linux-kernel - [PATCH 7/8] x86/mce: Don't disable MCA banks when offlining a CPU on AMD

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Message-Id: <20170613162835.30750-8-bp@alien8.de>
Date:   Tue, 13 Jun 2017 18:28:34 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     X86 ML <x86@...nel.org>
Cc:     LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH 7/8] x86/mce: Don't disable MCA banks when offlining a CPU on AMD

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

AMD systems have non-core, shared MCA banks within a die. These banks
are controlled by a master CPU per die. If this CPU is offlined then all
the shared banks are disabled in addition to the CPU's core banks.

Also, Fam17h systems may have SMT enabled. The MCA_CTL register is shared
between SMT thread siblings. If a CPU is offlined then all its sibling's
MCA banks are also disabled.

Extend the existing vendor check to AMD too.

Signed-off-by: Yazen Ghannam <yazen.ghannam@....com>
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/1496692427-7991-1-git-send-email-Yazen.Ghannam@amd.com
[ Fixup comment. ]
Signed-off-by: Borislav Petkov <bp@...e.de>
---
 arch/x86/kernel/cpu/mcheck/mce.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c
index 5cfbaeb6529a..3c54c2b9efc2 100644
--- a/arch/x86/kernel/cpu/mcheck/mce.c
+++ b/arch/x86/kernel/cpu/mcheck/mce.c
@@ -1912,12 +1912,13 @@ static void mce_disable_error_reporting(void)
 static void vendor_disable_error_reporting(void)
 {
 	/*
-	 * Don't clear on Intel CPUs. Some of these MSRs are socket-wide.
+	 * Don't clear on Intel or AMD CPUs. Some of these MSRs are socket-wide.
 	 * Disabling them for just a single offlined CPU is bad, since it will
 	 * inhibit reporting for all shared resources on the socket like the
 	 * last level cache (LLC), the integrated memory controller (iMC), etc.
 	 */
-	if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL)
+	if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL ||
+	    boot_cpu_data.x86_vendor == X86_VENDOR_AMD)
 		return;
 
 	mce_disable_error_reporting();
-- 
2.13.0