On ARM, mfn_to_gfn() is defined as an identity macro that unconditionally
returns the MFN as the GFN. This is incorrect for any non-direct-mapped domain.

It only has two call sites: getdomaininfo() and memory_exchange().
It causes getdomaininfo() to report the wrong shared_info_frame on ARM,
breaking any toolstack or test that relies on it. While as steal_page() is not
supported on arm, the error does not propagate to memory_exchange().

This series fixes the problem in the following steps:

- Generalize the existing per-page GFN storage in type_info so it is
  usable beyond xenheap pages.
- Introduce a shared_info_to_gfn() macro so getdomaininfo() switches to
  use page_get_xenheap_gfn() on ARM and still mfn_to_gfn() on x86
- Fix memory_exchange() to use page_set_gfn()/page_get_gfn(), which generalize
  the existing page_set_xenheap_gfn()/page_get_xenheap_gfn() from xenheap
  pages, instead of mfn_to_gfn() on ARM for stolen pages.

With all the above modification, we could remove the now-unused mfn_to_gfn()
macro on ARM.

Penny Zheng (3):
  xen/arm: generalize per-page GFN storage beyond xenheap pages
  xen: introduce shared_info_to_gfn()
  xen/arm: fix mfn_to_gfn() usage in memory_exchange()

 xen/arch/arm/include/asm/mm.h  | 40 +++++++++++++++++++++++-----------
 xen/arch/x86/include/asm/p2m.h |  3 +++
 xen/common/domctl.c            |  3 +--
 xen/common/memory.c            | 11 ++++++++++
 4 files changed, 42 insertions(+), 15 deletions(-)

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2.34.1