From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:37895 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753732AbcJNKCF (ORCPT ); Fri, 14 Oct 2016 06:02:05 -0400 Subject: Patch "xen/x86: Update topology map for PV VCPUs" has been added to the 4.8-stable tree To: boris.ostrovsky@oracle.com, david.vrabel@citrix.com, gregkh@linuxfoundation.org Cc: , From: Date: Fri, 14 Oct 2016 12:01:34 +0200 Message-ID: <1476439294226121@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: This is a note to let you know that I've just added the patch titled xen/x86: Update topology map for PV VCPUs to the 4.8-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: xen-x86-update-topology-map-for-pv-vcpus.patch and it can be found in the queue-4.8 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >>From a6a198bc60e6c980a56eca24d33dc7f29139f8ea Mon Sep 17 00:00:00 2001 From: Boris Ostrovsky Date: Wed, 5 Oct 2016 13:09:33 -0400 Subject: xen/x86: Update topology map for PV VCPUs From: Boris Ostrovsky commit a6a198bc60e6c980a56eca24d33dc7f29139f8ea upstream. Early during boot topology_update_package_map() computes logical_pkg_ids for all present processors. Later, when processors are brought up, identify_cpu() updates these values based on phys_pkg_id which is a function of initial_apicid. On PV guests the latter may point to a non-existing node, causing logical_pkg_ids to be set to -1. Intel's RAPL uses logical_pkg_id (as topology_logical_package_id()) to index its arrays and therefore in this case will point to index 65535 (since logical_pkg_id is a u16). This could lead to either a crash or may actually access random memory location. As a workaround, we recompute topology during CPU bringup to reset logical_pkg_id to a valid value. (The reason for initial_apicid being bogus is because it is initial_apicid of the processor from which the guest is launched. This value is CPUID(1).EBX[31:24]) Signed-off-by: Boris Ostrovsky Signed-off-by: David Vrabel Signed-off-by: Greg Kroah-Hartman --- arch/x86/xen/smp.c | 6 ++++++ 1 file changed, 6 insertions(+) --- a/arch/x86/xen/smp.c +++ b/arch/x86/xen/smp.c @@ -87,6 +87,12 @@ static void cpu_bringup(void) cpu_data(cpu).x86_max_cores = 1; set_cpu_sibling_map(cpu); + /* + * identify_cpu() may have set logical_pkg_id to -1 due + * to incorrect phys_proc_id. Let's re-comupte it. + */ + topology_update_package_map(apic->cpu_present_to_apicid(cpu), cpu); + xen_setup_cpu_clockevents(); notify_cpu_starting(cpu); Patches currently in stable-queue which might be from boris.ostrovsky@oracle.com are queue-4.8/xen-x86-update-topology-map-for-pv-vcpus.patch