Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935069AbXFFT3w (ORCPT ); Wed, 6 Jun 2007 15:29:52 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752061AbXFFT3m (ORCPT ); Wed, 6 Jun 2007 15:29:42 -0400 Received: from mga03.intel.com ([143.182.124.21]:31780 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751399AbXFFT3l (ORCPT ); Wed, 6 Jun 2007 15:29:41 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.16,390,1175497200"; d="scan'208";a="236331249" From: Jesse Barnes To: Andi Kleen , linux-kernel@vger.kernel.org Subject: [PATCH] trim memory not covered by WB MTRRs Date: Wed, 6 Jun 2007 12:29:23 -0700 User-Agent: KMail/1.9.6 Cc: Justin Piszcz , "Eric W. Biederman" MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200706061229.24486.jesse.barnes@intel.com> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 7366 Lines: 227 On some machines, buggy BIOSes don't properly setup WB MTRRs to cover all available RAM, meaning the last few megs (or even gigs) of memory will be marked uncached. Since Linux tends to allocate from high memory addresses first, this causes the machine to be unusably slow as soon as the kernel starts really using memory (i.e. right around init time). This patch works around the problem by scanning the MTRRs at boot and figuring out whether the current end_pfn value (setup by early e820 code) goes beyond the highest WB MTRR range, and if so, trimming it to match. A fairly obnoxious KERN_WARNING is printed too, letting the user know that not all of their memory is available due to a likely BIOS bug. Something similar could be done on i386 if needed, but the boot ordering would be slightly different, since the MTRR code on i386 depends on the boot_cpu_data structure being setup. Justin, can you please test and make sure this patch works for you too? It'll only work around the problem, but it's better than having to do mem= by hand or waiting for a fix from your BIOS vendor. Thanks, Jesse Signed-off-by: Jesse Barnes diff --git a/arch/i386/kernel/cpu/mtrr/generic.c b/arch/i386/kernel/cpu/mtrr/generic.c index c4ebb51..71fc768 100644 --- a/arch/i386/kernel/cpu/mtrr/generic.c +++ b/arch/i386/kernel/cpu/mtrr/generic.c @@ -13,7 +13,7 @@ #include "mtrr.h" struct mtrr_state { - struct mtrr_var_range *var_ranges; + struct mtrr_var_range var_ranges[NUM_VAR_RANGES]; mtrr_type fixed_ranges[NUM_FIXED_RANGES]; unsigned char enabled; unsigned char have_fixed; @@ -84,12 +84,6 @@ void get_mtrr_state(void) struct mtrr_var_range *vrs; unsigned lo, dummy; - if (!mtrr_state.var_ranges) { - mtrr_state.var_ranges = kmalloc(num_var_ranges * sizeof (struct mtrr_var_range), - GFP_KERNEL); - if (!mtrr_state.var_ranges) - return; - } vrs = mtrr_state.var_ranges; rdmsr(MTRRcap_MSR, lo, dummy); diff --git a/arch/i386/kernel/cpu/mtrr/if.c b/arch/i386/kernel/cpu/mtrr/if.c index c7d8f17..d7922ce 100644 --- a/arch/i386/kernel/cpu/mtrr/if.c +++ b/arch/i386/kernel/cpu/mtrr/if.c @@ -12,7 +12,7 @@ #include "mtrr.h" /* RED-PEN: this is accessed without any locking */ -extern unsigned int *usage_table; +extern unsigned int usage_table[]; #define FILE_FCOUNT(f) (((struct seq_file *)((f)->private_data))->private) diff --git a/arch/i386/kernel/cpu/mtrr/main.c b/arch/i386/kernel/cpu/mtrr/main.c index 1cf466d..c133856 100644 --- a/arch/i386/kernel/cpu/mtrr/main.c +++ b/arch/i386/kernel/cpu/mtrr/main.c @@ -38,8 +38,8 @@ #include #include +#include #include - #include #include #include @@ -47,7 +47,7 @@ u32 num_var_ranges = 0; -unsigned int *usage_table; +unsigned int usage_table[NUM_VAR_RANGES]; static DEFINE_MUTEX(mtrr_mutex); u64 size_or_mask, size_and_mask; @@ -121,11 +121,6 @@ static void __init init_table(void) int i, max; max = num_var_ranges; - if ((usage_table = kmalloc(max * sizeof *usage_table, GFP_KERNEL)) - == NULL) { - printk(KERN_ERR "mtrr: could not allocate\n"); - return; - } for (i = 0; i < max; i++) usage_table[i] = 1; } @@ -589,16 +584,11 @@ struct mtrr_value { unsigned long lsize; }; -static struct mtrr_value * mtrr_state; +static struct mtrr_value mtrr_state[NUM_VAR_RANGES]; static int mtrr_save(struct sys_device * sysdev, pm_message_t state) { int i; - int size = num_var_ranges * sizeof(struct mtrr_value); - - mtrr_state = kzalloc(size,GFP_ATOMIC); - if (!mtrr_state) - return -ENOMEM; for (i = 0; i < num_var_ranges; i++) { mtrr_if->get(i, @@ -620,7 +610,6 @@ static int mtrr_restore(struct sys_device * sysdev) mtrr_state[i].lsize, mtrr_state[i].ltype); } - kfree(mtrr_state); return 0; } @@ -631,6 +620,42 @@ static struct sysdev_driver mtrr_sysdev_driver = { .resume = mtrr_restore, }; +/** + * mtrr_trim_uncached_memory - trim RAM not covered by MTRRs + * + * Some buggy BIOSes don't setup the MTRRs properly for systems with certain + * memory configurations. This routine checks to make sure the MTRRs having + * a write back type cover all of the memory the kernel is intending to use. + * If not, it'll trim any memory off the end by adjusting end_pfn, removing + * it from the kernel's allocation pools, warning the user with an obnoxious + * message. + */ +void __init mtrr_trim_uncached_memory(void) +{ + unsigned long i, base, size, highest_addr = 0; + mtrr_type type; + + /* Find highest cached pfn */ + for (i = 0; i < num_var_ranges; i++) { + 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_addr >> PAGE_SHIFT) != end_pfn) { + printk(KERN_WARNING "***************\n"); + printk(KERN_WARNING "**** WARNING: likely BIOS bug\n"); + printk(KERN_WARNING "**** MTRRs don't cover all of " + "memory, trimmed %ld pages\n", end_pfn - + (highest_addr >> PAGE_SHIFT)); + printk(KERN_WARNING "***************\n"); + end_pfn = highest_addr >> PAGE_SHIFT; + } +} /** * mtrr_bp_init - initialize mtrrs on the boot CPU diff --git a/arch/i386/kernel/cpu/mtrr/mtrr.h b/arch/i386/kernel/cpu/mtrr/mtrr.h index 289dfe6..a29dcba 100644 --- a/arch/i386/kernel/cpu/mtrr/mtrr.h +++ b/arch/i386/kernel/cpu/mtrr/mtrr.h @@ -14,6 +14,7 @@ #define MTRRphysMask_MSR(reg) (0x200 + 2 * (reg) + 1) #define NUM_FIXED_RANGES 88 +#define NUM_VAR_RANGES 256 #define MTRRfix64K_00000_MSR 0x250 #define MTRRfix16K_80000_MSR 0x258 #define MTRRfix16K_A0000_MSR 0x259 diff --git a/arch/x86_64/kernel/bugs.c b/arch/x86_64/kernel/bugs.c index c3c6b91..c138eac 100644 --- a/arch/x86_64/kernel/bugs.c +++ b/arch/x86_64/kernel/bugs.c @@ -14,7 +14,6 @@ void __init check_bugs(void) { identify_cpu(&boot_cpu_data); - mtrr_bp_init(); #if !defined(CONFIG_SMP) printk("CPU: "); print_cpu_info(&boot_cpu_data); diff --git a/arch/x86_64/kernel/setup.c b/arch/x86_64/kernel/setup.c index eb6524f..409b63c 100644 --- a/arch/x86_64/kernel/setup.c +++ b/arch/x86_64/kernel/setup.c @@ -266,6 +266,10 @@ void __init setup_arch(char **cmdline_p) * we are rounding upwards: */ end_pfn = e820_end_of_ram(); + /* Trim memory not covered by WB MTRRs */ + mtrr_bp_init(); + mtrr_trim_uncached_memory(); + num_physpages = end_pfn; check_efer(); diff --git a/include/asm-x86_64/mtrr.h b/include/asm-x86_64/mtrr.h index b557c48..cc62bd8 100644 --- a/include/asm-x86_64/mtrr.h +++ b/include/asm-x86_64/mtrr.h @@ -78,6 +78,7 @@ extern int mtrr_add_page (unsigned long base, unsigned long size, unsigned int type, char increment); extern int mtrr_del (int reg, unsigned long base, unsigned long size); extern int mtrr_del_page (int reg, unsigned long base, unsigned long size); +extern void mtrr_trim_uncached_memory(void); # else static __inline__ int mtrr_add (unsigned long base, unsigned long size, unsigned int type, char increment) - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/