RE: [RFC v2 05/11] vfio: Make vfio_device_open() group agnostic

From: "Tian, Kevin" <kevin.tian@intel.com>
To: "Liu, Yi L" <yi.l.liu@intel.com>,
	"alex.williamson@redhat.com" <alex.williamson@redhat.com>,
	"jgg@nvidia.com" <jgg@nvidia.com>
Cc: "eric.auger@redhat.com" <eric.auger@redhat.com>,
	"cohuck@redhat.com" <cohuck@redhat.com>,
	"nicolinc@nvidia.com" <nicolinc@nvidia.com>,
	"yi.y.sun@linux.intel.com" <yi.y.sun@linux.intel.com>,
	"chao.p.peng@linux.intel.com" <chao.p.peng@linux.intel.com>,
	"mjrosato@linux.ibm.com" <mjrosato@linux.ibm.com>,
	"kvm@vger.kernel.org" <kvm@vger.kernel.org>
Subject: RE: [RFC v2 05/11] vfio: Make vfio_device_open() group agnostic
Date: Mon, 28 Nov 2022 08:17:28 +0000	[thread overview]
Message-ID: <BN9PR11MB5276CD3944B24228753883418C139@BN9PR11MB5276.namprd11.prod.outlook.com> (raw)
In-Reply-To: <20221124122702.26507-6-yi.l.liu@intel.com>

> From: Liu, Yi L <yi.l.liu@intel.com>
> Sent: Thursday, November 24, 2022 8:27 PM
> 
> This prepares for moving group specific code to separate file.
> 
> Signed-off-by: Yi Liu <yi.l.liu@intel.com>
> ---
>  drivers/vfio/vfio_main.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/vfio/vfio_main.c b/drivers/vfio/vfio_main.c
> index edcfa8a61096..fcb9f778fc9b 100644
> --- a/drivers/vfio/vfio_main.c
> +++ b/drivers/vfio/vfio_main.c
> @@ -878,9 +878,6 @@ static struct file *vfio_device_open(struct vfio_device
> *device)
>  	 */
>  	filep->f_mode |= (FMODE_PREAD | FMODE_PWRITE);
> 
> -	if (device->group->type == VFIO_NO_IOMMU)
> -		dev_warn(device->dev, "vfio-noiommu device opened by
> user "
> -			 "(%s:%d)\n", current->comm, task_pid_nr(current));
>  	/*
>  	 * On success the ref of device is moved to the file and
>  	 * put in vfio_device_fops_release()
> @@ -927,6 +924,10 @@ static int vfio_group_ioctl_get_device_fd(struct
> vfio_group *group,
>  		goto err_put_fdno;
>  	}
> 
> +	if (group->type == VFIO_NO_IOMMU)
> +		dev_warn(device->dev, "vfio-noiommu device opened by
> user "
> +			 "(%s:%d)\n", current->comm, task_pid_nr(current));
> +
>  	fd_install(fdno, filep);
>  	return fdno;
> 

Do we want to support no-iommu mode in future cdev path?

If yes keeping the check in vfio_device_open() makes more sense. Just
replace direct device->group reference with a helper e.g.:

	vfio_device_group_noiommu()