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>

diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c
index 95b81c18b6bce844a194b6239a7548a7f7f71d8b..0c34ff49ff4d1f50f0c9a8837f7470e702311fa0 100644 (file)
--- 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;