xen/arm: Enlarge identity map space to 10TB

xen/arm: Enlarge identity map space to 10TB

On ADLink AVA platform (Ampere Altra SoC with 32 Arm Neoverse N1 cores),
the physical memory regions are:

  DRAM memory regions:
    Node[0] Region[0]: 0x000080000000 - 0x0000ffffffff
    Node[0] Region[1]: 0x080000000000 - 0x08007fffffff
    Node[0] Region[2]: 0x080100000000 - 0x0807ffffffff

The UEFI loads Xen hypervisor and DTB into the high memory, the kernel
and ramdisk images are loaded into the low memory space:

  (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 8TB, which exceeds the
maximum supported identity map space of 2TB in Xen. Consequently, the
system fails to boot.

This patch enlarges identity map space to 10TB, allowing module loading
within the range of [0x0 .. 0x000009ff_ffff_ffff].

Fixes: 1c78d76b67 ("xen/arm64: mm: Introduce helpers to prepare/enable/disable")
Reported-by: Alexey Klimov <alexey.klimov@linaro.org>
Signed-off-by: Leo Yan <leo.yan@linaro.org>
Tested-by: Henry Wang <Henry.Wang@arm.com>
Release-acked-by: Henry Wang <Henry.Wang@arm.com>
Reviewed-by: Michal Orzel <michal.orzel@amd.com>
Reviewed-by: Bertrand Marquis <bertrand.marquis@arm.com>