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-rhev	Assignee:	Laurent Vivier <lvivier>
Status:	CLOSED ERRATA	QA Contact:	Xujun Ma <xuma>
Severity:	urgent	Docs Contact:
Priority:	urgent
Version:	7.5	CC:	knoel, lmiksik, lvivier, mdeng, michen, mtessun, qzhang, virt-maint, xianwang, xuma, yhong, yilzhang
Target Milestone:	rc	Keywords:	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