[PATCH kernel v10 00/34] powerpc/iommu/vfio: Enable Dynamic DMA windows

Alexey Kardashevskiy aik at ozlabs.ru
Tue May 12 01:38:49 AEST 2015

This enables sPAPR defined feature called Dynamic DMA windows (DDW).

Each Partitionable Endpoint (IOMMU group) has an address range on a PCI bus
where devices are allowed to do DMA. These ranges are called DMA windows.
By default, there is a single DMA window, 1 or 2GB big, mapped at zero
on a PCI bus.

Hi-speed devices may suffer from the limited size of the window.
The recent host kernels use a TCE bypass window on POWER8 CPU which implements
direct PCI bus address range mapping (with offset of 1<<59) to the host memory.

For guests, PAPR defines a DDW RTAS API which allows pseries guests
querying the hypervisor about DDW support and capabilities (page size mask
for now). A pseries guest may request an additional (to the default)
DMA windows using this RTAS API.
The existing pseries Linux guests request an additional window as big as
the guest RAM and map the entire guest window which effectively creates
direct mapping of the guest memory to a PCI bus.

The multiple DMA windows feature is supported by POWER7/POWER8 CPUs; however
this patchset only adds support for POWER8 as TCE tables are implemented
in POWER7 in a quite different way ans POWER7 is not the highest priority.

This patchset reworks PPC64 IOMMU code and adds necessary structures
to support big windows.

Once a Linux guest discovers the presence of DDW, it does:
1. query hypervisor about number of available windows and page size masks;
2. create a window with the biggest possible page size (today 4K/64K/16M);
3. map the entire guest RAM via H_PUT_TCE* hypercalls;
4. switche dma_ops to direct_dma_ops on the selected PE.

Once this is done, H_PUT_TCE is not called anymore for 64bit devices and
the guest does not waste time on DMA map/unmap operations.

Note that 32bit devices won't use DDW and will keep using the default
DMA window so KVM optimizations will be required (to be posted later).

This is pushed to git at github.com:aik/linux.git
 + 4d0247b...3a5fb80 vfio-for-github -> vfio-for-github (forced update)

The pushed branch contains all patches from this patchset and KVM
acceleration patches as well to give an idea about the current state
of in-kernel acceleration support.

* fixed&tested on SRIOV system
* fixed multiple comments from David; started thinking that I might have
to remove all acks and get them again :)
* added bunch of iommu device attachment reworks

* rebased on top of SRIOV (which is in upstream now)
* fixed multiple comments from David
* reworked ownership patches
* removed vfio: powerpc/spapr: Do cleanup when releasing the group (used to be #2)
as updated #1 should do this
* moved "powerpc/powernv: Implement accessor to TCE entry" to a separate patch
* added a patch which moves TCE Kill register address to PE from IOMMU table

* fixed a bug in error fallback in "powerpc/mmu: Add userspace-to-physical
addresses translation cache"
* fixed subject in "vfio: powerpc/spapr: Check that IOMMU page is fully
contained by system page"
* moved v2 documentation to the correct patch
* added checks for failed vzalloc() in "powerpc/iommu: Add userspace view
of TCE table"

* moved memory preregistration to the current process's MMU context
* added code preventing unregistration if some pages are still mapped;
for this, there is a userspace view of the table is stored in iommu_table
* added locked_vm counting for DDW tables (including userspace view of those)

* fixed a bunch of errors in "vfio: powerpc/spapr: Support Dynamic DMA windows"
* moved static IOMMU properties from iommu_table_group to iommu_table_group_ops

* added SPAPR_TCE_IOMMU_v2 to tell the userspace that there is a memory
pre-registration feature
* added backward compatibility
* renamed few things (mostly powerpc_iommu -> iommu_table_group)

* moved patches around to have VFIO and PPC patches separated as much as
* now works with the existing upstream QEMU

* redesigned the whole thing
* multiple IOMMU groups per PHB -> one PHB is needed for VFIO in the guest ->
no problems with locked_vm counting; also we save memory on actual tables
* guest RAM preregistration is required for DDW
* PEs (IOMMU groups) are passed to VFIO with no DMA windows at all so
we do not bother with iommu_table::it_map anymore
* added multilevel TCE tables support to support really huge guests

* added missing __pa() in "powerpc/powernv: Release replaced TCE"
* reposted to make some noise

