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Subject[RESEND][PATCH -tip 1/3] x86, mce: Revert "add mce_threshold option for intel cmci"
After having some discussion with Andi Kleen, we have concluded
that setting threshold >1 will not work properly. This patch
reverts the previous patch that introduces mce_threshold option.

However as Ingo pointed out, cmci is a new feature so having boot
controls to disable it is generally a good idea, and it might be
handy if the hw is misbehaving.

So instead of mce_threshold, I will introduce "mce=no_cmci" option
to support cmci disablement in later patch.
Compare with mce_threshold, it lacks threshold >1 support but it
does not matter because it will not work.

Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
---
Documentation/kernel-parameters.txt | 5 ---
arch/x86/include/asm/msr-index.h | 1 -
arch/x86/kernel/cpu/mcheck/mce_intel_64.c | 56 ++---------------------------
3 files changed, 3 insertions(+), 59 deletions(-)
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 5e966a9..6172e43 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1208,11 +1208,6 @@ and is between 256 and 4096 characters. It is defined in the file

mce=option [X86-64] See Documentation/x86/x86_64/boot-options.txt

- mce_threshold= [X86-64,intel] Default CMCI threshold
- Should be unsigned integer. Setting 0 disables cmci.
- Format: <integer>
- Default: 1
-
md= [HW] RAID subsystems devices and level
See Documentation/md.txt.

diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h
index bb144e4..ec41fc1 100644
--- a/arch/x86/include/asm/msr-index.h
+++ b/arch/x86/include/asm/msr-index.h
@@ -85,7 +85,6 @@
#define MSR_IA32_MC0_CTL2 0x00000280
#define CMCI_EN (1ULL << 30)
#define CMCI_THRESHOLD_MASK 0xffffULL
-#define CMCI_THRESHOLD_VAL_MASK 0x7fffULL

#define MSR_P6_PERFCTR0 0x000000c1
#define MSR_P6_PERFCTR1 0x000000c2
diff --git a/arch/x86/kernel/cpu/mcheck/mce_intel_64.c b/arch/x86/kernel/cpu/mcheck/mce_intel_64.c
index 8bd5d0c..d6b72df 100644
--- a/arch/x86/kernel/cpu/mcheck/mce_intel_64.c
+++ b/arch/x86/kernel/cpu/mcheck/mce_intel_64.c
@@ -103,6 +103,8 @@ static DEFINE_PER_CPU(mce_banks_t, mce_banks_owned);
*/
static DEFINE_SPINLOCK(cmci_discover_lock);

+#define CMCI_THRESHOLD 1
+
static int cmci_supported(int *banks)
{
u64 cap;
@@ -133,51 +135,6 @@ static void intel_threshold_interrupt(void)
mce_notify_user();
}

-/*
- * Default threshold, setting 0 disables cmci
- */
-static unsigned long threshold_limit = 1;
-
-static int __init mcheck_threshold(char *str)
-{
- int val;
-
- get_option(&str, &val);
- if (val < 0) {
- printk(KERN_INFO "mce_threshold argument ignored.\n");
- return 0;
- }
- threshold_limit = val;
-
- return 1;
-}
-__setup("mce_threshold=", mcheck_threshold);
-
-void static cmci_set_threshold(int bank)
-{
- u64 val, limit, max, new;
-
- rdmsrl(MSR_IA32_MC0_CTL2 + bank, val);
- limit = val & CMCI_THRESHOLD_VAL_MASK;
-
- /* Thresholding available? */
- if (!limit)
- return;
- /* Return if no need to change */
- if (limit == threshold_limit)
- return;
-
- /* Find the maximum threshold value */
- max = (val & ~CMCI_THRESHOLD_MASK) | CMCI_THRESHOLD_VAL_MASK;
- wrmsrl(MSR_IA32_MC0_CTL2 + bank, max);
- rdmsrl(MSR_IA32_MC0_CTL2 + bank, max);
- max &= CMCI_THRESHOLD_VAL_MASK;
- max = (threshold_limit > max ? max : threshold_limit);
-
- new = (val & ~CMCI_THRESHOLD_MASK) | max;
- wrmsrl(MSR_IA32_MC0_CTL2 + bank, new);
-}
-
static void print_update(char *type, int *hdr, int num)
{
if (*hdr == 0)
@@ -186,9 +143,6 @@ static void print_update(char *type, int *hdr, int num)
printk(KERN_CONT " %s:%d", type, num);
}

-/* Used to determine whether thresholding is available or not */
-#define CMCI_THRESHOLD_FIRST 1
-
/*
* Enable CMCI (Corrected Machine Check Interrupt) for available MCE banks
* on this CPU. Use the algorithm recommended in the SDM to discover shared
@@ -200,9 +154,6 @@ static void cmci_discover(int banks, int boot)
int hdr = 0;
int i;

- if (!threshold_limit)
- return;
-
spin_lock(&cmci_discover_lock);
for (i = 0; i < banks; i++) {
u64 val;
@@ -220,7 +171,7 @@ static void cmci_discover(int banks, int boot)
continue;
}

- val |= CMCI_EN | CMCI_THRESHOLD_FIRST;
+ val |= CMCI_EN | CMCI_THRESHOLD;
wrmsrl(MSR_IA32_MC0_CTL2 + i, val);
rdmsrl(MSR_IA32_MC0_CTL2 + i, val);

@@ -229,7 +180,6 @@ 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));
- cmci_set_threshold(i);
} else {
WARN_ON(!test_bit(i, __get_cpu_var(mce_poll_banks)));
}
--
1.6.2.2


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