From: Alex Williamson <alex.williamson@redhat.com>
To: alex.williamson@redhat.com
Cc: kvm@vger.kernel.org, linux-pci@vger.kernel.org,
linux-kernel@vger.kernel.org, david@gibson.dropbear.id.au
Subject: [PATCH] vfio-pci: Disable binding to PFs with SR-IOV enabled
Date: Thu, 12 Jul 2018 16:33:04 -0600 [thread overview]
Message-ID: <20180712223243.9593.24855.stgit@gimli.home> (raw)
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 <alex.williamson@redhat.com>
---
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;
next reply other threads:[~2018-07-12 22:44 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-12 22:33 Alex Williamson [this message]
2018-07-13 0:13 ` [PATCH] vfio-pci: Disable binding to PFs with SR-IOV enabled David Gibson
2018-07-13 5:02 ` Peter Xu
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