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From:   Smita Koralahalli <Smita.KoralahalliChannabasappa@amd.com>
To:     Tony Luck <tony.luck@intel.com>, Borislav Petkov <bp@alien8.de>
CC:     Smita Koralahalli <Smita.KoralahalliChannabasappa@amd.com>,
        <hpa@zytor.com>, Yazen Ghannam <yazen.ghannam@amd.com>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        <linux-edac@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        <x86@kernel.org>
Subject: [RFC PATCH 5/5] x86/mce: Handle AMD threshold interrupt storms
Date:   Wed, 6 Apr 2022 01:35:42 -0500
Message-ID: <20220406063542.183946-6-Smita.KoralahalliChannabasappa@amd.com>
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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.

Signed-off-by: Smita Koralahalli <Smita.KoralahalliChannabasappa@amd.com>
---
 arch/x86/kernel/cpu/mce/amd.c      | 49 ++++++++++++++++++++++++++++++
 arch/x86/kernel/cpu/mce/core.c     |  1 +
 arch/x86/kernel/cpu/mce/internal.h |  4 +++
 3 files changed, 54 insertions(+)

diff --git a/arch/x86/kernel/cpu/mce/amd.c b/arch/x86/kernel/cpu/mce/amd.c
index 1940d305db1c..941b09f4dac5 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 6caee488bf7d..c510dd17f2c5 100644
--- a/arch/x86/kernel/cpu/mce/core.c
+++ b/arch/x86/kernel/cpu/mce/core.c
@@ -2078,6 +2078,7 @@ static void __mcheck_cpu_init_vendor(struct cpuinfo_x86 *c)
 
 	case X86_VENDOR_AMD: {
 		mce_amd_feature_init(c);
+		mce_handle_storm = mce_amd_handle_storm;
 		break;
 		}
 
diff --git a/arch/x86/kernel/cpu/mce/internal.h b/arch/x86/kernel/cpu/mce/internal.h
index 49907cadf9ad..b9e8c8155c66 100644
--- a/arch/x86/kernel/cpu/mce/internal.h
+++ b/arch/x86/kernel/cpu/mce/internal.h
@@ -213,7 +213,11 @@ extern bool filter_mce(struct mce *m);
 
 #ifdef CONFIG_X86_MCE_AMD
 extern bool amd_filter_mce(struct mce *m);
+void track_cmci_storm(int bank, u64 status);
+void mce_amd_handle_storm(int bank, bool on);
 #else
+static inline void track_cmci_storm(int bank, u64 status) { }
+# define mce_amd_handle_storm mce_handle_storm_default
 static inline bool amd_filter_mce(struct mce *m) { return false; }
 #endif
 
-- 
2.17.1