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Date: Wed, 22 Aug 2012 18:00:54 +0530
From: "Naveen N. Rao" <naveen.n.rao@...ux.vnet.ibm.com>
To: tony.luck@...el.com, andi@...stfloor.org, bp@...64.org
Cc: gong.chen@...ux.intel.com, x86@...nel.org,
linux-kernel@...r.kernel.org, mingo@...hat.com, tglx@...utronix.de,
linux-edac@...r.kernel.org
Subject: [PATCH] x86: mce: Honour bios-set CMCI threshold
The ACPI spec doesn't provide for a way for the bios to pass down
recommended thresholds to the OS on a _per-bank_ basis. This patch adds
a new boot option, which if passed, allows bios to initialize the CMCI
threshold. In such a case, we simply skip programming any threshold
value.
As fail-safe, we initialize threshold to 1 if some banks have not been
initialized by the bios and warn the user.
Signed-off-by: Naveen N. Rao <naveen.n.rao@...ux.vnet.ibm.com>
---
Documentation/x86/x86_64/boot-options.txt | 5 ++++
arch/x86/include/asm/mce.h | 1 +
arch/x86/kernel/cpu/mcheck/mce.c | 4 +++
arch/x86/kernel/cpu/mcheck/mce_intel.c | 39 +++++++++++++++++++++++++++--
4 files changed, 46 insertions(+), 3 deletions(-)
diff --git a/Documentation/x86/x86_64/boot-options.txt b/Documentation/x86/x86_64/boot-options.txt
index c54b4f5..ec92540 100644
--- a/Documentation/x86/x86_64/boot-options.txt
+++ b/Documentation/x86/x86_64/boot-options.txt
@@ -50,6 +50,11 @@ Machine check
monarchtimeout:
Sets the time in us to wait for other CPUs on machine checks. 0
to disable.
+ mce=bios_cmci_threshold
+ Don't overwrite the bios-set CMCI threshold. This boot option
+ prevents Linux from overwriting the CMCI threshold set by the
+ bios. Without this option, Linux always sets the CMCI
+ threshold to 1.
nomce (for compatibility with i386): same as mce=off
diff --git a/arch/x86/include/asm/mce.h b/arch/x86/include/asm/mce.h
index a3ac52b..8ad5078 100644
--- a/arch/x86/include/asm/mce.h
+++ b/arch/x86/include/asm/mce.h
@@ -171,6 +171,7 @@ DECLARE_PER_CPU(struct device *, mce_device);
#ifdef CONFIG_X86_MCE_INTEL
extern int mce_cmci_disabled;
extern int mce_ignore_ce;
+extern int mce_bios_cmci_threshold;
void mce_intel_feature_init(struct cpuinfo_x86 *c);
void cmci_clear(void);
void cmci_reenable(void);
diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c
index 292d025..401359d 100644
--- a/arch/x86/kernel/cpu/mcheck/mce.c
+++ b/arch/x86/kernel/cpu/mcheck/mce.c
@@ -82,6 +82,7 @@ static int mce_panic_timeout __read_mostly;
static int mce_dont_log_ce __read_mostly;
int mce_cmci_disabled __read_mostly;
int mce_ignore_ce __read_mostly;
+int mce_bios_cmci_threshold __read_mostly;
int mce_ser __read_mostly;
struct mce_bank *mce_banks __read_mostly;
@@ -1907,6 +1908,7 @@ static struct miscdevice mce_chrdev_device = {
* check, or 0 to not wait
* mce=bootlog Log MCEs from before booting. Disabled by default on AMD.
* mce=nobootlog Don't log MCEs from before booting.
