[MINI-OS PATCH 10/19] e820: use special type for software reserved memory

[Juergen Gross <jgross@xxxxxxxx>]

For memory areas used to map foreign domain memory Mini-OS is using
the type E820_RESERVED in the memory map today. This is causing
problems with kexec, as the new kernel should not see those areas in
the memory map. Unfortunately the sequence of actions for calculating
the size of the memory map and the removal of those reserved areas
can't easily be adjusted to do the removal first, so another way must
be used to avoid passing those reserved areas to the new kernel.

Instead of using the type E820_RESERVED, which might be used for other
pages as well, just use a new type. Areas with that new type can
easily be filtered out when building the memory map for the new
kernel.

Introduce the type E820_TYPE_SOFT_RESERVED with the same value as the
Linux kernel is using for the same purpose.

Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
---
 arch/x86/kexec.c | 4 +++-
 e820.c           | 8 ++++----
 include/e820.h   | 2 ++
 3 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kexec.c b/arch/x86/kexec.c
index 3e3b64e2..804e7b6d 100644
--- a/arch/x86/kexec.c
+++ b/arch/x86/kexec.c
@@ -240,14 +240,16 @@ int kexec_get_entry(const char *cmdline)
 
     mmap = next;
     info->memmap_paddr = kexec_param_loc + (unsigned long)next - 
kexec_param_mem;
-    info->memmap_entries = e820_entries;
     for ( i = 0; i < e820_entries; i++ )
     {
+        if ( e820_map[i].type == E820_TYPE_SOFT_RESERVED )
+            continue;
         mmap->addr = e820_map[i].addr;
         mmap->size = e820_map[i].size;
         mmap->type = e820_map[i].type;
         mmap++;
     }
+    info->memmap_entries = mmap - (struct hvm_memmap_table_entry *)next;
     next = mmap;
 
     info->cmdline_paddr = kexec_param_loc + (unsigned long)next - 
kexec_param_mem;
diff --git a/e820.c b/e820.c
index 876d55b1..d8cfb1f4 100644
--- a/e820.c
+++ b/e820.c
@@ -367,8 +367,8 @@ unsigned long e820_get_reserved_pfns(int pages)
     for ( i = 0; i < e820_entries && e820_map[i].addr < last + needed; i++ )
         last = e820_map[i].addr + e820_map[i].size;
 
-    if ( i == 0 || e820_map[i - 1].type != E820_RESERVED )
-        e820_insert_entry_at(i, last, needed, E820_RESERVED);
+    if ( i == 0 || e820_map[i - 1].type != E820_TYPE_SOFT_RESERVED )
+        e820_insert_entry_at(i, last, needed, E820_TYPE_SOFT_RESERVED);
     else
         e820_map[i - 1].size += needed;
 
@@ -385,7 +385,7 @@ void e820_put_reserved_pfns(unsigned long start_pfn, int 
pages)
           i < e820_entries && addr >= e820_map[i].addr + e820_map[i].size;
           i++ );
 
-    BUG_ON(i == e820_entries || e820_map[i].type != E820_RESERVED ||
+    BUG_ON(i == e820_entries || e820_map[i].type != E820_TYPE_SOFT_RESERVED ||
            addr + size > e820_map[i].addr + e820_map[i].size);
 
     if ( addr == e820_map[i].addr )
@@ -405,7 +405,7 @@ void e820_put_reserved_pfns(unsigned long start_pfn, int 
pages)
 
     e820_insert_entry_at(i + 1, addr + size,
                          e820_map[i].addr + e820_map[i].size - addr - size,
-                         E820_RESERVED);
+                         E820_TYPE_SOFT_RESERVED);
     e820_map[i].size = addr - e820_map[i].addr;
 }
 #endif
diff --git a/include/e820.h b/include/e820.h
index ffa15aa9..ad5657ff 100644
--- a/include/e820.h
+++ b/include/e820.h
@@ -39,6 +39,8 @@
 #define E820_DISABLED     6
 #define E820_PMEM         7
 #define E820_TYPES        8
+/* Memory reserved for Mini-OS internal purpose. */
+#define E820_TYPE_SOFT_RESERVED   0xefffffff
 
 struct __packed e820entry {
     uint64_t addr;
-- 
2.43.0