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Commit 20651af9 authored by Yinghai Lu's avatar Yinghai Lu Committed by Ingo Molnar
Browse files

x86: fix mttr trimming 



Pavel Emelyanov reported that his networking card did not work
and bisected it down to:

"
The commit

  093af8d7
  x86_32: trim memory by updating e820

broke my e1000 card: on loading driver says that

  e1000: probe of 0000:04:03.0 failed with error -5

and the interface doesn't appear.
"

on a 32-bit kernel, base will overflow when try to do PAGE_SHIFT,
and highest_addr will always less 4G.

So use pfn instead of address to avoid the overflow when more than
4g RAM is installed on a 32-bit kernel.

Many thanks to Pavel Emelyanov for reporting and testing it.

Bisected-by: default avatarPavel Emelyanov <xemul@openvz.org>
Signed-off-by: default avatarYinghai Lu <yinghai.lu@sun.com>
Tested-by: default avatarPavel Emelyanov <xemul@openvz.org>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 971a52d6

arch/x86/kernel/cpu/mtrr/main.c

+9 −10
Original line number Diff line number Diff line
@@ -659,7 +659,7 @@ static __init int amd_special_default_mtrr(void) 
 */

int __init mtrr_trim_uncached_memory(unsigned long end_pfn)

{

	unsigned long i, base, size, highest_addr = 0, def, dummy;

	unsigned long i, base, size, highest_pfn = 0, def, dummy;

	mtrr_type type;

	u64 trim_start, trim_size;
@@ -682,28 +682,27 @@ int __init mtrr_trim_uncached_memory(unsigned long end_pfn) 
		mtrr_if->get(i, &base, &size, &type);

		if (type != MTRR_TYPE_WRBACK)

			continue;

		base <<= PAGE_SHIFT;

		size <<= PAGE_SHIFT;

		if (highest_addr < base + size)

			highest_addr = base + size;

		if (highest_pfn < base + size)

			highest_pfn = base + size;

	}



	/* kvm/qemu doesn't have mtrr set right, don't trim them all */

	if (!highest_addr) {

	if (!highest_pfn) {

		printk(KERN_WARNING "WARNING: strange, CPU MTRRs all blank?\n");

		WARN_ON(1);

		return 0;

	}



	if ((highest_addr >> PAGE_SHIFT) < end_pfn) {

	if (highest_pfn < end_pfn) {

		printk(KERN_WARNING "WARNING: BIOS bug: CPU MTRRs don't cover"

			" all of memory, losing %LdMB of RAM.\n",

			(((u64)end_pfn << PAGE_SHIFT) - highest_addr) >> 20);

			" all of memory, losing %luMB of RAM.\n",

			(end_pfn - highest_pfn) >> (20 - PAGE_SHIFT));



		WARN_ON(1);



		printk(KERN_INFO "update e820 for mtrr\n");

		trim_start = highest_addr;

		trim_start = highest_pfn;

		trim_start <<= PAGE_SHIFT;

		trim_size = end_pfn;

		trim_size <<= PAGE_SHIFT;

		trim_size -= trim_start;