[Intel-gfx] [PATCH v3 09/12] vfio/pci: Accept device fd in VFIO_DEVICE_PCI_HOT_RESET ioctl

[Eric Auger]

On 4/1/23 16:44, Yi Liu wrote:
> Now user can also provide an array of device fds as a 3rd method to verify
> the reset ownership. It's not useful at this point when the device fds are
> acquired via group fds. But it's necessary when moving to device cdev which
> allows the user to directly acquire device fds by skipping group. In that
> case this method can be used as a last resort when the preferred iommufd
> verification doesn't work, e.g. in noiommu usages.
>
> Clarify it in uAPI.
>
> Reviewed-by: Kevin Tian <kevin.tian at intel.com>
> Reviewed-by: Jason Gunthorpe <jgg at nvidia.com>
> Tested-by: Yanting Jiang <yanting.jiang at intel.com>
> Signed-off-by: Yi Liu <yi.l.liu at intel.com>
Reviewed-by: Eric Auger <eric.auger at redhat.com>

Eric
> ---
>  drivers/vfio/pci/vfio_pci_core.c | 9 +++++----
>  include/uapi/linux/vfio.h        | 3 ++-
>  2 files changed, 7 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/vfio/pci/vfio_pci_core.c b/drivers/vfio/pci/vfio_pci_core.c
> index da6325008872..19f5b075d70a 100644
> --- a/drivers/vfio/pci/vfio_pci_core.c
> +++ b/drivers/vfio/pci/vfio_pci_core.c
> @@ -1289,7 +1289,7 @@ vfio_pci_ioctl_pci_hot_reset_files(struct vfio_pci_core_device *vdev,
>  		return -ENOMEM;
>  	}
>  
> -	if (copy_from_user(fds, arg->group_fds,
> +	if (copy_from_user(fds, arg->fds,
>  			   hdr->count * sizeof(*fds))) {
>  		kfree(fds);
>  		kfree(files);
> @@ -1297,8 +1297,8 @@ vfio_pci_ioctl_pci_hot_reset_files(struct vfio_pci_core_device *vdev,
>  	}
>  
>  	/*
> -	 * Get the group file for each fd to ensure the group held across
> -	 * the reset
> +	 * Get the file for each fd to ensure the group/device file
> +	 * is held across the reset
>  	 */
>  	for (file_idx = 0; file_idx < hdr->count; file_idx++) {
>  		struct file *file = fget(fds[file_idx]);
> @@ -2469,7 +2469,8 @@ static int vfio_pci_dev_set_hot_reset(struct vfio_device_set *dev_set,
>  		 * cannot race being opened by another user simultaneously.
>  		 *
>  		 * Otherwise all opened devices in the dev_set must be
> -		 * contained by the set of groups provided by the user.
> +		 * contained by the set of groups/devices provided by
> +		 * the user.
>  		 *
>  		 * If user provides a zero-length array, then all the
>  		 * opened devices must be bound to a same iommufd_ctx.
> diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
> index 17aa5d09db41..25432ef213ee 100644
> --- a/include/uapi/linux/vfio.h
> +++ b/include/uapi/linux/vfio.h
> @@ -681,6 +681,7 @@ struct vfio_pci_hot_reset_info {
>   *
>   * The ownership can be proved by:
>   *   - An array of group fds
> + *   - An array of device fds
>   *   - A zero-length array
>   *
>   * In the last case all affected devices which are opened by this user
> @@ -694,7 +695,7 @@ struct vfio_pci_hot_reset {
>  	__u32	argsz;
>  	__u32	flags;
>  	__u32	count;
> -	__s32	group_fds[];
> +	__s32	fds[];
>  };
>  
>  #define VFIO_DEVICE_PCI_HOT_RESET	_IO(VFIO_TYPE, VFIO_BASE + 13)