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=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,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 C0743C433ED for ; Wed, 28 Apr 2021 06:39:36 +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 2441461413 for ; Wed, 28 Apr 2021 06:39:36 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2441461413 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=huawei.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:34972 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lbdrD-0002o4-6H for qemu-devel@archiver.kernel.org; Wed, 28 Apr 2021 02:39:35 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:59230) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lbdoK-0000Gi-7p; Wed, 28 Apr 2021 02:36:36 -0400 Received: from szxga02-in.huawei.com ([45.249.212.188]:2079) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lbdoH-0005Sf-EO; Wed, 28 Apr 2021 02:36:36 -0400 Received: from dggeml703-chm.china.huawei.com (unknown [172.30.72.57]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4FVTPC1D7MzYfBX; Wed, 28 Apr 2021 14:34:07 +0800 (CST) Received: from dggpemm500023.china.huawei.com (7.185.36.83) by dggeml703-chm.china.huawei.com (10.3.17.136) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2176.2; Wed, 28 Apr 2021 14:36:24 +0800 Received: from [10.174.187.128] (10.174.187.128) by dggpemm500023.china.huawei.com (7.185.36.83) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256) id 15.1.2176.2; Wed, 28 Apr 2021 14:36:21 +0800 Subject: Re: [RFC PATCH v2 2/6] hw/arm/virt: DT: Add cpu-map To: =?UTF-8?Q?Philippe_Mathieu-Daud=c3=a9?= , Andrew Jones References: <20210413080745.33004-1-wangyanan55@huawei.com> <20210413080745.33004-3-wangyanan55@huawei.com> <648ff988-35f6-1857-2194-0d3e11e0d15c@redhat.com> <20210427100442.elz3bjgl6mcntevc@gator.home> From: "wangyanan (Y)" Message-ID: <942cefdf-6d7c-8463-48b5-108b789988ae@huawei.com> Date: Wed, 28 Apr 2021 14:36:20 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.4.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-Originating-IP: [10.174.187.128] X-ClientProxiedBy: dggeme713-chm.china.huawei.com (10.1.199.109) To dggpemm500023.china.huawei.com (7.185.36.83) X-CFilter-Loop: Reflected Received-SPF: pass client-ip=45.249.212.188; envelope-from=wangyanan55@huawei.com; helo=szxga02-in.huawei.com X-Spam_score_int: -41 X-Spam_score: -4.2 X-Spam_bar: ---- X-Spam_report: (-4.2 / 5.0 requ) BAYES_00=-1.9, NICE_REPLY_A=-0.001, RCVD_IN_DNSWL_MED=-2.3, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action 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: Peter Maydell , "Michael S . Tsirkin" , qemu-devel@nongnu.org, Shannon Zhao , Igor Mammedov , qemu-arm@nongnu.org, Alistair Francis , prime.zeng@hisilicon.com, yangyicong@huawei.com, yuzenghui@huawei.com, wanghaibin.wang@huawei.com, zhukeqian1@huawei.com, Jiajie Li , David Gibson Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 2021/4/27 20:36, Philippe Mathieu-Daudé wrote: > On 4/27/21 12:04 PM, Andrew Jones wrote: >> On Tue, Apr 27, 2021 at 11:47:17AM +0200, Philippe Mathieu-Daudé wrote: >>> Hi Yanan, Drew, >>> >>> On 4/13/21 10:07 AM, Yanan Wang wrote: >>>> From: Andrew Jones >>>> >>>> Support device tree CPU topology descriptions. >>>> >>>> Signed-off-by: Andrew Jones >>>> Signed-off-by: Yanan Wang >>>> --- >>>> hw/arm/virt.c | 41 ++++++++++++++++++++++++++++++++++++++++- >>>> include/hw/arm/virt.h | 1 + >>>> 2 files changed, 41 insertions(+), 1 deletion(-) >>>> >>>> diff --git a/hw/arm/virt.c b/hw/arm/virt.c >>>> index 9f01d9041b..f4ae60ded9 100644 >>>> --- a/hw/arm/virt.c >>>> +++ b/hw/arm/virt.c >>>> @@ -352,10 +352,11 @@ static void fdt_add_cpu_nodes(const VirtMachineState *vms) >>>> int cpu; >>>> int addr_cells = 1; >>>> const MachineState *ms = MACHINE(vms); >>>> + const VirtMachineClass *vmc = VIRT_MACHINE_GET_CLASS(vms); >>>> int smp_cpus = ms->smp.cpus; >>>> >>>> /* >>>> - * From Documentation/devicetree/bindings/arm/cpus.txt >>>> + * See Linux Documentation/devicetree/bindings/arm/cpus.yaml >>>> * On ARM v8 64-bit systems value should be set to 2, >>>> * that corresponds to the MPIDR_EL1 register size. >>>> * If MPIDR_EL1[63:32] value is equal to 0 on all CPUs >>>> @@ -408,8 +409,45 @@ static void fdt_add_cpu_nodes(const VirtMachineState *vms) >>>> ms->possible_cpus->cpus[cs->cpu_index].props.node_id); >>>> } >>>> >>>> + if (ms->smp.cpus > 1 && !vmc->no_cpu_topology) { >>>> + qemu_fdt_setprop_cell(ms->fdt, nodename, "phandle", >>>> + qemu_fdt_alloc_phandle(ms->fdt)); >>>> + } >>>> + >>>> g_free(nodename); >>>> } >>>> + >>>> + if (ms->smp.cpus > 1 && !vmc->no_cpu_topology) { >>>> + /* >>>> + * See Linux Documentation/devicetree/bindings/cpu/cpu-topology.txt >>>> + * In a SMP system, the hierarchy of CPUs is defined through four >>>> + * entities that are used to describe the layout of physical CPUs >>>> + * in the system: socket/cluster/core/thread. >>>> + */ >>>> + qemu_fdt_add_subnode(ms->fdt, "/cpus/cpu-map"); >>>> + >>>> + for (cpu = ms->smp.cpus - 1; cpu >= 0; cpu--) { >>>> + char *cpu_path = g_strdup_printf("/cpus/cpu@%d", cpu); >>>> + char *map_path; >>>> + >>>> + if (ms->smp.threads > 1) { >>>> + map_path = g_strdup_printf( >>>> + "/cpus/cpu-map/%s%d/%s%d/%s%d", >>>> + "socket", cpu / (ms->smp.cores * ms->smp.threads), >>>> + "core", (cpu / ms->smp.threads) % ms->smp.cores, >>>> + "thread", cpu % ms->smp.threads); >>>> + } else { >>>> + map_path = g_strdup_printf( >>>> + "/cpus/cpu-map/%s%d/%s%d", >>>> + "socket", cpu / ms->smp.cores, >>>> + "core", cpu % ms->smp.cores); >>>> + } >>>> + qemu_fdt_add_path(ms->fdt, map_path); >>>> + qemu_fdt_setprop_phandle(ms->fdt, map_path, "cpu", cpu_path); >>>> + g_free(map_path); >>>> + g_free(cpu_path); >>>> + } >>>> + } >>>> } >>>> >>>> static void fdt_add_its_gic_node(VirtMachineState *vms) >>>> @@ -2769,6 +2807,7 @@ static void virt_machine_5_2_options(MachineClass *mc) >>>> virt_machine_6_0_options(mc); >>>> compat_props_add(mc->compat_props, hw_compat_5_2, hw_compat_5_2_len); >>>> vmc->no_secure_gpio = true; >>>> + vmc->no_cpu_topology = true; >>> Bare with me because "machine versioning" is something new to me, I was >>> expecting it to be only related to migrated fields. >>> Why do we need to care about not adding the FDT node in older machines? >>> Shouldn't the guest skip unknown FDT nodes? >> It probably should, the question is whether it would. Also, the nodes may >> not be unknown, so the guest will read the information and set up its >> topology as instructed. That topology may not be the same as what was >> getting used by default without the topology description. It's possible >> that a user's application has a dependency on the topology and if that >> topology gets changed under its feat it'll behave differently. > [*] > > I see. > >> In short, machine versioning isn't just about vmstate, it's also about >> keeping a machine type looking the same to the guest. > Yes, TIL. > >> Now, it's possible that we're being overly cautious here, but this compat >> variable doesn't complicate code too much. So I think I'd prefer to use it >> than not. > No problem. Could you or Yanan add your first paragraph ([*], reworded > in the commit description? I don't think a comment in the code is > useful, but having it in the commit is helpful IMO. Hi Philippe, Of course. I think I can do this for the commit description. Thanks, Yanan > Thanks, > > Phil. > > .