Hi Tejun,

On Wed, 3 Mar 2021 10:44:28 -0500, Tejun Heo [off-list ref] wrote:

On Sat, Feb 27, 2021 at 02:01:23PM -0800, Jacob Pan wrote:

quoted

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.

Thanks for the pointer.

Jacob

Thanks.

Thanks,

Jacob