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From: "Aviv B.D." <bd.aviv@gmail.com>
Date: Tue, 25 Oct 2016 13:07:05 +0300
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Subject: Re: [Qemu-devel] [PATCH v4 RESEND 3/3] IOMMU: enable intel_iommu
 map and unmap notifiers
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To: Peter Xu <peterx@redhat.com>
Cc: qemu-devel@nongnu.org, "Michael S. Tsirkin" <mst@redhat.com>, Alex Williamson <alex.williamson@redhat.com>, Jan Kiszka <jan.kiszka@siemens.com>

On Mon, Oct 24, 2016 at 11:02 AM, Peter Xu <peterx@redhat.com> wrote:

> On Mon, Oct 24, 2016 at 10:53:01AM +0300, Aviv B.D. wrote:
>
> [...]
>
> > This was my first algorithm, but VFIO do not support remapping of mapped
> > page.
> > Before each MAP operation in VFIO one must do unmap, and therefore I'm
> > sending
> > the unmap notifications blindly before.
> > I can rearrange my code closer to your suggestion.
>
> If so, I would suggest we solve the real problem first: we should not
> notify VFIO twice on map(), but only once. IMO either Alex's or
> David's suggestion (in the other mail) is a good start.
>
> OK. I will publish a new patch set that notify only once per page.
I prefer David's suggestion - adding the range information to the notifier
struct
and check it from inside the VFIO notification function.


> >
> >
> > >
> > > This is to follow your logic. I don't know whether this is efficient
> > > enough, maybe good for the first version. The problem is, when you
> > > call translate(), you will need to go over the page every time from
> > > root dir. A faster way may be: provide a function to walk specific
> > > address range. If you are going to implement the replay logic that
> > > Alex/David has mentioned, maybe that will help too (walk over the
> > > whole 64bit range).
> > >
> > > Interesting idea, but I prefer to add it in separate patch set after
> this
> > one committed, if it's OK.
>
> Sure.
>
> -- peterx
>

Thanks,
Aviv.