Re: [Xen-devel] Xen on ARM basic questions

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Fri, 22 Nov 2013, Vaibhav Bedia wrote:
> Hi Ian,
> 
> On Fri, Nov 22, 2013 at 10:22 AM, Ian Campbell <Ian.Campbell@xxxxxxxxxx> 
> wrote:
> > On Fri, 2013-11-22 at 10:05 -0500, Vaibhav Bedia wrote:
> >> >>  After going through the recent talk from Stefano [1] i got
> >> >> the impression getting network and SATA requires SWIOTLB support. Is
> >> >> that correct?
> >> >
> >> > The SWIOTLB or an IOMMU/SMMU is necessary for dom0 to drive the physical
> >> > devices and provide the virtual interfaces to the guests.
> >> >
> >> > Device passthrough will only be supported with an IOMMU/SMMU.
> >> >
> >>
> >> So on SoCs like OMAP5 which don't have an IOMMU device passthrough won't be
> >> supported? Or it can be done via SWIOTLB if someone works on it?
> >
> > I'm not in favour of supporting this. It's a big can of worms wrt
> > security.
> >
> 
> Ok. I'll leave it to the experts then :)

Just for clarity: the big can of worms is allowing device passthrough
without an IOMMU. (Except maybe for some ad-hoc static configurations
that might be desirable on embedded platform.)
Using the swiotlb for dom0 is OK.

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