[PATCH v2 5/5] x86/mce: Handle AMD threshold interrupt storms

[Tony Luck]

From: Smita Koralahalli <Smita.KoralahalliChannabasappa@xxxxxxx>

Extend the logic of handling CMCI storms to AMD threshold interrupts.

Rely on the similar approach as of Intel's CMCI to mitigate storms per
CPU and per bank. But, unlike CMCI, do not set thresholds and reduce
interrupt rate on a storm. Rather, disable the interrupt on the
corresponding CPU and bank. Re-enable back the interrupts if enough
consecutive polls of the bank show no corrected errors (30, as
programmed by Intel).

Turning off the threshold interrupts would be a better solution on AMD
systems as other error severities will still be handled even if the
threshold interrupts are disabled.

[Tony: Small tweak because mce_handle_storm() isn't a pointer now]

Signed-off-by: Smita Koralahalli <Smita.KoralahalliChannabasappa@xxxxxxx>
Signed-off-by: Tony Luck <tony.luck@xxxxxxxxx>
---
 arch/x86/kernel/cpu/mce/amd.c      | 49 ++++++++++++++++++++++++++++++
 arch/x86/kernel/cpu/mce/core.c     |  3 ++
 arch/x86/kernel/cpu/mce/internal.h |  2 ++
 3 files changed, 54 insertions(+)

diff --git a/arch/x86/kernel/cpu/mce/amd.c b/arch/x86/kernel/cpu/mce/amd.c
index 1c87501e0fa3..b7f92af065e1 100644
--- a/arch/x86/kernel/cpu/mce/amd.c
+++ b/arch/x86/kernel/cpu/mce/amd.c
@@ -466,6 +466,47 @@ static void threshold_restart_bank(void *_tr)
 	wrmsr(tr->b->address, lo, hi);
 }
 
+static void _reset_block(struct threshold_block *block)
+{
+	struct thresh_restart tr;
+
+	memset(&tr, 0, sizeof(tr));
+	tr.b = block;
+	threshold_restart_bank(&tr);
+}
+
+static void toggle_interrupt_reset_block(struct threshold_block *block, bool on)
+{
+	if (!block)
+		return;
+
+	block->interrupt_enable = !!on;
+	_reset_block(block);
+}
+
+void mce_amd_handle_storm(int bank, bool on)
+{
+	struct threshold_block *first_block = NULL, *block = NULL, *tmp = NULL;
+	struct threshold_bank **bp = this_cpu_read(threshold_banks);
+	unsigned long flags;
+
+	if (!bp)
+		return;
+
+	local_irq_save(flags);
+
+	first_block = bp[bank]->blocks;
+	if (!first_block)
+		goto end;
+
+	toggle_interrupt_reset_block(first_block, on);
+
+	list_for_each_entry_safe(block, tmp, &first_block->miscj, miscj)
+		toggle_interrupt_reset_block(block, on);
+end:
+	local_irq_restore(flags);
+}
+
 static void mce_threshold_block_init(struct threshold_block *b, int offset)
 {
 	struct thresh_restart tr = {
@@ -867,6 +908,7 @@ static void amd_threshold_interrupt(void)
 	struct threshold_block *first_block = NULL, *block = NULL, *tmp = NULL;
 	struct threshold_bank **bp = this_cpu_read(threshold_banks);
 	unsigned int bank, cpu = smp_processor_id();
+	u64 status;
 
 	/*
 	 * Validate that the threshold bank has been initialized already. The
@@ -880,6 +922,13 @@ static void amd_threshold_interrupt(void)
 		if (!(per_cpu(bank_map, cpu) & (1 << bank)))
 			continue;
 
+		rdmsrl(mca_msr_reg(bank, MCA_STATUS), status);
+		track_cmci_storm(bank, status);
+
+		/* Return early on an interrupt storm */
+		if (this_cpu_read(bank_storm[bank]))
+			return;
+
 		first_block = bp[bank]->blocks;
 		if (!first_block)
 			continue;
diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c
index d27daa199523..6121f0afe45a 100644
--- a/arch/x86/kernel/cpu/mce/core.c
+++ b/arch/x86/kernel/cpu/mce/core.c
@@ -2072,6 +2072,9 @@ void mce_handle_storm(int bank, bool on)
 	case X86_VENDOR_INTEL:
 		mce_intel_handle_storm(bank, on);
 		break;
+	case X86_VENDOR_AMD:
+		mce_amd_handle_storm(bank, on);
+		break;
 	}
 }
 
diff --git a/arch/x86/kernel/cpu/mce/internal.h b/arch/x86/kernel/cpu/mce/internal.h
index d7cad839a6a9..24b2b1f1bfdc 100644
--- a/arch/x86/kernel/cpu/mce/internal.h
+++ b/arch/x86/kernel/cpu/mce/internal.h
@@ -206,7 +206,9 @@ extern bool filter_mce(struct mce *m);
 
 #ifdef CONFIG_X86_MCE_AMD
 extern bool amd_filter_mce(struct mce *m);
+void mce_amd_handle_storm(int bank, bool on);
 #else
+static inline void mce_amd_handle_storm(int bank, bool on) {}
 static inline bool amd_filter_mce(struct mce *m) { return false; }
 #endif
 
-- 
2.35.3