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Date:   Fri, 13 Oct 2023 11:03:57 -0300
From:   Jason Gunthorpe <jgg@nvidia.com>
To:     Nicolin Chen <nicolinc@nvidia.com>
Cc:     Yi Liu <yi.l.liu@intel.com>, joro@8bytes.org,
        alex.williamson@redhat.com, kevin.tian@intel.com,
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        chao.p.peng@linux.intel.com, yi.y.sun@linux.intel.com,
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        linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org,
        zhenzhong.duan@intel.com, joao.m.martins@oracle.com
Subject: Re: [PATCH v4 01/17] iommu: Add hwpt_type with user_data for
 domain_alloc_user op
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On Thu, Oct 12, 2023 at 05:34:58PM -0700, Nicolin Chen wrote:
> On Tue, Oct 10, 2023 at 01:58:44PM -0300, Jason Gunthorpe wrote:
> > On Thu, Sep 21, 2023 at 12:51:22AM -0700, Yi Liu wrote:
> > > diff --git a/include/linux/iommu.h b/include/linux/iommu.h
> > > index 660dc1931dc9..12e12e5563e6 100644
> > > --- a/include/linux/iommu.h
> > > +++ b/include/linux/iommu.h
> > > @@ -14,6 +14,7 @@
> > >  #include <linux/err.h>
> > >  #include <linux/of.h>
> > >  #include <uapi/linux/iommu.h>
> > > +#include <uapi/linux/iommufd.h>
> > 
> > Oh we should definately avoid doing that!
> >   
> > Maybe this is a good moment to start a new header file exclusively for
> > iommu drivers and core subsystem to include?
> > 
> >  include/linux/iommu-driver.h
> > 
> > ?
> > 
> > Put iommu_copy_user_data() and  struct iommu_user_data in there
> > 
> > Avoid this include in this file.
> 
> By looking closer, it seems that we included the uapi header for:
> +	struct iommu_domain *(*domain_alloc_user)(struct device *dev, u32 flags,
> +						  enum iommu_hwpt_data_type data_type,
> +						  struct iommu_domain *parent,
> +						  const struct iommu_user_data *user_data);
> 
> So we could drop the include, and instead add this next to structs:
> +enum iommu_hwpt_data_type;
> 
> Then it's not that necessary to have a new header? We could mark a
> section of "driver exclusively functions" in iommu.h, I think.

Yeah, OK, though I still have a desire to split this header..

(though can you really forward declare enums and then pass it by value?)

Jason