From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756736AbbLDXHF (ORCPT ); Fri, 4 Dec 2015 18:07:05 -0500 Received: from mx2.suse.de ([195.135.220.15]:57460 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755114AbbLDXHD (ORCPT ); Fri, 4 Dec 2015 18:07:03 -0500 Date: Sat, 5 Dec 2015 00:06:54 +0100 From: Borislav Petkov To: Ashok Raj Cc: linux-kernel@vger.kernel.org, linux-edac@vger.kernel.org, Tony Luck Subject: Re: [Patch V1] x86, mce: Ensure offline CPU's don't participate in mce rendezvous process. Message-ID: <20151204230654.GC21529@pd.tnic> References: <20151204235725.GA13057@otc-brkl-03.jf.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20151204235725.GA13057@otc-brkl-03.jf.intel.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Dec 04, 2015 at 06:57:31PM -0500, Ashok Raj wrote: > Linux has logical cpu offline capability. That can be triggered by: > > # echo 0 > /sys/devices/system/cpu/cpuX/online > > In Intel Architecture, MCE's are broadcasted to all CPUs in the system. > > This includes the CPUs marked offline by Linux. Unless the CPU's were removed > via an ACPI notification, in which case the cpu's are removed from the > cpu_present_map. > > This patch ensures offline CPU's don't participate in MCE rendezvous, but > simply perform clearing some status bits to ensure a second MCE wont cause > automatic shutdown. > > Without the patch, mce_start will increment mce_callin, but mce_start would > only wait for all online_cpus. So offline cpu's should avoid participating > in the rendezvous process. > > Reviewed-by: Tony Luck > Cc: stable@vger.kernel.org > Signed-off-by: Ashok Raj > --- > arch/x86/kernel/cpu/mcheck/mce.c | 15 ++++++++++++++- > 1 file changed, 14 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c > index c5b0d56..72ea044 100644 > --- a/arch/x86/kernel/cpu/mcheck/mce.c > +++ b/arch/x86/kernel/cpu/mcheck/mce.c > @@ -998,7 +998,20 @@ void do_machine_check(struct pt_regs *regs, long error_code) > u64 recover_paddr = ~0ull; > int flags = MF_ACTION_REQUIRED; > int lmce = 0; > + unsigned int cpu = smp_processor_id(); > > + /* > + * if this cpu is offline, just bail out. > + */ > + if (cpu_is_offline(cpu)) { > + u64 mcgstatus; > + > + mcgstatus = mce_rdmsrl(MSR_IA32_MCG_STATUS); > + if (mcgstatus & MCG_STATUS_RIPV) { > + mce_wrmsrl(MSR_IA32_MCG_STATUS, 0); > + return; > + } > + } > ist_enter(regs); > > this_cpu_inc(mce_exception_count); > @@ -1142,8 +1155,8 @@ void do_machine_check(struct pt_regs *regs, long error_code) > > if (worst > 0) > mce_report_event(regs); > - mce_wrmsrl(MSR_IA32_MCG_STATUS, 0); > out: > + mce_wrmsrl(MSR_IA32_MCG_STATUS, 0); > sync_core(); > > if (recover_paddr == ~0ull) > -- With that hunk here you want to clear MSR_IA32_MCG_STATUS in the !cfg->banks case, right? If so, this should be a separate patch. Also, CC: stable with an explanation why. Thanks. -- Regards/Gruss, Boris. SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg) --