Re: [PATCH v2 1/2] mce: acpi/apei: Honour Firmware First for MCAbanks listed in APEI HEST CMC

[Naveen N. Rao]

Tony, Boris,
Can you please see if the comments in the below patch include the details you
were expecting?

Thanks,
Naveen

--
Add comments to clarify usage of the various bitfields in the MCA subsystem

Signed-off-by: Naveen N. Rao <naveen.n.rao@xxxxxxxxxxxxxxxxxx>
---
 arch/x86/kernel/cpu/mcheck/mce.c       |    5 ++++-
 arch/x86/kernel/cpu/mcheck/mce_intel.c |    9 +++++++++
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c
index 9239504..bf49cdb 100644
--- a/arch/x86/kernel/cpu/mcheck/mce.c
+++ b/arch/x86/kernel/cpu/mcheck/mce.c
@@ -89,7 +89,10 @@ static DECLARE_WAIT_QUEUE_HEAD(mce_chrdev_wait);
 static DEFINE_PER_CPU(struct mce, mces_seen);
 static int			cpu_missing;
 
-/* MCA banks polled by the period polling timer for corrected events */
+/*
+ * MCA banks polled by the period polling timer for corrected events.
+ * With Intel CMCI, this only has MCA banks which do not support CMCI (if any).
+ */
 DEFINE_PER_CPU(mce_banks_t, mce_poll_banks) = {
 	[0 ... BITS_TO_LONGS(MAX_NR_BANKS)-1] = ~0UL
 };
diff --git a/arch/x86/kernel/cpu/mcheck/mce_intel.c b/arch/x86/kernel/cpu/mcheck/mce_intel.c
index ae1697c..2816f53 100644
--- a/arch/x86/kernel/cpu/mcheck/mce_intel.c
+++ b/arch/x86/kernel/cpu/mcheck/mce_intel.c
@@ -24,6 +24,15 @@
  * Also supports reliable discovery of shared banks.
  */
 
+/*
+ * Indicates MCA banks controlled by the current cpu for CMCI. Note that this
+ * can change when a cpu is offlined or brought online since some MCA banks
+ * are shared across cpus. When a cpu is offlined, cmci_clear() disables CMCI
+ * on all banks owned by the cpu and clears this bitfield. At this point,
+ * cmci_rediscover() kicks in and a different cpu may end up taking
+ * ownership of some of the shared MCA banks that were previously owned
+ * by the offlined cpu.
+ */
 static DEFINE_PER_CPU(mce_banks_t, mce_banks_owned);
 
 /*

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