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 713F7C4332B for ; Fri, 20 Mar 2020 11:36:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 535A120754 for ; Fri, 20 Mar 2020 11:36:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727113AbgCTLgB (ORCPT ); Fri, 20 Mar 2020 07:36:01 -0400 Received: from szxga07-in.huawei.com ([45.249.212.35]:48830 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726814AbgCTLgA (ORCPT ); Fri, 20 Mar 2020 07:36:00 -0400 Received: from DGGEMS411-HUB.china.huawei.com (unknown [172.30.72.58]) by Forcepoint Email with ESMTP id 83C19E8B7FC2A4E3E951; Fri, 20 Mar 2020 19:35:48 +0800 (CST) Received: from [127.0.0.1] (10.173.222.27) by DGGEMS411-HUB.china.huawei.com (10.3.19.211) with Microsoft SMTP Server id 14.3.487.0; Fri, 20 Mar 2020 19:35:41 +0800 Subject: Re: [PATCH v5 23/23] KVM: arm64: GICv4.1: Expose HW-based SGIs in debugfs To: Marc Zyngier CC: Auger Eric , , , , , Lorenzo Pieralisi , Jason Cooper , "Robert Richter" , Thomas Gleixner , "James Morse" , Julien Thierry , Suzuki K Poulose References: <20200304203330.4967-1-maz@kernel.org> <20200304203330.4967-24-maz@kernel.org> <4cb4c3d4-7b02-bb77-cd7a-c185346b6a2f@redhat.com> <45c282bddd43420024633943c1befac3@kernel.org> From: Zenghui Yu Message-ID: <8d7fdb7f-7a21-da22-52a2-51ee8ac9393f@huawei.com> Date: Fri, 20 Mar 2020 19:35:39 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.2.0 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: [10.173.222.27] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Marc, On 2020/3/20 17:09, Marc Zyngier wrote: > Hi Zenghui, > > On 2020-03-20 04:38, Zenghui Yu wrote: >> Hi Marc, >> >> On 2020/3/19 23:21, Marc Zyngier wrote: >>> With GICv4.1, you can introspect the HW state for SGIs. You can also >>> look at the vLPI state by peeking at the virtual pending table, but >>> you'd need to unmap the VPE first, >> >> Out of curiosity, could you please point me to the "unmap the VPE" >> requirement in the v4.1 spec? I'd like to have a look. > > Sure. See IHI0069F, 5.3.19 (VMAPP GICv4.1), "Caching of virtual LPI data > structures", and the bit that says: > > "A VMAPP with {V,Alloc}=={0,1} cleans and invalidates any caching of the > Virtual Pending Table and Virtual Configuration Table associated with the > vPEID held in the GIC" > > which is what was crucially missing from the GICv4.0 spec (it doesn't say > when the GIC is done writing to memory). OK. Thanks for the pointer! > > Side note: it'd be good to know what the rules are for your own GICv4 > implementations, so that we can at least make sure the current code is > safe. As far as I know, there will be some clean and invalidate operations when v4.0 VPENDBASER.Valid gets programmed. But not sure about behaviors on VMAPP (unmap), it may be a totally v4.1 stuff. I'll have a talk with our SOC team. But how can the current code be unsafe? Is anywhere in the current code will peek/poke the vpt (whilst GIC continues writing things into it)? Thanks, Zenghui