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 Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 0BC5EC433EF for ; Sun, 23 Jan 2022 10:32:07 +0000 (UTC) Received: from list by lists.xenproject.org with outflank-mailman.259659.448096 (Exim 4.92) (envelope-from ) id 1nBaA2-000155-G2; Sun, 23 Jan 2022 10:31:50 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 259659.448096; Sun, 23 Jan 2022 10:31:50 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1nBaA2-00014y-Ct; Sun, 23 Jan 2022 10:31:50 +0000 Received: by outflank-mailman (input) for mailman id 259659; Sun, 23 Jan 2022 10:31:49 +0000 Received: from mail.xenproject.org ([104.130.215.37]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1nBaA1-00014r-9e for xen-devel@lists.xenproject.org; Sun, 23 Jan 2022 10:31:49 +0000 Received: from xenbits.xenproject.org ([104.239.192.120]) by mail.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1nBa9x-000252-Iw; Sun, 23 Jan 2022 10:31:45 +0000 Received: from [54.239.6.188] (helo=[192.168.0.182]) by xenbits.xenproject.org with esmtpsa (TLS1.3:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.92) (envelope-from ) id 1nBa9x-0007sT-2d; Sun, 23 Jan 2022 10:31:45 +0000 X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=xen.org; s=20200302mail; h=Content-Transfer-Encoding:Content-Type:In-Reply-To:From: References:Cc:To:Subject:MIME-Version:Date:Message-ID; bh=w0XxSOGH+XvHAsTVZiGIs6orEU6a6R8p0FKJzzQLeX4=; b=mrZWqYFlx4EH8K44mX+bJhu54T DlL79+2MkfICkuISGgJVeOpNsknQhv1tUQb8w0A/jVN+Hx2MdAVBNDxJGOSiZVl0gaX4SmxPjhTXP pkZPig1ld1BWedYQ7B1x6SYTrJNW46j7NGAaouhFEtMkJwv0drKeOnJB3Wx9itJI8xV4=; Message-ID: <0052921f-c582-a07f-748a-0520b6beeafd@xen.org> Date: Sun, 23 Jan 2022 14:31:38 +0400 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:91.0) Gecko/20100101 Thunderbird/91.5.0 Subject: Re: [PATCH v4] xen/arm: Allow QEMU platform to be built with GICv2 To: Dongjiu Geng , Bertrand Marquis Cc: Stefano Stabellini , Volodymyr Babchuk , xen-devel References: <20220117064003.3367188-1-gengdongjiu1@gmail.com> <2a1a0dd5-b8a7-8072-2961-b1fbe9ec746a@xen.org> <9A7FAD16-3D4A-4C22-8288-A4719A993CDD@arm.com> From: Julien Grall In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Hi, On 19/01/2022 15:30, Dongjiu Geng wrote: > Bertrand Marquis 于2022年1月18日周二 17:17写道： >> >> Hi Dongju, >> >>> On 18 Jan 2022, at 08:58, Dongjiu Geng wrote: >>> >>> Bertrand Marquis 于2022年1月18日周二 16:48写道： >>>> >>>> Hi Dongju, >>>> >>>>> On 18 Jan 2022, at 08:45, Dongjiu Geng wrote: >>>>> >>>>> Julien Grall 于2022年1月17日周一 22:16写道： >>>>>> >>>>>> Hi, >>>>>> >>>>>> On 17/01/2022 10:40, Dongjiu Geng wrote: >>>>>>> It turns out that QEMU has been supporting GICv2 virtualization since >>>>>>> v3.1.0. So remove the dependencies on GICv3. >>>>>> >>>>>> >>>>>> Technically, the current form of CONFIG_QEMU allows the same binary to >>>>>> boot on QEMU with GICv2 or GICv3. >>>>>> >>>>>>> If we want to use GICv3, >>>>>>> we can select the QEMU_LEGACY configuration. >>>>>> >>>>>> AFAIK, GICv3 is not a legacy feature... So it feels a bit odd to name it >>>>>> like that (see more below). >>>>> >>>>> Legacy means QEMU platform only supports GICV3, now it can support >>>>> both GICv2 and GICv3. The scope of support has been expanded >>>>> Not mean GICv3 is a legacy feature. >>>> >>>> You might be misleading a bit here. >>>> In the current configuration, Xen support GICv2, GICv3 and vgic. >>>> The only thing not supported is actually the new VGIC but this is an unsupported feature not fully functional which shall be used with caution. >>>> >>>> What issue exactly do you have in Qemu configured for gicv2 when you use the default configuration ? >>> >>> I want to use NEW_VGIC with GICv2, but QEMU only select GICV3, when >>> GICv3 is select, the NEW_VGIC can not be used. I try the NEW_VGIC >>> with GICv2, not found issue. so I want to remove this limitation. >>> If you think we should not support NEW_VGIC feature, we can ignore >>> this patch. thanks! >> >> Supporting GICv2 makes sense but using NEW_VGIC in Xen might not as it is not security supported and does not support ITS and MSIs. > It is surely that NEW_VGIC not support ITS and MSI. but I think > QEMU platform should not limit user select it. The goal of the option CONFIG_ is to select the minimal set of CONFIG_* to allow booting on a given platform. Given that QEMU is supporting both GICv2 and GICv3, then I think it is correct to select both options. > Selecting GICv2、GICv3 > or NEW_VGIC may be chosen by users. But I find user can select it at > all. > >> >> Do you have a reason to use the NEW_VGIC implementation instead of the standard one ? > > I add some features which is ported from KVM, NEW_VGIC is refereed to > KVM，so it easily integrate Ok. So why does this needs to be done with CONFIG_QEMU? Can't you use defconfig + select the NEW_VGIC by hand? Cheers, -- Julien Grall