SR-IOV and Xen

I have an SR-IOV network card (Intel 82576), and I’m trying to pass a function through to a PV domU. I can attach the function without error (xm pci-attach <domU> 0000:09:10.0). However, in the domU, all I see is the following:

    1.001725] pcifront pci-0: Installing PCI frontend
    1.001853] pcifront pci-0: Creating PCI Frontend Bus 0000:00
    1.051244] pci-stub: invalid id string ""


  342.002602] pcifront pci-0: Rescanning PCI Frontend Bus 0000:00

depending on when I attach, and if there are other devices present.
The device never shows up in lspci.
I know pci passthrough is working, because I can successfully pass through a non-SR-IOV pci device.

Has anyone gotten this configuration to work?
I know this could be construed as a Xen question, but these features seem kernel-dependent, so I guess I’m really wondering if the support for SR-IOV is present in kernel
Thanks in advance for any help.