[PATCH v4 09/11] Revert "xen/arm: Remove unused BOOT_RELOC_VIRT_START"

[Carlo Nonato <carlo.nonato@xxxxxxxxxxxxxxx>]

This reverts commit 0c18fb76323bfb13615b6f13c98767face2d8097 (not clean).

This is not a clean revert since the rework of the memory layout, but it is
sufficiently similar to a clean one.
The only difference is that the BOOT_RELOC_VIRT_START must match the new
layout.

Cache coloring support for Xen needs to relocate Xen code and data in a new
colored physical space. The BOOT_RELOC_VIRT_START will be used as the virtual
base address for a temporary mapping to this new space.

Signed-off-by: Carlo Nonato <carlo.nonato@xxxxxxxxxxxxxxx>
Signed-off-by: Marco Solieri <marco.solieri@xxxxxxxxxxxxxxx>
---
 xen/arch/arm/include/asm/config.h | 4 +++-
 xen/arch/arm/mm.c                 | 1 +
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/xen/arch/arm/include/asm/config.h 
b/xen/arch/arm/include/asm/config.h
index c5d407a749..5359acd529 100644
--- a/xen/arch/arm/include/asm/config.h
+++ b/xen/arch/arm/include/asm/config.h
@@ -96,7 +96,8 @@
  *   2M -   4M   Xen text, data, bss
  *   4M -   6M   Fixmap: special-purpose 4K mapping slots
  *   6M -  10M   Early boot mapping of FDT
- *  10M -  12M   Livepatch vmap (if compiled in)
+ *  10M -  12M   Early relocation address (used when relocating Xen)
+ *               and later for livepatch vmap (if compiled in)
  *
  *   1G -   2G   VMAP: ioremap and early_ioremap
  *
@@ -133,6 +134,7 @@
 #define BOOT_FDT_VIRT_START     (FIXMAP_VIRT_START + FIXMAP_VIRT_SIZE)
 #define BOOT_FDT_VIRT_SIZE      _AT(vaddr_t, MB(4))
 
+#define BOOT_RELOC_VIRT_START   (BOOT_FDT_VIRT_START + BOOT_FDT_VIRT_SIZE)
 #ifdef CONFIG_LIVEPATCH
 #define LIVEPATCH_VMAP_START    (BOOT_FDT_VIRT_START + BOOT_FDT_VIRT_SIZE)
 #define LIVEPATCH_VMAP_SIZE    _AT(vaddr_t, MB(2))
diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c
index b9c698088b..7015a0f841 100644
--- a/xen/arch/arm/mm.c
+++ b/xen/arch/arm/mm.c
@@ -145,6 +145,7 @@ static void __init __maybe_unused build_assertions(void)
     /* 2MB aligned regions */
     BUILD_BUG_ON(XEN_VIRT_START & ~SECOND_MASK);
     BUILD_BUG_ON(FIXMAP_ADDR(0) & ~SECOND_MASK);
+    BUILD_BUG_ON(BOOT_RELOC_VIRT_START & ~SECOND_MASK);
     /* 1GB aligned regions */
 #ifdef CONFIG_ARM_32
     BUILD_BUG_ON(XENHEAP_VIRT_START & ~FIRST_MASK);
-- 
2.34.1