x86: make e820_update_range() handle small range update

Impact: enhance e820 code to handle more cases

Try to handle new range which could be covered by one entry.

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Cc: jbeulich@novell.com
LKML-Reference: <49B9F0C1.10402@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 19 insertions, 4 deletions

diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c
index 95b81c18b6bc..0c34ff49ff4d 100644
--- a/arch/x86/kernel/e820.c
+++ b/arch/x86/kernel/e820.c
@@ -427,6 +427,7 @@ static u64 __init __e820_update_range(struct e820map *e820x, u64 start,
                                         u64 size, unsigned old_type,
                                         unsigned new_type)
 {
+        u64 end;
         unsigned int i;
         u64 real_updated_size = 0;
 
@@ -435,21 +436,35 @@ static u64 __init __e820_update_range(struct e820map *e820x, u64 start,
         if (size > (ULLONG_MAX - start))
                 size = ULLONG_MAX - start;
 
+        end = start + size;
         for (i = 0; i < e820x->nr_map; i++) {
                 struct e820entry *ei = &e820x->map[i];
                 u64 final_start, final_end;
+                u64 ei_end;
+
                 if (ei->type != old_type)
                         continue;
-                /* totally covered? */
-                if (ei->addr >= start &&
-                    (ei->addr + ei->size) <= (start + size)) {
+
+                ei_end = ei->addr + ei->size;
+                /* totally covered by new range? */
+                if (ei->addr >= start && ei_end <= end) {
                         ei->type = new_type;
                         real_updated_size += ei->size;
                         continue;
                 }
+
+                /* new range is totally covered? */
+                if (ei->addr < start && ei_end > end) {
+                        __e820_add_region(e820x, start, size, new_type);
+                        __e820_add_region(e820x, end, ei_end - end, ei->type);
+                        ei->size = start - ei->addr;
+                        real_updated_size += size;
+                        continue;
+                }
+
                 /* partially covered */
                 final_start = max(start, ei->addr);
-                final_end = min(start + size, ei->addr + ei->size);
+                final_end = min(end, ei_end);
                 if (final_start >= final_end)
                         continue;