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

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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>
This commit is contained in:
Alex Williamson 2018-07-12 16:33:04 -06:00
parent 544c05a60a
commit 0dd0e297f0
1 changed files with 13 additions and 0 deletions
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13
drivers/vfio/pci/vfio_pci.c
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@ -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;