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Date:   Thu, 19 Mar 2020 18:44:53 +0100
From:   Cornelia Huck <cohuck@redhat.com>
To:     Alex Williamson <alex.williamson@redhat.com>
Cc:     kvm@vger.kernel.org, linux-pci@vger.kernel.org,
        linux-kernel@vger.kernel.org, dev@dpdk.org, mtosatti@redhat.com,
        thomas@monjalon.net, bluca@debian.org, jerinjacobk@gmail.com,
        bruce.richardson@intel.com, kevin.tian@intel.com
Subject: Re: [PATCH v3 5/7] vfio/pci: Add sriov_configure support
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On Wed, 11 Mar 2020 15:59:12 -0600
Alex Williamson <alex.williamson@redhat.com> wrote:

> With the VF Token interface we can now expect that a vfio userspace
> driver must be in collaboration with the PF driver, an unwitting
> userspace driver will not be able to get past the GET_DEVICE_FD step
> in accessing the device.  We can now move on to actually allowing
> SR-IOV to be enabled by vfio-pci on the PF.  Support for this is not
> enabled by default in this commit, but it does provide a module option
> for this to be enabled (enable_sriov=1).  Enabling VFs is rather
> straightforward, except we don't want to risk that a VF might get
> autoprobed and bound to other drivers, so a bus notifier is used to
> "capture" VFs to vfio-pci using the driver_override support.  We
> assume any later action to bind the device to other drivers is
> condoned by the system admin and allow it with a log warning.
> 
> vfio-pci will disable SR-IOV on a PF before releasing the device,
> allowing a VF driver to be assured other drivers cannot take over the
> PF and that any other userspace driver must know the shared VF token.
> This support also does not provide a mechanism for the PF userspace
> driver itself to manipulate SR-IOV through the vfio API.  With this
> patch SR-IOV can only be enabled via the host sysfs interface and the
> PF driver user cannot create or remove VFs.
> 
> Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
> ---
>  drivers/vfio/pci/vfio_pci.c         |  106 +++++++++++++++++++++++++++++++----
>  drivers/vfio/pci/vfio_pci_private.h |    2 +
>  2 files changed, 97 insertions(+), 11 deletions(-)
> 

Reviewed-by: Cornelia Huck <cohuck@redhat.com>