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 39D93C433F5 for ; Mon, 18 Apr 2022 03:18:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235978AbiDRDUu (ORCPT ); Sun, 17 Apr 2022 23:20:50 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46426 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235974AbiDRDUr (ORCPT ); Sun, 17 Apr 2022 23:20:47 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 323BC18352 for ; Sun, 17 Apr 2022 20:18:10 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1650251889; 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=eGhAlcxii7QqMRje2u/QDFqEFvc6pyhs2TfDi3CMnFk=; b=F97xLbZ/t9Y0BEPQW2lRCPjrNJ5pqvL3CCzfKbqOGrHg8GJp8yG1dYbQXQPQ/Ds+iCAVgQ 5bVdaTNoBWRmlza1T71zBmp2bDmSvSYlps4b1nvIsXeL6agWec5V0vf8Wgqa37bYiDjNkD /1G2iMaJIOgn2vjNlG+AfLz+5Mdu41E= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-313-qYoevzl6N2eV151CuYM9IA-1; Sun, 17 Apr 2022 23:18:04 -0400 X-MC-Unique: qYoevzl6N2eV151CuYM9IA-1 Received: from smtp.corp.redhat.com (int-mx10.intmail.prod.int.rdu2.redhat.com [10.11.54.10]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 8FC2C85A5A8; Mon, 18 Apr 2022 03:18:03 +0000 (UTC) Received: from localhost (ovpn-12-21.pek2.redhat.com [10.72.12.21]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 55887416361; Mon, 18 Apr 2022 03:18:02 +0000 (UTC) Date: Mon, 18 Apr 2022 11:17:59 +0800 From: Baoquan He To: Eric DeVolder , sourabhjain@linux.ibm.com 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, david@redhat.com, konrad.wilk@oracle.com, boris.ostrovsky@oracle.com Subject: Re: [PATCH v7 4/8] crash: add generic infrastructure for crash hotplug support Message-ID: References: <20220413164237.20845-1-eric.devolder@oracle.com> <20220413164237.20845-5-eric.devolder@oracle.com> <4eea2373-32f3-9960-cbec-21dc1a428807@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4eea2373-32f3-9960-cbec-21dc1a428807@oracle.com> X-Scanned-By: MIMEDefang 2.85 on 10.11.54.10 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/14/22 at 05:29pm, Eric DeVolder wrote: > Hi Baoquan, > Inline comments below. > Thanks! > eric > > On 4/13/22 21:45, Baoquan He wrote: > > On 04/13/22 at 12:42pm, Eric DeVolder wrote: > > > Upon CPU and memory changes, a generic crash_hotplug_handler() > > > dispatches the hot plug/unplug event to the architecture specific > > > arch_crash_hotplug_handler(). During the process, the kexec_mutex > > > is held. > > > > > > To support cpu hotplug, a callback is registered to capture the > > > CPUHP_AP_ONLINE_DYN online and ofline events via > > > cpuhp_setup_state_nocalls(). > > > > > > To support memory hotplug, a notifier is registered to capture the > > > MEM_ONLINE and MEM_OFFLINE events via register_memory_notifier(). > > > > > > The cpu callback and memory notifier then call crash_hotplug_handler() > > > to handle the hot plug/unplug event. > > > > > > Signed-off-by: Eric DeVolder > > > --- > > > include/linux/kexec.h | 16 +++++++ > > > kernel/crash_core.c | 101 ++++++++++++++++++++++++++++++++++++++++++ > > > 2 files changed, 117 insertions(+) > > > > > > diff --git a/include/linux/kexec.h b/include/linux/kexec.h > > > index f93f2591fc1e..02daff1f47dd 100644 > > > --- a/include/linux/kexec.h > > > +++ b/include/linux/kexec.h > > > @@ -306,6 +306,13 @@ struct kimage { > > > /* Information for loading purgatory */ > > > struct purgatory_info purgatory_info; > > > + > > > +#ifdef CONFIG_CRASH_HOTPLUG > > > + bool hotplug_event; > > > + unsigned int offlinecpu; > > > + bool elfcorehdr_index_valid; > > > + int elfcorehdr_index; > > > +#endif > > > #endif > > > #ifdef CONFIG_IMA_KEXEC > > > @@ -322,6 +329,15 @@ struct kimage { > > > unsigned long elf_load_addr; > > > }; > > > +#ifdef CONFIG_CRASH_HOTPLUG > > > +void arch_crash_hotplug_handler(struct kimage *image, > > > + unsigned int hp_action, unsigned int cpu); > > > +#define KEXEC_CRASH_HP_REMOVE_CPU 0 > > > +#define KEXEC_CRASH_HP_ADD_CPU 1 > > > +#define KEXEC_CRASH_HP_REMOVE_MEMORY 2 > > > +#define KEXEC_CRASH_HP_ADD_MEMORY 3 > > > +#endif /* CONFIG_CRASH_HOTPLUG */ > > > + > > > /* kexec interface functions */ > > > extern void machine_kexec(struct kimage *image); > > > extern int machine_kexec_prepare(struct kimage *image); > > > diff --git a/kernel/crash_core.c b/kernel/crash_core.c > > > index 256cf6db573c..ecf746243ab2 100644 > > > --- a/kernel/crash_core.c > > > +++ b/kernel/crash_core.c > > > @@ -9,12 +9,17 @@ > > > #include > > > #include > > > #include > > > +#include > > > +#include > > > +#include > > > #include > > > #include > > > #include > > > +#include "kexec_internal.h" > > > + > > > /* vmcoreinfo stuff */ > > > unsigned char *vmcoreinfo_data; > > > size_t vmcoreinfo_size; > > > @@ -491,3 +496,99 @@ static int __init crash_save_vmcoreinfo_init(void) > > > } > > > subsys_initcall(crash_save_vmcoreinfo_init); > > > + > > > +#ifdef CONFIG_CRASH_HOTPLUG > > > +void __weak arch_crash_hotplug_handler(struct kimage *image, > > > + unsigned int hp_action, unsigned int cpu) > > > +{ > > > + pr_warn("crash hp: %s not implemented", __func__); > > > +} > > > + > > > +static void crash_hotplug_handler(unsigned int hp_action, > > > + unsigned int cpu) > > > +{ > > > + /* 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, cpu %u", hp_action, cpu); > > > + > > > + /* 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, cpu); > > > + > > > + /* 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; > > > + > > > + switch (val) { > > > + case MEM_ONLINE: > > > + crash_hotplug_handler(KEXEC_CRASH_HP_ADD_MEMORY, -1U); > > We don't differentiate the memory add/remove, cpu add, except of cpu > > remove. Means the hp_action only differentiate cpu remove from the other > > action. Maybe only making two types? > > > > #define KEXEC_CRASH_HP_REMOVE_CPU 0 > > #define KEXEC_CRASH_HP_UPDATE_OTHER 1 > > > Sourabh Jain's work with PPC uses REMOVE_CPU, REMOVE_MEMORY, and ADD_MEMORY. > Do you still want to consolidate these? I checked Sourabh's ppc patches, am wondering why memory hotplug is not handled. Is it going to be that CONFIG_MEMORY_HOTPLUG is enabled on ppc, while Sourabh is not willing to handle it for now? Only passing KEXEC_CRASH_HP_ADD_MEMORY/KEXEC_CRASH_HP_REMOVE_MEMORY to indicate that they are not supported sounds weird to me, honestly.