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From: Yinghai Lu on 30 Mar 2010 22:30
Rusty found on lguest with trim_bios_range, max_pfn is not right anymore, and
looks e820_remove_range does not work right.

[ 0.000000] BIOS-provided physical RAM map:
[ 0.000000] LGUEST: 0000000000000000 - 0000000004000000 (usable)
[ 0.000000] Notice: NX (Execute Disable) protection missing in CPU or disabled in BIOS!
[ 0.000000] DMI not present or invalid.
[ 0.000000] last_pfn = 0x3fa0 max_arch_pfn = 0x100000
[ 0.000000] init_memory_mapping: 0000000000000000-0000000003fa0000

root cause is: the e820_remove_range doesn't handle that all cover case.
e820_remove_range(BIOS_START, BIOS_END - BIOS_start, ,,)
get miss one left range.

Make that is corresponding to e820_update_range() to handle that case too.

Reported-by: Rusty Russell <rusty(a)rustcorp.com.au>
Signed-off-by: Yinghai Lu <yinghai(a)kernel.org>
---
arch/x86/kernel/e820.c | 24 ++++++++++++++++++++----
1 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c
index 740b440..7bca3c6 100644
--- a/arch/x86/kernel/e820.c
+++ b/arch/x86/kernel/e820.c
@@ -519,29 +519,45 @@ u64 __init e820_remove_range(u64 start, u64 size, unsigned old_type,
printk(KERN_DEBUG "e820 remove range: %016Lx - %016Lx ",
(unsigned long long) start,
(unsigned long long) end);
- e820_print_type(old_type);
+ if (checktype)
+ e820_print_type(old_type);
printk(KERN_CONT "\n");

for (i = 0; i < e820.nr_map; i++) {
struct e820entry *ei = &e820.map[i];
u64 final_start, final_end;
+ u64 ei_end;

if (checktype && ei->type != old_type)
continue;
+
+ ei_end = ei->addr + ei->size;
/* totally covered? */
- if (ei->addr >= start &&
- (ei->addr + ei->size) <= (start + size)) {
+ if (ei->addr >= start && ei_end <= end) {
real_removed_size += ei->size;
memset(ei, 0, sizeof(struct e820entry));
continue;
}
+
+ /* new range is totally covered? */
+ if (ei->addr < start && ei_end > end) {
+ e820_add_region(end, ei_end - end, ei->type);
+ ei->size = start - ei->addr;
+ real_removed_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;
real_removed_size += final_end - final_start;

+ /*
+ * left range could be head or tail, so need to update
+ * size at first.
+ */
ei->size -= final_end - final_start;
if (ei->addr < final_start)
continue;
--
1.6.4.2

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