From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alex Williamson Subject: [PATCH] vfio-pci: Disable binding to PFs with SR-IOV enabled Date: Thu, 12 Jul 2018 16:33:04 -0600 Message-ID: <20180712223243.9593.24855.stgit@gimli.home> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Cc: kvm@vger.kernel.org, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, david@gibson.dropbear.id.au To: alex.williamson@redhat.com Return-path: Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org 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. Signed-off-by: Alex Williamson --- drivers/vfio/pci/vfio_pci.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c index b423a309a6e0..f372f209c5c2 100644 --- a/drivers/vfio/pci/vfio_pci.c +++ b/drivers/vfio/pci/vfio_pci.c @@ -1189,6 +1189,19 @@ 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;