Re: [PATCH v4 01/17] iommu: Add hwpt_type with user_data for domain_alloc_user op

[Yi Liu]

On 2023/9/27 09:08, Tian, Kevin wrote:
> > From: Jason Gunthorpe <jgg@xxxxxxxxxx>
> > Sent: Wednesday, September 27, 2023 12:29 AM
> >
> > On Tue, Sep 26, 2023 at 06:37:55AM +0000, Tian, Kevin wrote:
> > > > From: Robin Murphy <robin.murphy@xxxxxxx>
> > > > Sent: Friday, September 22, 2023 5:48 PM
> > > >
> > > > I could go on enjoying myself, but basically yeah, "default" can't be a
> > > > type in itself (at best it would be a meta-type which could be
> > > > requested, such that it resolves to some real type to actually
> > > > allocate), so a good name should reflect what the type functionally
> > > > *means* to the user. IIUC the important distinction is that it's an
> > > > abstract kernel-owned pagetable for the user to indirectly control via
> > > > the API, rather than one it owns and writes directly (and thus has to be
> > > > in a specific agreed format).
> > >
> > > IOMMU_HWPT_TYPE_KERNEL then?
> > >
> > > IOMMU_HWPT_TYPE_GENERIC also doesn't sound a straight word.
> >
> > At the end of the day this enum is the type tag for:
> >
> >   struct iommu_hwpt_alloc {
> >   	__u32 size;
> >   	__u32 pt_id;
> >   	__u32 out_hwpt_id;
> >   	__u32 __reserved;
> > +	__u32 hwpt_type;
> > +	__u32 data_len;
> > +	__aligned_u64 data_uptr;
> >   };
> >
> > That pointer.
> >
> > IOMMU_HWPT_ALLOC_DATA_NONE = 0
> > IOMMU_HWPT_ALLOC_DATA_INTEL_VTD
> > IOMMU_HWPT_ALLOC_DATA_ARM_SMMUV3
> >
> > etc?
> >
> > DATA_NONE requires data_len == 0
>
> Looks good. Probably hwpt_type can be also renamed to data_type
> to better match this interpretation.

ack.

--
Regards,
Yi Liu