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Date:   Thu, 6 May 2021 09:22:22 -0300
From:   Jason Gunthorpe <jgg@nvidia.com>
To:     "Raj, Ashok" <ashok.raj@intel.com>
Cc:     Jacob Pan <jacob.jun.pan@linux.intel.com>,
        "Tian, Kevin" <kevin.tian@intel.com>,
        Alex Williamson <alex.williamson@redhat.com>,
        "Liu, Yi L" <yi.l.liu@intel.com>,
        Auger Eric <eric.auger@redhat.com>,
        Jean-Philippe Brucker <jean-philippe@linaro.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Joerg Roedel <joro@8bytes.org>,
        Lu Baolu <baolu.lu@linux.intel.com>,
        David Woodhouse <dwmw2@infradead.org>,
        "iommu@lists.linux-foundation.org" <iommu@lists.linux-foundation.org>,
        "cgroups@vger.kernel.org" <cgroups@vger.kernel.org>,
        Tejun Heo <tj@kernel.org>, Li Zefan <lizefan@huawei.com>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Jean-Philippe Brucker <jean-philippe@linaro.com>,
        Jonathan Corbet <corbet@lwn.net>, "Wu, Hao" <hao.wu@intel.com>,
        "Jiang, Dave" <dave.jiang@intel.com>
Subject: Re: [PATCH V4 05/18] iommu/ioasid: Redefine IOASID set and
 allocation APIs
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On Wed, May 05, 2021 at 04:23:19PM -0700, Raj, Ashok wrote:
> > Which implies the API to the iommu driver should be more like:
> > 
> >   'assign an IOASID to this RID and return the PASID'
> >   'reserve a PASID from every RID'
> 
> I don't think this has any decent change of success. Its rather round about
> way to get a global PASID namespace.
> 
> >   'assign an IOASID to this RID and use this specific PASID'
> 
> This seems a bit complicated. Another way to specify this.

Maybe, but I don't like that the driver-based iommu API has been
corrupted by injecting a global 'first driver to claim it'
resource. It is not properly layered anymore.

Jason