[tip: ras/core] x86/mce: Handle Intel threshold interrupt storms
From: tip-bot2 for Tony Luck
Date: Fri Dec 15 2023 - 11:10:18 EST
The following commit has been merged into the ras/core branch of tip:
Commit-ID: 1f68ce2a027250aeeb1756391110cdc4dc97c797
Gitweb: https://git.kernel.org/tip/1f68ce2a027250aeeb1756391110cdc4dc97c797
Author: Tony Luck <tony.luck@xxxxxxxxx>
AuthorDate: Wed, 15 Nov 2023 11:54:50 -08:00
Committer: Borislav Petkov (AMD) <bp@xxxxxxxxx>
CommitterDate: Fri, 15 Dec 2023 14:53:42 +01:00
x86/mce: Handle Intel threshold interrupt storms
Add an Intel specific hook into machine_check_poll() to keep track of
per-CPU, per-bank corrected error logs (with a stub for the
CONFIG_MCE_INTEL=n case).
When a storm is observed the rate of interrupts is reduced by setting
a large threshold value for this bank in IA32_MCi_CTL2. This bank is
added to the bitmap of banks for this CPU to poll. The polling rate is
increased to once per second.
When a storm ends reset the threshold in IA32_MCi_CTL2 back to 1, remove
the bank from the bitmap for polling, and change the polling rate back
to the default.
If a CPU with banks in storm mode is taken offline, the new CPU that
inherits ownership of those banks takes over management of storm(s) in
the inherited bank(s).
The cmci_discover() function was already very large. These changes
pushed it well over the top. Refactor with three helper functions to
bring it back under control.
Signed-off-by: Tony Luck <tony.luck@xxxxxxxxx>
Signed-off-by: Borislav Petkov (AMD) <bp@xxxxxxxxx>
Link: https://lore.kernel.org/r/20231115195450.12963-4-tony.luck@xxxxxxxxx
---
arch/x86/kernel/cpu/mce/intel.c | 205 ++++++++++++++++++++-------
arch/x86/kernel/cpu/mce/internal.h | 2 +-
arch/x86/kernel/cpu/mce/threshold.c | 3 +-
3 files changed, 160 insertions(+), 50 deletions(-)
diff --git a/arch/x86/kernel/cpu/mce/intel.c b/arch/x86/kernel/cpu/mce/intel.c
index fc4ffc4..399b62e 100644
--- a/arch/x86/kernel/cpu/mce/intel.c
+++ b/arch/x86/kernel/cpu/mce/intel.c
@@ -54,8 +54,27 @@ static DEFINE_RAW_SPINLOCK(cmci_discover_lock);
*/
static DEFINE_SPINLOCK(cmci_poll_lock);
+/* Linux non-storm CMCI threshold (may be overridden by BIOS) */
#define CMCI_THRESHOLD 1
+/*
+ * MCi_CTL2 threshold for each bank when there is no storm.
+ * Default value for each bank may have been set by BIOS.
+ */
+static u16 cmci_threshold[MAX_NR_BANKS];
+
+/*
+ * High threshold to limit CMCI rate during storms. Max supported is
+ * 0x7FFF. Use this slightly smaller value so it has a distinctive
+ * signature when some asks "Why am I not seeing all corrected errors?"
+ * A high threshold is used instead of just disabling CMCI for a
+ * bank because both corrected and uncorrected errors may be logged
+ * in the same bank and signalled with CMCI. The threshold only applies
+ * to corrected errors, so keeping CMCI enabled means that uncorrected
+ * errors will still be processed in a timely fashion.
+ */
+#define CMCI_STORM_THRESHOLD 32749
+
static int cmci_supported(int *banks)
{
u64 cap;
@@ -111,6 +130,31 @@ static bool lmce_supported(void)
}
/*
+ * Set a new CMCI threshold value. Preserve the state of the
+ * MCI_CTL2_CMCI_EN bit in case this happens during a
+ * cmci_rediscover() operation.
