linux-kernel - [PATCH tip:ras/core 3/3] x86/MCE: Make correctable error detection look at the Deferred bit

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Date:   Mon, 18 Dec 2017 12:37:14 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     X86 ML <x86@...nel.org>
Cc:     LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH tip:ras/core 3/3] x86/MCE: Make correctable error detection look at the Deferred bit

From: Yazen Ghannam <yazen.ghannam@....com>

AMD systems may log Deferred errors. These are errors that are uncorrected
but which do not need immediate action. The MCA_STATUS[UC] bit may not be
set for Deferred errors.

Flag the error as not correctable when MCA_STATUS[Deferred] is set and
do not feed it into the Correctable Errors Collector.

Signed-off-by: Yazen Ghannam <yazen.ghannam@....com>
Cc: stable@...r.kernel.org # 4.13.x
Cc: Tony Luck <tony.luck@...el.com>
Cc: linux-edac <linux-edac@...r.kernel.org>
Cc: x86-ml <x86@...nel.org>
Link: http://lkml.kernel.org/r/20171212165143.27475-1-Yazen.Ghannam@amd.com
[ Massage commit message. ]
Signed-off-by: Borislav Petkov <bp@...e.de>
---
 arch/x86/kernel/cpu/mcheck/mce.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c
index 321c7a80be66..1b2c11473376 100644
--- a/arch/x86/kernel/cpu/mcheck/mce.c
+++ b/arch/x86/kernel/cpu/mcheck/mce.c
@@ -528,6 +528,17 @@ bool mce_is_memory_error(struct mce *m)
 }
 EXPORT_SYMBOL_GPL(mce_is_memory_error);
 
+static bool mce_is_correctable(struct mce *m)
+{
+	if (m->cpuvendor == X86_VENDOR_AMD && m->status & MCI_STATUS_DEFERRED)
+		return false;
+
+	if (m->status & MCI_STATUS_UC)
+		return false;
+
+	return true;
+}
+
 static bool cec_add_mce(struct mce *m)
 {
 	if (!m)
@@ -535,7 +546,7 @@ static bool cec_add_mce(struct mce *m)
 
 	/* We eat only correctable DRAM errors with usable addresses. */
 	if (mce_is_memory_error(m) &&
-	    !(m->status & MCI_STATUS_UC) &&
+	    mce_is_correctable(m)  &&
 	    mce_usable_address(m))
 		if (!cec_add_elem(m->addr >> PAGE_SHIFT))
 			return true;
-- 
2.13.0