Using `iovctl` I can create VFs for cxgbe0, cxgbe1. They show up in `pciconf -lv` in the ppt devclass. However, most of the device configuration appears to be invalid (see pciconf output below). In particular, the hdr=0x7f means `ppt_probe()` will return ENXIO for the device instead of BUS_PROBE_WILDCARD, preventing the device from being passed through to a bhyve VM.
I naively tried modifying the vmm driver to bypass the cfg.hdrtype check, which allowed me to pass the device through to a VM, but the kernel in the VM then failed to recognize the VF as anything. It is not present in `pciconf -l` inside the VM and I see no messages about it in the VM console.
ppt0@pci0:1:1:0: class=0xffffff card=0x00000000 chip=0x48011425 rev=0xff hdr=0x7f
vendor = 'Chelsio Communications Inc'
device = 'T420-CR Unified Wire Ethernet Controller [VF]'