Re: [PATCH v2] Intel IOMMU patch to reprocess RMRR info

[Joerg Roedel <joro-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>]

On Fri, Sep 28, 2012 at 07:01:06PM +0200, Joerg Roedel wrote:
> On Fri, Sep 28, 2012 at 12:36:05PM -0400, Linda Knippers wrote:
> > I can only speak to the HP servers.  We have been shipping devices
> > 'for a while' that provide sensor-type data to the platform.  The
> > device does DMA writes to a range of memory (the RMRR) and
> > iLO does DMA reads of that data.
> 
> And what PCI request-ids are used for these DMA transfers? Are this
> request-ids which belong to devices Linux handles on its own?
> 
> > If we address Alex's comments and we make a change to disallow the
> > devices (non-USB devices?) with RMRRs from being assigned to
> > a guest, will those changes be considered?
> 
> This is overkill in my eyes. It means that *any* device which has an
> RMRR defined, whether it is on your platform or not, can not be assigned
> to a guest.
> 
> I think it is better to have the RMRR regions mapped in the domains used
> for DMA-API mappings and disallow to assign these devices to guests.

Of course I meant "allow to assign these devices to guests."

> For devices where this breaks we can implement some quirk-solution and
> disallow guest assignment. But disallowing assignment of devices with
> RMRR defined in general is pure overkill.
> 
> 
> 	Joerg
> 
> 
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