Re: [PATCH 4/5] intel-iommu: Reinstate RMRRs if a device isremoved from passthrough domain

[Alex Williamson]

On Tue, 2009-10-27 at 08:15 +0000, David Woodhouse wrote:
> On Mon, 2009-10-26 at 17:25 -0600, Alex Williamson wrote:
> > When a device is setup for passthrough it has full access to memory
> > so processing the RMRRs is unnecessary.  However, if we remove the device
> > from the si_domain, we need to reinstate the associated RMRRs.
> > 
> > Signed-off-by: Alex Williamson <alex.williamson@xxxxxx>
> 
> If your device is doing DMA to host memory autonomously, you may still
> have problems with this patch -- you take it out of the si_domain and
> then there's a period of time before you reapply the RMRRs, during which
> its DMA may be prevented.
> 
> You want to set up the new domain first, then switch the device over to
> it atomically.

Yes, good point.  I'm not seeing any convenient ways to setup a new
domain for a device while it's still a member of the si_domain.  It
looks like I'd need to extract parts of the get_valid_domain_for_dev()
path and ignore any bits about using the already existing domain.  Is
there an easier way?  Thanks,

Alex


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/