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 CB074C6FD19 for ; Thu, 16 Mar 2023 10:12:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230289AbjCPKMY (ORCPT ); Thu, 16 Mar 2023 06:12:24 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:32950 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230179AbjCPKMO (ORCPT ); Thu, 16 Mar 2023 06:12:14 -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 ESMTPS id 67AF3B78B2 for ; Thu, 16 Mar 2023 03:11:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1678961497; 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=85fsDNz+lL7FHNJ1iBNzrAf34oVvetUItgQ6w01KkXg=; b=CFuZBAiqcmFiQPbH10yxQEHkhAt0jkDW0vRJP6sF1MPfJOTV49iB6XJ0kVFhXSEO2mm3XZ 2eOAec3ljGUY7fsCALOVqXhekXfNgsn/p0AQ6Ei7t7OwurE/4zTg1Yu8qJBzLnpsX5DrIg qbh8kdteHMTSWOzcEeERIuaMmqdn5LI= 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-225-6DMdYaQDM0Kz1urE3t7CmQ-1; Thu, 16 Mar 2023 06:11:33 -0400 X-MC-Unique: 6DMdYaQDM0Kz1urE3t7CmQ-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 8FE3B800B23; Thu, 16 Mar 2023 10:11:31 +0000 (UTC) Received: from localhost (ovpn-12-81.pek2.redhat.com [10.72.12.81]) by smtp.corp.redhat.com (Postfix) with ESMTPS id E59B32A68; Thu, 16 Mar 2023 10:11:29 +0000 (UTC) Date: Thu, 16 Mar 2023 18:11:26 +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, david@redhat.com, sourabhjain@linux.ibm.com, konrad.wilk@oracle.com, boris.ostrovsky@oracle.com Subject: Re: [PATCH v19 2/7] crash: add generic infrastructure for crash hotplug support Message-ID: References: <20230306162228.8277-1-eric.devolder@oracle.com> <20230306162228.8277-3-eric.devolder@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230306162228.8277-3-eric.devolder@oracle.com> X-Scanned-By: MIMEDefang 3.1 on 10.11.54.5 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 03/06/23 at 11:22am, Eric DeVolder wrote: ...... > +static void crash_handle_hotplug_event(unsigned int hp_action, unsigned int cpu) > +{ > + /* Obtain lock while changing crash information */ > + if (kexec_trylock()) { > + > + /* Check kdump is loaded */ > + if (kexec_crash_image) { > + struct kimage *image = kexec_crash_image; > + > + if (hp_action == KEXEC_CRASH_HP_ADD_CPU || > + hp_action == KEXEC_CRASH_HP_REMOVE_CPU) > + pr_debug("hp_action %u, cpu %u\n", hp_action, cpu); > + else > + pr_debug("hp_action %u\n", hp_action); > + > + /* > + * When the struct kimage is allocated, the elfcorehdr_index > + * is set to -1. Find the segment containing the elfcorehdr, > + * if not already found. This works for both the kexec_load > + * and kexec_file_load paths. > + */ > + if (image->elfcorehdr_index < 0) { > + unsigned long mem; > + unsigned char *ptr; > + unsigned int n; > + > + for (n = 0; n < image->nr_segments; n++) { > + mem = image->segment[n].mem; > + ptr = kmap_local_page(pfn_to_page(mem >> PAGE_SHIFT)); > + if (ptr) { > + /* The segment containing elfcorehdr */ > + if (memcmp(ptr, ELFMAG, SELFMAG) == 0) { > + image->elfcorehdr_index = (int)n; > + } > + kunmap_local(ptr); > + } > + } > + } > + > + if (image->elfcorehdr_index < 0) { > + pr_err("unable to locate elfcorehdr segment"); > + goto out; > + } > + > + /* Needed in order for the segments to be updated */ > + arch_kexec_unprotect_crashkres(); > + > + /* Differentiate between normal load and hotplug update */ > + image->hp_action = hp_action; > + > + /* Now invoke arch-specific update handler */ > + arch_crash_handle_hotplug_event(image); > + > + /* No longer handling a hotplug event */ > + image->hp_action = KEXEC_CRASH_HP_NONE; > + image->elfcorehdr_updated = true; It's good to initialize the image->hp_action here, however where do you check it? Do you plan to add some check somewhere? > + > + /* Change back to read-only */ > + arch_kexec_protect_crashkres(); > + } > + > +out: > + /* Release lock now that update complete */ > + kexec_unlock(); > + } > +} ......