Re: [PATCH RFC 2/3] vfio: report group noiommu status

Alex Williamson
2016-04-18T18:56:58Z

On Mon, 18 Apr 2016 12:58:20 +0300
"Michael S. Tsirkin" <mst@redhat.com> wrote:

> When using vfio, callers might want to know whether device is added to a
> regular group or an non-iommu group.
>
> Report this status from vfio_add_group_dev.
>
> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> ---

What about making an interface to query this rather than playing games
with magic return values?

bool vfio_iommu_group_is_noiommu(struct iommu_group *group)
{
return iommu_group_get_iommudata(group) == &noiommu;
}

> drivers/vfio/pci/vfio_pci.c | 2 +-
> drivers/vfio/platform/vfio_platform_common.c | 2 +-
> drivers/vfio/vfio.c | 5 ++++-
> Documentation/vfio.txt | 4 +++-
> 4 files changed, 9 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
> index 712a849..d622a41 100644
> --- a/drivers/vfio/pci/vfio_pci.c
> +++ b/drivers/vfio/pci/vfio_pci.c
> @@ -1119,7 +1119,7 @@ static int vfio_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
> spin_lock_init(&vdev->irqlock);
>
> ret = vfio_add_group_dev(&pdev->dev, &vfio_pci_ops, vdev);
> - if (ret) {
> + if (ret < 0) {
> vfio_iommu_group_put(group, &pdev->dev);
> kfree(vdev);
> return ret;
> diff --git a/drivers/vfio/platform/vfio_platform_common.c b/drivers/vfio/platform/vfio_platform_common.c
> index e65b142..bf74e21 100644
> --- a/drivers/vfio/platform/vfio_platform_common.c
> +++ b/drivers/vfio/platform/vfio_platform_common.c
> @@ -568,7 +568,7 @@ int vfio_platform_probe_common(struct vfio_platform_device *vdev,
> }
>
> ret = vfio_add_group_dev(dev, &vfio_platform_ops, vdev);
> - if (ret) {
> + if (ret < 0) {
> iommu_group_put(group);
> return ret;
> }
> diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
> index 6fd6fa5..67db231 100644
> --- a/drivers/vfio/vfio.c
> +++ b/drivers/vfio/vfio.c
> @@ -756,6 +756,7 @@ int vfio_add_group_dev(struct device *dev,
> struct iommu_group *iommu_group;
> struct vfio_group *group;
> struct vfio_device *device;
> + int noiommu;
>
> iommu_group = iommu_group_get(dev);
> if (!iommu_group)
> @@ -791,6 +792,8 @@ int vfio_add_group_dev(struct device *dev,
> return PTR_ERR(device);
> }
>
> + noiommu = group->noiommu;
> +
> /*
> * Drop all but the vfio_device reference. The vfio_device holds
> * a reference to the vfio_group, which holds a reference to the
> @@ -798,7 +801,7 @@ int vfio_add_group_dev(struct device *dev,
> */
> vfio_group_put(group);
>
> - return 0;
> + return noiommu;
> }
> EXPORT_SYMBOL_GPL(vfio_add_group_dev);
>
> diff --git a/Documentation/vfio.txt b/Documentation/vfio.txt
> index 1dd3fdd..d76be0f 100644
> --- a/Documentation/vfio.txt
> +++ b/Documentation/vfio.txt
> @@ -259,7 +259,9 @@ extern void *vfio_del_group_dev(struct device *dev);
>
> vfio_add_group_dev() indicates to the core to begin tracking the
> specified iommu_group and register the specified dev as owned by
> -a VFIO bus driver. The driver provides an ops structure for callbacks
> +a VFIO bus driver. A negative return value indicates failure.
> +A positive return value indicates that an unsafe noiommu mode
> +is in use. The driver provides an ops structure for callbacks
> similar to a file operations structure:
>
> struct vfio_device_ops {