Re: [Xen-devel] [RFC PATCH 0/7] Implement Xen PV-IOMMU interface

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

On Wed, Feb 10, 2016 at 10:33:24AM +0000, Malcolm Crossley wrote:
> This RFC series implements the PV-IOMMU interface according to the PV-IOMMU
> design draft D.
> 
> The PV-IOMMU interface is currently restricted to being used by the hardware
> domain only as non hardware domain callers have not been fully tested yet.
> 
> Significant effort was put into implementing a m2b tracking structure without
> increasing the size of struct page but no union was found that could be safely
> used in all cases when a page is allocated to an HVM domain. Comments and
> feedback on the m2b design are most welcome.
> 
> The hardware domain specific IOMMU pre map mechanism was implemented in order
> to keep performance parity with current out of tree mechanisms to obtain BFNs
> for foreign guest owned memory. The pre map mechanism is not a weakening of
> the current security model of Xen and is only allowed when the hardware domain
> is allowed relaxed IOMMU mappings.

I would recommend you add to this patchset:

- docs/misc/pv-iommu.txt describing the design of this.
- Add yourself to the maintainers file for this code: xen/common/pv_iommu? 
perhaps?
- Compile this under ARM as well - and figure out what is missing there?
- Add an KConfig entry so folks have the option of not compiling the Xen
  hypervisor with this?
- Have these patches in a git tree for easier testing.

> 
> 
> Malcolm Crossley (7):
>   common/pv-iommu: Add stub hypercall for PV-IOMMU
>   iommu: add iommu_lookup_page to lookup guest gfn for a particular
>     IOMMU mapping
>   VT-d: Add iommu_lookup_page support
>   common/pv-iommu: Add query, map and unmap ops
>   x86/m2b: Add a tracking structure for mfn to bfn mappings per page
>   common/pv-iommu: Add foreign ops to PV-IOMMU interface
>   common/pv-iommu: Allow hardware_domain to pre IOMMU map foreign
>     memory
> 
>  xen/arch/x86/domain.c               |  12 +-
>  xen/arch/x86/mm/Makefile            |   1 +
>  xen/arch/x86/mm/m2b.c               | 211 ++++++++++++
>  xen/arch/x86/x86_64/compat/entry.S  |   2 +
>  xen/arch/x86/x86_64/entry.S         |   2 +
>  xen/common/Makefile                 |   1 +
>  xen/common/memory.c                 |  11 +
>  xen/common/pv_iommu.c               | 633 
> ++++++++++++++++++++++++++++++++++++
>  xen/drivers/passthrough/iommu.c     |  21 ++
>  xen/drivers/passthrough/vtd/iommu.c |  31 ++
>  xen/drivers/passthrough/vtd/iommu.h |   1 +
>  xen/include/asm-x86/domain.h        |   1 +
>  xen/include/asm-x86/m2b.h           |  65 ++++
>  xen/include/asm-x86/mm.h            |  12 +-
>  xen/include/public/hvm/ioreq.h      |   1 +
>  xen/include/public/pv-iommu.h       |  93 ++++++
>  xen/include/public/xen.h            |   1 +
>  xen/include/xen/iommu.h             |   2 +
>  xen/include/xen/sched.h             |   4 +
>  xen/include/xsm/dummy.h             |   6 +
>  xen/include/xsm/xsm.h               |   6 +
>  xen/xsm/dummy.c                     |   1 +
>  22 files changed, 1116 insertions(+), 2 deletions(-)
>  create mode 100644 xen/arch/x86/mm/m2b.c
>  create mode 100644 xen/common/pv_iommu.c
>  create mode 100644 xen/include/asm-x86/m2b.h
>  create mode 100644 xen/include/public/pv-iommu.h
> 
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