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

[Alexander Duyck <alexander.duyck@gmail.com>]

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?

> ---
> 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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