From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6FB93C433EF for ; Wed, 23 Feb 2022 04:00:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238017AbiBWEAj (ORCPT ); Tue, 22 Feb 2022 23:00:39 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57148 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231979AbiBWEAh (ORCPT ); Tue, 22 Feb 2022 23:00:37 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 71A285D19B for ; Tue, 22 Feb 2022 20:00:10 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1645588809; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=cZg/zOsjS1zgxZzshOQCrxDaITSJ0qnWWjX9sbQEFec=; b=WeG2UwzBNxErOE2AOqookx2RWR6QQ4WiN/UFUeP0x0mZlswR7jua6GwFbNcvaZ1OQcWUc4 WAo0ZBkMh0vHdPUY+tINl6dYbyh6LC/eMK/24Z30VzJxCVhwUf/s2fPZ5FWgqPHGVoohbL y4moIPYScLb1wKjsekDrlltbPGxGaJU= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-620-GclCn2EeO2q5o9pGQDTEZA-1; Tue, 22 Feb 2022 23:00:02 -0500 X-MC-Unique: GclCn2EeO2q5o9pGQDTEZA-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id C46101006AA6; Wed, 23 Feb 2022 04:00:00 +0000 (UTC) Received: from localhost (ovpn-14-1.pek2.redhat.com [10.72.14.1]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 2E6FF4D702; Wed, 23 Feb 2022 03:59:56 +0000 (UTC) Date: Wed, 23 Feb 2022 11:59:54 +0800 From: Baoquan He To: Eric DeVolder Cc: linux-kernel@vger.kernel.org, x86@kernel.org, kexec@lists.infradead.org, ebiederm@xmission.com, dyoung@redhat.com, vgoyal@redhat.com, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com, nramas@linux.microsoft.com, thomas.lendacky@amd.com, robh@kernel.org, efault@gmx.de, rppt@kernel.org, konrad.wilk@oracle.com, boris.ostrovsky@oracle.com Subject: Re: [PATCH v4 06/10] crash hp: generic crash hotplug support infrastructure Message-ID: References: <20220209195706.51522-1-eric.devolder@oracle.com> <20220209195706.51522-7-eric.devolder@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220209195706.51522-7-eric.devolder@oracle.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/09/22 at 02:57pm, Eric DeVolder wrote: > This patch introduces a generic crash hot plug/unplug infrastructure > for CPU and memory changes. Upon CPU and memory changes, a generic > crash_hotplug_handler() obtains the appropriate lock, does some > important house keeping and then dispatches the hot plug/unplug event > to the architecture specific arch_crash_hotplug_handler(), and when > that handler returns, the lock is released. > > This patch modifies crash_core.c to implement a subsys_initcall() > function that installs handlers for hot plug/unplug events. If CPU > hotplug is enabled, then cpuhp_setup_state() is invoked to register a > handler for CPU changes. Similarly, if memory hotplug is enabled, then > register_memory_notifier() is invoked to install a handler for memory > changes. These handlers in turn invoke the common generic handler > crash_hotplug_handler(). > > On the CPU side, cpuhp_setup_state_nocalls() is invoked with parameter > CPUHP_AP_ONLINE_DYN. While this works, when a CPU is being unplugged, > the CPU still shows up in foreach_present_cpu() during the regeneration > of the new CPU list, thus the need to explicitly check and exclude the > soon-to-be offlined CPU in crash_prepare_elf64_headers(). > > On the memory side, each un/plugged memory block passes through the > handler. For example, if a 1GiB DIMM is hotplugged, that generate 8 > memory events, one for each 128MiB memblock. This looks good to me. As I commented in patch 3, these both may need be merged. > > Signed-off-by: Eric DeVolder > --- > kernel/crash_core.c | 104 ++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 104 insertions(+) > > diff --git a/kernel/crash_core.c b/kernel/crash_core.c > index 0ff06d0698ad..524470e18883 100644 > --- a/kernel/crash_core.c > +++ b/kernel/crash_core.c > @@ -10,12 +10,16 @@ > #include > #include > #include > +#include > +#include > > #include > #include > > #include > > +#include "kexec_internal.h" > + > /* vmcoreinfo stuff */ > unsigned char *vmcoreinfo_data; > size_t