+ */
+static void cmci_set_threshold(int bank, int thresh)
+{
+ unsigned long flags;
+ u64 val;
+
+ raw_spin_lock_irqsave(&cmci_discover_lock, flags);
+ rdmsrl(MSR_IA32_MCx_CTL2(bank), val);
+ val &= ~MCI_CTL2_CMCI_THRESHOLD_MASK;
+ wrmsrl(MSR_IA32_MCx_CTL2(bank), val | thresh);
+ raw_spin_unlock_irqrestore(&cmci_discover_lock, flags);
+}
+
+void mce_intel_handle_storm(int bank, bool on)
+{
+ if (on)
+ cmci_set_threshold(bank, CMCI_STORM_THRESHOLD);
+ else
+ cmci_set_threshold(bank, cmci_threshold[bank]);
+}
+
+/*
* The interrupt handler. This is called on every event.
* Just call the poller directly to log any events.
* This could in theory increase the threshold under high load,
@@ -122,71 +166,129 @@ static void intel_threshold_interrupt(void)
}
/*
+ * Check all the reasons why current CPU cannot claim
+ * ownership of a bank.
+ * 1: CPU already owns this bank
+ * 2: BIOS owns this bank
+ * 3: Some other CPU owns this bank
+ */
+static bool cmci_skip_bank(int bank, u64 *val)
+{
+ unsigned long *owned = (void *)this_cpu_ptr(&mce_banks_owned);
+
+ if (test_bit(bank, owned))
+ return true;
+
+ /* Skip banks in firmware first mode */
+ if (test_bit(bank, mce_banks_ce_disabled))
+ return true;
+
+ rdmsrl(MSR_IA32_MCx_CTL2(bank), *val);
+
+ /* Already owned by someone else? */
+ if (*val & MCI_CTL2_CMCI_EN) {
+ clear_bit(bank, owned);
+ __clear_bit(bank, this_cpu_ptr(mce_poll_banks));
+ return true;
+ }
+
+ return false;
+}
+
+/*
+ * Decide which CMCI interrupt threshold to use:
+ * 1: If this bank is in storm mode from whichever CPU was
+ * the previous owner, stay in storm mode.
+ * 2: If ignoring any threshold set by BIOS, set Linux default
+ * 3: Try to honor BIOS threshold (unless buggy BIOS set it at zero).
+ */
+static u64 cmci_pick_threshold(u64 val, int *bios_zero_thresh)
+{
+ if ((val & MCI_CTL2_CMCI_THRESHOLD_MASK) == CMCI_STORM_THRESHOLD)
+ return val;
+
+ if (!mca_cfg.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;
+ }
+
+ return val;
+}
+
+/*
+ * Try to claim ownership of a bank.
+ */
+static void cmci_claim_bank(int bank, u64 val, int bios_zero_thresh, int *bios_wrong_thresh)
+{
+ struct mca_storm_desc *storm = this_cpu_ptr(&storm_desc);
+
+ val |= MCI_CTL2_CMCI_EN;
+ wrmsrl(MSR_IA32_MCx_CTL2(bank), val);
+ rdmsrl(MSR_IA32_MCx_CTL2(bank), val);
+
+ /* If the enable bit did not stick, this bank should be polled. */
+ if (!(val & MCI_CTL2_CMCI_EN)) {
+ WARN_ON(!test_bit(bank, this_cpu_ptr(mce_poll_banks)));
+ storm->banks[bank].poll_only = true;
+ return;
+ }
+
+ /* This CPU successfully set the enable bit. */
+ set_bit(bank, (void *)this_cpu_ptr(&mce_banks_owned));
+
+ if ((val & MCI_CTL2_CMCI_THRESHOLD_MASK) == CMCI_STORM_THRESHOLD) {
+ pr_notice("CPU%d BANK%d CMCI inherited storm\n", smp_processor_id(), bank);
+ mce_inherit_storm(bank);
+ cmci_storm_begin(bank);
+ } else {
+ __clear_bit(bank, this_cpu_ptr(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 (mca_cfg.bios_cmci_threshold && bios_zero_thresh &&
+ (val & MCI_CTL2_CMCI_THRESHOLD_MASK))
+ *bios_wrong_thresh = 1;
+
+ /* Save default threshold for each bank */
+ if (cmci_threshold[bank] == 0)
+ cmci_threshold[bank] = val & MCI_CTL2_CMCI_THRESHOLD_MASK;
+}
+
+/*
* Enable CMCI (Corrected Machine Check Interrupt) for available MCE banks
* on this CPU. Use the algorithm recommended in the SDM to discover shared
- * banks.
