From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754065AbdKFRq4 (ORCPT ); Mon, 6 Nov 2017 12:46:56 -0500 Received: from mail.skyhub.de ([5.9.137.197]:52838 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752246AbdKFRqz (ORCPT ); Mon, 6 Nov 2017 12:46:55 -0500 From: Borislav Petkov To: X86 ML Cc: LKML Subject: [PATCH 1/2] x86/MCE/AMD: Always give panic severity for UC errors in kernel context Date: Mon, 6 Nov 2017 18:46:32 +0100 Message-Id: <20171106174633.13576-1-bp@alien8.de> X-Mailer: git-send-email 2.13.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Yazen Ghannam The AMD severity grading function was introduced in kernel 4.1. The current logic can possibly give MCE_AR_SEVERITY for uncorrectable errors in kernel context. The system may then get stuck in a loop as memory_failure() will try to handle the bad kernel memory and find it busy. Return MCE_PANIC_SEVERITY for all UC errors IN_KERNEL context on AMD systems. After: b2f9d678e28c ("x86/mce: Check for faults tagged in EXTABLE_CLASS_FAULT exception table entries") was accepted in v4.6, this issue was masked because of the tail-end attempt at kernel mode recovery in the #MC handler. However, uncorrectable errors IN_KERNEL context should always be considered unrecoverable and cause a panic. Signed-off-by: Yazen Ghannam Cc: Tony Luck Cc: linux-edac Cc: x86-ml Link: http://lkml.kernel.org/r/1509562746-6313-1-git-send-email-Yazen.Ghannam@amd.com Fixes: bf80bbd7dcf5 (x86/mce: Add an AMD severities-grading function) Cc: # 4.9.x Signed-off-by: Borislav Petkov --- arch/x86/kernel/cpu/mcheck/mce-severity.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) diff --git a/arch/x86/kernel/cpu/mcheck/mce-severity.c b/arch/x86/kernel/cpu/mcheck/mce-severity.c index 87cc9ab7a13c..4b8187639c2d 100644 --- a/arch/x86/kernel/cpu/mcheck/mce-severity.c +++ b/arch/x86/kernel/cpu/mcheck/mce-severity.c @@ -245,6 +245,9 @@ static int mce_severity_amd(struct mce *m, int tolerant, char **msg, bool is_exc if (m->status & MCI_STATUS_UC) { + if (ctx == IN_KERNEL) + return MCE_PANIC_SEVERITY; + /* * On older systems where overflow_recov flag is not present, we * should simply panic if an error overflow occurs. If @@ -255,10 +258,6 @@ static int mce_severity_amd(struct mce *m, int tolerant, char **msg, bool is_exc if (mce_flags.smca) return mce_severity_amd_smca(m, ctx); - /* software can try to contain */ - if (!(m->mcgstatus & MCG_STATUS_RIPV) && (ctx == IN_KERNEL)) - return MCE_PANIC_SEVERITY; - /* kill current process */ return MCE_AR_SEVERITY; } else { -- 2.13.0