Commit 0dd0e297 authored Jul 12, 2018 by Alex Williamson

vfio-pci: Disable binding to PFs with SR-IOV enabled

We expect to receive PFs with SR-IOV disabled, however some host
drivers leave SR-IOV enabled at unbind. This puts us in a state where
we can potentially assign both the PF and the VF, leading to both
functionality as well as security concerns due to lack of managing the
SR-IOV state as well as vendor dependent isolation from the PF to VF.
If we were to attempt to actively disable SR-IOV on driver probe, we
risk VF bound drivers blocking, potentially risking live lock
scenarios. Therefore simply refuse to bind to PFs with SR-IOV enabled
with a warning message indicating the issue. Users can resolve this
by re-binding to the host driver and disabling SR-IOV before
attempting to use the device with vfio-pci.

Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

parent 544c05a6

drivers/vfio/pci/vfio_pci.c

+13 −0

Original line number	Diff line number	Diff line
		@@ -1193,6 +1193,19 @@ static int vfio_pci_probe(struct pci_dev pdev, const struct pci_device_id id)
		if (pdev->hdr_type != PCI_HEADER_TYPE_NORMAL)
		return -EINVAL;

		/*
		* Prevent binding to PFs with VFs enabled, this too easily allows
		* userspace instance with VFs and PFs from the same device, which
		* cannot work. Disabling SR-IOV here would initiate removing the
		* VFs, which would unbind the driver, which is prone to blocking
		* if that VF is also in use by vfio-pci. Just reject these PFs
		* and let the user sort it out.
		*/
		if (pci_num_vf(pdev)) {
		pci_warn(pdev, "Cannot bind to PF with SR-IOV enabled\n");
		return -EBUSY;
		}

		group = vfio_iommu_group_get(&pdev->dev);
		if (!group)
		return -EINVAL;