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

Yi Liu
2023-03-20T14:30:44Z

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