From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jacob Pan <jacob.jun.pan-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
Subject: Re: [RFC PATCH 15/18] cgroup: Introduce ioasids controller
Date: Wed, 3 Mar 2021 16:02:05 -0800
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To: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Cc: "Tian, Kevin" <kevin.tian-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>, Alex Williamson <alex.williamson-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>, Raj Ashok <ashok.raj-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>, Jonathan Corbet <corbet-T1hC0tSOHrs@public.gmane.org>, Jean-Philippe Brucker <jean-philippe-68IGFXMjmZ7QT0dZR+AlfA@public.gmane.org>, LKML <linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>, Dave Jiang <dave.jiang-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>, iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, Jason Gunthorpe <jgg-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>, Johannes Weiner <hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org>, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Wu Hao <hao.wu-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>, David Woodhouse <dwmw2-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>

Hi Jacob,

On Wed, 3 Mar 2021 13:17:26 -0800, Jacob Pan
<jacob.jun.pan-VuQAYsv1563Yd54FQh9/CA@public.gmane.org> wrote:

> Hi Tejun,
> 
> On Wed, 3 Mar 2021 10:44:28 -0500, Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org> wrote:
> 
> > On Sat, Feb 27, 2021 at 02:01:23PM -0800, Jacob Pan wrote:  
> > > IOASIDs are used to associate DMA requests with virtual address
> > > spaces. They are a system-wide limited resource made available to the
> > > userspace applications. Let it be VMs or user-space device drivers.
> > > 
> > > This RFC patch introduces a cgroup controller to address the following
> > > problems:
> > > 1. Some user applications exhaust all the available IOASIDs thus
> > > depriving others of the same host.
> > > 2. System admins need to provision VMs based on their needs for
> > > IOASIDs, e.g. the number of VMs with assigned devices that perform
> > > DMA requests with PASID.    
> > 
> > Please take a look at the proposed misc controller:
> > 
> >  http://lkml.kernel.org/r/20210302081705.1990283-2-vipinsh-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org
> > 
> > Would that fit your bill?  
> 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.

> Thanks for the pointer.
> 
> Jacob
> 
> > 
> > Thanks.
> >   
> 
> 
> Thanks,
> 
> Jacob


Thanks,

Jacob