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=-2.5 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,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 B943DC433DF for ; Thu, 21 May 2020 14:18:34 +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 774D120721 for ; Thu, 21 May 2020 14:18:34 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="BGhZikAY"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="hk9BuL52" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 774D120721 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org 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-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=X80jyDHlnKREooIQb6JvTHjlmdkIbtWG6AoR+oB8u4M=; b=BGhZikAYxqdQPu rxO7AFTPEPbIjif+ODmxlBMGB6B3760UyuqNJcW8cwPjh9Qq9ajxeFygdFnNV5S+KnJu2SfjCjccD QFxlRHlVz1KhfQ2t7BpDLvtaz/0MpBcDZp8oi3Mpfa2dW5zYz9ngDcSsppKimfdcqUMwo+HeZ+HJT Aeft/crk3JEch9Dtr9zRjLdgYcv7TgWyK+xmH3SSbB8q9fLML5KvMEtiq2sRPKnG7nVhGz6JfmlsA ploFeT1xLKFDkUlCUHVJo+5TbECgvjQK1yeiux+jyK2ztOQSGs6Mv0NNFfxv/AmKZQRfA5nIgmk8q /N46CUuH7KR9Tlnf5SGA==; 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 1jbm1o-0002lp-SQ; Thu, 21 May 2020 14:18:32 +0000 Received: from mail.kernel.org ([198.145.29.99]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1jbm0w-00022V-4x for linux-arm-kernel@lists.infradead.org; Thu, 21 May 2020 14:17:39 +0000 Received: from willie-the-truck (236.31.169.217.in-addr.arpa [217.169.31.236]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 6A49A20721; Thu, 21 May 2020 14:17:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1590070657; bh=5MRn3H5sZAZmyAJ7ms4hcDmOF+0kJdAcWrKPmQYOlR0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=hk9BuL52Yd+s1F9PZBKDi1fOj/hBpMdLhnVRrqDGLJHOMJUJ4cx1CtTqJjqji14lA se04HPgcV50e35bBPs6oZN10HauSB5SCTxRi9BAEpAi6JOpzQotWs8pN2P23RLU3T9 jRk0X8KLGknqWO03sXQQpGyIbmzpKdaGmJhlarzo= Date: Thu, 21 May 2020 15:17:31 +0100 From: Will Deacon To: Jean-Philippe Brucker Subject: Re: [PATCH v7 13/24] iommu/arm-smmu-v3: Enable broadcast TLB maintenance Message-ID: <20200521141730.GJ6608@willie-the-truck> References: <20200519175502.2504091-1-jean-philippe@linaro.org> <20200519175502.2504091-14-jean-philippe@linaro.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200519175502.2504091-14-jean-philippe@linaro.org> User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200521_071738_219222_C46F9227 X-CRM114-Status: GOOD ( 10.85 ) 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: devicetree@vger.kernel.org, kevin.tian@intel.com, jacob.jun.pan@linux.intel.com, maz@kernel.org, jgg@ziepe.ca, linux-pci@vger.kernel.org, joro@8bytes.org, Jonathan.Cameron@huawei.com, fenghua.yu@intel.com, hch@infradead.org, linux-mm@kvack.org, iommu@lists.linux-foundation.org, zhangfei.gao@linaro.org, catalin.marinas@arm.com, felix.kuehling@amd.com, xuzaibo@huawei.com, robin.murphy@arm.com, christian.koenig@amd.com, linux-arm-kernel@lists.infradead.org, baolu.lu@linux.intel.com 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 [+Marc] On Tue, May 19, 2020 at 07:54:51PM +0200, Jean-Philippe Brucker wrote: > The SMMUv3 can handle invalidation targeted at TLB entries with shared > ASIDs. If the implementation supports broadcast TLB maintenance, enable it > and keep track of it in a feature bit. The SMMU will then be affected by > inner-shareable TLB invalidations from other agents. > > A major side-effect of this change is that stage-2 translation contexts > are now affected by all invalidations by VMID. VMIDs are all shared and > the only ways to prevent over-invalidation, since the stage-2 page tables > are not shared between CPU and SMMU, are to either disable BTM or allocate > different VMIDs. This patch does not address the problem. This sounds like a potential performance issue, particularly as we expose stage-2 contexts via VFIO directly. Maybe we could reserve some portion of VMID space for the SMMU? Marc, what do you reckon? Will _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel