Re: [Intel-gfx] [PATCH v5 17/19] vfio: Add VFIO_DEVICE_AT[DE]TACH_IOMMUFD_PT

[Jason Gunthorpe <jgg@nvidia.com>]

On Wed, Mar 01, 2023 at 02:04:00PM +0000, Liu, Yi L wrote:
> diff --git a/drivers/vfio/group.c b/drivers/vfio/group.c
> index 2a13442add43..ed3ffe7ceb3f 100644
> --- a/drivers/vfio/group.c
> +++ b/drivers/vfio/group.c
> @@ -777,6 +777,11 @@ void vfio_device_group_unregister(struct vfio_device *device)
>  	mutex_unlock(&device->group->device_lock);
>  }
>  
> +bool vfio_device_group_uses_container(struct vfio_device *device)
> +{
> +	return READ_ONCE(device->group->container);
> +}

As I said this should take in the vfio_device_file because as long as
a vfio_device_file exists then group->contianer is required to be stable.

> diff --git a/drivers/vfio/vfio_main.c b/drivers/vfio/vfio_main.c
> index 121a75fadceb..4b5b17e8aaa1 100644
> --- a/drivers/vfio/vfio_main.c
> +++ b/drivers/vfio/vfio_main.c
> @@ -422,9 +422,22 @@ static int vfio_device_first_open(struct vfio_device_file *df)
>  	if (!try_module_get(device->dev->driver->owner))
>  		return -ENODEV;
>  
> +	/*
> +	 * The handling here depends on what the user is using.
> +	 *
> +	 * If user uses iommufd in the group compat mode or the
> +	 * cdev path, call vfio_iommufd_bind().
> +	 *
> +	 * If user uses container in the group legacy mode, call
> +	 * vfio_device_group_use_iommu().
> +	 *
> +	 * If user doesn't use iommufd nor container, this is
> +	 * the noiommufd mode in the cdev path, nothing needs
> +	 * to be done here just go ahead to open device.
> +	 */
>  	if (iommufd)
>  		ret = vfio_iommufd_bind(device, iommufd);
> -	else
> +	else if (vfio_device_group_uses_container(device))
>  		ret = vfio_device_group_use_iommu(device);

But yes, this makes alot more sense..

Jason