From nobody Sat Feb 7 07:10:24 2026 Delivered-To: importer@patchew.org Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zohomail.com; dkim=fail; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail(p=none dis=none) header.from=redhat.com ARC-Seal: i=1; a=rsa-sha256; t=1575480193; cv=none; d=zohomail.com; s=zohoarc; b=WNLu2fG98PDv6q/REVMxVZ6+6g6fWllbo0jYb+89IY5tCHh9oJc2oo6zAkFOlHV03pwbOG1f1ecKHmAc99LXDFEkqEB4kWq1J0onvZvAAfKJbYdMpVBeNoGWx1rORAiKUscWFyZejtdbMRM1WZBxLSM7ZbBmbkxhMhkubsE7PWs= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1575480193; h=Content-Type:Content-Transfer-Encoding:Cc:Date:From:In-Reply-To:List-Subscribe:List-Post:List-Id:List-Archive:List-Help:List-Unsubscribe:Message-ID:References:Sender:Subject:To; bh=TqJTzapMD48SAnuXvSZ6ni4aF2WLRnsexaD2qQGsFgo=; b=V+mqd+aa3ut1IO+lhg8zwEmdRFfZGWvb56T6e86rbcQkct9rYTr/xfggkBqCJQwKLhSvgauRYpQfMiY6XHNhH0x5hIXmOy/iwtLZGJwnSC/pSwqEbIIGh6PrC16+92UjMQbWHyNWVgbWtQ1MdMN9Xz4mkkF+25sX5PXYGoWn00k= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=fail; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail header.from= (p=none dis=none) header.from= Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1575480193826415.45177862410947; Wed, 4 Dec 2019 09:23:13 -0800 (PST) Received: from localhost ([::1]:42156 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1icYMq-0000bk-3f for importer@patchew.org; Wed, 04 Dec 2019 12:23:12 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:43629) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1icY6V-0005Sa-08 for qemu-devel@nongnu.org; Wed, 04 Dec 2019 12:06:21 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1icY6L-0008Ei-02 for qemu-devel@nongnu.org; Wed, 04 Dec 2019 12:06:14 -0500 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:30514 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 1icY6K-0007pd-Ev for qemu-devel@nongnu.org; Wed, 04 Dec 2019 12:06:08 -0500 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-278-0Rwf_ThgOKmzxVGdVfLX0A-1; Wed, 04 Dec 2019 12:05:58 -0500 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 0625C1083E8F for ; Wed, 4 Dec 2019 17:05:58 +0000 (UTC) Received: from dell-r430-03.lab.eng.brq.redhat.com (dell-r430-03.lab.eng.brq.redhat.com [10.37.153.18]) by smtp.corp.redhat.com (Postfix) with ESMTP id D207F5D6BB; Wed, 4 Dec 2019 17:05:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1575479167; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=TqJTzapMD48SAnuXvSZ6ni4aF2WLRnsexaD2qQGsFgo=; b=g6aFAtesY2pBQrtrvwU3x2QOn9nxIdCY1yC2KdiusEcmdmoYCIj3l4ceLbSXXfP/XDgTBT 6rr7Zuqyff8Irh8z5mBk9atajSzptp0kjx+zVZhXqHD0Bi5LvaQm5OWjPC7w59Gud9onWo CZb2RsFSXTPZoUv8G/KnVi51YIV2cfA= From: Igor Mammedov To: qemu-devel@nongnu.org Subject: [PATCH for-5.0 8/8] acpi: cpuhp: spec: document procedure for enabling modern CPU hotplug Date: Wed, 4 Dec 2019 18:05:47 +0100 Message-Id: <1575479147-6641-9-git-send-email-imammedo@redhat.com> In-Reply-To: <1575479147-6641-1-git-send-email-imammedo@redhat.com> References: <1575479147-6641-1-git-send-email-imammedo@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-MC-Unique: 0Rwf_ThgOKmzxVGdVfLX0A-1 X-Mimecast-Spam-Score: 0 Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 205.139.110.120 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, lersek@redhat.com, mst@redhat.com Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: fail (Header signature does not verify) MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" 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(-) 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-o= nly. 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. =20 =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D -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 =20 Typical usecases: + - (x86) Detecting and enabling modern CPU hotplug interface. + QEMU starts with legacy CPU hotplug interface enabled. Detecting= and + switching to modern interface is based on the 2 legacy CPU hotpl= ug features: + 1. Writes into CPU bitmap are ignored. + 2. CPU bitmap always has bit#0 set, corresponding to boot CPU. + + Use following steps to detect and enable modern CPU hotplug inte= rface: + 1. Store 0x0 to the 'CPU selector' register, + attempting to switch to modern mode + 2. Store 0x0 to the 'CPU selector' register, + to ensure valid selector value + 3. Store 0x3 to the 'Command field' register, + sets the 'Command data 2' register into architecture specif= ic + CPU identifier mode + 4. Read the 'Command data 2' register. + If read value is 0x0, the modern interface is enabled. + Otherwise legacy or no CPU hotplug interface available + - Get a cpu with pending event 1. Store 0x0 to the 'CPU selector' register. 2. Store 0x0 to the 'Command field' register. --=20 2.7.4