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=-9.6 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,NICE_REPLY_A,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,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 B11B4C4363D for ; Wed, 23 Sep 2020 06:32:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5DFA521D43 for ; Wed, 23 Sep 2020 06:32:56 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="ZCQbjFVv" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726710AbgIWGcz (ORCPT ); Wed, 23 Sep 2020 02:32:55 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:36674 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726179AbgIWGcz (ORCPT ); Wed, 23 Sep 2020 02:32:55 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1600842774; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=KNYXvNzELYq54wu7W3RCN3nmnlEFmyGx388a6Bc/HMA=; b=ZCQbjFVvQLI5Rjr75v+L+cJbGMNprnFc6Kmv9o9n1NYwxPe+Kp39tuXEJCp1cRJFiCR4jf 6Bm6gPmhnzXH5j7fvYhk8cOzDCugTSyjAaHchLJlMlCwUXYTMPeUUG+gm7UTUFdJ4iMzYU vQbBr1hk2qSyIu+S4DowishcqvaZtMg= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-447-OsAsDADyNyWgWEaMZInWBA-1; Wed, 23 Sep 2020 02:32:49 -0400 X-MC-Unique: OsAsDADyNyWgWEaMZInWBA-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id BD408807100; Wed, 23 Sep 2020 06:32:47 +0000 (UTC) Received: from [10.36.112.29] (ovpn-112-29.ams2.redhat.com [10.36.112.29]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 4694B78822; Wed, 23 Sep 2020 06:32:45 +0000 (UTC) Subject: Re: [PATCH v2] iommu/arm: Add module parameter to set msi iova address To: Will Deacon , Vennila Megavannan Cc: jean-philippe@linaro.org, joro@8bytes.org, linux-kernel@vger.kernel.org, shameerali.kolothum.thodi@huawei.com, iommu@lists.linux-foundation.org, tyhicks@linux.microsoft.com, srinath.mannam@broadcom.com, bcm-kernel-feedback-list@broadcom.com, robin.murphy@arm.com, linux-arm-kernel@lists.infradead.org References: <20200914181307.117792-1-vemegava@linux.microsoft.com> <20200921204545.GA3811@willie-the-truck> From: Auger Eric Message-ID: <85f7d1ae-71a9-4e95-8a30-03cc699d4794@redhat.com> Date: Wed, 23 Sep 2020 08:32:43 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.5.0 MIME-Version: 1.0 In-Reply-To: <20200921204545.GA3811@willie-the-truck> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Will, On 9/21/20 10:45 PM, Will Deacon wrote: > On Mon, Sep 14, 2020 at 11:13:07AM -0700, Vennila Megavannan wrote: >> From: Srinath Mannam >> >> Add provision to change default value of MSI IOVA base to platform's >> suitable IOVA using module parameter. The present hardcoded MSI IOVA base >> may not be the accessible IOVA ranges of platform. >> >> If any platform has the limitaion to access default MSI IOVA, then it can >> be changed using "arm-smmu.msi_iova_base=0xa0000000" command line argument. >> >> Signed-off-by: Srinath Mannam >> Co-developed-by: Vennila Megavannan >> Signed-off-by: Vennila Megavannan >> --- >> drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 5 ++++- >> drivers/iommu/arm/arm-smmu/arm-smmu.c | 5 ++++- >> 2 files changed, 8 insertions(+), 2 deletions(-) > > This feels pretty fragile. Wouldn't it be better to realise that there's > a region conflict with iommu_dma_get_resv_regions() and move the MSI window > accordingly at runtime? Since cd2c9fcf5c66 ("iommu/dma: Move PCI window region reservation back into dma specific path"), the PCI host bridge windows are not exposed by iommu_dma_get_resv_regions() anymore. If I understood correctly, what is attempted here is to avoid the collision between such PCI host bridge window and the MSI IOVA range. Thanks Eric > > Will > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel >