From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933375AbcJLPGt (ORCPT ); Wed, 12 Oct 2016 11:06:49 -0400 Received: from mx1.redhat.com ([209.132.183.28]:54302 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933197AbcJLPG1 (ORCPT ); Wed, 12 Oct 2016 11:06:27 -0400 Message-ID: <57FE5171.3030305@redhat.com> Date: Wed, 12 Oct 2016 11:06:25 -0400 From: Prarit Bhargava User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 MIME-Version: 1.0 To: linux-kernel@vger.kernel.org CC: Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , x86@kernel.org, Peter Zijlstra , Len Brown , Borislav Petkov , Tim Chen , Andi Kleen , Boris Ostrovsky , Jiri Olsa Subject: Re: [PATCH] arch/x86: Remove second call to topology_update_package_map() References: <1476282988-9476-1-git-send-email-prarit@redhat.com> In-Reply-To: <1476282988-9476-1-git-send-email-prarit@redhat.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.30]); Wed, 12 Oct 2016 15:06:26 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/12/2016 10:36 AM, Prarit Bhargava wrote: > This was noticed during the investigation of > > http://git.kernel.org/tip/2a51fe083eba7f99cbda72f5ef90cdf2f4df882c > > A note for reviewers on the cleanup in smp_init_package_map(): The > per_cpu variable x86_bios_cpu_apicid is initialized to BAD_APICID, and the > bitmaps are set to false by default so the code isn't necessary. The > pr_warn() can also be dropped as generic_processor_info() will do a > pr_warning() in the same situation. > > P. > > -----8<----- > > After commit 1f12e32f4cd5 ("x86/topology: Create logical package id"), > topology_update_package_map() is called twice on a CPU. The first call is in > generic_processor_info(), which is called on all present cpus (found in either > mptable or ACPI MADT). The second call is in smp_init_package_map() which > is called later on in the init sequence. > > Only a single call is necessary for the kernel to initialize the data > structures properly. This patch drops the later call in smp_init_package_map() > and moves smp_init_package_map() out of smp_store_boot_cpu_info(). > Self-NAK. This seems to not work on systems with an empty socket :/. Looking into this now. P. > Signed-off-by: Prarit Bhargava > Cc: Thomas Gleixner > Cc: Ingo Molnar > Cc: "H. Peter Anvin" > Cc: x86@kernel.org > Cc: Peter Zijlstra > Cc: Len Brown > Cc: Borislav Petkov > Cc: Tim Chen > Cc: Andi Kleen > Cc: Boris Ostrovsky > Cc: Jiri Olsa > --- > arch/x86/kernel/smpboot.c | 20 +++----------------- > 1 file changed, 3 insertions(+), 17 deletions(-) > > diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c > index 951f093a96fe..0ff74f8bb5e9 100644 > --- a/arch/x86/kernel/smpboot.c > +++ b/arch/x86/kernel/smpboot.c > @@ -271,7 +271,7 @@ int topology_update_package_map(unsigned int apicid, unsigned int cpu) > if (!physical_package_map) > return 0; > > - if (pkg >= max_physical_pkg_id) > + if (!apic->apic_id_valid(apicid) || pkg >= max_physical_pkg_id) > return -EINVAL; > > /* Set the logical package id */ > @@ -310,7 +310,7 @@ int topology_phys_to_logical_pkg(unsigned int phys_pkg) > > static void __init smp_init_package_map(void) > { > - unsigned int ncpus, cpu; > + unsigned int ncpus; > size_t size; > > /* > @@ -342,7 +342,6 @@ static void __init smp_init_package_map(void) > } > > __max_logical_packages = DIV_ROUND_UP(total_cpus, ncpus); > - logical_packages = 0; > > /* > * Possibly larger than what we need as the number of apic ids per > @@ -355,19 +354,6 @@ static void __init smp_init_package_map(void) > size = BITS_TO_LONGS(max_physical_pkg_id) * sizeof(unsigned long); > physical_package_map = kzalloc(size, GFP_KERNEL); > > - for_each_present_cpu(cpu) { > - unsigned int apicid = apic->cpu_present_to_apicid(cpu); > - > - if (apicid == BAD_APICID || !apic->apic_id_valid(apicid)) > - continue; > - if (!topology_update_package_map(apicid, cpu)) > - continue; > - pr_warn("CPU %u APICId %x disabled\n", cpu, apicid); > - per_cpu(x86_bios_cpu_apicid, cpu) = BAD_APICID; > - set_cpu_possible(cpu, false); > - set_cpu_present(cpu, false); > - } > - > if (logical_packages > __max_logical_packages) { > pr_warn("Detected more packages (%u), then computed by BIOS data (%u).\n", > logical_packages, __max_logical_packages); > @@ -385,7 +371,6 @@ void __init smp_store_boot_cpu_info(void) > > *c = boot_cpu_data; > c->cpu_index = id; > - smp_init_package_map(); > } > > /* > @@ -1285,6 +1270,7 @@ void __init native_smp_prepare_cpus(unsigned int max_cpus) > * Setup boot CPU information > */ > smp_store_boot_cpu_info(); /* Final full version of the data */ > + smp_init_package_map(); > cpumask_copy(cpu_callin_mask, cpumask_of(0)); > mb(); > >