Documentation/memory-layout.txt

   1 Memory Layout of the Jailhouse Hypervisor
   2 =========================================
   3
   4 While the hypervisor is running, two memory regions are visible in its address
   5 space: the hypervisor region and the remapping region. Jailhouse cells are not
   6 mapped into the hypervisor's address space, with the exception of explicitly
   7 shared pages and pages that are temporarily mapped, e.g. during MMIO instruction
   8 parsing.
   9
  10
  11 Hypervisor region
  12 -----------------
  13
  14 The hypervisor region contains both code and data of the hypervisor. It
  15 consists of contiguous physical RAM, mapped at a fixed virtual address, both
  16 in the hypervisor and the Linux address space. This identical mapping is
  17 required during startup and shutdown of the hypervisor.
  18
  19 Virtual address: JAILHOUSE_BASE
  20 Size: as defined in the system configuration (see hypervisor_memory.size) [1]
  21
  22         +--------------------------------------+ - lower address
  23         | Header [2]                           |
  24         +--------------------------------------+
  25         | Text Segment                         |
  26         |                                      |
  27         |                                      |
  28         +--------------------------------------+
  29         | Read-only Data Segment               |
  30         |                                      |
  31         +--------------------------------------+
  32         | Data Segment                         |
  33         |                                      |
  34         +--------------------------------------+
  35         | BSS Segment                          |
  36         |                                      |
  37         +--------------------------------------+
  38         | Page +-----------------------------+ |
  39         | Pool | Per-CPU Data                | |
  40         |      |                             | |
  41         |      |                             | |
  42         |      +-----------------------------+ |
  43         |      | System Config               | |
  44         |      |                             | |
  45         |      +-----------------------------+ |
  46         |      | Page Pool Allocation Bitmap | |
  47         |      +-----------------------------+ |
  48         |      | Dynamic Page Pool           | |
  49         :      :                             : :
  50         :      :                             : :
  51         |      |                             | |
  52         |      +-----------------------------+ |
  53         +--------------------------------------+ - higher address
  54
  55
  56 Remapping region
  57 ----------------
  58
  59 The remapping region is a range of reserved virtual memory in the hypervisor
  60 address space. It is used to map MMIO, platform configuration memory (ACPI on
  61 x86) and, temporarily, selected guest pages for hypervisor access.
  62
  63 Virtual address: REMAP_BASE
  64 Size: PAGE_SIZE * NUM_REMAP_BITMAP_PAGES * PAGE_SIZE * 8
  65
  66         +--------------------------------------+ - lower address
  67         | Per-CPU Temporary Mapping Region     |
  68         |                                      |
  69         +--------------------------------------+
  70         | Dynamic Remapping Page pool          |
  71         :                                      :
  72         :                                      :
  73         |                                      |
  74         +--------------------------------------+ - higher address
  75
  76
  77 References
  78 ----------
  79
  80 [1] Documentation/configuration-format.txt
  81 [2] Documentation/bootstrap-interface.txt