[PATCH 1/7] x86/mce: Handle an in-kernel MCE decoder

[Borislav Petkov]

From: Borislav Petkov <bp@xxxxxxx>

Change the MCE decoding flow to issue the trace_mce_record() tracepoint
only when there's no decoder registered on the decoder chain. If there
is, it will do some massaging on the MCE info before issuing it through
the tracepoint.

Signed-off-by: Borislav Petkov <bp@xxxxxxx>
---
 arch/x86/include/asm/mce.h       | 4 +++-
 arch/x86/kernel/cpu/mcheck/mce.c | 9 ++++++++-
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/mce.h b/arch/x86/include/asm/mce.h
index 181264989db5..ba4c99ace544 100644
--- a/arch/x86/include/asm/mce.h
+++ b/arch/x86/include/asm/mce.h
@@ -146,6 +146,7 @@ struct mca_config {
 	bool ser;
 	bool recovery;
 	bool bios_cmci_threshold;
+	bool has_decoder;
 	u8 banks;
 	s8 bootlog;
 	int tolerant;
@@ -195,7 +196,8 @@ enum mce_notifier_prios {
 	MCE_PRIO_SRAO		= INT_MAX - 1,
 	MCE_PRIO_EXTLOG		= INT_MAX - 2,
 	MCE_PRIO_NFIT		= INT_MAX - 3,
-	MCE_PRIO_EDAC		= INT_MAX - 4,
+	MCE_PRIO_DECODER	= INT_MAX - 4,
+	MCE_PRIO_EDAC		= INT_MAX - 5,
 	MCE_PRIO_MCELOG		= 1,
 	MCE_PRIO_LOWEST		= 0,
 };
diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c
index 3b413065c613..dcf75f40e031 100644
--- a/arch/x86/kernel/cpu/mcheck/mce.c
+++ b/arch/x86/kernel/cpu/mcheck/mce.c
@@ -163,6 +163,9 @@ void mce_register_decode_chain(struct notifier_block *nb)
 
 	atomic_inc(&num_notifiers);
 
+	if (nb->priority == MCE_PRIO_DECODER)
+		mca_cfg.has_decoder = true;
+
 	blocking_notifier_chain_register(&x86_mce_decoder_chain, nb);
 }
 EXPORT_SYMBOL_GPL(mce_register_decode_chain);
@@ -171,6 +174,9 @@ void mce_unregister_decode_chain(struct notifier_block *nb)
 {
 	atomic_dec(&num_notifiers);
 
+	if (nb->priority == MCE_PRIO_DECODER)
+		mca_cfg.has_decoder = false;
+
 	blocking_notifier_chain_unregister(&x86_mce_decoder_chain, nb);
 }
 EXPORT_SYMBOL_GPL(mce_unregister_decode_chain);
@@ -557,7 +563,8 @@ static int mce_first_notifier(struct notifier_block *nb, unsigned long val,
 		return NOTIFY_STOP;
 
 	/* Emit the trace record: */
-	trace_mce_record(m);
+	if (!mca_cfg.has_decoder)
+		trace_mce_record(m);
 
 	set_bit(0, &mce_need_notify);
 
-- 
2.13.0