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

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Date:   Mon,  5 Jun 2017 14:53:47 -0500
From:   Yazen Ghannam <Yazen.Ghannam@....com>
To:     linux-edac@...r.kernel.org
Cc:     Borislav Petkov <bp@...e.de>, Tony Luck <tony.luck@...el.com>,
        x86@...nel.org, linux-kernel@...r.kernel.org,
        Yazen Ghannam <yazen.ghannam@....com>
Subject: [PATCH] x86/mce: Don't disable MCA banks when offlining a CPU on AMD systems

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.

Do a vendor check for AMD and return early when offling a CPU.

Signed-off-by: Yazen Ghannam <yazen.ghannam@....com>
---
 arch/x86/kernel/cpu/mcheck/mce.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c
index 5cfbaeb..e317a95 100644
--- a/arch/x86/kernel/cpu/mcheck/mce.c
+++ b/arch/x86/kernel/cpu/mcheck/mce.c
@@ -1917,7 +1917,8 @@ static void vendor_disable_error_reporting(void)
 	 * 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();
-- 
2.7.4