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Date:   Wed, 3 Mar 2021 20:23:57 -0400
From:   Jason Gunthorpe <jgg@nvidia.com>
To:     Jacob Pan <jacob.jun.pan@linux.intel.com>
CC:     Tejun Heo <tj@kernel.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>, <cgroups@vger.kernel.org>,
        Johannes Weiner <hannes@cmpxchg.org>,
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        "Tian, Kevin" <kevin.tian@intel.com>, Yi Liu <yi.l.liu@intel.com>,
        Wu Hao <hao.wu@intel.com>, Dave Jiang <dave.jiang@intel.com>
Subject: Re: [RFC PATCH 15/18] cgroup: Introduce ioasids controller
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On Wed, Mar 03, 2021 at 04:02:05PM -0800, Jacob Pan wrote:
> > The interface definitely can be reused. But IOASID has a different
> > behavior in terms of migration and ownership checking. I guess SEV key
> > IDs are not tied to a process whereas IOASIDs are. Perhaps this can be
> > solved by adding
> > +	.can_attach	= ioasids_can_attach,
> > +	.cancel_attach	= ioasids_cancel_attach,
> > Let me give it a try and come back.
> > 
> While I am trying to fit the IOASIDs cgroup in to the misc cgroup proposal.
> I'd like to have a direction check on whether this idea of using cgroup for
> IOASID/PASID resource management is viable.
> 
> Alex/Jason/Jean and everyone, your feedback is much appreciated.

IMHO I can't think of anything else to enforce some limit on a HW
scarce resource that unpriv userspace can consume.

Jason