* [PATCH] vfio-pci: Disable binding to PFs with SR-IOV enabled
@ 2018-07-12 22:33 Alex Williamson
2018-07-13 0:13 ` David Gibson
2018-07-13 5:02 ` Peter Xu
0 siblings, 2 replies; 3+ messages in thread
From: Alex Williamson @ 2018-07-12 22:33 UTC (permalink / raw)
To: alex.williamson; +Cc: kvm, linux-pci, linux-kernel, david
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;
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] vfio-pci: Disable binding to PFs with SR-IOV enabled
2018-07-12 22:33 [PATCH] vfio-pci: Disable binding to PFs with SR-IOV enabled Alex Williamson
@ 2018-07-13 0:13 ` David Gibson
2018-07-13 5:02 ` Peter Xu
1 sibling, 0 replies; 3+ messages in thread
From: David Gibson @ 2018-07-13 0:13 UTC (permalink / raw)
To: Alex Williamson; +Cc: kvm, linux-pci, linux-kernel
[-- Attachment #1: Type: text/plain, Size: 2247 bytes --]
On Thu, Jul 12, 2018 at 04:33:04PM -0600, Alex Williamson wrote:
> 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>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
> ---
> 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;
>
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 833 bytes --]
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] vfio-pci: Disable binding to PFs with SR-IOV enabled
2018-07-12 22:33 [PATCH] vfio-pci: Disable binding to PFs with SR-IOV enabled Alex Williamson
2018-07-13 0:13 ` David Gibson
@ 2018-07-13 5:02 ` Peter Xu
1 sibling, 0 replies; 3+ messages in thread
From: Peter Xu @ 2018-07-13 5:02 UTC (permalink / raw)
To: Alex Williamson; +Cc: kvm, linux-pci, linux-kernel, david
On Thu, Jul 12, 2018 at 04:33:04PM -0600, Alex Williamson wrote:
> 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>
Reviewed-by: Peter Xu <peterx@redhat.com>
--
Peter Xu
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2018-07-13 5:02 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2018-07-12 22:33 [PATCH] vfio-pci: Disable binding to PFs with SR-IOV enabled Alex Williamson
2018-07-13 0:13 ` David Gibson
2018-07-13 5:02 ` Peter Xu
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).