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=-8.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 200F4C2D0DB for ; Fri, 24 Jan 2020 16:05:53 +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 D71FF206D4 for ; Fri, 24 Jan 2020 16:05:52 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="B8dAG05R" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D71FF206D4 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]:44020 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iv1Sx-0007bz-UP for qemu-devel@archiver.kernel.org; Fri, 24 Jan 2020 11:05:51 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:32789) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1iv1SG-00076m-14 for qemu-devel@nongnu.org; Fri, 24 Jan 2020 11:05:09 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1iv1SD-0002ZC-98 for qemu-devel@nongnu.org; Fri, 24 Jan 2020 11:05:06 -0500 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:48373 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 1iv1SC-0002WV-VS for qemu-devel@nongnu.org; Fri, 24 Jan 2020 11:05:05 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1579881904; 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=GE4uj/mcUi/1pU7izGoiIfH3HPVnNAkWsQ0yNZrw24Y=; b=B8dAG05RrUSkzcFvGELet1UWpLMJX3PZQlCPxVINFiWo9aWMtDWsaGAp2FkpYFnIilm7Cq FfPhIHRygGODVkNokyaXAOsjK4SgaITncjPq/bmzvjvV/VKeKcCGJJcR8YQ2szwHOftPqf zUcKpwNIE0jQSfOifOm39PadkgkRQMY= 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-92-ZnEiu1KHN0SuhnM0Mrm47A-1; Fri, 24 Jan 2020 11:05:02 -0500 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 598FF8010D8 for ; Fri, 24 Jan 2020 16:05:01 +0000 (UTC) Received: from lacos-laptop-7.usersys.redhat.com (ovpn-117-77.ams2.redhat.com [10.36.117.77]) by smtp.corp.redhat.com (Postfix) with ESMTP id 2DB7B5DDB1; Fri, 24 Jan 2020 16:04:55 +0000 (UTC) Subject: Re: [PATCH] acpi: cpuhp: document how to use CPHP_GET_CPU_ID_CMD command To: Igor Mammedov , qemu-devel@nongnu.org References: <1579879065-3873-1-git-send-email-imammedo@redhat.com> From: Laszlo Ersek Message-ID: <5e8dcfed-b2ba-9e7f-c80b-0b9dcb4c79b3@redhat.com> Date: Fri, 24 Jan 2020 17:04:55 +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: <1579879065-3873-1-git-send-email-imammedo@redhat.com> Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-MC-Unique: ZnEiu1KHN0SuhnM0Mrm47A-1 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com 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] 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: philmd@redhat.com, mst@redhat.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Hi Igor, On 01/24/20 16:17, Igor Mammedov wrote: > Commit 3a61c8db9d25 introduced CPHP_GET_CPU_ID_CMD command but > did not sufficiently described how to use it. Fix it by adding > missing command documentation and suggested work-flow to enumerate > possible architecture specific CPU IDs. > > Fixes: 3a61c8db9d25 ("acpi: cpuhp: add CPHP_GET_CPU_ID_CMD command") > Signed-off-by: Igor Mammedov > --- > docs/specs/acpi_cpu_hotplug.txt | 15 +++++++++++++++ > 1 file changed, 15 insertions(+) > > diff --git a/docs/specs/acpi_cpu_hotplug.txt b/docs/specs/acpi_cpu_hotplug.txt > index a8ce5e7..81b4534 100644 > --- a/docs/specs/acpi_cpu_hotplug.txt > +++ b/docs/specs/acpi_cpu_hotplug.txt > @@ -94,6 +94,8 @@ write access: > register in QEMU > 2: following writes to 'Command data' register set OST status > register in QEMU > + 3: following reads from 'Command data' and 'Command data 2' return > + architecture specific CPU ID value for currently selected CPU. > other values: reserved > [0x6-0x7] reserved > [0x8] Command data: (DWORD access) Looks good. > @@ -147,3 +149,16 @@ Typical usecases: > 11. Otherwise store 0x0 to the 'CPU selector' register, to put it > into a valid state and exit. > The iterator at this point equals "max_cpus". > + > + - Enumerate present/non present CPUs architecture specific IDs > + (in case of x86: ACPIC IDs) > + 01: Use "Enumerate CPUs present/non present CPUs" to get max_cpus OK, this includes the last step of that procedure too, i.e.: 11. Otherwise store 0x0 to the 'CPU selector' register, to put it into a valid state and exit. [...] > + 02: Store 0x3 in the 'Command field' register > + 03: Set 'current cpu selector' iterator to 0x0 > + 04: Store the iterator to the 'CPU selector' register > + 05: Read from registers 'Command data' and 'Command data 2' parts of ID, > + combine them into ID like following: > + 'Command data 2' << 32 | 'Command data' > + and store pair 'current cpu selector' : ID for further processing > + 06: Increment the iterator and if the iterator < max_cpus go to step 4 > + 07: Otherwise store 0x0 to the 'CPU selector' register and exit. > This looks good as well. I'm happy to R-b this patch, with one caveat: in edk2, I might not want to -- or have to -- fetch the full array of arch-specific CPU IDs in advance. That's one possibility, yes -- but it's also possible that I'll only fetch the arch CPU ID for the freshly hotplugged CPU in the SMI handler. I don't know yet. So, as long as OVMF is not expected to *only* implement the typical use case here, I'm OK with this algorithm, because it looks valid to me. I'd just like to keep the option open to use the CPHP_GET_CPU_ID_CMD command for such a CPU as well that has been selected with -- say -- CPHP_GET_NEXT_CPU_WITH_EVENT_CMD. With that: Reviewed-by: Laszlo Ersek (If you like, you could also split this patch in two -- repost the first half (with the register documentation update) with my R-b at once, and delay the second half (the typical use case for CPHP_GET_CPU_ID_CMD) until I "get there" in edk2. Up to you.) Thanks! Laszlo