Re: [RFC 08/20] vfio/pci: Add VFIO_DEVICE_BIND_IOMMUFD

Jason Gunthorpe
2021-09-22T23:01:28Z

On Wed, Sep 22, 2021 at 03:01:01PM -0600, Alex Williamson wrote:
> On Tue, 21 Sep 2021 14:29:39 -0300
> Jason Gunthorpe <jgg@nvidia.com> wrote:
>
> > On Sun, Sep 19, 2021 at 02:38:36PM +0800, Liu Yi L wrote:
> > > +struct vfio_device_iommu_bind_data {
> > > + __u32 argsz;
> > > + __u32 flags;
> > > + __s32 iommu_fd;
> > > + __u64 dev_cookie;
> >
> > Missing explicit padding
> >
> > Always use __aligned_u64 in uapi headers, fix all the patches.
>
> We don't need padding or explicit alignment if we just swap the order
> of iommu_fd and dev_cookie. Thanks,

Yes, the padding should all be checked and minimized

But it is always good practice to always use __aligned_u64 in the uapi
headers just in case someone messes it up someday - it prevents small
mistakes from becoming an ABI mess.

Jason