From patchwork Fri Jan 15 23:58:19 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kamal Mostafa X-Patchwork-Id: 569026 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from huckleberry.canonical.com (huckleberry.canonical.com [91.189.94.19]) by ozlabs.org (Postfix) with ESMTP id F2D35140B0E; Sun, 17 Jan 2016 01:31:03 +1100 (AEDT) Received: from localhost ([127.0.0.1] helo=huckleberry.canonical.com) by huckleberry.canonical.com with esmtp (Exim 4.76) (envelope-from ) id 1aKRsZ-0002g1-GL; Sat, 16 Jan 2016 14:30:59 +0000 Received: from youngberry.canonical.com ([91.189.89.112]) by huckleberry.canonical.com with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.76) (envelope-from ) id 1aKEG7-0008WA-Vp for kernel-team@lists.ubuntu.com; Fri, 15 Jan 2016 23:58:23 +0000 Received: from 1.general.kamal.us.vpn ([10.172.68.52] helo=fourier) by youngberry.canonical.com with esmtpsa (TLS1.0:DHE_RSA_AES_128_CBC_SHA1:16) (Exim 4.76) (envelope-from ) id 1aKEG7-0007WK-DA; Fri, 15 Jan 2016 23:58:23 +0000 Received: from kamal by fourier with local (Exim 4.82) (envelope-from ) id 1aKEG4-00086F-IH; Fri, 15 Jan 2016 15:58:20 -0800 From: Kamal Mostafa To: Ashok Raj Subject: [4.2.y-ckt stable] Patch "x86/mce: Ensure offline CPUs don't participate in rendezvous process" has been added to the 4.2.y-ckt tree Date: Fri, 15 Jan 2016 15:58:19 -0800 Message-Id: <1452902299-31105-1-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 1.9.1 X-Extended-Stable: 4.2 X-Mailman-Approved-At: Sat, 16 Jan 2016 14:30:22 +0000 Cc: Tony Luck , Peter Zijlstra , Kamal Mostafa , kernel-team@lists.ubuntu.com, "H. Peter Anvin" , Thomas Gleixner , Borislav Petkov , Linus Torvalds , Ingo Molnar , linux-edac X-BeenThere: kernel-team@lists.ubuntu.com X-Mailman-Version: 2.1.14 Precedence: list List-Id: Kernel team discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: kernel-team-bounces@lists.ubuntu.com Sender: kernel-team-bounces@lists.ubuntu.com This is a note to let you know that I have just added a patch titled x86/mce: Ensure offline CPUs don't participate in rendezvous process to the linux-4.2.y-queue branch of the 4.2.y-ckt extended stable tree which can be found at: http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-4.2.y-queue This patch is scheduled to be released in version 4.2.8-ckt2. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 4.2.y-ckt tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Kamal ---8<------------------------------------------------------------ From d088f049ede62fe0e3e0c1ccdd0fb7afde34f936 Mon Sep 17 00:00:00 2001 From: Ashok Raj Date: Thu, 10 Dec 2015 11:12:26 +0100 Subject: x86/mce: Ensure offline CPUs don't participate in rendezvous process commit d90167a941f62860f35eb960e1012aa2d30e7e94 upstream. Intel's MCA implementation broadcasts MCEs to all CPUs on the node. This poses a problem for offlined CPUs which cannot participate in the rendezvous process: Kernel panic - not syncing: Timeout: Not all CPUs entered broadcast exception handler Kernel Offset: disabled Rebooting in 100 seconds.. More specifically, Linux does a soft offline of a CPU when writing a 0 to /sys/devices/system/cpu/cpuX/online, which doesn't prevent the #MC exception from being broadcasted to that CPU. Ensure that offline CPUs don't participate in the MCE rendezvous and clear the RIP valid status bit so that a second MCE won't cause a shutdown. Without the patch, mce_start() will increment mce_callin and wait for all CPUs. Offlined CPUs should avoid participating in the rendezvous process altogether. Signed-off-by: Ashok Raj [ Massage commit message. ] Signed-off-by: Borislav Petkov Reviewed-by: Tony Luck Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: linux-edac Link: http://lkml.kernel.org/r/1449742346-21470-2-git-send-email-bp@alien8.de Signed-off-by: Ingo Molnar Signed-off-by: Thomas Gleixner Signed-off-by: Kamal Mostafa --- arch/x86/kernel/cpu/mcheck/mce.c | 11 +++++++++++ 1 file changed, 11 insertions(+) -- 1.9.1 diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c index df919ff..32ec29d 100644 --- a/arch/x86/kernel/cpu/mcheck/mce.c +++ b/arch/x86/kernel/cpu/mcheck/mce.c @@ -1055,6 +1055,17 @@ void do_machine_check(struct pt_regs *regs, long error_code) int flags = MF_ACTION_REQUIRED; int lmce = 0; + /* If this CPU is offline, just bail out. */ + if (cpu_is_offline(smp_processor_id())) { + u64 mcgstatus; + + mcgstatus = mce_rdmsrl(MSR_IA32_MCG_STATUS); + if (mcgstatus & MCG_STATUS_RIPV) { + mce_wrmsrl(MSR_IA32_MCG_STATUS, 0); + return; + } + } + prev_state = ist_enter(regs); this_cpu_inc(mce_exception_count);