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From: Jean-Philippe Brucker <jean-philippe-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
Subject: Re: [PATCH V4 05/18] iommu/ioasid: Redefine IOASID set and
 allocation APIs
Date: Fri, 19 Mar 2021 14:41:32 +0100
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To: Jason Gunthorpe <jgg-DDmLM1+adcrQT0dZR+AlfA@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, Li Zefan <lizefan-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>, Johannes Weiner <hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org>, Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Wu Hao <hao.wu-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>, David Woodhouse <dwmw2-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>

On Fri, Mar 19, 2021 at 09:46:45AM -0300, Jason Gunthorpe wrote:
> On Fri, Mar 19, 2021 at 10:58:41AM +0100, Jean-Philippe Brucker wrote:
> 
> > Although there is no use for it at the moment (only two upstream users and
> > it looks like amdkfd always uses current too), I quite like the
> > client-server model where the privileged process does bind() and programs
> > the hardware queue on behalf of the client process.
> 
> This creates a lot complexity, how do does process A get a secure
> reference to B? How does it access the memory in B to setup the HW?

mm_access() for example, and passing addresses via IPC

> Why do we need separation anyhow? SVM devices are supposed to be
> secure or they shouldn't do SVM.

Right

Thanks,
Jean