Description of problem:
Cannot use AVIC with AMD CPUs. AVIC helps accelerate interrupts in virtual environments. If AVIC is enabled oVirt reports the CPU type as unsupported because AVIC conflicts with x2apic. The x2apic flag is added to every CPU model by default when kvm is enabled (see the RHEL bug below).
Enabling AVIC worked under 4.2, but 4.3 seems to be more strict with detecting CPU features/capabilities.
See the following bugzilla reports for more information:
Initial oVirt report for unsupported CPU type:
RHEL Bug for x2apic flag requirement, and details the problem at the qemu/libvirt level:
Version-Release number of selected component (if applicable):
Steps to Reproduce:
1. Set host to maintenance mode.
2. Set the kvm module option 'options kvm_amd avic=1'.
3. Clear the capabilities cache rm -f /var/cache/libvirt/qemu/capabilities/*.xml
4. Reboot the host or reload the kvm module and restart libvirtd
5. Try to activate the host.
Reports CPU type as unsupported.
Host activates, can use AVIC. Either oVirt ignores the x2apic flag mismatch or directly supports the AVIC flag.
Tested on AMD EPYC 7551P
can you please doublecheck the latest state in AV 8.2?
Nisim, I don't have AMD hardware available. Can you check, please?
We are past 4.5.0 feature freeze, please re-target.
in 8.6 it may very well work, but closing the bug as we don't seem to have anyone who can verify this