[Xen-devel] [PATCH RFC 0/5] pvh: dom0 special memory regions mapping

[Elena Ufimtseva <elena.ufimtseva@xxxxxxxxxx>]

This patch set introduces xen boot option dom0_iommu_rwmem for special
memory regions that are not reported by ACPI as RMRRs and are reserved
in e820 map but require iommu mapping RW permissions (per experiment, only R).
The problem was discovered in few systems. See discussion:
http://lists.xenproject.org/archives/html/xen-devel/2015-01/msg02513.html

The patch set fixes the problem booting dom0 in pvh mode on some machines.
It introduces p2m_sys_rw memory type for these special regions and maps
with RW permissions with vtd iommu. The rmrrs regions are kept in
list rwmem_ranges in hvm_arch structure where rmmrs are also reside.
This may not be plausible solution and comments and suggestions are welcome.

The patch set is split in 5 patches:

- iommu: need_iommu set early
        sets need_iommu early so dom0 pvh specific functions can take this
        into account and perform proper iommu mapping;
- p2m: introduce misc type p2m_sys_rw for mmio rw mappings
        p2m_sys_rw type introduces to provide correct mapping permissions and
        distinguish from other types;
- pvh: add rwmem_ranges to keep mapped special regions
        to keep special regions in arch_hvm_iommu.
- pvh: dom0 add rw mapping for dom0_iommu_rwmem boot opt
        sets correct permissions for ept entry corresponding to specified
        region;
- pvh: dom0 boot option to specify iommu rw ranges
        defines boot option and parses it into the list of of rwmem_ranges;

Your comments and suggestions are welcome as there is a room for improvement
and desire to be in sync with other design proposals as rmmrs design.

Elena Ufimtseva (5):
  iommu: need_iommu set early
  p2m: introduce misc type p2m_sys_rw for mmio rw mappings
  pvh: add rwmem_ranges to keep mapped special regions
  pvh: dom0 add rw mapping for dom0_iommu_rwmem boot opt
  pvh: dom0 boot option to specify iommu rw ranges

 xen/arch/x86/domain_build.c         |   50 +++++++++++++++++++++++++++++++
 xen/arch/x86/mm/p2m-ept.c           |    7 +++--
 xen/arch/x86/mm/p2m.c               |    2 +-
 xen/drivers/passthrough/iommu.c     |   55 ++++++++++++++++++++++++++++++++++-
 xen/drivers/passthrough/vtd/iommu.c |    7 +++++
 xen/drivers/passthrough/x86/iommu.c |    1 +
 xen/include/asm-x86/hvm/iommu.h     |    2 ++
 xen/include/asm-x86/p2m.h           |    5 +++-
 xen/include/xen/iommu.h             |    5 ++++
 9 files changed, 128 insertions(+), 6 deletions(-)

-- 
1.7.10.4


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