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=-0.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED 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 16612C3A5A9 for ; Mon, 4 May 2020 15:09:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E6DE4206D7 for ; Mon, 4 May 2020 15:09:38 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=linaro.org header.i=@linaro.org header.b="QNbwqk4D" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727784AbgEDPJi (ORCPT ); Mon, 4 May 2020 11:09:38 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58372 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1726509AbgEDPJi (ORCPT ); Mon, 4 May 2020 11:09:38 -0400 Received: from mail-wr1-x443.google.com (mail-wr1-x443.google.com [IPv6:2a00:1450:4864:20::443]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B7992C061A0F for ; Mon, 4 May 2020 08:09:37 -0700 (PDT) Received: by mail-wr1-x443.google.com with SMTP id e16so16276080wra.7 for ; Mon, 04 May 2020 08:09:37 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=ymxZ/AHKc54MsFnFnjiy487/cd2cO0lIerw33LQLJwg=; b=QNbwqk4D1MPIi3P7kInzB1wd9Nwnz4c2VQo9LuhJOdRLdMrPzNMgpvKqTLZMK1uPi+ P2pe+v2OCrrPEexPYdYwl192CIA5G6xYliglrRqqtdaIAR+usOr6a/3cJuAgWCIrlSe1 OdskZIteDeuDIgetVe9zuT/oEpmFwh99LEyLr+Zq8PUuCUTWaKKGaTmfFvbQ2/+u5d3b tftW1WWsJsddoYK8llhhdNTtirX5vLRtjEeFAIEdNjNGfsIxaS1xLDMsskU7xZaWG3ng uBZkgyMKL71WDmOBvkjPrl5x7RLtobyGsphgAfOHe28m7ebcN/qz+Xrs9em6Jezxz6jQ 4Kkg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=ymxZ/AHKc54MsFnFnjiy487/cd2cO0lIerw33LQLJwg=; b=iMOVpHJGgJgsOkQi8h+89Z/V1Sl4BhDVQXZFE3CbJmz650YZqhw55u3EEBUQZkJwuC MaARa04o1q0B49gbAsYyHvRS5xD8tpggwq3xSaTUSdgQla23YAb7ij93Bune226J52PX h6smKPWHm4G2IfMxGt1RioWCDNpROOkO9KGkH8CU8x71jmNaTqqHSnpj8hbYOrZMPXta fS13O3nlcpku1rmJM4G2le57Dm2YQQGl06b/x9YLBu7UCjGAmEg59WToT+rvk5ETcd5O DCnw/K1sGSj6vznvSNejdTHuoUwRJbsB7WT33HuM00gdMIvnh95LPe8HIHajcRV5uUxV rONw== X-Gm-Message-State: AGi0PuabHU8uDhH+TyTH3gs0xvdxCsfA4NK6U8LPRwQua7XC7saywTPo PvbQ4DeESxsGHdk0cEIG3b+Zmw== X-Google-Smtp-Source: APiQypIDrGUvuteScMrJ9fLWEogSG6ijt2/PYwyFrJ0NSjLGFvyO34VY4LnIIaZoFl/ctKT+r9PVxQ== X-Received: by 2002:adf:ee86:: with SMTP id b6mr56993wro.419.1588604976411; Mon, 04 May 2020 08:09:36 -0700 (PDT) Received: from myrica ([2001:171b:226e:c200:c43b:ef78:d083:b355]) by smtp.gmail.com with ESMTPSA id w83sm14711145wmb.37.2020.05.04.08.09.35 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 04 May 2020 08:09:35 -0700 (PDT) Date: Mon, 4 May 2020 17:09:26 +0200 From: Jean-Philippe Brucker To: Jacob Pan Cc: iommu@lists.linux-foundation.org, devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-pci@vger.kernel.org, linux-mm@kvack.org, joro@8bytes.org, catalin.marinas@arm.com, will@kernel.org, robin.murphy@arm.com, kevin.tian@intel.com, baolu.lu@linux.intel.com, Jonathan.Cameron@huawei.com, christian.koenig@amd.com, felix.kuehling@amd.com, zhangfei.gao@linaro.org, jgg@ziepe.ca, xuzaibo@huawei.com, fenghua.yu@intel.com, hch@infradead.org, "Liu, Yi L" Subject: Re: [PATCH v6 00/25] iommu: Shared Virtual Addressing for SMMUv3 Message-ID: <20200504150926.GA176594@myrica> References: <20200430143424.2787566-1-jean-philippe@linaro.org> <20200430141816.595b758f@jacob-builder> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200430141816.595b758f@jacob-builder> Sender: devicetree-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org On Thu, Apr 30, 2020 at 02:18:16PM -0700, Jacob Pan wrote: > On Thu, 30 Apr 2020 16:33:59 +0200 > Jean-Philippe Brucker wrote: > > > Shared Virtual Addressing (SVA) allows to share process page tables > > with devices using the IOMMU, PASIDs and I/O page faults. Add SVA > > support to the Arm SMMUv3 driver. > > > > Since v5 [1]: > > > > * Added patches 1-3. Patch 1 adds a PASID field to mm_struct as > > discussed in [1] and [2]. This is also needed for Intel ENQCMD. > > Patch 2 adds refcounts to IOASID and patch 3 adds a couple of helpers > > to allocate the PASID. > > > > * Dropped most of iommu-sva.c. After getting rid of io_mm following > > review of v5, there wasn't enough generic code left to justify the > > indirect branch overhead of io_mm_ops in the MMU notifiers. I ended > > up with more glue than useful code, and couldn't find an easy way to > > deal with domains in the SMMU driver (we keep PASID tables per domain, > > while x86 keeps them per device). The direct approach in patch 17 is > > nicer and a little easier to read. The SMMU driver only gained 160 > > lines, while iommu-sva lost 470 lines. > > > > As a result I dropped the MMU notifier patch. > > > > Jacob, one upside of this rework is that we now free ioasids in > > blocking context, which might help with your addition of notifiers > > to ioasid.c > > > Thanks for the note. It does make notifier much easier, plus the > refcount can alleviate the constraint on ordering. > > I guess we don't share mmu notifier code for now :) I think it's more efficient for each IOMMU driver to at least implement their own invalidate_range() callback and avoid indirect branches. For the rest I couldn't find a lot of code to share, most of it is writing PASID tables and invalidating. We can revisit later, as long as we agree on the bind() API the implementations should be similar enough. Thanks, Jean