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Date:   Fri, 28 May 2021 17:03:11 -0300
From:   Jason Gunthorpe <jgg@nvidia.com>
To:     "Tian, Kevin" <kevin.tian@intel.com>
Cc:     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>,
        "kvm@vger.kernel.org" <kvm@vger.kernel.org>,
        "Alex Williamson (alex.williamson@redhat.com)" 
        <alex.williamson@redhat.com>, Jason Wang <jasowang@redhat.com>,
        Eric Auger <eric.auger@redhat.com>,
        Jonathan Corbet <corbet@lwn.net>,
        "Raj, Ashok" <ashok.raj@intel.com>,
        "Liu, Yi L" <yi.l.liu@intel.com>, "Wu, Hao" <hao.wu@intel.com>,
        "Jiang, Dave" <dave.jiang@intel.com>,
        Jacob Pan <jacob.jun.pan@linux.intel.com>,
        Jean-Philippe Brucker <jean-philippe@linaro.org>,
        David Gibson <david@gibson.dropbear.id.au>,
        Kirti Wankhede <kwankhede@nvidia.com>,
        Robin Murphy <robin.murphy@arm.com>
Subject: Re: [RFC] /dev/ioasid uAPI proposal
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On Thu, May 27, 2021 at 07:58:12AM +0000, Tian, Kevin wrote:
> /dev/ioasid provides an unified interface for managing I/O page tables for 
> devices assigned to userspace. Device passthrough frameworks (VFIO, vDPA, 
> etc.) are expected to use this interface instead of creating their own logic to 
> isolate untrusted device DMAs initiated by userspace. 

It is very long, but I think this has turned out quite well. It
certainly matches the basic sketch I had in my head when we were
talking about how to create vDPA devices a few years ago.

When you get down to the operations they all seem pretty common sense
and straightfoward. Create an IOASID. Connect to a device. Fill the
IOASID with pages somehow. Worry about PASID labeling.

It really is critical to get all the vendor IOMMU people to go over it
and see how their HW features map into this.

Thanks,
Jason