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=-2.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,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 B1BF8C19759 for ; Thu, 1 Aug 2019 10:51:42 +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 836BE214DA for ; Thu, 1 Aug 2019 10:51:42 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="Jsvxsr7q" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 836BE214DA Authentication-Results: mail.kernel.org; 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Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1ht8gQ-0003Ya-13; Thu, 01 Aug 2019 10:51:42 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1ht8gN-0003Y7-4O for linux-arm-kernel@lists.infradead.org; Thu, 01 Aug 2019 10:51:40 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id BB2661570; Thu, 1 Aug 2019 03:51:36 -0700 (PDT) Received: from [10.1.197.61] (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 5FC803F575; Thu, 1 Aug 2019 03:51:35 -0700 (PDT) Subject: Re: [PATCH] arm64: Relax ICC_PMR_EL1 accesses when ICC_CTLR_EL1.PMHE is clear To: Will Deacon , Julien Thierry References: <1564496445-53486-1-git-send-email-julien.thierry.kdev@gmail.com> <20190801104119.quzlr5artm4s2sbc@willie-the-truck> From: Marc Zyngier Openpgp: preference=signencrypt Autocrypt: addr=marc.zyngier@arm.com; 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Linux aarch64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20190801104119.quzlr5artm4s2sbc@willie-the-truck> Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190801_035139_264273_D34989F5 X-CRM114-Status: GOOD ( 12.66 ) 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: Suzuki K Poulose , Marc Zyngier , guohanjun@huawei.com, James Morse , huawei.libin@huawei.com, Catalin Marinas , liwei391@huawei.com, linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 01/08/2019 11:41, Will Deacon wrote: > On Tue, Jul 30, 2019 at 03:20:45PM +0100, Julien Thierry wrote: >> From: Marc Zyngier >> >> The GICv3 architecture specification is incredibly misleading when it >> comes to PMR and the requirement for a DSB. It turns out that this DSB >> is only required if the CPU interface sends an Upstream Control >> message to the redistributor in order to update the RD's view of PMR. >> >> This message is only sent when ICC_CTLR_EL1.PMHE is set, which isn't >> the case in Linux. It can still be set from EL3, so some special care >> is required. But the upshot is that in the (hopefuly large) majority >> of the cases, we can drop the DSB altogether. >> >> This requires yet another capability and some more runtime patching. > > Hmm, does this actually require explicit runtime patching, or can we make > things a bit simpler with a static key? The hunk in entry.S is the blocker, AFAICS. Do we have a way to express static keys in asm? M. -- Jazz is not dead. It just smells funny... _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel