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Date: Wed, 14 Sep 2016 16:17:26 +0800
From: Peter Xu <peterx@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH v4 1/3] memory: introduce IOMMUNotifier and
 its caps
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To: David Gibson <david@gibson.dropbear.id.au>
Cc: mst@redhat.com, jasowang@redhat.com, qemu-devel@nongnu.org, cornelia.huck@de.ibm.com, alex.williamson@redhat.com, wexu@redhat.com, dgibson@redhat.com, vkaplans@redhat.com, pbonzini@redhat.com

On Wed, Sep 14, 2016 at 05:15:03PM +1000, David Gibson wrote:

[...]

> Peter suggested commenting this next to the IOTLBEntry definition, and
> I think that's probably ok for now.

Looks like we have something already (just not that obvious):

/**
 * memory_region_notify_iommu: notify a change in an IOMMU translation entry.
 *
 * @mr: the memory region that was changed
 * @entry: the new entry in the IOMMU translation table.  The entry
 *         replaces all old entries for the same virtual I/O address range.
 *         Deleted entries have .@perm == 0.
 */
void memory_region_notify_iommu(MemoryRegion *mr,
                                IOMMUTLBEntry entry);

Though it's quite simple, it did explain that perm==0 is for deleted
entries.

Thanks,

-- peterx