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Commit 9f3a5f52 authored by Yinghai Lu's avatar Yinghai Lu Committed by H. Peter Anvin
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x86: Make e820_remove_range to handle all covered case 



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 the all covered
case.  e820_remove_range(BIOS_START, BIOS_END - BIOS_START, ...)
produces a bogus range as a result.

Make it match e820_update_range() by handling that case too.

Reported-by: default avatarRusty Russell <rusty@rustcorp.com.au>
Signed-off-by: default avatarYinghai Lu <yinghai@kernel.org>
Tested-by: default avatarRusty Russell <rusty@rustcorp.com.au>
LKML-Reference: <4BB18E55.6090903@kernel.org>
Signed-off-by: default avatarH. Peter Anvin <hpa@zytor.com>
parent 8ae06d22

arch/x86/kernel/e820.c

+20 −4
Original line number Diff line number Diff line
@@ -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);

	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;