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 X-Spam-Level: X-Spam-Status: No, score=-8.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 31703C43603 for ; Fri, 6 Dec 2019 16:57:08 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id F0742206DF for ; Fri, 6 Dec 2019 16:57:07 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="Pm+Mlw7Q" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org F0742206DF Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:41338 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1idGuh-0002mM-0m for qemu-devel@archiver.kernel.org; Fri, 06 Dec 2019 11:57:07 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:39564) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1idFBm-0006wU-1t for qemu-devel@nongnu.org; Fri, 06 Dec 2019 10:06:39 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1idFBk-0005go-LQ for qemu-devel@nongnu.org; Fri, 06 Dec 2019 10:06:37 -0500 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:45128 helo=us-smtp-1.mimecast.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1idFBi-0005es-NA for qemu-devel@nongnu.org; Fri, 06 Dec 2019 10:06:34 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1575644793; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=DB7Dl0O/SdQi/C44lTRSAKFanxqyAJjtE6937CoG+lc=; b=Pm+Mlw7Q61xyTVoz5xBuIaf6iCNwTnXUTKIh/H+jAKpQ0YN/TUbOroiGqJpU7aO3GaE7+J 9qlnJp9Li5LowNHwFoHmbA/b8UodSUYlztAjqZAjLmjWz0TKHFLlZijPEbBKNMJ7FzbCg0 m1WbRucAe4P9pSCWSw35cmZrVcuM1oc= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-423-FLCEaU9mPxGqzzK7hxfqQQ-1; Fri, 06 Dec 2019 10:06:32 -0500 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 4A3679126C for ; Fri, 6 Dec 2019 15:06:31 +0000 (UTC) Received: from lacos-laptop-7.usersys.redhat.com (ovpn-116-235.ams2.redhat.com [10.36.116.235]) by smtp.corp.redhat.com (Postfix) with ESMTP id C960C67E52; Fri, 6 Dec 2019 15:06:25 +0000 (UTC) Subject: Re: [PATCH for-5.0 8/8] acpi: cpuhp: spec: document procedure for enabling modern CPU hotplug To: Igor Mammedov References: <1575479147-6641-1-git-send-email-imammedo@redhat.com> <1575479147-6641-9-git-send-email-imammedo@redhat.com> <20191206144940.091bef52@redhat.com> From: Laszlo Ersek Message-ID: Date: Fri, 6 Dec 2019 16:06:24 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20191206144940.091bef52@redhat.com> Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-MC-Unique: FLCEaU9mPxGqzzK7hxfqQQ-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 207.211.31.120 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: pbonzini@redhat.com, philmd@redhat.com, qemu-devel@nongnu.org, mst@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 12/06/19 14:49, Igor Mammedov wrote: > On Thu, 5 Dec 2019 15:07:53 +0100 > Laszlo Ersek wrote: > >> On 12/04/19 18:05, Igor Mammedov wrote: >>> Describe how to enable and detect modern CPU hotplug interface. >>> Detection part is based on new CPHP_GET_CPU_ID_CMD command, >>> introduced by "acpi: cpuhp: add CPHP_GET_CPU_ID_CMD command" patch. >>> >>> Signed-off-by: Igor Mammedov >>> --- >>> docs/specs/acpi_cpu_hotplug.txt | 22 ++++++++++++++++++++-- >>> 1 file changed, 20 insertions(+), 2 deletions(-) >> >> Could we make this usecase / workflow independent of the new >> CPHP_GET_CPU_ID_CMD command please? >> >> I'd like to suggest the following: >> >>> diff --git a/docs/specs/acpi_cpu_hotplug.txt b/docs/specs/acpi_cpu_hotplug.txt >>> index bb33144..667b264 100644 >>> --- a/docs/specs/acpi_cpu_hotplug.txt >>> +++ b/docs/specs/acpi_cpu_hotplug.txt >>> @@ -15,14 +15,14 @@ CPU present bitmap for: >>> PIIX-PM (IO port 0xaf00-0xaf1f, 1-byte access) >>> One bit per CPU. Bit position reflects corresponding CPU APIC ID. Read-only. >>> The first DWORD in bitmap is used in write mode to switch from legacy >>> - to new CPU hotplug interface, write 0 into it to do switch. >>> + to modern CPU hotplug interface, write 0 into it to do switch. >>> --------------------------------------------------------------- >>> QEMU sets corresponding CPU bit on hot-add event and issues SCI >>> with GPE.2 event set. CPU present map is read by ACPI BIOS GPE.2 handler >>> to notify OS about CPU hot-add events. CPU hot-remove isn't supported. >>> >>> ===================================== >>> -ACPI CPU hotplug interface registers: >>> +Modern ACPI CPU hotplug interface registers: >>> ------------------------------------- >>> Register block base address: >>> ICH9-LPC IO port 0x0cd8 >>> @@ -105,6 +105,24 @@ write access: >>> other values: reserved >>> >>> Typical usecases: >>> + - (x86) Detecting and enabling modern CPU hotplug interface. >> >> (1) I think we can drop the (x86) restriction. (Because, we don't need >> to depend on APIC ID specifics; see below.) > I'd rather keep it x86 specific, as enabling interface and talking about > legacy bitmap applies only to x86 impl. > ARM one won't have any of it, it will just be enabled in a future QEMU > (probably even without version-ed machine type). > So could we just say usual "use firmware X.Y with QEMU Z to use CPU hotplug" > in that case? > Do we really need it to be arch agnostic? No, I only suggested removing the x86 reference as a possible "extra" improvement, from not depending on CPHP_GET_CPU_ID_CMD / APIC ID. Thanks, Laszlo