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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 796C9C4360C for ; Fri, 27 Sep 2019 02:01:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 548A320835 for ; Fri, 27 Sep 2019 02:01:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728078AbfI0CBf (ORCPT ); Thu, 26 Sep 2019 22:01:35 -0400 Received: from szxga05-in.huawei.com ([45.249.212.191]:2790 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726145AbfI0CBf (ORCPT ); Thu, 26 Sep 2019 22:01:35 -0400 Received: from DGGEMS408-HUB.china.huawei.com (unknown [172.30.72.59]) by Forcepoint Email with ESMTP id F33E9AE4EF0C1B462D03; Fri, 27 Sep 2019 10:01:30 +0800 (CST) Received: from [127.0.0.1] (10.184.12.158) by DGGEMS408-HUB.china.huawei.com (10.3.19.208) with Microsoft SMTP Server id 14.3.439.0; Fri, 27 Sep 2019 10:01:20 +0800 Subject: Re: [PATCH 10/35] irqchip/gic-v4.1: VPE table (aka GICR_VPROPBASER) allocation To: Marc Zyngier , , CC: Lorenzo Pieralisi , Jason Cooper , Thomas Gleixner References: <20190923182606.32100-1-maz@kernel.org> <20190923182606.32100-11-maz@kernel.org> <155660c2-7f30-e188-ca8d-c37fabea6d97@huawei.com> <6f4ccdfd-4b63-04cb-e7c0-f069e620127f@kernel.org> <14111988-74c9-12c3-1322-1580ff6ba11f@huawei.com> From: Zenghui Yu Message-ID: <56ddfedd-5d8c-0507-c164-b04d63f51a1e@huawei.com> Date: Fri, 27 Sep 2019 09:59:16 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:64.0) Gecko/20100101 Thunderbird/64.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.184.12.158] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2019/9/26 23:57, Marc Zyngier wrote: > On 26/09/2019 16:19, Zenghui Yu wrote: >> On 2019/9/25 22:41, Marc Zyngier wrote: >>> >>> Indeed. The whole idea is that ITSs and RDs can share a vPE table if >>> they are in the same affinity group (such as a socket, for example). >>> This is what is missing from v4.0 where the ITS knows about vPEs, but >>> doesn't know about residency. With that in place, the HW is able to do a >>> lot more for us. >> >> Thanks for your education! >> >> I really want to know *how* does GICv4.1 ITS know about the vPE >> residency (in hardware level)? > > Hey, I'm a SW guy, I don't design the hardware! ;-) > >> I can understand that Redistributor can easily achieve it by >> VPENDBASER's Valid and vPEID field. And it's necessary for ITS to >> know the residency so that it can determine whether it's appropriate >> to trigger default doorbell for vPE. But I have no knowledge about >> how can it be achieved in hardware details. > > My take is that the RD and the ITS can communicate over the shared > table, hence my remark above about SVPET==0. But as I said, I'm not a HW > guy. ;-) I should have asked our GIC engineers for these things. Thanks, zenghui