RE: [PATCH v2 1/5] iommufd: Add nesting related data structures for Intel VT-d

[Liu, Yi L]

> From: Jason Gunthorpe <jgg@xxxxxxxxxx>
> Sent: Monday, March 20, 2023 9:50 PM
> 
> On Thu, Mar 09, 2023 at 12:22:03AM -0800, Yi Liu wrote:
> 
> > +struct iommu_hwpt_invalidate_intel_vtd {
> > +	__u8 granularity;
> > +	__u8 padding[7];
> > +	__u32 flags;
> > +	__u32 __reserved;
> > +	__u64 addr;
> > +	__u64 granule_size;
> > +	__u64 nb_granules;
> > +};
> 
> Is there a reason this has such a weird layout? Put the granularity in
> the __reserved slot?

No special reason. This layout was from the previous merged version.
Will modify it as you suggested.

> Consider the discussion on ARM if you prefer to use the native HW
> command structure instead?

Yes, will think about it. at least granule_size and nb_granules are not
necessary. They was added in the previous abstracted invalidation
uapi structure.

Regards,
Yi Liu