[Xen-devel] [PATCH v2 0/2] map grant refs at pfn = mfn

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

Hi all,
this patch series introduces a second p2m mapping of grant reference on
ARM at guest physical address == machine address of the grant ref.  It
is safe because dom0 is already mapped 1:1. We export
XENFEAT_grant_map_identity to signal the guest that this second p2m
mapping is
available.

One reason for wanting the second p2m mapping is to avoid tracking mfn
to pfn mappings in the guest kernel. Since the same mfn can be granted
multiple times to the backend, finding the right pfn corresponding to a
given mfn can be difficult and expensive. Providing a second mapping at
a known address allow the kernel to access the page without knowing the
pfn.



Stefano Stabellini (2):
      xen: introduce arch_iommu_grant_(un)map_page
      xen/arm: introduce XENFEAT_grant_map_identity

 xen/arch/arm/p2m.c            |   19 +++++++++++++++++++
 xen/common/grant_table.c      |   35 +++++++++++++++++++++++++++--------
 xen/common/kernel.c           |    2 ++
 xen/include/asm-arm/p2m.h     |    4 ++++
 xen/include/asm-x86/p2m.h     |   13 +++++++++++++
 xen/include/public/features.h |    3 +++
 6 files changed, 68 insertions(+), 8 deletions(-)

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