I have found out that AVIC is not supported on this HW. The CPUID 0x8000000A EDX indicates no support for AVIC. That means the IOMMU guest AVIC support should not be exposed at all. I have prepared a fix for it already by hiding the guest AVIC capability in IOMMU and disabling the feature. So far it works and no more WARNs is visible in dmesg.
I have found out that AVIC is not supported on this HW. The CPUID 0x8000000A EDX indicates no support for AVIC. That means the IOMMU guest AVIC support should not be exposed at all. I have prepared a fix for it already by hiding the guest AVIC capability in IOMMU and disabling the feature. So far it works and no more WARNs is visible in dmesg.
Originally posted by @miczyg1 in https://github.com/Dasharo/dasharo-issues/issues/1134#issuecomment-2475797045