[RFC PATCH 0/5] virtio-iommu: Add VT-d IO page table

Tina Zhang
2023-11-06T07:12:21Z

The proposal about virtio-iommu support page tables is being discussed in
the virtio-comment mailing list[1]. This patch-set based on Jean's
virtio-iommu/pgtables branch[2] tries to follow the proposal and add the
basic VT-d IO page table support to virtio-iommu.

On Intel platform with VT-d nested translation enabled, there are two
main benefits for enabling virtual IOMMU support VT-d IO page table:
1) Allowing vSVM (aka vSVA) usage. Virtual Shared Virtual Addressing
   (vSVA) allows the virtual processor and virtual device to use the
   same virtual addresses.
2) Accelerating DMA buffer map operation for vIOVA usage by removing
   the context switch on DMA buffer map operation.
(Note: this patch-set doesn't include the whole patch-set for enabling
vSVM on virtio-iommu, only includes the part for vIOVA case. However,
the vSVM enabling patch-set needs to base on this patch-set.)

There are three changes in this patch-set:
1) The first patch is a bug fixing patch that tries to resolve an issue
   about IOTLB invalidation request with incorrect page size.
2) The next 3 patches are about adding generic IO page table support to
   VT-d driver.
3) The last one introduces the VT-d page format table to virtio-iommu
   driver.

The patch-set is also available at github:
https://github.com/TinaZhangZW/linux/tree/vt-d-pgtable

The QEMU part is available here:
https://github.com/TinaZhangZW/qemu/tree/virtio-iommu/vt-d-pgtable


[1]:https://lists.oasis-open.org/archives/virtio-comment/202310/msg00018.html
[2]:https://jpbrucker.net/git/linux/log/?h=virtio-iommu/pgtables

Tina Zhang (5):
  iommu/virtio-iommu: Correct the values of granule and nr_pages
  iommu/vt-d: Add generic IO page table support
  iommu/io-pgtable: Introduce struct vtd_cfg
  iommu/vt-d: Adapt alloc_pgtable interface to be used by others
  iommu/virtio-iommu: Support attaching VT-d IO pgtable

 drivers/iommu/intel/Kconfig       |   1 +
 drivers/iommu/intel/iommu.c       | 157 ++++++++++++++++++++++++++++++
 drivers/iommu/intel/iommu.h       |   7 ++
 drivers/iommu/io-pgtable.c        |   3 +
 drivers/iommu/virtio-iommu.c      |  27 ++++-
 include/linux/io-pgtable.h        |   7 ++
 include/uapi/linux/virtio_iommu.h |  26 +++++
 7 files changed, 226 insertions(+), 2 deletions(-)

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2.39.3