Re: [Qemu-devel] [RFC PATCH 00/10] spapr: vfio: Enable Dynamic DMA windows (DDW)

[Alexey Kardashevskiy <aik@ozlabs.ru>]

On 07/31/2014 07:34 PM, Alexey Kardashevskiy wrote:
> At the moment sPAPR PHB supports only a single 32bit window
> which is normally 1..2GB which is not enough for high performance devices.
> 
> PAPR spec enables creating an additional window(s) to support 64bit
> DMA and bigger page sizes.
> 
> This patchset adds DDW support for pseries. The host kernel changes are
> required.
> 
> This was tested on POWER8 system which allows one additional DMA window
> which is mapped at 0x800.0000.0000.0000 and supports 16MB pages.
> Existing guests check for DDW capabilities in PHB's device tree and if it
> is present, they request for an additional window and map entire guest RAM
> using H_PUT_TCE/... hypercalls once at boot time and switch to direct DMA
> operations.
> 
> TCE tables still may be big enough for guests backed with 64K pages but they
> are reasonably small for guests backed by 16MB pages.
> 
> Please comment. Thanks!


Alexander Graf, ping!



> Alexey Kardashevskiy (10):
>   qom: Make object_child_foreach safe for objects removal
>   spapr_iommu: Disable in-kernel IOMMU tables for >4GB windows
>   spapr_pci: Make find_phb()/find_dev() public
>   spapr_iommu: Make spapr_tce_find_by_liobn() public
>   linux headers update for DDW
>   spapr_rtas: Add Dynamic DMA windows (DDW) RTAS calls support
>   spapr: Add "ddw" machine option
>   spapr_pci: Enable DDW
>   spapr_pci_vfio: Enable DDW
>   vfio: Enable DDW ioctls to VFIO IOMMU driver
> 
>  hw/misc/vfio.c              |   4 +
>  hw/ppc/Makefile.objs        |   3 +
>  hw/ppc/spapr.c              |  15 +++
>  hw/ppc/spapr_iommu.c        |   8 +-
>  hw/ppc/spapr_pci.c          |  87 +++++++++++--
>  hw/ppc/spapr_pci_vfio.c     |  75 +++++++++++
>  hw/ppc/spapr_rtas_ddw.c     | 296 ++++++++++++++++++++++++++++++++++++++++++++
>  include/hw/pci-host/spapr.h |  27 ++++
>  include/hw/ppc/spapr.h      |   7 +-
>  linux-headers/linux/vfio.h  |  37 +++++-
>  qom/object.c                |   4 +-
>  trace-events                |   4 +
>  vl.c                        |   4 +
>  13 files changed, 552 insertions(+), 19 deletions(-)
>  create mode 100644 hw/ppc/spapr_rtas_ddw.c
> 


-- 
Alexey