From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jacob Pan <jacob.jun.pan-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
Subject: Re: [PATCH V4 05/18] iommu/ioasid: Redefine IOASID set and
 allocation APIs
Date: Mon, 10 May 2021 20:56:32 -0700
Message-ID: <20210510205632.13ff7308@jacob-builder>
References: <YJOZhPGheTSlHtQc@myrica>
        <20210506122730.GQ1370958@nvidia.com>
        <20210506163240.GA9058@otc-nc-03>
        <MWHPR11MB188698FBEE62AF1313E0F7AC8C569@MWHPR11MB1886.namprd11.prod.outlook.com>
        <20210510123729.GA1002214@nvidia.com>
        <20210510152502.GA90095@otc-nc-03>
        <20210510153111.GB1002214@nvidia.com>
        <20210510162212.GB90095@otc-nc-03>
        <20210510163956.GD1002214@nvidia.com>
        <20210510152854.793ee594@jacob-builder>
        <20210510234500.GI1002214@nvidia.com>
Mime-Version: 1.0
Content-Transfer-Encoding: 7bit
Return-path: <cgroups-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>
In-Reply-To: <20210510234500.GI1002214-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
List-ID: <cgroups.vger.kernel.org>
Content-Type: text/plain; charset="us-ascii"
To: Jason Gunthorpe <jgg-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
Cc: "Raj, Ashok" <ashok.raj-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>, "Tian, Kevin" <kevin.tian-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>, Jean-Philippe Brucker <jean-philippe-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>, Alex Williamson <alex.williamson-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>, "Liu, Yi L" <yi.l.liu-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>, Auger Eric <eric.auger-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>, LKML <linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>, Joerg Roedel <joro-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>, Lu Baolu <baolu.lu-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>, David Woodhouse <dwmw2-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>, "iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org" <iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org>, "cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" <cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>, Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>, Johannes Weiner <hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org>, Jean-Philippe Brucker <jean-philippe-68IGFXMjmZ7QT0dZR+AlfA@public.gmane.org>, Jonathan Corbet <corbet-T1hC0tSOHrs@public.gmane.org>, "Wu, Hao" <hao.wu-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>, "Jiang, Dave" <dave.jiang-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>, jacob.jun.pan-VuQAYsv1563Yd54FQh9/CA@public.gmane.org

Hi Jason,

On Mon, 10 May 2021 20:45:00 -0300, Jason Gunthorpe <jgg-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org> wrote:

> On Mon, May 10, 2021 at 03:28:54PM -0700, Jacob Pan wrote:
> 
> > To satisfy your "give me a PASID for this RID" proposal, can we just use
> > the RID's struct device as the token? Also add a type field to
> > explicitly indicate global vs per-set(per-RID). i.e.  
> 
> You've got it backwards, the main behavior should be to allocate PASID
> per RID.
> 
Sure, we can make the local PASID as default. My point was that the
ioasid_set infrastructure's opaque token can support RID-local allocation
scheme. Anyway, this is a small detail as compared to uAPI.

> The special behavior is to bundle a bunch of PASIDs into a grouping
> and then say the PASID number space is shared between all the group
> members. 
> 
> /dev/ioasid should create and own this grouping either implicitly or
> explicitly. Jumping ahead to in-kernel APIs has missed the critical
> step of defining the uAPI and all the behaviors together in a
> completed RFC proposal.
> 
Agreed, the requirements for kernel API should come from uAPI.

> Jason


Thanks,

Jacob