+ * mce=bios_cmci_threshold Don't program the CMCI threshold
*/
static int __init mcheck_enable(char *str)
{
@@ -1926,6 +1928,8 @@ static int __init mcheck_enable(char *str)
mce_ignore_ce = 1;
else if (!strcmp(str, "bootlog") || !strcmp(str, "nobootlog"))
mce_bootlog = (str[0] == 'b');
+ else if (!strcmp(str, "bios_cmci_threshold"))
+ mce_bios_cmci_threshold = 1;
else if (isdigit(str[0])) {
get_option(&str, &tolerant);
if (*str == ',') {
diff --git a/arch/x86/kernel/cpu/mcheck/mce_intel.c b/arch/x86/kernel/cpu/mcheck/mce_intel.c
index 38e49bc..b869040 100644
--- a/arch/x86/kernel/cpu/mcheck/mce_intel.c
+++ b/arch/x86/kernel/cpu/mcheck/mce_intel.c
@@ -84,10 +84,16 @@ static void cmci_discover(int banks, int boot)
unsigned long flags;
int hdr = 0;
int i;
+ int bios_wrong_thresh = 0;
+
+ if (boot && mce_bios_cmci_threshold)
+ printk_once(KERN_INFO
+ "bios_cmci_threshold: Using bios-set threshold values for CMCI");
raw_spin_lock_irqsave(&cmci_discover_lock, flags);
for (i = 0; i < banks; i++) {
u64 val;
+ int bios_zero_thresh = 0;
if (test_bit(i, owned))
continue;
@@ -102,8 +108,20 @@ static void cmci_discover(int banks, int boot)
continue;
}
- val &= ~MCI_CTL2_CMCI_THRESHOLD_MASK;
- val |= MCI_CTL2_CMCI_EN | CMCI_THRESHOLD;
+ if (!mce_bios_cmci_threshold) {
+ val &= ~MCI_CTL2_CMCI_THRESHOLD_MASK;
+ val |= CMCI_THRESHOLD;
+ } else if (!(val & MCI_CTL2_CMCI_THRESHOLD_MASK)) {
+ /*
+ * If bios_cmci_threshold boot option was specified
+ * but the threshold is zero, we'll try to initialize
+ * it to 1.
+ */
+ bios_zero_thresh = 1;
+ val |= CMCI_THRESHOLD;
+ }
+
+ val |= MCI_CTL2_CMCI_EN;
wrmsrl(MSR_IA32_MCx_CTL2(i), val);
rdmsrl(MSR_IA32_MCx_CTL2(i), val);
@@ -112,6 +130,15 @@ static void cmci_discover(int banks, int boot)
if (!test_and_set_bit(i, owned) && !boot)
print_update("CMCI", &hdr, i);
__clear_bit(i, __get_cpu_var(mce_poll_banks));
+ /*
+ * We are able to set thresholds for some banks that
+ * had a threshold of 0. This means the BIOS has not
+ * set the thresholds properly or does not work with
+ * this boot option. Note down now and report later.
+ */
+ if (mce_bios_cmci_threshold && bios_zero_thresh &&
+ (val & MCI_CTL2_CMCI_THRESHOLD_MASK))
+ bios_wrong_thresh = 1;
} else {
WARN_ON(!test_bit(i, __get_cpu_var(mce_poll_banks)));
}
@@ -119,6 +146,12 @@ static void cmci_discover(int banks, int boot)
raw_spin_unlock_irqrestore(&cmci_discover_lock, flags);
if (hdr)
printk(KERN_CONT "\n");
+ if (boot && mce_bios_cmci_threshold && bios_wrong_thresh) {
+ printk_once(KERN_INFO
+ "bios_cmci_threshold: Some banks do not have valid thresholds set");
+ printk_once(KERN_INFO
+ "bios_cmci_threshold: Make sure your BIOS supports this boot option");
+ }
}
/*
@@ -156,7 +189,7 @@ void cmci_clear(void)
continue;
/* Disable CMCI */
rdmsrl(MSR_IA32_MCx_CTL2(i), val);
- val &= ~(MCI_CTL2_CMCI_EN|MCI_CTL2_CMCI_THRESHOLD_MASK);
+ val &= ~MCI_CTL2_CMCI_EN;
wrmsrl(MSR_IA32_MCx_CTL2(i), val);
__clear_bit(i, __get_cpu_var(mce_banks_owned));
}
--
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