linux-kernel - Re: [PATCH v2 1/2] mce: acpi/apei: Honour Firmware First for MCA banks listed in APEI HEST CMC

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Date:	Tue, 25 Jun 2013 23:16:32 +0530
From:	"Naveen N. Rao" <naveen.n.rao@...ux.vnet.ibm.com>
To:	tony.luck@...el.com, bp@...en8.de
Cc:	ananth@...ibm.com, masbock@...ux.vnet.ibm.com,
	lcm@...ux.vnet.ibm.com, linux-kernel@...r.kernel.org,
	linux-acpi@...r.kernel.org, ying.huang@...el.com
Subject: Re: [PATCH v2 1/2] mce: acpi/apei: Honour Firmware First for MCA
 banks listed in APEI HEST CMC

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@...ux.vnet.ibm.com>
---
 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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