vmcoreinfo_size; > @@ -521,5 +525,105 @@ void unmap_crash_pages(void **ptr) > *ptr = NULL; > } > } > + > +void __weak arch_crash_hotplug_handler(struct kimage *image, > + unsigned int hp_action, unsigned long a, unsigned long b) > +{ > + pr_warn("crash hp: %s not implemented", __func__); > +} > + > +static void crash_hotplug_handler(unsigned int hp_action, > + unsigned long a, unsigned long b) > +{ > + /* Obtain lock while changing crash information */ > + if (!mutex_trylock(&kexec_mutex)) > + return; > + > + /* Check kdump is loaded */ > + if (kexec_crash_image) { > + pr_debug("crash hp: hp_action %u, a %lu, b %lu", hp_action, > + a, b); > + > + /* Needed in order for the segments to be updated */ > + arch_kexec_unprotect_crashkres(); > + > + /* Flag to differentiate between normal load and hotplug */ > + kexec_crash_image->hotplug_event = true; > + > + /* Now invoke arch-specific update handler */ > + arch_crash_hotplug_handler(kexec_crash_image, hp_action, a, b); > + > + /* No longer handling a hotplug event */ > + kexec_crash_image->hotplug_event = false; > + > + /* Change back to read-only */ > + arch_kexec_protect_crashkres(); > + } > + > + /* Release lock now that update complete */ > + mutex_unlock(&kexec_mutex); > +} > + > +#if defined(CONFIG_MEMORY_HOTPLUG) > +static int crash_memhp_notifier(struct notifier_block *nb, > + unsigned long val, void *v) > +{ > + struct memory_notify *mhp = v; > + unsigned long start, end; > + > + start = mhp->start_pfn << PAGE_SHIFT; > + end = ((mhp->start_pfn + mhp->nr_pages) << PAGE_SHIFT) - 1; > + > + switch (val) { > + case MEM_ONLINE: > + crash_hotplug_handler(KEXEC_CRASH_HP_ADD_MEMORY, > + start, end-start); > + break; > + > + case MEM_OFFLINE: > + crash_hotplug_handler(KEXEC_CRASH_HP_REMOVE_MEMORY, > + start, end-start); > + break; > + } > + return NOTIFY_OK; > +} > + > +static struct notifier_block crash_memhp_nb = { > + .notifier_call = crash_memhp_notifier, > + .priority = 0 > +}; > #endif > > +#if defined(CONFIG_HOTPLUG_CPU) > +static int crash_cpuhp_online(unsigned int cpu) > +{ > + crash_hotplug_handler(KEXEC_CRASH_HP_ADD_CPU, cpu, 0); > + return 0; > +} > + > +static int crash_cpuhp_offline(unsigned int cpu) > +{ > + crash_hotplug_handler(KEXEC_CRASH_HP_REMOVE_CPU, cpu, 0); > + return 0; > +} > +#endif > + > +static int __init crash_hotplug_init(void) > +{ > + int result = 0; > + > +#if defined(CONFIG_MEMORY_HOTPLUG) > + register_memory_notifier(&crash_memhp_nb); > +#endif > + > +#if defined(CONFIG_HOTPLUG_CPU) > + result = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, > + "crash/cpuhp", > + crash_cpuhp_online, crash_cpuhp_offline); > +#endif > + > + return result; > +} > + > +subsys_initcall(crash_hotplug_init); > +#endif /* CONFIG_CRASH_HOTPLUG */ > -- > 2.27.0 > From mboxrd@z Thu Jan 1 00:00:00 1970 From: Baoquan He Date: Wed, 23 Feb 2022 11:59:54 +0800 Subject: [PATCH v4 06/10] crash hp: generic crash hotplug support infrastructure In-Reply-To: <20220209195706.51522-7-eric.devolder@oracle.com> References: <20220209195706.51522-1-eric.devolder@oracle.com> <20220209195706.51522-7-eric.devolder@oracle.com> Message-ID: List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: kexec@lists.infradead.org On 02/09/22 at 02:57pm, Eric DeVolder wrote: > This patch introduces a generic crash hot plug/unplug infrastructure > for CPU and memory changes. Upon CPU and memory changes, a generic > crash_hotplug_handler() obtains the appropriate lock, does some > important house keeping and then dispatches the hot plug/unplug event > to the architecture specific arch_crash_hotplug_handler(), and when > that handler returns, the lock is released. > > This patch modifies crash_core.c to implement a subsys_initcall() > function that installs handlers for hot plug/unplug events. If CPU > hotplug is enabled, then cpuhp_setup_state() is invoked to register a > handler for CPU changes. Similarly, if memory hotplug is enabled, then > register_memory_notifier() is invoked to install a handler for