+ * banks. Called during initial bootstrap, and also for hotplug CPU operations
+ * to rediscover/reassign machine check banks.
*/
static void cmci_discover(int banks)
{
- unsigned long *owned = (void *)this_cpu_ptr(&mce_banks_owned);
+ int bios_wrong_thresh = 0;
unsigned long flags;
int i;
- int bios_wrong_thresh = 0;
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;
-
- /* Skip banks in firmware first mode */
- if (test_bit(i, mce_banks_ce_disabled))
+ if (cmci_skip_bank(i, &val))
continue;
- rdmsrl(MSR_IA32_MCx_CTL2(i), val);
-
- /* Already owned by someone else? */
- if (val & MCI_CTL2_CMCI_EN) {
- clear_bit(i, owned);
- __clear_bit(i, this_cpu_ptr(mce_poll_banks));
- continue;
- }
-
- if (!mca_cfg.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);
-
- /* Did the enable bit stick? -- the bank supports CMCI */
- if (val & MCI_CTL2_CMCI_EN) {
- set_bit(i, owned);
- __clear_bit(i, this_cpu_ptr(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 (mca_cfg.bios_cmci_threshold && bios_zero_thresh &&
- (val & MCI_CTL2_CMCI_THRESHOLD_MASK))
- bios_wrong_thresh = 1;
- } else {
- WARN_ON(!test_bit(i, this_cpu_ptr(mce_poll_banks)));
- }
+ val = cmci_pick_threshold(val, &bios_zero_thresh);
+ cmci_claim_bank(i, val, bios_zero_thresh, &bios_wrong_thresh);
}
raw_spin_unlock_irqrestore(&cmci_discover_lock, flags);
if (mca_cfg.bios_cmci_threshold && bios_wrong_thresh) {
@@ -225,6 +327,9 @@ static void __cmci_disable_bank(int bank)
val &= ~MCI_CTL2_CMCI_EN;
wrmsrl(MSR_IA32_MCx_CTL2(bank), val);
__clear_bit(bank, this_cpu_ptr(mce_banks_owned));
+
+ if ((val & MCI_CTL2_CMCI_THRESHOLD_MASK) == CMCI_STORM_THRESHOLD)
+ cmci_storm_end(bank);
}
/*
diff --git a/arch/x86/kernel/cpu/mce/internal.h b/arch/x86/kernel/cpu/mce/internal.h
index 157b2f2..01f8f03 100644
--- a/arch/x86/kernel/cpu/mce/internal.h
+++ b/arch/x86/kernel/cpu/mce/internal.h
@@ -41,6 +41,7 @@ struct dentry *mce_get_debugfs_dir(void);
extern mce_banks_t mce_banks_ce_disabled;
#ifdef CONFIG_X86_MCE_INTEL
+void mce_intel_handle_storm(int bank, bool on);
void cmci_disable_bank(int bank);
void intel_init_cmci(void);
void intel_init_lmce(void);
@@ -48,6 +49,7 @@ void intel_clear_lmce(void);
bool intel_filter_mce(struct mce *m);
bool intel_mce_usable_address(struct mce *m);
#else
+static inline void mce_intel_handle_storm(int bank, bool on) { }
static inline void cmci_disable_bank(int bank) { }
static inline void intel_init_cmci(void) { }
static inline void intel_init_lmce(void) { }
diff --git a/arch/x86/kernel/cpu/mce/threshold.c b/arch/x86/kernel/cpu/mce/threshold.c
index 0e19884..89e31e1 100644
--- a/arch/x86/kernel/cpu/mce/threshold.c
+++ b/arch/x86/kernel/cpu/mce/threshold.c
@@ -60,6 +60,9 @@ void mce_set_storm_mode(bool storm)
static void mce_handle_storm(unsigned int bank, bool on)
{
switch (boot_cpu_data.x86_vendor) {
+ case X86_VENDOR_INTEL:
+ mce_intel_handle_storm(bank, on);
+ break;
}
}