RE: [PATCH] Enable SR-IOV instantiation through /sys file

From: Wang, Liang-min
Date: Tue Oct 24 2017 - 17:49:23 EST


Just like any PCIe devices that supports SR-IOV. There are restrictions set for VF. Also, there is a concept of trust VF now available for PF to manage certain features that only selected VF could exercise. Are you saying all the devices supporting SR-IOV all have security issue?

Larry

> -----Original Message-----
> From: Alex Williamson [mailto:alex.williamson@xxxxxxxxxx]
> Sent: Tuesday, October 24, 2017 5:44 PM
> To: Kirsher, Jeffrey T <jeffrey.t.kirsher@xxxxxxxxx>
> Cc: Wang, Liang-min <liang-min.wang@xxxxxxxxx>; kvm@xxxxxxxxxxxxxxx;
> linux-pci@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
> bhelgaas@xxxxxxxxxx; Duyck, Alexander H <alexander.h.duyck@xxxxxxxxx>
> Subject: Re: [PATCH] Enable SR-IOV instantiation through /sys file
>
> On Tue, 24 Oct 2017 13:04:26 -0700
> Jeff Kirsher <jeffrey.t.kirsher@xxxxxxxxx> wrote:
>
> > From: Liang-Min Wang <liang-min.wang@xxxxxxxxx>
> >
> > When a SR-IOV supported device is bound with vfio-pci, the driver
> > could not create SR-IOV instance through /sys/bus/pci/devices/...
> > /sriov_numvfs. This patch re-activates this capability for a PCIe
> > device that supports SR-IOV and is bound with vfio-pci.ko.
> >
> > Signed-off-by: Liang-Min Wang <liang-min.wang@xxxxxxxxx>
> > ---
> > drivers/vfio/pci/vfio_pci.c | 12 ++++++++++++
> > 1 file changed, 12 insertions(+)
>
>
> Why? The PF bound to vfio-pci can be assigned to a user. PFs often
> have backdoors into the VF. Therefore this enables creation of a VF in
> the host that may be snooped or manipulated by a user. This clearly
> seems like a security issue. Thanks,
>
> Alex
>
>
> > diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
> > index f041b1a6cf66..8fbd362607e1 100644
> > --- a/drivers/vfio/pci/vfio_pci.c
> > +++ b/drivers/vfio/pci/vfio_pci.c
> > @@ -1256,6 +1256,7 @@ static void vfio_pci_remove(struct pci_dev *pdev)
> > if (!vdev)
> > return;
> >
> > + pci_disable_sriov(pdev);
> > vfio_iommu_group_put(pdev->dev.iommu_group, &pdev->dev);
> > kfree(vdev->region);
> > kfree(vdev);
> > @@ -1303,12 +1304,23 @@ static const struct pci_error_handlers
> vfio_err_handlers = {
> > .error_detected = vfio_pci_aer_err_detected,
> > };
> >
> > +static int vfio_sriov_configure(struct pci_dev *pdev, int num_vfs)
> > +{
> > + if (!num_vfs) {
> > + pci_disable_sriov(pdev);
> > + return 0;
> > + }
> > +
> > + return pci_enable_sriov(pdev, num_vfs);
> > +}
> > +
> > static struct pci_driver vfio_pci_driver = {
> > .name = "vfio-pci",
> > .id_table = NULL, /* only dynamic ids */
> > .probe = vfio_pci_probe,
> > .remove = vfio_pci_remove,
> > .err_handler = &vfio_err_handlers,
> > + .sriov_configure = vfio_sriov_configure,
> > };
> >
> > struct vfio_devices {