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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4963DC6FA99 for ; Fri, 10 Mar 2023 15:52:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230314AbjCJPwA convert rfc822-to-8bit (ORCPT ); Fri, 10 Mar 2023 10:52:00 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58544 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231429AbjCJPvj (ORCPT ); Fri, 10 Mar 2023 10:51:39 -0500 Received: from frasgout.his.huawei.com (frasgout.his.huawei.com [185.176.79.56]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id ADEBEEAB99 for ; Fri, 10 Mar 2023 07:44:06 -0800 (PST) Received: from lhrpeml100003.china.huawei.com (unknown [172.18.147.206]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4PY9Lh6fFLz6J6rP; Fri, 10 Mar 2023 23:43:24 +0800 (CST) Received: from lhrpeml500005.china.huawei.com (7.191.163.240) by lhrpeml100003.china.huawei.com (7.191.160.210) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.21; Fri, 10 Mar 2023 15:44:03 +0000 Received: from lhrpeml500005.china.huawei.com ([7.191.163.240]) by lhrpeml500005.china.huawei.com ([7.191.163.240]) with mapi id 15.01.2507.021; Fri, 10 Mar 2023 15:44:03 +0000 From: Shameerali Kolothum Thodi To: Jason Gunthorpe , Eric Auger CC: Nicolin Chen , "robin.murphy@arm.com" , "will@kernel.org" , "kevin.tian@intel.com" , "baolu.lu@linux.intel.com" , "joro@8bytes.org" , "jean-philippe@linaro.org" , "linux-arm-kernel@lists.infradead.org" , "iommu@lists.linux.dev" , "linux-kernel@vger.kernel.org" Subject: RE: [PATCH v1 01/14] iommu: Add iommu_get_unmanaged_domain helper Thread-Topic: [PATCH v1 01/14] iommu: Add iommu_get_unmanaged_domain helper Thread-Index: AQHZUnWRmBwtrmleCk69JH8tQLhaPq7zzWuAgABY2gCAAAIMsA== Date: Fri, 10 Mar 2023 15:44:02 +0000 Message-ID: References: <9b1077601cace998533129327f5e7ad946752d29.1678348754.git.nicolinc@nvidia.com> In-Reply-To: Accept-Language: en-GB, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.202.227.178] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > -----Original Message----- > From: Jason Gunthorpe [mailto:jgg@nvidia.com] > Sent: 10 March 2023 15:33 > To: Eric Auger > Cc: Nicolin Chen ; robin.murphy@arm.com; > will@kernel.org; kevin.tian@intel.com; baolu.lu@linux.intel.com; > joro@8bytes.org; Shameerali Kolothum Thodi > ; jean-philippe@linaro.org; > linux-arm-kernel@lists.infradead.org; iommu@lists.linux.dev; > linux-kernel@vger.kernel.org > Subject: Re: [PATCH v1 01/14] iommu: Add iommu_get_unmanaged_domain > helper > > On Fri, Mar 10, 2023 at 11:14:59AM +0100, Eric Auger wrote: > > Hi Nicolin, > > > > On 3/9/23 11:53, Nicolin Chen wrote: > > > The nature of ITS virtualization on ARM is done via hypercalls, so > > > kernel handles all IOVA mappings for the MSI doorbell in > > > iommu_dma_prepare_msi() and iommu_dma_compose_msi_msg(). The > current > > > virtualization solution with a 2-stage nested translation setup is > > > to do 1:1 IOVA mappings at stage-1 > > Note that if we still intend to use that trick there is a known issue > > at kernel side that needs to be fixed. > > > > ARM DEN 0049E.b IORT specification mandates that when RMRs are > > present, the OS must preserve PCIe configuration performed by the boot > > FW. > > This limitation doesn't seem necessary for this MSI stuff? > > What is it for? That is to make sure the Stream Ids specified in RMR are still valid and is not being reassigned by OS. The kernel checks for this(iort_rmr_has_dev()), https://lore.kernel.org/linux-arm-kernel/20220420164836.1181-5-shameerali.kolothum.thodi@huawei.com/ Thanks, Shameer