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From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Date: Fri, 12 Oct 2012 13:36:01 +1100
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Subject: Re: [Qemu-devel] [RFC v1 0/7] IOMMU support
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To: Avi Kivity <avi@redhat.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>, liu ping fan <qemulist@gmail.com>, qemu-devel@nongnu.org, Blue Swirl <blauwirbel@gmail.com>, Alex Williamson <alex.williamson@redhat.com>, Anthony Liguori <anthony@codemonkey.ws>, Paolo Bonzini <pbonzini@redhat.com>

On Thu, 2012-10-11 at 15:26 +0200, Avi Kivity wrote:
> These patches add IOMMU support to the memory core. IOMMUs can be added anywhere in
> the memory hierarchy, and may be arranged in series.

I haven't had a chance to review in details yet, but one thing I noticed
is that you basically have a single read/write protection information
for a translation.

This is a loss of functionality to some extent (well, maybe not from the
existing iommu layer but from what could be done by our HW) in that we
have separate read and write permission bits.

This is actually worth fixing I think. Catching incorrect reads from
write-only regions is probably worth it in term of debugging drivers.

Cheers,
Ben.

> Avi Kivity (7):
>   memory: fix address space initialization/destruction
>   memory: limit sections in the radix tree to the actual address space
>     size
>   memory: iommu support
>   pci: switch iommu to using the memory API
>   i440fx: add an iommu
>   vfio: abort if an emulated iommu is used
>   vhost: abort if an emulated iommu is used
> 
>  exec.c             |  43 ++++++++++++++++++---
>  hw/pci.c           |  59 +++++++++++++++++-----------
>  hw/pci.h           |   7 +++-
>  hw/pci_internals.h |   5 ++-
>  hw/piix_pci.c      |  74 +++++++++++++++++++++++++++++++++++
>  hw/spapr.h         |   2 +
>  hw/spapr_iommu.c   |  35 ++++++++---------
>  hw/spapr_pci.c     |  26 +++++++++++--
>  hw/spapr_pci.h     |   1 +
>  hw/vfio_pci.c      |   2 +
>  hw/vhost.c         |   2 +
>  memory.c           | 110 +++++++++++++++++++++++++++++++++++++++++++++++++++++
>  memory.h           |  46 ++++++++++++++++++++++
>  13 files changed, 356 insertions(+), 56 deletions(-)
>