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Date:   Thu, 4 Mar 2021 15:02:53 -0400
From:   Jason Gunthorpe <jgg@nvidia.com>
To:     Jacob Pan <jacob.jun.pan@linux.intel.com>
CC:     Jean-Philippe Brucker <jean-philippe@linaro.org>,
        Tejun Heo <tj@kernel.org>, LKML <linux-kernel@vger.kernel.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 Thu, Mar 04, 2021 at 11:01:44AM -0800, Jacob Pan wrote:

> > For something like qemu I'd expect to put the qemu process in a cgroup
> > with 1 PASID. Who cares what qemu uses the PASID for, or how it was
> > allocated?
> 
> For vSVA, we will need one PASID per guest process. But that is up to the
> admin based on whether or how many SVA capable devices are directly
> assigned.

I hope the virtual IOMMU driver can communicate the PASID limit and
the cgroup machinery in the guest can know what the actual limit is.

I was thinking of a case where qemu is using a single PASID to setup
the guest kVA or similar

Jason