Known Issues for Oracle Linux KVM

4 Known Issues for Oracle Linux KVM

This chapter provides information about known issues for Oracle Linux KVM. If a workaround is available, that information is also provided.

Upgrading From QEMU 3.10 to Version 4.2.1 Can Prevent Existing KVM Guests From Starting on Oracle Linux 7

Attempting to upgrade a KVM host from QEMU version 3.10 to version 4.2.1 results in a libvirt server error that can prevent existing KVM guests from starting on an Oracle Linux 7 host.

An error similar to the following is displayed:

Upgrade qemu-3.1.0-7.el7.x86_64 to qemu-4.2.1-4.el7.x86_64, kvm can not be
started, got below libvirt service error:

Dec 21 15:10:48 ca-ex05db01.us.oracle.com libvirtd[23588]: Unable to read
from monitor: Connection reset by peer
Dec 21 15:10:48 ca-ex05db01.us.oracle.com libvirtd[23588]: internal error:
qemu unexpectedly closed the monitor: 2020-12-21T23:10:48.306929Z
qemu-system-x86_64: We need to set caching-mode=on for intel-iommu to enable
device assignment with IOMMU protection.
Dec 21 15:10:52 ca-ex05db01.us.oracle.com libvirtd[23588]: internal error:
Failed to autostart VM 'ca-ex05db01vm01.us.oracle.com': internal error: qemu
unexpectedly closed the monitor: 2020-12-21T23:10:48.306929Z
qemu-system-x86_64: We need to set caching-mode=on for intel-iommu to enable
device assignment with IOMMU protection.
Dec 21 15:10:52 ca-ex05db01.us.oracle.com libvirtd[23588]: nl_recv returned
with error: No buffer space available

To work around this issue so that KVM guests can run the updated qemu version, edit the XML file of each KVM guest, adding the caching_mode='on' parameter to the iommu section for each driver sub-element, as shown in the following example:

<iommu model='intel'>
      <driver aw_bits='48' caching_mode='on'/>
    </iommu>

(Bug ID 32312933)

Using vTPM With a Guest Fails on Oracle Linux 9 if FIPS Mode Is Enabled

If FIPS mode is enabled on an Oracle Linux 9 host and a VM is configured to use vTPM, the guest operating system fails to install or the VM is unable to launch. The current workaround is to disable FIPS mode if you need to run guests with vTPM.

(Bug 34290427)

Downgrading Application Streams Fail

The virt:kvm_utils2 application stream is updated with additional packages. If you try to downgrade to a previous version of the virt:kvm_utils2 application stream, the downgrade process fails with several package conflict error messages. This issue is the result of a limitation in DNF for handling dependencies in application streams.

To resolve this issue, you must remove the existing packages, reset the virt:kvm_utils2 application stream, enable the older version of the virt:kvm_utils2 application stream and then reinstall the packages. See Switching to the Oracle KVM Stack for steps to remove existing packages, resetting the application stream and then installing packages.

(Bug ID 34623368)