[Qemu-devel] [PATCH RFC 0/3] virtio-pci: iommu support

[Michael S. Tsirkin]

This is an attempt to allow enabling IOMMU for DMA.
Design:
        - new feature bit IOMMU_PLATFORM which means
          host won't bypass IOMMU
        - virtio core uses DMA API if it sees IOMMU_PLATFORM
        - add quirk for vfio to disable device unless IOMMU_PLATFORM is set
          or the no-iommu mode is enabled
        - while I'm not sure how it will be used, it seems like a good idea to
          also have ability to distinguish between a legacy device and one
          where iommu is bypassed intentionally.  To this end, add another 
feature bit
          IOMMU_PASSTHROUGH. We don't acknowledge it if IOMMU_PLATFORM is set.

TODO:
        - I'm not sure whether there are setups that mix IOMMU
          and no-IOMMU configs. If so, failing on probe might not
          be the right thing to do, should fail binding to IOMMU group instead.


Michael S. Tsirkin (3):
  virtio: add features for IOMMU control
  vfio: report group noiommu status
  vfio: add virtio pci quirk

 drivers/vfio/pci/vfio_pci_private.h          |   1 +
 include/uapi/linux/virtio_config.h           |  10 +-
 drivers/vfio/pci/vfio_pci.c                  |  13 ++-
 drivers/vfio/pci/vfio_pci_virtio.c           | 142 +++++++++++++++++++++++++++
 drivers/vfio/platform/vfio_platform_common.c |   2 +-
 drivers/vfio/vfio.c                          |   5 +-
 drivers/virtio/virtio_ring.c                 |  18 +++-
 Documentation/vfio.txt                       |   4 +-
 drivers/vfio/pci/Makefile                    |   1 +
 9 files changed, 190 insertions(+), 6 deletions(-)
 create mode 100644 drivers/vfio/pci/vfio_pci_virtio.c

-- 
MST