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=-5.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,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 8E5A1C7619F for ; Mon, 17 Feb 2020 09:18:31 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 5AE502070B for ; Mon, 17 Feb 2020 09:18:31 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="upLS5S8x" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5AE502070B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=huawei.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender:Content-Type: Content-Transfer-Encoding:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date:Message-ID:From: References:To:Subject:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=OVEf1PkXYrM5HLGyWvKTit5wJjDIw0Y6CJVoZKd3eFQ=; b=upLS5S8xtuFUAxwXwCDZSUe1D HN8Y2eom4XpeRZ3kxyO9Ivfkg0wonwP9fUKWYKH5n/zcgJCVhrLsOZVnpdeFqsH+arZuJC9EiVuvx OuOBPT7O0aEGUY8/zT4S62AcTrYjZVcdPVbGBiwgxnLcrhsYl9D5CmNE8pUgBSEQxuxlG28VFnQ1+ HAHMhN9yq8Qe4UYYsBa2CspgXQJqKY3YkQeFKe20ba3O54RLe+gTWI1VZL8Wb1ofIQE8baIUd9DSs TphlPbzMVt+MOGlMbe5Q+zHgFhlHzgBucyne620JiIpfmxiyaHHRMcexPcDH7EP/qRUEATgyWirsC UBXWmdIxQ==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1j3cXp-0001bI-MA; Mon, 17 Feb 2020 09:18:25 +0000 Received: from szxga04-in.huawei.com ([45.249.212.190] helo=huawei.com) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1j3cXn-0001av-63 for linux-arm-kernel@lists.infradead.org; Mon, 17 Feb 2020 09:18:24 +0000 Received: from DGGEMS413-HUB.china.huawei.com (unknown [172.30.72.59]) by Forcepoint Email with ESMTP id 8B5BF7C85E4B5CC973CB; Mon, 17 Feb 2020 17:18:18 +0800 (CST) Received: from [127.0.0.1] (10.173.222.27) by DGGEMS413-HUB.china.huawei.com (10.3.19.213) with Microsoft SMTP Server id 14.3.439.0; Mon, 17 Feb 2020 17:18:11 +0800 Subject: Re: [PATCH v4 02/20] irqchip/gic-v3: Use SGIs without active state if offered To: Marc Zyngier , , , , References: <20200214145736.18550-1-maz@kernel.org> <20200214145736.18550-3-maz@kernel.org> From: Zenghui Yu Message-ID: Date: Mon, 17 Feb 2020 17:18:10 +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: <20200214145736.18550-3-maz@kernel.org> Content-Language: en-US X-Originating-IP: [10.173.222.27] X-CFilter-Loop: Reflected X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200217_011823_396320_773D6146 X-CRM114-Status: GOOD ( 12.11 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Lorenzo Pieralisi , Jason Cooper , Suzuki K Poulose , Eric Auger , Robert Richter , James Morse , Thomas Gleixner , Julien Thierry Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Marc, On 2020/2/14 22:57, Marc Zyngier wrote: > To allow the direct injection of SGIs into a guest, the GICv4.1 > architecture has to sacrifice the Active state so that SGIs look > a lot like LPIs (they are injected by the same mechanism). > > In order not to break existing software, the architecture gives > offers guests OSs the choice: SGIs with or without an active > state. It is the hypervisors duty to honor the guest's choice. > > For this, the architecture offers a discovery bit indicating whether > the GIC supports GICv4.1 SGIs (GICD_TYPER2.nASSGIcap), and another > bit indicating whether the guest wants Active-less SGIs or not > (controlled by GICD_CTLR.nASSGIreq). > > A hypervisor not supporting GICv4.1 SGIs would leave nASSGIcap > clear, and a guest not knowing about GICv4.1 SGIs (or definitely > wanting an Active state) would leave nASSGIreq clear (both being > thankfully backward compatible with oler revisions of the GIC). older? > > Since Linux is perfectly happy without an active state on SGIs, > inform the hypervisor that we'll use that if offered. > > Signed-off-by: Marc Zyngier Per the description of these two bits in the commit message, Reviewed-by: Zenghui Yu Thanks _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel