Note: This bug is displayed in read-only format because the product is no longer active in Red Hat Bugzilla.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.

Description of problem:

If management console configures "emulatorpin" libvirt option to same isolated physical CPU's on which vCPU's are already pinned, guest won't boot. Libvirt can validate this setting and if required can configure emulator threads to run on different physical CPU's.

This behaviour is visible in realtime KVM where vCPU's having realtime priority are run in dedicated isolated physical CPU's. Other non-realtime threads won't get chance to run resulting in non-execution of emulator threads, hence Guest won't boot up. 


Version-Release number of selected component (if applicable):
libvirt-1.2.17-13.el7_2.4.x86_64
qemu-kvm-rhev-2.3.0-31.el7_2.7.x86_64
kernel-rt-kvm-3.10.0-306.0.1.rt56.179.el7.x86_64

How reproducible:


Steps to Reproduce:
1. Isolate physical cores to run vCPU threads.
2. pin vCPU threads to these isolated cores with RT priority.
3. Configure emulator threads also run on same cores

Actual results:
Guest does not boot.

Expected results:
1] Throw error in logs for configuration validation.

2] Configure guest emulator thread to run on any of the non-isolated core and throw a warning, so that atleast guest boots.

Additional info:

Well, even though it does not boot, the configuration is valid from libvirt's point of view.  This is the problem in management layers above libvirt, particularly whoever is setting up the isolated cores.

Martin,

I already opened a BZ with Nova for this:1298079
I wanted suggestion if validation in 'libvirt' side for this can help irrespective of management layer.

Thanks,
Pankaj

(In reply to pagupta from comment #3)
I don't see how else we could "help" management layers to see this error, especially if it originates from them.  Since this configuration might be indistinguishable from a valid one from libvirt's POV, I'm closing it as NOTABUG.  Feel free to add more information in case I missed something.