memory > changes. These handlers in turn invoke the common generic handler > crash_hotplug_handler(). > > On the CPU side, cpuhp_setup_state_nocalls() is invoked with parameter > CPUHP_AP_ONLINE_DYN. While this works, when a CPU is being unplugged, > the CPU still shows up in foreach_present_cpu() during the regeneration > of the new CPU list, thus the need to explicitly check and exclude the > soon-to-be offlined CPU in crash_prepare_elf64_headers(). > > On the memory side, each un/plugged memory block passes through the > handler. For example, if a 1GiB DIMM is hotplugged, that generate 8 > memory events, one for each 128MiB memblock. This looks good to me. As I commented in patch 3, these both may need be merged. > > Signed-off-by: Eric DeVolder > --- > kernel/crash_core.c | 104 ++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 104 insertions(+) > > diff --git a/kernel/crash_core.c b/kernel/crash_core.c > index 0ff06d0698ad..524470e18883 100644 > --- a/kernel/crash_core.c > +++ b/kernel/crash_core.c > @@ -10,12 +10,16 @@ > #include > #include > #include > +#include > +#include > > #include > #include > > #include > > +#include "kexec_internal.h" > + > /* vmcoreinfo stuff */ > unsigned char *vmcoreinfo_data; > size_t vmcoreinfo_size; > @@ -521,5 +525,105 @@ void unmap_crash_pages(void **ptr) > *ptr = NULL; > } > } > + > +void __weak arch_crash_hotplug_handler(struct kimage *image, > + unsigned int hp_action, unsigned long a, unsigned long b) > +{ > + pr_warn("crash hp: %s not implemented", __func__); > +} > + > +static void crash_hotplug_handler(unsigned int hp_action, > + unsigned long a, unsigned long b) > +{ > + /* Obtain lock while changing crash information */ > + if (!mutex_trylock(&kexec_mutex)) > + return; > + > + /* Check kdump is loaded */ > + if (kexec_crash_image) { > + pr_debug("crash hp: hp_action %u, a %lu, b %lu", hp_action, > + a, b); > + > + /* Needed in order for the segments to be updated */ > + arch_kexec_unprotect_crashkres(); > + > + /* Flag to differentiate between normal load and hotplug */ > + kexec_crash_image->hotplug_event = true; > + > + /* Now invoke arch-specific update handler */ > + arch_crash_hotplug_handler(kexec_crash_image, hp_action, a, b); > + > + /* No longer handling a hotplug event */ > + kexec_crash_image->hotplug_event = false; > + > + /* Change back to read-only */ > + arch_kexec_protect_crashkres(); > + } > + > + /* Release lock now that update complete */ > + mutex_unlock(&kexec_mutex); > +} > + > +#if defined(CONFIG_MEMORY_HOTPLUG) > +static int crash_memhp_notifier(struct notifier_block *nb, > + unsigned long val, void *v) > +{ > + struct memory_notify *mhp = v; > + unsigned long start, end; > + > + start = mhp->start_pfn << PAGE_SHIFT; > + end = ((mhp->start_pfn + mhp->nr_pages) << PAGE_SHIFT) - 1; > + > + switch (val) { > + case MEM_ONLINE: > + crash_hotplug_handler(KEXEC_CRASH_HP_ADD_MEMORY, > + start, end-start); > + break; > + > + case MEM_OFFLINE: > + crash_hotplug_handler(KEXEC_CRASH_HP_REMOVE_MEMORY, > + start, end-start); > + break; > + } > + return NOTIFY_OK; > +} > + > +static struct notifier_block crash_memhp_nb = { > + .notifier_call = crash_memhp_notifier, > + .priority = 0 > +}; > #endif > > +#if defined(CONFIG_HOTPLUG_CPU) > +static int crash_cpuhp_online(unsigned int cpu) > +{ > + crash_hotplug_handler(KEXEC_CRASH_HP_ADD_CPU, cpu, 0); > + return 0; > +} > + > +static int crash_cpuhp_offline(unsigned int cpu) > +{ > + crash_hotplug_handler(KEXEC_CRASH_HP_REMOVE_CPU, cpu, 0); > + return 0; > +} > +#endif > + > +static int __init crash_hotplug_init(void) > +{ > + int result = 0; > + > +#if defined(CONFIG_MEMORY_HOTPLUG) > + register_memory_notifier(&crash_memhp_nb); > +#endif > + > +#if defined(CONFIG_HOTPLUG_CPU) > + result = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, > + "crash/cpuhp", > + crash_cpuhp_online, crash_cpuhp_offline); > +#endif > + > + return result; > +} > + > +subsys_initcall(crash_hotplug_init); > +#endif /* CONFIG_CRASH_HOTPLUG */ > -- > 2.27.0 >