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[Xen-devel] [Patch V3] support guest virtual mapped p2m list

The x86 struct arch_shared_info field pfn_to_mfn_frame_list_list
currently contains the mfn of the top level page frame of the 3 level
p2m tree, which is used by the Xen tools during saving and restoring
(and live migration) of pv domains and for crash dump analysis. With
three levels of the p2m tree it is possible to support up to 512 GB of
RAM for a 64 bit pv domain.

A 32 bit pv domain can support more, as each memory page can hold 1024
instead of 512 entries, leading to a limit of 4 TB.

To be able to support more RAM on x86-64 switch to a virtual mapped
p2m list.

Changes in V3:
- removed XENFEAT_virtual_p2m completely as the linear p2m list and the
  3 level p2m tree can be used in parallel unless the domain size exceeds
  the limit mentioned above
- updated comments to reflect the parallel use of both p2m schemes

Changes in V2:
- add new structure member p2m_generation in arch_shared_info
- rename structure member referencing the p2m address space to p2m_cr3
- add some comments
- removed patches 2-4 as overriding missing XENFEAT_virtual_p2m will be
  done via kernel parameter (patch 2 will be resent after Xen 4.5 is out)

Juergen Gross (1):
  expand x86 arch_shared_info to support linear p2m list

 xen/include/public/arch-x86/xen.h | 36 +++++++++++++++++++++++++++++++++---
 1 file changed, 33 insertions(+), 3 deletions(-)


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