Re: [virtio-dev] [PATCH] virtio_pci: support enabling VFs

["Michael S. Tsirkin" <mst@redhat.com>]

On Wed, May 30, 2018 at 09:10:57AM -0700, Alexander Duyck wrote:
> On Wed, May 30, 2018 at 1:55 AM, Tiwei Bie <tiwei.bie@intel.com> wrote:
> > There is a new feature bit allocated in virtio spec to
> > support SR-IOV (Single Root I/O Virtualization):
> >
> > https://github.com/oasis-tcs/virtio-spec/issues/11
> >
> > This patch enables the support for this feature bit in
> > virtio driver.
> >
> > Signed-off-by: Tiwei Bie <tiwei.bie@intel.com>
> 
> So from a quick glance it looks like we are leaving SR-IOV enabled if
> the driver is removed. Do we want to have that behavior or should we
> be adding the code to disable SR-IOV and free the VFs on driver
> removal?

Could pci core handle it for us somehow?

> > ---
> > This patch depends on below proposal:
> > https://lists.oasis-open.org/archives/virtio-dev/201805/msg00154.html
> >
> > This patch depends on below patch:
> > https://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci.git/commit/?h=pci/virtualization&id=8effc395c2097e258fcedfc02ed4a66d45fb4238
> >
> >  drivers/virtio/virtio_pci_common.c | 20 ++++++++++++++++++++
> >  drivers/virtio/virtio_pci_modern.c | 14 ++++++++++++++
> >  include/uapi/linux/virtio_config.h |  7 ++++++-
> >  3 files changed, 40 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/virtio/virtio_pci_common.c b/drivers/virtio/virtio_pci_common.c
> > index 48d4d1cf1cb6..023da80a7a3e 100644
> > --- a/drivers/virtio/virtio_pci_common.c
> > +++ b/drivers/virtio/virtio_pci_common.c
> > @@ -588,6 +588,25 @@ static void virtio_pci_remove(struct pci_dev *pci_dev)
> >         put_device(dev);
> >  }
> >
> > +static int virtio_pci_sriov_configure(struct pci_dev *pci_dev, int num_vfs)
> > +{
> > +       struct virtio_pci_device *vp_dev = pci_get_drvdata(pci_dev);
> > +       struct virtio_device *vdev = &vp_dev->vdev;
> > +       int (*sriov_configure)(struct pci_dev *pci_dev, int num_vfs);
> > +
> > +       if (!(vdev->config->get_status(vdev) & VIRTIO_CONFIG_S_DRIVER_OK))
> > +               return -EBUSY;
> > +
> > +       if (!__virtio_test_bit(vdev, VIRTIO_F_SR_IOV))
> > +               return -EINVAL;
> > +
> > +       sriov_configure = pci_sriov_configure_simple;
> > +       if (sriov_configure == NULL)
> > +               return -ENOENT;
> > +
> > +       return sriov_configure(pci_dev, num_vfs);
> > +}
> > +
> >  static struct pci_driver virtio_pci_driver = {
> >         .name           = "virtio-pci",
> >         .id_table       = virtio_pci_id_table,
> > @@ -596,6 +615,7 @@ static struct pci_driver virtio_pci_driver = {
> >  #ifdef CONFIG_PM_SLEEP
> >         .driver.pm      = &virtio_pci_pm_ops,
> >  #endif
> > +       .sriov_configure = virtio_pci_sriov_configure,
> >  };
> >
> >  module_pci_driver(virtio_pci_driver);
> > diff --git a/drivers/virtio/virtio_pci_modern.c b/drivers/virtio/virtio_pci_modern.c
> > index 2555d80f6eec..07571daccfec 100644
> > --- a/drivers/virtio/virtio_pci_modern.c
> > +++ b/drivers/virtio/virtio_pci_modern.c
> > @@ -153,14 +153,28 @@ static u64 vp_get_features(struct virtio_device *vdev)
> >         return features;
> >  }
> >
> > +static void vp_transport_features(struct virtio_device *vdev, u64 features)
> > +{
> > +       struct virtio_pci_device *vp_dev = to_vp_device(vdev);
> > +       struct pci_dev *pci_dev = vp_dev->pci_dev;
> > +
> > +       if ((features & BIT_ULL(VIRTIO_F_SR_IOV)) &&
> > +                       pci_find_ext_capability(pci_dev, PCI_EXT_CAP_ID_SRIOV))
> > +               __virtio_set_bit(vdev, VIRTIO_F_SR_IOV);
> > +}
> > +
> >  /* virtio config->finalize_features() implementation */
> >  static int vp_finalize_features(struct virtio_device *vdev)
> >  {
> >         struct virtio_pci_device *vp_dev = to_vp_device(vdev);
> > +       u64 features = vdev->features;
> >
> >         /* Give virtio_ring a chance to accept features. */
> >         vring_transport_features(vdev);
> >
> > +       /* Give virtio_pci a chance to accept features. */
> > +       vp_transport_features(vdev, features);
> > +
> >         if (!__virtio_test_bit(vdev, VIRTIO_F_VERSION_1)) {
> >                 dev_err(&vdev->dev, "virtio: device uses modern interface "
> >                         "but does not have VIRTIO_F_VERSION_1\n");
> > diff --git a/include/uapi/linux/virtio_config.h b/include/uapi/linux/virtio_config.h
> > index 308e2096291f..b7c1f4e7d59e 100644
> > --- a/include/uapi/linux/virtio_config.h
> > +++ b/include/uapi/linux/virtio_config.h
> > @@ -49,7 +49,7 @@
> >   * transport being used (eg. virtio_ring), the rest are per-device feature
> >   * bits. */
> >  #define VIRTIO_TRANSPORT_F_START       28
> > -#define VIRTIO_TRANSPORT_F_END         34
> > +#define VIRTIO_TRANSPORT_F_END         38
> >
> >  #ifndef VIRTIO_CONFIG_NO_LEGACY
> >  /* Do we get callbacks when the ring is completely used, even if we've
> > @@ -71,4 +71,9 @@
> >   * this is for compatibility with legacy systems.
> >   */
> >  #define VIRTIO_F_IOMMU_PLATFORM                33
> > +
> > +/*
> > + * Does the device support Single Root I/O Virtualization?
> > + */
> > +#define VIRTIO_F_SR_IOV                        37
> >  #endif /* _UAPI_LINUX_VIRTIO_CONFIG_H */
> > --
> > 2.17.0
> >
> >
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