Bug 1756946

Summary:	[zKVM] Re-enable KVM_CAP_S390_AIS for new machine types
Product:	Red Hat Enterprise Linux 8	Reporter:	Thomas Huth <thuth>
Component:	qemu-kvm	Assignee:	Thomas Huth <thuth>
qemu-kvm sub component:	CPU Models	QA Contact:	smitterl
Status:	CLOSED ERRATA	Docs Contact:
Severity:	low
Priority:	low	CC:	borntraeger, bugproxy, cohuck, ddepaula, dhildenb, dzheng, gkurz, hannsj_uhl, juzhang, jwboyer, ngu, qzhang, tstaudt, virt-maint
Version:	8.3	Keywords:	FutureFeature, Triaged
Target Milestone:	beta
Target Release:	8.3
Hardware:	s390x
OS:	Linux
Whiteboard:
Fixed In Version:	qemu-kvm-4.2.0-28.module+el8.3.0+7105+0cc49779	Doc Type:	If docs needed, set a value
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2020-11-04 02:53:03 UTC	Type:	Feature Request
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:	qemu-5.0
Embargoed:
Bug Depends On:
Bug Blocks:	1776265

Description Thomas Huth 2019-09-30 09:22:12 UTC

Description of problem:
The "adapter interrupt suppression" capability KVM_CAP_S390_AIS has been disabled since there were some issues with migration:

 https://git.qemu.org/?p=qemu.git;a=commitdiff;h=3f2d07b3b01ea61126b

The commit message of that commit said that the migration problems would be fixed and AIS would be enabled again, but so far this has not happen yet. Since this is likely a useful feature, we should try to get this enabled again (first in upstream, then in downstream).

How reproducible:
100%

Steps to Reproduce:
/usr/libexec/qemu-kvm -nographic -accel kvm -cpu host,ais=true

Actual results:
qemu-kvm: Some features requested in the CPU model are not available in the configuration: ais  

Expected results:
It should be possible to use "-accel kvm -cpu host,ais=true" without problems

Comment 2 Thomas Huth 2020-01-16 13:34:09 UTC

Suggested a patch upstream here:
https://lists.gnu.org/archive/html/qemu-devel/2020-01/msg03309.html

Comment 3 Thomas Huth 2020-01-29 08:24:07 UTC

Patch has been merged here:
https://git.qemu.org/?p=qemu.git;a=commitdiff;h=a5c8617af6919515b84256978452edf07401c45e

We should get it with the next rebase, so I'm moving this BZ to POST.

Comment 4 Ademar Reis 2020-02-05 23:06:48 UTC

QEMU has been recently split into sub-components and as a one-time operation to avoid breakage of tools, we are setting the QEMU sub-component of this BZ to "General". Please review and change the sub-component if necessary the next time you review this BZ. Thanks

Comment 14 smitterl 2020-06-30 08:37:30 UTC

Reproduced with:
qemu-kvm-4.2.0-19.module+el8.3.0+6473+93e27135.s390x

1. /usr/libexec/qemu-kvm -accel kvm -cpu host,ais=true
>> qemu-kvm: Some features requested in the CPU model are not available in the configuration: ais

Verified with:
qemu-kvm-4.2.0-29.module+el8.3.0+7212+401047e6.s390x
1. /usr/libexec/qemu-kvm -accel kvm -cpu host,ais=true
VNC server running on ::1:5900

Comment 17 errata-xmlrpc 2020-11-04 02:53:03 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 (Moderate: virt:rhel and virt-devel:rhel security, bug fix, and enhancement update), 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-2020:4676