Bug 1843534

Summary:	libvirt: Fix virConnectGetDomainCapabilities() call with empty cache [rhel-8.2.0.z]
Product:	Red Hat Enterprise Linux Advanced Virtualization	Reporter:	Oneata Mircea Teodor <toneata>
Component:	libvirt	Assignee:	Andrea Bolognani <abologna>
Status:	CLOSED ERRATA	QA Contact:	Luyao Huang <lhuang>
Severity:	urgent	Docs Contact:
Priority:	urgent
Version:	8.2	CC:	abologna, crobinso, dyuan, fdeutsch, jdenemar, jsuchane, knoel, lhuang, lijin, lmen, mtessun, toneata, virt-maint, xuzhang, yalzhang
Target Milestone:	rc	Keywords:	ZStream
Target Release:	8.2	Flags:	pm-rhel: mirror+
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:
Fixed In Version:	libvirt-6.0.0-17.3.el8	Doc Type:	Bug Fix
Doc Text:	Cause: With version 6.0.0, libvirt started querying emulator capabilities lazily to improve startup time: this means that information about the default emulator for the host are only fetched if at least one of the defined VMs uses it. Consequence: If no VMs using it are defined, virConnectGetDomainCapabilities() fails because information about the default emulator for the host are not found in the cache. Fix: When virConnectGetDomainCapabilities() is called, information about the default emulator for the host are fetched unconditionally. Result: virConnectGetDomainCapabilities() succeeds and reports information about the default emulator for the host.	Story Points:	---
Clone Of:	1836351	Environment:
Last Closed:	2020-07-29 22:30:00 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:
Bug Depends On:	1836351
Bug Blocks:	1842869

Comment 6 yalzhang@redhat.com 2020-06-08 09:42:59 UTC

reproduce this bug on libvirt-libs-6.0.0-17.2.module+el8.2.0+6629+3fc0f2c2.x86_64
1. make sure there is no guest and no cache file

# ll /var/cache/libvirt/qemu/
total 0

# virsh list --all
 Id   Name   State
--------------------

2. run domcapabilities command

# virsh domcapabilities
error: failed to get emulator capabilities
error: invalid argument: unable to find any emulator to serve 'x86_64' architecture

3. use virt-install to install an vm, then try above command:
# virsh domcapabilities 
<domainCapabilities>
  <path>/usr/libexec/qemu-kvm</path>
  <domain>kvm</domain>
...

4. update the libvirt to latest libvirt-libs-6.0.0-17.3.module+el8.2.0+6907+6abdb1b6.x86_64
# ll /var/cache/libvirt/qemu
total 0

# virsh list --all
 Id   Name   State
--------------------

# virsh domcapabilities 
<domainCapabilities>
  <path>/usr/libexec/qemu-kvm</path>
  <domain>kvm</domain>
  <machine>pc-i440fx-rhel7.6.0</machine>
  <arch>x86_64</arch>
...

the result is as expected, set the bug to be verified.

Comment 8 errata-xmlrpc 2020-07-29 22:30:00 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/RHBA-2020:3234