Re: [PATCH v6 21/24] vfio: Add VFIO_DEVICE_BIND_IOMMUFD

[Yi Liu <yi.l.liu@xxxxxxxxx>]

On 2023/3/20 22:09, Jason Gunthorpe wrote:
> On Wed, Mar 15, 2023 at 04:40:19AM +0000, Liu, Yi L wrote:
>
> > # if IS_ENABLED(CONFIG_VFIO_GROUP)
> > static inline bool vfio_device_is_noiommu(struct vfio_device *vdev)
> > {
> >          return IS_ENABLED(CONFIG_VFIO_NOIOMMU) &&
> >                 vdev->group->type == VFIO_NO_IOMMU;
> > }
> > #else
> > static inline bool vfio_device_is_noiommu(struct vfio_device *vdev)
> > {
> >          struct iommu_group *iommu_group;
> >
> >          if (!IS_ENABLED(CONFIG_VFIO_NOIOMMU) || !vfio_noiommu)
> >                  return -EINVAL;
> >
> >          iommu_group = iommu_group_get(vdev->dev);
> >          if (iommu_group)
> >                  iommu_group_put(iommu_group);
> >
> >          return !iommu_group;
>
> If we don't have VFIO_GROUP then no-iommu is signaled by a NULL
> iommu_ctx pointer in the vdev, don't mess with groups

yes, NULL iommufd_ctx pointer would be set in vdev and passed to the
vfio_device_open(). But here, we want to use this helper to check if
user can use noiommu mode. This is before calling vfio_device_open().
e.g. if the device is protected by iommu, then user cannot use noiommu
mode on it.

--
Regards,
Yi Liu