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=-7.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,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 A3F57C4361B for ; Wed, 9 Dec 2020 20:07:51 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 13D4723A02 for ; Wed, 9 Dec 2020 20:07:50 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 13D4723A02 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 2001A8D0053; Wed, 9 Dec 2020 15:07:50 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 1AFAA8D0031; Wed, 9 Dec 2020 15:07:50 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 0C5408D0053; Wed, 9 Dec 2020 15:07:50 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0203.hostedemail.com [216.40.44.203]) by kanga.kvack.org (Postfix) with ESMTP id EA38B8D0031 for ; Wed, 9 Dec 2020 15:07:49 -0500 (EST) Received: from smtpin05.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id AFE3D181AEF1D for ; Wed, 9 Dec 2020 20:07:49 +0000 (UTC) X-FDA: 77574829458.05.meat56_2600759273f2 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin05.hostedemail.com (Postfix) with ESMTP id 991391802E8A5 for ; Wed, 9 Dec 2020 20:07:49 +0000 (UTC) X-HE-Tag: meat56_2600759273f2 X-Filterd-Recvd-Size: 3185 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf48.hostedemail.com (Postfix) with ESMTP for ; Wed, 9 Dec 2020 20:07:49 +0000 (UTC) Date: Wed, 9 Dec 2020 20:07:42 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1607544468; bh=RwtPuIYol40kyDSA4Jk5Z51qfhMMaedTf5Q+9030Dtg=; h=From:To:Cc:Subject:References:In-Reply-To:From; b=WjTRYZErNqmS7HSgHfZJvcGSudj6QQ/BoaTG0mpwRSde3DtGgpDV/4KNjtqyEp4N+ 2SFusGgwv6iZgTJCRLikjacas6bF+LBJeIO0GTHgZ4EvroAXOfs4Of64brnCCAiEL/ NS4gCLeuTP+i1+ZCKXLR4nYVtPRM5cuymwlc4I/UEatT/px6/DX1ax9KzE7bxb22m0 D2BA2bOs49gRHUGRFhScPxtDW0b+fk74I1a1oBmW5xKntFJsqo1uuXPCsQPbHQGka9 x7PsjSp1nxXDMK0hxlRclxlkbHpcjvFPaN5DcSyltP56QCuHoa53NMckH935C/JDn1 FhQiUpC9ttZAw== From: Will Deacon To: Krishna Reddy Cc: Jean-Philippe Brucker , "fenghua.yu@intel.com" , Suzuki K Poulose , "catalin.marinas@arm.com" , "linux-mm@kvack.org" , "iommu@lists.linux-foundation.org" , "zhangfei.gao@linaro.org" , "robin.murphy@arm.com" , "linux-arm-kernel@lists.infradead.org" , Sachin Nikam , Pritesh Raithatha , Vikram Sethi , Jason Gunthorpe , Alistair Popple , Yu-Huan Hsu , Shameerali Kolothum Thodi Subject: Re: [PATCH v10 10/13] iommu/arm-smmu-v3: Check for SVA features Message-ID: <20201209200741.GA8992@willie-the-truck> References: <20200918101852.582559-1-jean-philippe@linaro.org> <20200918101852.582559-11-jean-philippe@linaro.org> <753bcd76c21c4ea98ef1d4e492db01f4@huawei.com> <20200924101340.GC170808@myrica> <47b244b99f284790b82b2c0a968ba830@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, Dec 09, 2020 at 07:49:09PM +0000, Krishna Reddy wrote: > > > Why is BTM mandated for SVA? I couldn't find this requirement in > > > SMMU spec (Sorry if I missed it or this got discussed earlier). But > > > if performance is the > > only concern here, > > > is it better just to allow it with a warning rather than limiting > > > SMMUs without > > BTM? > > > > It's a performance concern and requires to support multiple > > configurations, but the spec allows it. Are there SMMUs without BTM > > that need it? > > The Tegra Next Generation SOC uses arm-smmu-v3, but it doesn't have support for BTM. > Do you have plan to get your earlier patch to handle invalidate > notifications into upstream sometime soon? Is that a limitation of the SMMU implementation, the interconnect or the integration? Will