From 20651af9ac60fd6e31360688ad44861a7d05256a Mon Sep 17 00:00:00 2001 From: Yinghai Lu Date: Wed, 6 Feb 2008 22:39:45 +0100 Subject: [PATCH] x86: fix mttr trimming Pavel Emelyanov reported that his networking card did not work and bisected it down to: " The commit 093af8d7f0ba3c6be1485973508584ef081e9f93 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: Pavel Emelyanov Signed-off-by: Yinghai Lu Tested-by: Pavel Emelyanov Signed-off-by: Ingo Molnar --- arch/x86/kernel/cpu/mtrr/main.c | 19 +++++++++---------- 1 file changed, 9 insertions(+), 10 deletions(-) diff --git a/arch/x86/kernel/cpu/mtrr/main.c b/arch/x86/kernel/cpu/mtrr/main.c index 1e27b69a7a..b6e136f23d 100644 --- a/arch/x86/kernel/cpu/mtrr/main.c +++ b/arch/x86/kernel/cpu/mtrr/main.c @@ -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; -- 2.39.5