[PATCH v1 2/2] xen/arm: Enlarge identity map space to 127TiB

[Leo Yan <leo.yan@xxxxxxxxxx>]

On some platforms, the memory regions could be:

  (XEN) MODULE[0]: 00000807f6df0000 - 00000807f6f3e000 Xen
  (XEN) MODULE[1]: 00000807f8054000 - 00000807f8056000 Device Tree
  (XEN) MODULE[2]: 00000000fa834000 - 00000000fc5de1d5 Ramdisk
  (XEN) MODULE[3]: 00000000fc5df000 - 00000000ffb3f810 Kernel

In this case, the Xen binary is loaded above 2TB, so Xen fails to boot
up due to the out of the identity map space.

This patch enlarges identity map space to 127TiB, which can support the
memory space [0x0 .. 0x00007eff_ffff_ffff], thus it has flexibility for
support different platforms.

Fixes: 1c78d76b67 ("xen/arm64: mm: Introduce helpers to prepare/enable/disable")
Reported-by: Alexey Klimov <alexey.klimov@xxxxxxxxxx>
Signed-off-by: Leo Yan <leo.yan@xxxxxxxxxx>
---
 xen/arch/arm/include/asm/config.h | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/xen/arch/arm/include/asm/config.h 
b/xen/arch/arm/include/asm/config.h
index 21f4e68a40..3e97c95b57 100644
--- a/xen/arch/arm/include/asm/config.h
+++ b/xen/arch/arm/include/asm/config.h
@@ -87,11 +87,11 @@
  *   2G -   4G   Domheap: on-demand-mapped
  *
  * ARM64 layout:
- * 0x0000000000000000 - 0x000001ffffffffff (2TB, L0 slots [0..3])
+ * 0x0000000000000000 - 0x00007effffffffff (127TB, L0 slots [0..253])
  *
  *  Reserved to identity map Xen
  *
- * 0x0000020000000000 - 0x0000027fffffffff (512GB, L0 slot [4])
+ * 0x000007f000000000 - 0x00007fffffffffff (1TB, L0 slot [254..255])
  *  (Relative offsets)
  *   0  -   2M   Unmapped
  *   2M -  10M   Xen text, data, bss
@@ -103,9 +103,6 @@
  *
  *  32G -  64G   Frametable: 56 bytes per page for 2TB of RAM
  *
- * 0x0000028000000000 - 0x00007fffffffffff (125TB, L0 slots [5..255])
- *  Unused
- *
  * 0x0000800000000000 - 0x000084ffffffffff (5TB, L0 slots [256..265])
  *  1:1 mapping of RAM
  *
@@ -117,7 +114,7 @@
 #define XEN_VIRT_START          _AT(vaddr_t, MB(2))
 #else
 
-#define IDENTITY_MAPPING_AREA_NR_L0    4
+#define IDENTITY_MAPPING_AREA_NR_L0    254
 #define XEN_VM_MAPPING                 SLOT0(IDENTITY_MAPPING_AREA_NR_L0)
 
 #define SLOT0_ENTRY_BITS  39
-- 
2.39.2