Re: [Qemu-devel] [V9 0/4] AMD IOMMU

[Michael S. Tsirkin]

On Sun, May 01, 2016 at 04:47:44PM +0300, Michael S. Tsirkin wrote:
> On Sat, Apr 30, 2016 at 01:42:39AM +0300, David Kiarie wrote:
> > These series adds AMD IOMMU support to Qemu. It's currently in the 9th 
> > version.
> > 
> > In this series I have (hopefully) addressed all the comments made in the 
> > previous version.
> 
> changelog?
> 
> > I have also tested and successfully passed-through PCI device 'ac97' with 
> > more devices to be tested.
> 
> 
> A fundamental problem with AMD IOMMUs is that the VMM must write-protect
> guest I/O page tables from the guest in order to intercept all guest
> updates and propagate the updates to the shadow I/O page tables.
> 
> AMD manual says as much.

Actually while it says so, it's wrong.
There's an NPcache flag which makes guest to invalidations
for invalid to valid transitions.

> Until this is implemented, I think device assignment must be disabled
> when AMD IOMMU is in use.

So I take this back. I would, however, like to see how this
interacts with Aviv's patches enabling VFIO support for IOMMU.

> 
> > 
> > David Kiarie (4):
> >   hw/i386: Introduce AMD IOMMU
> >   hw/i386: ACPI table for AMD IOMMU
> >   hw/core: Add AMD IOMMU to machine properties
> >   hw/pci-host: Emulate AMD IOMMU
> > 
> >  hw/acpi/aml-build.c           |    2 +-
> >  hw/acpi/core.c                |   13 -
> >  hw/core/machine.c             |   33 +-
> >  hw/i386/Makefile.objs         |    1 +
> >  hw/i386/acpi-build.c          |   93 ++-
> >  hw/i386/amd_iommu.c           | 1426 
> > +++++++++++++++++++++++++++++++++++++++++
> >  hw/i386/amd_iommu.h           |  398 ++++++++++++
> >  hw/pci-host/q35.c             |   25 +-
> >  include/hw/acpi/acpi-defs.h   |   14 +
> >  include/hw/acpi/acpi.h        |   16 +
> >  include/hw/acpi/aml-build.h   |    1 +
> >  include/hw/boards.h           |    7 +
> >  include/hw/i386/intel_iommu.h |    1 +
> >  include/hw/pci/pci.h          |    2 +
> >  qemu-options.hx               |    7 +-
> >  util/qemu-config.c            |    8 +-
> >  16 files changed, 2012 insertions(+), 35 deletions(-)
> >  create mode 100644 hw/i386/amd_iommu.c
> >  create mode 100644 hw/i386/amd_iommu.h
> > 
> > -- 
> > 2.1.4