Alexey Kardashevskiy (34):
  powerpc/eeh/ioda2: Use device::iommu_group to check IOMMU group
  powerpc/iommu/powernv: Get rid of set_iommu_table_base_and_group
  powerpc/powernv/ioda: Clean up IOMMU group registration
  powerpc/iommu: Put IOMMU group explicitly
  powerpc/iommu: Always release iommu_table in iommu_free_table()
  vfio: powerpc/spapr: Move page pinning from arch code to VFIO IOMMU
  vfio: powerpc/spapr: Check that IOMMU page is fully contained by
    system page
  vfio: powerpc/spapr: Use it_page_size
  vfio: powerpc/spapr: Move locked_vm accounting to helpers
  vfio: powerpc/spapr: Disable DMA mappings on disabled container
  vfio: powerpc/spapr: Moving pinning/unpinning to helpers
  vfio: powerpc/spapr: Rework groups attaching
  powerpc/powernv: Do not set "read" flag if direction==DMA_NONE
  powerpc/iommu: Move tce_xxx callbacks from ppc_md to iommu_table
  powerpc/powernv/ioda/ioda2: Rework TCE invalidation in
  powerpc/spapr: vfio: Replace iommu_table with iommu_table_group
  powerpc/spapr: vfio: Switch from iommu_table to new iommu_table_group
  vfio: powerpc/spapr/iommu/powernv/ioda2: Rework IOMMU ownership
  powerpc/iommu: Fix IOMMU ownership control functions
  powerpc/powernv/ioda2: Move TCE kill register address to PE
  powerpc/powernv/ioda2: Add TCE invalidation for all attached groups
  powerpc/powernv: Implement accessor to TCE entry
  powerpc/iommu/powernv: Release replaced TCE
  powerpc/powernv/ioda2: Rework iommu_table creation
  powerpc/powernv/ioda2: Introduce helpers to allocate TCE pages
  powerpc/powernv/ioda2: Introduce pnv_pci_ioda2_set_window
  powerpc/powernv: Implement multilevel TCE tables
  vfio: powerpc/spapr: powerpc/powernv/ioda: Define and implement DMA
    windows API
  powerpc/powernv/ioda2: Use new helpers to do proper cleanup on PE
  powerpc/iommu/ioda2: Add get_table_size() to calculate the size of
    future table
  vfio: powerpc/spapr: powerpc/powernv/ioda2: Use DMA windows API in
    ownership control
  powerpc/mmu: Add userspace-to-physical addresses translation cache
  vfio: powerpc/spapr: Register memory and define IOMMU v2
  vfio: powerpc/spapr: Support Dynamic DMA windows

 Documentation/vfio.txt                      |   50 +-
 arch/powerpc/include/asm/iommu.h            |  117 ++-
 arch/powerpc/include/asm/machdep.h          |   25 -
 arch/powerpc/include/asm/mmu-hash64.h       |    3 +
 arch/powerpc/include/asm/mmu_context.h      |   17 +
 arch/powerpc/include/asm/pci-bridge.h       |    2 +-
 arch/powerpc/kernel/eeh.c                   |    4 +-
 arch/powerpc/kernel/iommu.c                 |  237 +++---
 arch/powerpc/kernel/vio.c                   |    5 +
 arch/powerpc/mm/Makefile                    |    1 +
 arch/powerpc/mm/mmu_context_hash64.c        |    6 +
 arch/powerpc/mm/mmu_context_hash64_iommu.c  |  221 ++++++
 arch/powerpc/platforms/cell/iommu.c         |    8 +-
 arch/powerpc/platforms/pasemi/iommu.c       |    7 +-
 arch/powerpc/platforms/powernv/pci-ioda.c   |  767 ++++++++++++++-----
 arch/powerpc/platforms/powernv/pci-p5ioc2.c |   35 +-
 arch/powerpc/platforms/powernv/pci.c        |  165 ++--
 arch/powerpc/platforms/powernv/pci.h        |   18 +-
 arch/powerpc/platforms/pseries/iommu.c      |  182 +++--
 arch/powerpc/sysdev/dart_iommu.c            |   12 +-
 drivers/vfio/vfio_iommu_spapr_tce.c         | 1095 ++++++++++++++++++++++++---
 include/uapi/linux/vfio.h                   |   88 ++-
 22 files changed, 2457 insertions(+), 608 deletions(-)
 create mode 100644 arch/powerpc/mm/mmu_context_hash64_iommu.c


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