mbox series

[v3,00/10] virtio-iommu: Add ACPI support

Message ID 20210914142004.2433568-1-jean-philippe@linaro.org (mailing list archive)
Headers show
Series virtio-iommu: Add ACPI support | expand

Message

Jean-Philippe Brucker Sept. 14, 2021, 2:19 p.m. UTC 
Allow instantiating a virtio-iommu device on ACPI systems by adding a
Virtual I/O Translation table (VIOT). Enable x86 support for VIOT.

Changes since v2 [1]:
* Use acpi_table_begin() and acpi_table_end().

  This series now depends on "acpi: refactor error prone build_header()
  and packed structures usage in ACPI tables" [2]

* Dropped ACPI header definitions.
* Dropped doc patch, to be revisited later.
* Squashed patch 5.
* Added tests for q35 and virt machines: patch 6 temporarily enables
  blob updates (for bisectability), patch 7 adds the two test cases and
  patches 8-10 add the three reference tables.


There is an important caveat at the moment: when virtio-iommu is
instantiated, device DMA faults until the guest configures the IOMMU.
Firmware is therefore unable to access storage devices and load the
bootloader and OS. Upcoming patches will align virtio-iommu with other
vIOMMUs and let DMA bypass the IOMMU during boot. In the meantime there
are several ways to circumvent the problem:
* Use plain old virtio-blk as storage, without enabling the
  'iommu_platform' property. DMA from the device bypasses the IOMMU.
* Place the storage device behind a PCI bus that bypasses the IOMMU,
  using the new 'bypass_iommu' bridge property.
  See docs/bypass-iommu.txt
* Use non-PCI storage devices, for example virtio-blk-device on the
  arm64 virt machine.

You can find a description of the VIOT table, which will be included in
next ACPI version, here: https://jpbrucker.net/virtio-iommu/viot/viot-v9.pdf

[1] https://lore.kernel.org/qemu-devel/20210903143208.2434284-1-jean-philippe@linaro.org/
[2] https://lore.kernel.org/qemu-devel/20210907144814.741785-1-imammedo@redhat.com/

Jean-Philippe Brucker (10):
  hw/acpi: Add VIOT table
  hw/arm/virt-acpi-build: Add VIOT table for virtio-iommu
  hw/arm/virt: Remove device tree restriction for virtio-iommu
  hw/arm/virt: Reject instantiation of multiple IOMMUs
  pc: Allow instantiating a virtio-iommu device
  tests/acpi: allow updates of VIOT expected data files
  tests/acpi: add test cases for VIOT
  tests/acpi: add expected VIOT blob for virt machine
  tests/acpi: add expected DSDT blob for VIOT test on q35
  tests/acpi: add expected VIOT blob for q35 machine

 hw/acpi/viot.h                 |  13 ++++
 include/hw/i386/pc.h           |   2 +
 hw/acpi/viot.c                 | 112 +++++++++++++++++++++++++++++++++
 hw/arm/virt-acpi-build.c       |   7 +++
 hw/arm/virt.c                  |  15 +++--
 hw/i386/acpi-build.c           |   5 ++
 hw/i386/pc.c                   |  28 ++++++++-
 hw/virtio/virtio-iommu-pci.c   |   7 ---
 tests/qtest/bios-tables-test.c |  39 ++++++++++++
 hw/acpi/Kconfig                |   4 ++
 hw/acpi/meson.build            |   1 +
 hw/arm/Kconfig                 |   1 +
 hw/i386/Kconfig                |   1 +
 tests/data/acpi/q35/DSDT.viot  | Bin 0 -> 9415 bytes
 tests/data/acpi/q35/VIOT.viot  | Bin 0 -> 112 bytes
 tests/data/acpi/virt/VIOT      | Bin 0 -> 88 bytes
 16 files changed, 219 insertions(+), 16 deletions(-)
 create mode 100644 hw/acpi/viot.h
 create mode 100644 hw/acpi/viot.c
 create mode 100644 tests/data/acpi/q35/DSDT.viot
 create mode 100644 tests/data/acpi/q35/VIOT.viot
 create mode 100644 tests/data/acpi/virt/VIOT