib/kdump/initrd.img /var/lib/kdump/vmlinuz
root@boslcp4g5:~# kdump-config status
current state   : ready to kdump
root@boslcp4g5:~# echo c > /proc/sysrq-trigger
[  176.911191] sysrq: SysRq : This sysrq operation is disabled.
root@boslcp4g5:~# sysctl -w kernel.sysrq=1
kernel.sysrq = 1
root@boslcp4g5:~# echo c > /proc/sysrq-trigger
[  240.304466] sysrq: SysRq : Trigger a crash
[  240.304545] Unable to handle kernel paging request for data at address 
0x00000000
[  240.304656] Faulting instruction address: 0xc000000000792f88
[  240.304771] Oops: Kernel access of bad area, sig: 11 [#1]
[  240.304846] SMP NR_CPUS=2048
[  240.304848] NUMA
[  240.304903] pSeries
[  240.305000] Modules linked in: sctp_diag sctp libcrc32c dccp_diag dccp 
tcp_diag udp_diag raw_diag inet_diag unix_diag af_packet_diag netlink_diag 
rpcsec_gss_krb5 auth_rpcgss nfsv4 nfs lockd grace fscache dm_service_time 
vmx_crypto crct10dif_vpmsum binfmt_misc dm_multipath scsi_dh_rdac scsi_dh_emc 
scsi_dh_alua sunrpc sch_fq_codel ip_tables x_tables autofs4 btrfs xor raid6_pq 
crc32c_vpmsum virtio_net virtio_scsi
[  240.305776] CPU: 12 PID: 1860 Comm: bash Not tainted 4.13.0-25-generic 
#29-Ubuntu
[  240.305886] task: c0000000ff904500 task.stack: c0000001f2d7c000
[  240.305979] NIP: c000000000792f88 LR: c000000000793eb8 CTR: c000000000792f60
[  240.306087] REGS: c0000001f2d7f9f0 TRAP: 0300   Not tainted  
(4.13.0-25-generic)
[  240.306195] MSR: 8000000000009033 <SF,EE,ME,IR,DR,RI,LE>
[  240.306207]   CR: 28422222  XER: 20040000
[  240.306338] CFAR: c000000000793eb4 DAR: 0000000000000000 DSISR: 42000000 
SOFTE: 1
[  240.306338] GPR00: c000000000793eb8 c0000001f2d7fc70 c0000000015f6200 
0000000000000063
[  240.306338] GPR04: c0000001feeeade8 c0000001fef02068 6967676572206120 
63726173680d0a72
[  240.306338] GPR08: 0000000000000007 0000000000000001 0000000000000000 
0000000000000000
[  240.306338] GPR12: c000000000792f60 c000000007ac7e00 0000000010180df8 
0000000010189e30
[  240.306338] GPR16: 0000000010189ea8 0000000010151210 000000001018bd58 
000000001018de48
[  240.306338] GPR20: 0000000028bc0268 0000000000000001 0000000010164590 
0000000010163bb0
[  240.306338] GPR24: 00007fffdcb37d34 00007fffdcb37d30 c0000000014fa770 
0000000000000002
[  240.306338] GPR28: 0000000000000063 0000000000000007 c0000000014824f4 
c0000000014fab10
[  240.307346] NIP [c000000000792f88] sysrq_handle_crash+0x28/0x30
[  240.307474] LR [c000000000793eb8] __handle_sysrq+0xf8/0x2b0
[  240.307553] Call Trace:
[  240.307594] [c0000001f2d7fc70] [c000000000793e98] __handle_sysrq+0xd8/0x2b0 
(unreliable)
[  240.307715] [c0000001f2d7fd10] [c0000000007946b4] 
write_sysrq_trigger+0x64/0x90
[  240.307850] [c0000001f2d7fd40] [c00000000044fb28] proc_reg_write+0x88/0xd0
[  240.307951] [c0000001f2d7fd70] [c0000000003a160c] __vfs_write+0x3c/0x70
[  240.308049] [c0000001f2d7fd90] [c0000000003a3248] vfs_write+0xd8/0x220
[  240.308149] [c0000001f2d7fde0] [c0000000003a50c8] SyS_write+0x68/0x110
[  240.308248] [c0000001f2d7fe30] [c00000000000b184] system_call+0x58/0x6c
[  240.308340] Instruction dump:
[  240.308400] 4bfff9f1 4bfffe50 3c4c00e6 384232a0 7c0802a6 60000000 39200001 
3d42001d
[  240.308522] 394adab0 912a0000 7c0004ac 39400000 <992a0000> 4e800020 3c4c00e6 
38423270
[  240.308644] ---[ end trace 97aaa45518689ad0 ]---
[  240.314197]
[  240.314408] Sending IPI to other CPUs
[  240.357424] IPI complete
[  240.377038] kexec: Starting switchover sequence.
 <<<<<<<<<<<<  it stops here.....

