Re: [Qemu-devel] [PATCH v5 3/3] intel_iommu: allow UNMAP notifiers

[David Gibson <david@gibson.dropbear.id.au>]

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On Tue, Sep 20, 2016 at 03:28:08PM +0800, Peter Xu wrote:
> On Tue, Sep 20, 2016 at 04:14:09PM +1000, David Gibson wrote:
> > On Wed, Sep 14, 2016 at 04:25:48PM +0800, Peter Xu wrote:
> > > Intel vIOMMU is still lacking of a complete IOMMU notifier mechanism.
> > > Before that is achieved, let's open a door for vhost DMAR support, which
> > > only requires cache invalidations (UNMAP operations).
> > > 
> > > Meanwhile, converting hw_error() to error_report() and exit(1), to make
> > > the error messages clean and obvious (so no CPU registers will be
> > > dumped).
> > 
> > Erm... AIUI currently the intel iommu driver doesn't do any
> > notifications.  Surely it's only valid to allow this once you've
> > implemented unmap side notifications.
> 
> Yes, I suppose vhost DMAR patches will be based upon this one. I can
> postpone this patch until Jason wants to pick it up, but it actually
> does not hurt if we just enable it now, anyway no one is using it.

Even so, I think it's misleading to implicitly advertise a capability
that's not yet implemented.  Changing this warning should happen after
or at the same time as implementing the notifications in the vIOMMU
model.

> So... I see no bad to merge this along with the series, so that we can
> reduce one entry from Jason's TODO list. :)
> 
> Thanks!
> 
> -- peterx
> 

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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