Note: This bug is displayed in read-only format because the product is no longer active in Red Hat Bugzilla.
RHEL Engineering is moving the tracking of its product development work on RHEL 6 through RHEL 9 to Red Hat Jira (issues.redhat.com). If you're a Red Hat customer, please continue to file support cases via the Red Hat customer portal. If you're not, please head to the "RHEL project" in Red Hat Jira and file new tickets here. Individual Bugzilla bugs in the statuses "NEW", "ASSIGNED", and "POST" are being migrated throughout September 2023. Bugs of Red Hat partners with an assigned Engineering Partner Manager (EPM) are migrated in late September as per pre-agreed dates. Bugs against components "kernel", "kernel-rt", and "kpatch" are only migrated if still in "NEW" or "ASSIGNED". If you cannot log in to RH Jira, please consult article #7032570. That failing, please send an e-mail to the RH Jira admins at rh-issues@redhat.com to troubleshoot your issue as a user management inquiry. The email creates a ServiceNow ticket with Red Hat. Individual Bugzilla bugs that are migrated will be moved to status "CLOSED", resolution "MIGRATED", and set with "MigratedToJIRA" in "Keywords". The link to the successor Jira issue will be found under "Links", have a little "two-footprint" icon next to it, and direct you to the "RHEL project" in Red Hat Jira (issue links are of type "https://issues.redhat.com/browse/RHEL-XXXX", where "X" is a digit). This same link will be available in a blue banner at the top of the page informing you that that bug has been migrated.

Bug 1535752

Summary: Device tree incorrectly advertises compatibility modes for secondary CPUs
Product: Red Hat Enterprise Linux 7 Reporter: David Gibson <dgibson>
Component: qemu-kvm-rhevAssignee: Laurent Vivier <lvivier>
Status: CLOSED ERRATA QA Contact: Xujun Ma <xuma>
Severity: urgent Docs Contact:
Priority: urgent    
Version: 7.5CC: knoel, lmiksik, lvivier, mdeng, michen, mtessun, qzhang, virt-maint, xianwang, xuma, yhong, yilzhang
Target Milestone: rcKeywords: Regression
Target Release: ---   
Hardware: ppc64le   
OS: Unspecified   
Whiteboard:
Fixed In Version: qemu-kvm-rhev-2.10.0-18.el7 Doc Type: If docs needed, set a value
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2018-04-11 00:58:52 UTC Type: Bug
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:

Description David Gibson 2018-01-18 01:44:47 UTC 
Description of problem:

The fix for bug 1528234 unfortunately introduced a different regression.  The compatibility modes for hotplugged CPUs are now set correctly in the hardware.  However, the device tree entries for non-boot cpus no longer correctly advertise their compatibility mode in the device tree.

Version-Release number of selected component (if applicable):

qemu-kvm-rhev-2.10.0-17.el7

How reproducible:

100%

Precised reproducer steps coming...
Comment 3 David Gibson 2018-01-18 02:21:36 UTC 
Steps to reproduce:
   1. Start a guest with:

 $QEMU -name bz1535752 -nographic -vga none -nodefaults \
	-machine pseries,accel=kvm,max-cpu-compat=power8 \
	-smp 2 \
	-m 2048 -cpu host -enable-kvm \
	-chardev stdio,id=conmon,mux=on,signal=off -mon conmon -device spapr-vty,chardev=conmon \
	-drive file=$DIR/disk.qcow2,if=none,id=hd0 \
	-device virtio-scsi-pci,id=scsi \
	-device scsi-hd,bus=scsi.0,drive=hd0 \
	-netdev tap,id=hostnet0,script=/etc/qemu-ifup,downscript=/etc/qemu-ifdown \
	-device virtio-net-pci,netdev=hostnet0 \
	"$@"

    2. In the guest run:

$ lsprop lsprop /proc/device-tree/cpus/PowerPC\,POWER9\@*/cpu-version

Actual results:

/proc/device-tree/cpus/PowerPC,POWER9@0/cpu-version
		 0f000004 (251658244)
/proc/device-tree/cpus/PowerPC,POWER9@1/cpu-version
		 004e1200 (5116416)

Expected results:

/proc/device-tree/cpus/PowerPC,POWER9@0/cpu-version
		 0f000004 (251658244)
/proc/device-tree/cpus/PowerPC,POWER9@1/cpu-version
		 0f000004 (251658244)
Comment 4 David Gibson 2018-01-18 02:22:59 UTC 
Greg Kurz has some upstream patches for this which I am reviewing.
Comment 5 David Gibson 2018-01-18 04:07:46 UTC 
I've reviewed and merged Greg's relevant patch, it should go into my next pull request.
Comment 8 Miroslav Rezanina 2018-01-23 13:01:05 UTC 
Fix included in qemu-kvm-rhev-2.10.0-18.el7
Comment 10 Xujun Ma 2018-01-25 06:17:17 UTC 
Reproduced this bug：
test env:
qemu-kvm-rhev-2.10.0-17.el7
kernel-4.14.0-22.el7a.ppc64le

Steps:
1.Boot up a P8-compat guest on power9 host:
/usr/libexec/qemu-kvm \
 -vga std \
 -smp 2 \
 -m 20480\
 -vnc :9 \
 -nographic \
 -device qemu-xhci,id=xhci \
 -device usb-kbd,id=kbd \
 -device usb-tablet,id=tablet \
 -device virtio-scsi-pci,bus=pci.0 \
 -device scsi-hd,id=scsi-hd0,drive=scsi-hd0-dr0,bootindex=0 \
 -device virtio-net-pci,netdev=net0,id=nic0,mac=52:54:00:c4:e7:84 \
 -netdev tap,id=net0,script=/etc/qemu-ifup,downscript=/etc/qemu-ifdown,vhost=on \
 -drive file=rhel75-ppc64le-virtio-scsi.qcow2,if=none,id=scsi-hd0-dr0,format=qcow2,cache=none \
 -machine pseries,max-cpu-compat=power8 \
 -chardev socket,path=monitor,id=vty,server,nowait,signal=off \
 -mon chardev=vty,mode=readline \
2.Check compatibility modes of non-boot cpus from device tree in guest
#lsprop /proc/device-tree/cpus/PowerPC\,POWER9\@*/cpu-version

Actual results:
/proc/device-tree/cpus/PowerPC,POWER9@0/cpu-version
		 0f000004 (251658244)
/proc/device-tree/cpus/PowerPC,POWER9@1/cpu-version
		 004e1200 (5116416)

Verified this bug：
test env:
qemu-kvm-rhev-2.10.0-18.el7
kernel-4.14.0-22.el7a.ppc64le

Steps:
The same as steps to reproduce.

Actual results:
/proc/device-tree/cpus/PowerPC,POWER9@0/cpu-version
		 0f000004 (251658244)
/proc/device-tree/cpus/PowerPC,POWER9@8/cpu-version
		 0f000004 (251658244)

Base the results above,set status to verified.
Comment 12 errata-xmlrpc 2018-04-11 00:58:52 UTC 
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHSA-2018:1104