== Comment: #2 - MAMATHA INAMDAR <mainam...@in.ibm.com> - 2018-01-24 01:07:12 ==
Hi Chanh,

We need following patch which will fix this issue. I think this patch is
not integrated in 18.04 kernel

>From 2621e945fbf1d6df5f3f0ba7be5bae3d2cf9b6a5 Mon Sep 17 00:00:00 2001
From: Michael Ellerman <m...@ellerman.id.au>
Date: Fri, 24 Nov 2017 14:51:02 +1100
Subject: [PATCH] powerpc/kexec: Fix kexec/kdump in P9 guest kernels

The code that cleans up the IAMR/AMOR before kexec'ing failed to
remember that when we're running as a guest AMOR is not writable, it's
hypervisor privileged.

They symptom is that the kexec stops before entering purgatory and
nothing else is seen on the console. If you examine the state of the
system all threads will be in the 0x700 program check handler.

Fix it by making the write to AMOR dependent on HV mode.

Fixes: 1e2a516e89fc ("powerpc/kexec: Fix radix to hash kexec due to IAMR/AMOR")
Cc: sta...@vger.kernel.org # v4.10+
Reported-by: Yilin Zhang <yilzh...@redhat.com>
Debugged-by: David Gibson <da...@gibson.dropbear.id.au>
Signed-off-by: Michael Ellerman <m...@ellerman.id.au>
Acked-by: Balbir Singh <bsinghar...@gmail.com>
Reviewed-by: David Gibson <da...@gibson.dropbear.id.au>
Tested-by: David Gibson <da...@gibson.dropbear.id.au>
Signed-off-by: Michael Ellerman <m...@ellerman.id.au>

diff --git a/arch/powerpc/kernel/misc_64.S b/arch/powerpc/kernel/misc_64.S
index 8ac0bd2..3280953 100644
--- a/arch/powerpc/kernel/misc_64.S
+++ b/arch/powerpc/kernel/misc_64.S
@@ -623,7 +623,9 @@ BEGIN_FTR_SECTION
         * NOTE, we rely on r0 being 0 from above.
         */
        mtspr   SPRN_IAMR,r0
+BEGIN_FTR_SECTION_NESTED(42)
        mtspr   SPRN_AMOR,r0
+END_FTR_SECTION_NESTED_IFSET(CPU_FTR_HVMODE, 42)
 END_FTR_SECTION_IFSET(CPU_FTR_ARCH_300)

        /* save regs for local vars on new stack.
--

** Affects: kernel-package (Ubuntu)
     Importance: Undecided
     Assignee: Ubuntu on IBM Power Systems Bug Triage (ubuntu-power-triage)
         Status: New


** Tags: architecture-ppc64le bugnameltc-163889 severity-critical 
targetmilestone-inin---

** Tags added: architecture-ppc64le bugnameltc-163889 severity-critical
targetmilestone-inin---

** Changed in: ubuntu
     Assignee: (unassigned) => Ubuntu on IBM Power Systems Bug Triage 
(ubuntu-power-triage)

** Package changed: ubuntu => kernel-package (Ubuntu)

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Title:
  ISST-LTE: KVM:UBUNTU1804: kdump is not working on UbuntuKVM  guest

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