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Wed, 24 Mar 2021 17:03:41 +0000 Received: from DM6PR12MB3834.namprd12.prod.outlook.com ([fe80::1c62:7fa3:617b:ab87]) by DM6PR12MB3834.namprd12.prod.outlook.com ([fe80::1c62:7fa3:617b:ab87%6]) with mapi id 15.20.3955.027; Wed, 24 Mar 2021 17:03:41 +0000 Date: Wed, 24 Mar 2021 14:03:38 -0300 From: Jason Gunthorpe To: Jacob Pan Cc: Jean-Philippe Brucker , LKML , Joerg Roedel , Lu Baolu , David Woodhouse , iommu@lists.linux-foundation.org, cgroups@vger.kernel.org, Tejun Heo , Li Zefan , Johannes Weiner , Jean-Philippe Brucker , Alex Williamson , Eric Auger , Jonathan Corbet , Raj Ashok , "Tian, Kevin" , Yi Liu , Wu Hao , Dave Jiang Subject: Re: [PATCH V4 05/18] iommu/ioasid: Redefine IOASID set and allocation APIs Message-ID: <20210324170338.GM2356281@nvidia.com> References: <1614463286-97618-1-git-send-email-jacob.jun.pan@linux.intel.com> <1614463286-97618-6-git-send-email-jacob.jun.pan@linux.intel.com> <20210318172234.3e8c34f7@jacob-builder> <20210319124645.GP2356281@nvidia.com> <20210319135432.GT2356281@nvidia.com> <20210319112221.5123b984@jacob-builder> <20210324100246.4e6b8aa1@jacob-builder> Content-Type: text/plain; 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Would that go through the same path as > > /dev/ioasid and use the cgroup of current task? > > For the in-kernel private use, I don't think we should restrict based on > cgroup, since there is no affinity to user processes. I also think the > PASID allocation should just use kernel API instead of /dev/ioasid. Why > would user space need to know the actual PASID # for device private domains? > Maybe I missed your idea? There is not much in the kernel that isn't triggered by a process, I would be careful about the idea that there is a class of users that can consume a cgroup controlled resource without being inside the cgroup. We've got into trouble before overlooking this and with something greenfield like PASID it would be best built in to the API to prevent a mistake. eg accepting a cgroup or process input to the allocator. Jason