Re: [RFC PATCH 15/18] cgroup: Introduce ioasids controller

Jacob Pan
2021-03-04T00:02:05Z

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