Re: [Qemu-devel] [PATCH v2 0/2] intel_iommu: Add support for translation for devices behind bridges

[Marcel Apfelbaum <marcel.apfelbaum@gmail.com>]

On 09/01/2015 09:48 PM, Knut Omang wrote:
> This patch set changes the data structure used to handle address spaces within
> the emulated Intel iommu to support traversal also if bus numbers are dynamically
> allocated, as is the case for devices that sit behind root ports or downstream switches.
> This means that we cannot use bus number as index, instead a QLIST is used.
>
> This requires a change in the API for setup of IOMMUs which is taken care of by
> the first patch. The second patch implements the fix.
>
> The initial patch set had some discussion related to whether this fix, applied to the
> bridge code, was applicable to all bridges. No clear conclusion arised as far as I understood,
> in the meantime a number of people have run into the same issue as I did which lead me
> to implement this, so I gather it might be a useful intermediate solution that works until
> a better approach can be found? I believe the IOMMU emulation code has limited usefulness
> if it only supports devices sitting directly on the root complex.
Hi,

Thank you for (re)sending the patches!

While I believe you are perfectly right and IOMMU
would benefit from this addition, I saw that are some reviews
in the  prev thread that are not purely theoretical/philosophical.
E.g. PCIDevice *dev field in VTDAddressSpace and maybe a few more.

I would suggest to address them so it will be easier to continue the review process.

Thank you,
Marcel

>
> This is the thread following the initial patch set:
>
>    http://thread.gmane.org/gmane.comp.emulators.qemu/302246
>
> The patch set was also discussed in this thread:
>
>    http://thread.gmane.org/gmane.comp.emulators.qemu/316949
>
> Changes from v1:
>    - Rebased to current master
>    - Fixed minor syntax issues
>
> Knut Omang (2):
>    iommu: Replace bus+devfn arguments with PCIDevice* in PCIIOMMUFunc
>    intel_iommu: Add support for translation for devices behind bridges.
>
>   hw/alpha/typhoon.c            |  2 +-
>   hw/i386/intel_iommu.c         | 56 +++++++++++++++++++------------------------
>   hw/pci-host/apb.c             |  2 +-
>   hw/pci-host/prep.c            |  3 +--
>   hw/pci-host/q35.c             | 42 +++++++++++++-------------------
>   hw/pci/pci.c                  |  7 +++---
>   hw/pci/pci_bridge.c           |  6 +++++
>   hw/ppc/spapr_pci.c            |  2 +-
>   include/hw/i386/intel_iommu.h |  6 +++--
>   include/hw/pci/pci.h          |  5 +++-
>   10 files changed, 62 insertions(+), 69 deletions(-)
>
> --
> 2.4.3
>