RE: [PATCH 01/12] iommu: Add new iommu op to create domains owned by userspace

[Liu, Yi L]

> From: Jason Gunthorpe <jgg@xxxxxxxxxx>
> Sent: Friday, March 10, 2023 8:56 AM
> 
> On Thu, Mar 09, 2023 at 12:08:59AM -0800, Yi Liu wrote:
> > diff --git a/include/linux/iommu.h b/include/linux/iommu.h
> > index 3ef84ee359d2..a269bc62a31c 100644
> > --- a/include/linux/iommu.h
> > +++ b/include/linux/iommu.h
> > @@ -229,6 +229,7 @@ struct iommu_iotlb_gather {
> >   *           after use. Return the data buffer if success, or ERR_PTR on
> >   *           failure.
> >   * @domain_alloc: allocate iommu domain
> > + * @domain_alloc_user: allocate user iommu domain
> >   * @probe_device: Add device to iommu driver handling
> >   * @release_device: Remove device from iommu driver handling
> >   * @probe_finalize: Do final setup work after the device is added to an
> IOMMU
> > @@ -266,6 +267,9 @@ struct iommu_ops {
> >
> >  	/* Domain allocation and freeing by the iommu driver */
> >  	struct iommu_domain *(*domain_alloc)(unsigned
> iommu_domain_type);
> > +	struct iommu_domain *(*domain_alloc_user)(struct device *dev,
> > +						  struct iommu_domain
> *parent,
> > +						  const void *user_data);
> 
> Since the kernel does the copy from user and manages the zero fill
> compat maybe this user_data have a union like Robin suggested.
>
> But yes, this is the idea.

Ok. so it's a union like the below, and in this patch may be only an empty
union can be added as the struct iommu_hwpt_intel_vtd and
struct iommu_hwpt_arm_smmuv3 would be added by the vendor nesting
patch series.

union iommu_hwpt_alloc_user_data {
	struct iommu_hwpt_intel_vtd vtd;
	struct iommu_hwpt_arm_smmuv3 smmuv3;
};

Regards,
Yi Liu