[vfio-users] libvirt.libvirtError: unsupported configuration: host doesn't support passthrough of host PCI devices

[Patrick O'Callaghan]

I'm getting the above error after a fresh install of Fedora 31 on the
same hardware Fedora 30 previously worked on. I've restored my libvirt
and qemu installations from backups, and everything works except for
VFIO passthrough. The only difference is that now I'm booting the host
via EFI instead of BIOS (the Windows guest has always been UEFI) but I
don't see why that should matter.

These are the relevant templates:

   $ cat vfio-grub
   GRUB_TIMEOUT=5
   GRUB_DISTRIBUTOR="$(sed 's, release .*$,,g' /etc/system-release)"
   GRUB_DEFAULT=saved
   GRUB_DISABLE_SUBMENU=true
   GRUB_TERMINAL_OUTPUT="console"
   GRUB_CMDLINE_LINUX="modprobe.blacklist=nvidia modprobe.blacklist=nouveau rd.blacklist=nvidia rd.blacklist=nouveau intel_iommu=on,igfx_off iommu=pt rd.driver.pre=vfio-pci vconsole.font=latarcyrheb-sun16 $([ -x /usr/sbin/rhcrashkernel-param ] && /usr/sbin/rhcrashkernel-param || :) rhgb quiet resume=UUID=15d273c5-488c-48d6-a864-e11968ee970e audit=0 hugepages=4096"
   GRUB_DISABLE_RECOVERY="true"

   $ cat vfio.conf
   options vfio-pci ids=10de:1c81,10de:0fb9

   $ cat local.conf
   force_drivers+="vfio vfio_iommu_type1 vfio_pci vfio_virqfd"

I've done the following (same as always):

   $ sudo cp vfio.conf /etc/modprobe.d/vfio.conf
   $ sudo cp local.conf /etc/dracut.conf.d/local.conf
   $ sudo cp vfio-grub /etc/sysconfig/grub
   $ sudo grub2-mkconfig -o /etc/grub2.cfg
   $ sudo dracut -f --kver `uname -r`

The kernel vfio modules are loaded:

   $ lsmod|grep vfio
   vfio_pci               61440  0
   irqbypass              16384  2 vfio_pci,kvm
   vfio_virqfd            16384  1 vfio_pci
   vfio_iommu_type1       32768  0
   vfio                   36864  2 vfio_iommu_type1,vfio_pci

For completeness, the kernel boot line reads:

   $ cat /proc/cmdline         
   BOOT_IMAGE=(hd1,gpt2)/vmlinuz-5.3.8-300.fc31.x86_64 root=/dev/mapper/fedora_localhost--live-root ro resume=/dev/mapper/fedora_localhost--live-swap rd.lvm.lv=fedora_localhost-live/root rd.lvm.lv=fedora_localhost
   -live/swap modprobe.blacklist=nvidia modprobe.blacklist=nouveau rd.blacklist=nvidia rd.blacklist=nouveau rhgb quiet


I must be missing something but can't think what it is. Any ideas would
be welcome.

poc